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Rift Valley fever phlebovirus (RVFV) is a mosquito-transmitted phlebovirus (Family: Phenuiviridae, Order: Bunyavirales) causing severe neonatal mortality and abortion primarily in domestic ruminants. The susceptibility of young domestic swine to RVFV and this species’ role in geographic expansion and establishment of viral endemicity is unclear. Six commercially bred Landrace-cross piglets were inoculated subcutaneously with 105 plaque-forming units of RVFV ZH501 strain and two piglets received a sham inoculum. All animals were monitored for clinical signs, viremia, viral shedding, and antibody response for 14 days. Piglets did not develop evidence of clinical disease, become febrile, or experience decreased weight gain during the study period. A brief lymphopenia followed by progressive lymphocytosis was observed following inoculation in all piglets. Four piglets developed a brief viremia for 2 days post-inoculation and three of these had detectable virus in oronasal secretions three days post-inoculation. Primary inoculated piglets seroconverted and those that developed detectable viremias had the highest titers assessed by serum neutralization (1:64–1:256). Two viremic piglets had a lymphoplasmacytic encephalitis with glial nodules; RVFV was not detected by immunohistochemistry in these sections. While young piglets do not appear to readily develop clinical disease following RVFV infection, results suggest swine could be subclinically infected with RVFV.

Epidemic vector-borne viral infections pose a serious threat to public health worldwide. There is currently no specific preventive treatment for most of them. One of the promising solutions for combating viral fevers is development of vector vaccines, including MVA-based vaccines, which have virtually no adverse side effects. The safety of the MVA strain and absent reactogenicity of recombinant MVA vaccines have been supported by many clinical trials.The article focuses on test results for similar preventive products against viral fevers: Crimean-Congo hemorrhagic fever, Rift Valley fever, yellow fever, Chikungunya and Zika fevers.Their immunogenicity was evaluated on immunocompetent and immunocompromised white mice; their protective efficacy was assessed on immunocompromised white mice deficient in IFN-α/β receptors, that are used for experimental modeling of the infection. Nearly all the new recombinant vaccines expressing immunodominant antigens demonstrated 100% protective efficacy. It has been found that although the vaccine expressing Zika virus structural proteins induced antibodies against specific viral glycoproteins, it can be associated with high risks when used for prevention of Zika fever in individuals who had dengue fever in the past, due to the phenomenon known as antibody-dependent enhancement of infection, which can occur in diseases caused by antigenically related flaviruses. For this reason, the vaccine expressing non-structural protein 1 (NS1) was developed for vaccination against Zika fever.The yellow fever vaccine developed on the MVA platform had immunogenicity similar to that of the commercial 17D vaccine, outperforming the latter in safety.

Aims: Livestock is the largest subsector of the Sudanese domestic economy and is a growing contributor to exports. Rift Valley fever (RVF) is an economically important arthropod-borne virus disease in Africa, primarily affecting sheep, goats, and cattle. RVF causes paramount loss in sheep industry in Sudan. The objective of this study was to detect RVF in sheep. Methodology: Five hundred and fifty-six sheep blood Serum from inoculated animals was collected from six study areas in the Gezira (Sudan)was evaluated for the presence of neutralizing antibodies using the diagnostic kit (ID. Vet.) for detecting antibodies directly against the RVFV nucleoprotein (NP) in serum and Reverse transcription (RT)-Polymerase Chain Reaction (PCR) protocol was used as standard test to diagnose and confirm RVFV among studied animals. Results: The ELISA test indicated that the highest Seroprevalence was found at Shikaira (38%), while samples from Albasabeir, Wad alnaem and Umalqura tested positive for antibodies against RVFV by 15%, 10% and 9% respectively. The lowest Seroprevalence found at Wad anor and Shabona (5% and 2%). The overall seroprevalence was 14.2% in the study sites, there is no significant difference among the six study sites with respect to seroprevalence. The Rt-PCR provided more sensitive and specific detection of RVFV in serum samples (sensitivity= 95% specificity = 80%). Conclusion: The results from this study showed the presence of anti-RVFV antibodies in all study sites, suggesting that RVFV is actively circulating among sheep in Gezira state. The high seroprevalence of RVFV infection in Gezira state indicates its endemicity. Test validation using ROC analysis was able to distinguished between ELISA (actual class) and the PCR (predicted class) and the AUC = 0.79 which indicate that the PCR is gold standard test. Thus Rt-PCR used in the present study is reliable to detect precisely the M segment of RVFV and it is valuable for Wide area survey, among both sheep and Aedes spp. Targeting the prevailing genotypes of RVF-M segment, especially at high-risk areas and as a confirmatory test that should be considered by reference laboratories in the region.

Introduction. Rift Valley fever (RVF) is a mosquito-borne viral zoonosis. The Uganda Ministry of Health received alerts of suspected viral haemorrhagic fever in humans from Kiruhura, Buikwe, Kiboga, and Mityana districts. Laboratory results from Uganda Virus Research Institute indicated that human cases were positive for Rift Valley fever virus (RVFV) by polymerase chain reaction. We investigated to determine the scope of outbreaks, identify exposure factors, and recommend evidence-based control and prevention measures. Methods. A suspected case was defined as a person with acute fever onset, negative malaria test result, and at least two of the following symptoms: headache, muscle or joint pain, bleeding, and any gastroenteritis symptom (nausea, vomiting, abdominal pain, diarrhoea) in a resident of Kiruhura, Buikwe, Mityana, and Kiboga districts from 1st October 2017 to 30th January 2018. A confirmed case was defined as a suspected case with laboratory confirmation by either detection of RVF nucleic acid by reverse-transcriptase polymerase chain reaction (RT-PCR) or demonstration of serum IgM or IgG antibodies by ELISA. Community case finding was conducted in all affected districts. In-depth interviews were conducted with human cases that were infected with RVF who included herdsmen and slaughterers/meat handlers to identify exposure factors for RVF infection. A total of 24 human and 362 animal blood samples were tested. Animal blood samples were purposively collected from farms that had reported stormy abortions in livestock and unexplained death of animals after a short illness (107 cattle, 83 goats, and 43 sheep). Convenient sampling for the wildlife (10 zebras, 1 topi, and 1 impala) was conducted to investigate infection in animals from Kiruhura, Buikwe, Mityana, and Kiboga districts. Human blood was tested for anti-RVFV IgM and IgG and animal blood for anti-RVFV IgG. Environmental assessments were conducted during the outbreaks in all the affected districts. Results. Sporadic RVF outbreaks occurred from mid-October 2017 to mid-January 2018 affecting humans, domestic animals, and wildlife. Human cases were reported from Kiruhura, Buikwe, Kiboga, and Mityana districts. Of the 24 human blood samples tested, anti-RVFV IgG was detected in 7 (29%) human samples; 1 human sample had detectable IgM only, and 6 had both IgM and IgG. Three of the seven confirmed human cases died among humans. Results from testing animal blood samples obtained from Kiruhura district indicated that 44% (64/146) cattle, 46% (35/76) goats, and 45% (9/20) sheep tested positive for RVF. Among wildlife, (1/10) zebras, (1/1) topi, and (1/1) impala tested positive for RVFV by serological tests. One blood sample from sheep in Kiboga district tested RVFV positive. All the human cases were exposed through contact or consumption of meat from infected animals. Conclusion. RVF outbreaks occurred in humans and animals in Kiruhura, Buikwe, Mityana, and Kiboga districts. Human cases were potentially infected through contact with infected animals and their products.

Background Fourteen-years after the last Rift Valley fever (RVF) virus (RVFV) outbreak, Somalia still suffers from preventable transboundary diseases. The tradition of unheated milk consumption and handling of aborted materials poses a public health risk for zoonotic diseases. Limited data are available on RVF and Brucella spp. in Somali people and their animals. Hence, this study has evaluated the occurrence of RVFV and Brucella spp. antibodies in cattle, goats and sheep sera from Afgoye and Jowhar districts of Somalia. Methods Serum samples from 609 ruminants (201 cattle, 203 goats and 205 sheep), were serologically screened for RVF by a commercial cELISA, and Brucella species by modified Rose Bengal Plate Test (mRBPT) and a commercial iELISA. Results Two out of 609 (0.3 %; 95 %CI: 0.04–1.2 %) ruminants were RVF seropositive, both were female cattle from both districts. Anti-Brucella spp. antibodies were detected in 64/609 (10.5 %; 95 %CI: 8.2–13.2 %) ruminants by mRBPT, which were 39/201 (19.4 %) cattle, 16/203 (7.9 %) goats and 9/205 (4.4 %) sheep. Cattle were 5.2 and 2.8 times more likely to be Brucella-seropositive than sheep (p = 0.000003) and goats (p = 0.001), respectively. When mRBPT-positive samples were tested by iELISA, 29/64 (45.3 %; 95 %CI: 32.8–58.3 %) ruminant sera were positive for Brucella spp. Only 23/39 (58.9 %) cattle sera and 6/16 (37.5 %) goat sera were positive to Brucella spp. by iELISA. Conclusions The present study showed the serological evidence of RVF and brucellosis in ruminants from Afgoye and Jowhar districts of Somalia. Considering the negligence of the zoonotic diseases at the human-animal interface in Somali communities, a One Health approach is needed to protect public health.

Objective To determine the seroprevalence of selected zoonotic viral hemorrhagic fevers (VHFs) and their associated risk factors in Tanzania. Methods Blood samples were collected from consenting outpatients and community members in eight districts selected from five ecological zones of Tanzania. Serum was harvested and tested for the presence of immunoglobulin G (IgG) and M (IgM) antibodies against Crimean-Congo hemorrhagic fever (CCHF), Ebola virus disease (EVD), Marburg virus disease (MVD), Rift Valley fever (RVF), and yellow fever (YF). Results The presence of IgM and IgG antibodies against CCHF, EVD, MVD, RVF, and YF was detected in 64 of 500 samples (12.8%). The prevalences of IgM and IgG antibodies to CCHF, EVD, MVD, RFV, and YF were 2.0%, 3.4%, 1.2%, 4.8%, and 1.4%, respectively. Contact with wild animals (OR = 1.2, CI = 1.3–1.6) and keeping goats (OR = 1.3, CI = 1.5–1.9) were significantly associated with RVF, while contact with bats (OR = 1.2, CI = 1.1–1.5) was associated with MVD. Conclusion The findings of this study provide evidence of exposure to CCHF, EVD, MVD, RVF, and YF in Tanzania. Since most of these VHFs occurred without apparent clinical forms of the disease, these findings call for the need to strengthen the surveillance system and management of febrile illnesses in Tanzania.

Rift Valley Fever (RVF) and West Nile virus (WNV) are two important emerging Arboviruses transmitted by Aedes and Culex mosquitoes, typically Ae. caspius, Ae. detritus and Cx. pipiens in temperate regions. In Morocco, several outbreaks of WNV (1996, 2003 and 2010), affecting horses mostly, have been reported in north-western regions resulting in the death of 55 horses and one person cumulatively. Serological evidence of WNV local circulation, performed one year after the latest outbreak, revealed WNV neutralizing bodies in 59 out of 499 tested participants (El Rhaffouli et al., 2012). The country also shares common borders with northern Mauritania, where RVF is often documented. Human movement, livestock trade, climate changes and the availability of susceptible mosquito vectors are expected to increase the spread of these diseases in the country. Thus, in this study, we gathered a data set summarizing occurrences of Ae. caspius, Ae. detritus and Cx. pipiens in the country, and generated model prediction for their potential distribution under both current and future (2050) climate conditions, as a proxy to identify regions at-risk of RVF and WNV probable expansion. We found that the north-western regions (where the population is most concentrated), specifically along the Atlantic coastline, are highly suitable for Ae. caspius, Ae. detritus and Cx. pipiens, under present-day conditions. Future model scenarios anticipated possible range changes for the three mosquitoes under all climatic assumptions. All of the studied species are prospected to gain new areas that are currently not suitable, even under the most optimist scenario, thus placing additional human populations at risk. Our maps and predictions offer an opportunity to strategically target surveillance and control programmes. Public health officials, entomological surveillance and control delegation must augment efforts and continuously monitor these areas to reduce and minimize human infection risk.

Background Prior to the first recorded outbreak of Rift Valley fever (RVF) in Uganda, in March 2016, earlier studies done until the 1970’s indicated the presence of the RVF virus (RVFV) in the country, without any recorded outbreaks in either man or animals. While severe outbreaks of RVF occurred in the neighboring countries, none were reported in Uganda despite forecasts that placed some parts of Uganda at similar risk. The Ministry of Agriculture, Animal Industry and Fisheries (MAAIF) undertook studies to determine the RVF sero-prevalence in risk prone areas. Three datasets from cattle sheep and goats were obtained; one from retrospective samples collected in 2010–2011 from the northern region; the second from the western region in 2013 while the third was from a cross-sectional survey done in 2016 in the south-western region. Laboratory analysis involved the use of the Enzyme Linked Immunosorbent Assays (ELISA). Data were subjected to descriptive statistical analyses, including non-parametric chi-square tests for comparisons between districts and species in the regions. Results During the Yellow Fever outbreak investigation of 2010–2011 in the northern region, a total sero-prevalence of 6.7% was obtained for anti RVFV reacting antibodies (IgG and IgM) among the domestic ruminant population. The 2013 sero-survey in the western region showed a prevalence of 18.6% in cattle and 2.3% in small ruminants. The 2016 sero-survey in the districts of Kabale, Kanungu, Kasese, Kisoro and Rubirizi, in the south-western region, had the respective district RVF sero-prevalence of 16.0, 2.1, 0.8, 15.1and 2.7% among the domestic ruminants combined for this region; bovines exhibited the highest cumulative sero-prevalence of 15.2%, compared to 5.3 and 4.0% respectively for sheep and goats per species for the region. Conclusions The absence of apparent outbreaks in Uganda, despite neighboring enzootic areas, having minimal restrictions to the exchange of livestock and their products across borders, suggest an unexpected RVF activity in the study areas that needs to be unraveled. Therefore, more in-depth studies are planned to mitigate the risk of an overt RVF outbreak in humans and animals as has occurred in neighboring countries.

Objective: This review describes the current scenario of a priority group of emerging infectious diseases (EIDs) listed by World Health Organization (WHO), and their main determinants and drivers for the emergence/spread of the diseases. The gaps and strategies developed by India to meet the WHO guidelines on the effective control of epidemic-prone diseases and outbreaks are also presented in the review. Methods: Epidemiologic information of EIDs, namely Crimean-Congo hemorrhagic fever (CCHF), Ebola and Marburg viruses (EboV and MarV), Zika virus (ZIKAV), Rift Valley fever (RVF), Middle East respiratory syndrome, severe acute respiratory syndrome (SARS), Nipah and Hendra virus (NiV and HeV), and Lassa fever virus (LASV), was drawn from international and national electronic databases to assess the situation. A brief view on the novel coronavirus disease 2019 (COVID-19) in India is also included. Results: There are no reports for human infection of EboV, MarV, RVF, and LASV in India. CCHF, SARS, ZIKAV, and NiV have been involved in outbreaks in eight states of India, while COVID-19 is currently reported from majority of states. India has deeply strengthened its surveillance and response system of outbreaks and epidemic-prone diseases. Conclusions: Despite its enormous improvements made in the anticipation of such threats, still more efforts are needed in sensitization of populations as well as hospital management in the context to EIDs, as addressed in the review. Furthermore, there is still a need for more research and development activities to efficiently control EIDs.

Rift Valley fever (RVF) is a zoonotic, vector-borne infectious disease of ruminants and camels transmitted mainly by the Aedes and Culex mosquito species. Contact with the blood or organs of infected animals may infect humans. Its etiological factor is the Rift Valley fever virus (RVFV) of the Phlebovirus genus and Bunyaviridae family. Sheep and goats are most susceptible to infection and newborns and young individuals endure the most severe disease course. High abortion rates and infant mortality are typical for RVF; its clinical signs are high fever, lymphadenitis, nasal and ocular secretions and vomiting. Conventional diagnosis is done by the detection of specific IgM or IgG antibodies and RVFV nucleic acids and by virus isolation. Inactivated and live-attenuated vaccines obtained from virulent RVFV isolates are available for livestock. RVF is endemic in sub-Saharan Africa and the Arabian Peninsula, but in the last two decades, it was also reported in other African regions. Seropositive animals were detected in Turkey, Tunisia and Libya. The wide distribution of competent vectors in non-endemic areas coupled with global climate change threaten to spread RVF transboundarily. The EFSA considers the movement of infected animals and vectors to be other plausible pathways of RVF introduction into Europe. A very low risk both of introduction of the virus through an infected animal or vector and of establishment of the virus, and a moderate risk of its transmission through these means was estimated for Poland. The risk of these specific modes of disease introduction into Europe is rated as very low, but surveillance and response capabilities and cooperation with the proximal endemic regions are recommended.

Mosquito resistance to insecticides has recently increased the burden of the majority of mosquito-borne diseases, and controlling the spread of these diseases should mainly rely on vector control m...

Many mosquito species are considered as vectors of several pathogens responsible of serious infectious diseases including Malaria, Dengue, Chikungunia and Rift Valley Fever. The characterization of the larval habitat of these arthropods is an important step for a nuisance/vector control program. In this study we aimed to identify mosquito larvae species in the Tizi-Ouzou area (north-central of Algeria) and to examine the physico-chemical parameters of their permanent breeding sites. Surveys are carried out during the dry and rainy seasons (2018/2019), the larval stages of the mosquitoes were sampled using the dipping technique and the physico-chemical parameters of the breeding sites were measured. The morpho-taxonomic examination of the Culicidae samples allowed the identification of 14 species belonging to five genera and two subfamilies. Interestingly, Culex pipiens was the most abundant species found in all entomological surveys. Moreover, Culex pipiens and Culiseta longiareolata species showed high ecological plasticity and were the best correlated species to the studied physico-chemical parameters. Temperature was positively correlated with the density of most inventoried species. Our data would be of great interest in the context of developing a nuisance control program and the prevention of vector-borne diseases.

Rift Valley fever virus (RVFV) is a mosquito-transmitted bunyavirus that causes severe outbreaks among wild and domesticated ruminants, of which sheep are the most susceptible. Outbreaks are characterised by high mortality rates among new-born lambs and abortion storms, in which all pregnant ewes in a flock may abort their foetuses. In endemic areas, Rift Valley fever (RVF) can be controlled by vaccination with either inactivated or live-attenuated vaccines. Inactivated vaccines are safe for animals during all physiological stages, including pregnancy. However, optimal efficacy of these vaccines depends on multiple vaccinations and yearly re-vaccination. Live-attenuated vaccines are generally highly efficacious after a single vaccination, but currently available live-attenuated vaccines may transmit to the ovine foetus, resulting in stillbirths, congenital malformations or abortion. We have previously reported the development of a novel live-attenuated RVFV vaccine, named RVFV-4s. This vaccine virus was created by splitting the M genome segment and deleting the major virulence determinant NSs, and was shown to be safe even for the most susceptible species, including pregnant ewes. The demonstrated efficacy and safety profile suggests that RVFV-4s holds promise for veterinary and human application. The RVFV-4s vaccine for veterinary application, here referred to as vRVFV-4s, was shown to provide complete protection after a single vaccination of lambs, goats and cattle. In this work, we evaluated the efficacy of the vRVFV-4s vaccine in pregnant ewes. Anticipating on the extremely high susceptibility of pregnant ewes for RVFV, both a single vaccination and double vaccination were evaluated in two independent experiments. The combined results suggest that a single vaccination with vRVFV-4s is sufficient to protect pregnant ewes and to prevent transmission to the ovine foetus.

The current epidemiological characteristics of pathogens of especially dangerous infections abroad and in the Russian Federation are given. The biology of the causative agents of hemorrhagic fevers, as well as their species and subspecies, is especially reflected. The biology and epidemiology of the most common causative agents of hemorrhagic fevers are described in more detail: Dengue, Ebola, Marburg, Lassa, Machupo (Bolivian), Hanin (Argentinean) fever, Rift Valley fever, Omsk, Congo-Crimean, and renal fever their intermediate hosts - mosquitoes and ticks, the options for getting these pathogens into the human body. The most severe and widespread human infections, caused by alpha viruses and flaviviruses, the most severe epidemics in various countries are characterized. The modern systematics and immunopathogenesis of the causative agents of these infections, the features of virological and immunological diagnostics using both classical and modern techniques are presented. The new pathogens of hemorrhagic fevers, which have been fatal in recent years, are described. Given the current tense situation associated with the causative agents of hemorrhagic fevers, measures are proposed that are aimed at preventing the entry of pathogens into the Russian Federation, as well as the algorithm of actions of employees of medical institutions when patients with suspected infection associated with causative agents of especially dangerous infections are admitted.

We report a unique outbreak of Rift Valley fever in the Eldamar area, Sudan, May-July 2019, that resulted in 1,129 case-patients and 19 (1.7%) deaths. Patients exhibited clinical signs including fever (100%), headache (79%), and bleeding (4%). Most (98%) patients also reported death and abortions among their livestock.

Introduction Rift Valley fever (RVF) and West Nile fever (WNF) are re-emerging mosquito-borne zoonotic diseases that cause public health and economic crises. Ethiopia shares borders with South Sudan and Kenya, where these diseases are often documented. The free movement of animals and humans across these borders expects to increase the spread of these diseases. The current study was conducted to assess the occurrence of these diseases in the Gambella region of Ethiopia. Methodology We collected a total of 368 cattle serum samples from the Lare district on the border of South Sudan and measured the presence of IgG antibody against RVF and WNF virus infections using enzyme-linked immunosorbent assays (ELISA). Results The prevalence of anti-RVF virus IgG antibody was 7.6% (95% CI: 5.3-10.82%), while that of anti-WNF virus IgG antibody was 5.4% (95% CI: 3.52-8.29%). In this study higher seroprevalence of IgG antibodies to RVF virus infection was observed comparing to the WNF virus in cattle. There was no significant association between the prevalence and the cattle age, sex or sampled locations. Conclusion The detection of IgG antibody to RVF and WNF virus infections in the Gambella region warrants further study of active case findings and the dynamics of transmission.

On the last week of May of 2018, a community-based syndromic surveillance system detected mass abortions and deaths of young livestock in northeastern Kenya. Two weeks later, Rift Valley fever (RVF) was confirmed in humans presenting with febrile illness and hemorrhagic syndrome in the same region. A joint animal and human response team carried out an investigation to characterize the outbreak and identify drivers of disease transmission. Here, we describe the outbreak investigation and findings. A total of 106 human cases were identified in the months of May and June 2018: 92% (98) and 8% (8) of these cases occurring in the northern and western regions of Kenya, respectively. Seventy-six (72%) were probable cases, and 30 (28%) were laboratory confirmed by ELISA and/or PCR. Among the confirmed cases, the median age was 27.5 years (interquartile range = 20), and 60% (18) were males. Overall, the case fatality rate was 7% (n = 8). The majority of the confirmed cases, 19 (63%), reported contact with livestock during slaughter and consumption of meat from sick animals. All confirmed cases had fever, 40% (12) presented with hemorrhagic syndrome, and 23% (7) presented with jaundice. Forty-three livestock herds with at least one suspect and/or confirmed animal case were identified. Death of young animals was reported in 93% (40) and abortions in 84% (36) of livestock herds. The outbreak is indicative of the emergence potential of RVF in traditionally high- and low-risk areas and the risk posed by zoonosis to livestock keepers.

There is a considerable increase in vector-borne zoonotic diseases around the world, including Turkey, such as Crimean-Congo hemorrhagic fever (CCHF), tick borne encephalitis (TBE), Rift Valley fever (RVF), and West Nile fever (WNF), causing disease and death in humans and animals and significant economical losses. Hence, the aim of this study was to investigate the presence of CCHF virus (CCHFV) and TBE virus (TBEV) in ticks and RVF virus (RVFV) and WNF virus (WNV) in mosquitos, as well as in sheep and cattle, in the Thrace district of the Marmara region, which borders Bulgaria and Greece. Buffy-coat samples from 86 cattle and 81 sheep, as well as 563 ticks and 7390 mosquitos, were collected and examined by quantitative real-time RT-PCR for the presence of CCHFV, TBEV, RVFV, and WNV. All buffy-coat samples from cattle and sheep were negative for these viruses. Similarly, all tick samples were negative for CCHFV-RNA and TBEV-RNA. Among 245 pools representing 7390 mosquitos, only 1 pool sample was found to be positive for WNV-RNA and was confirmed by sequencing. Phylogenetic analysis revealed that it was WNV lineage-2. No RVFV-RNA was detected in the 245 mosquito pools. In conclusion, results of this study indicate that CCHFV, TBEV, and RVFV are not present in livestock and respective vectors in the Thrace district of Marmara region of Turkey, whereas WNV-RNA was found in mosquitos from this region.

Rift Valley fever is an arboviral zoonoses causing severe morbidity and mortality among humans and animals in many African countries. A cross-sectional study in populations of sheep reared around the Gidan-Waya Forest Reserve located in Jema'a LGA of Kaduna State, Nigeria to determine the serological evidence of exposure to Rift Valley fever virus (RVFV) using a commercial competitive enzyme-linked immunosorbent assay. Of the 200 sheep sampled, 9 (4.5%; 95 CI 2.23-8.33) were positive for antibodies to the RVFV. The detection of antibodies suggests a covert circulation among the sheep and may be indicative of a subclinical infection.

Rift Valley fever (RVF) is a zoonotic, viral disease, transmitted by mosquitoes, characterized by high mortality rates in young animals. RVF is an endemic and enzootic disease in the Arabian Peninsula and Africa, causing public health and economic instability. Therefore, it is important to develop vaccines to minimize outbreaks and combat the disease. We documented the stability of the thermo-stability of live attenuated RVF CL13T and recombinant arMP-12ΔNSm21/384 vaccine candidates at different temperatures, including these vaccine viruses in liquid and lyophilized form. The study revealed that both CL13T and recombinant arMP-12ΔNSm21/384 strains were stable for more than 18 months at 4°C. We show that at room temperatures (37°C and 45°C) the CL13T was less temperature sensitive than MP-12NSm-del in both lyophilized and liquid form. These findings are useful for the preparation of RVF vaccines that will avoid the need for a cold chain and therefore, will improve the application of the vaccines under field conditions.

Amyloid fibrils result from the aggregation of host cell-encoded proteins, many giving rise to specific human illnesses such as Alzheimer’s disease. Here we show that the major virulence factor of Rift Valley fever virus, the protein NSs, forms filamentous structures in the brain of mice and affects mortality. NSs assembles into nuclear and cytosolic disulfide bond-dependent fibrillary aggregates in infected cells. NSs structural arrangements exhibit characteristics typical for amyloids, such as an ultrastructure of 12 nm-width fibrils, a strong detergent resistance, and interactions with the amyloid-binding dye Thioflavin-S. The assembly dynamics of viral amyloid-like fibrils can be visualized in real-time. They form spontaneously and grow in an amyloid fashion within 5 hours. Together, our results demonstrate that viruses can encode amyloid-like fibril-forming proteins and have strong implications for future research on amyloid aggregation and toxicity in general., Rift Valley fever virus (RVFV) can cause severe diseases in humans, including encephalitis. Here the authors show that NSs, the major virulence factor of RVFV, is an amyloidogenic protein forming fibrils in infected mouse brains and causing increased mortality in mice.

Rift Valley fever virus (RVFV) causes severe disease in domestic ungulates (cattle, goats, and sheep) and a febrile illness in humans (with ∼1% case fatality rate). This virus has been spreading geographically, and there is concern of it spreading to Europe or the Americas. Environmental temperature can significantly affect the ability of mosquitoes to transmit an arbovirus. However, these effects are not consistent among viruses or mosquito species. Therefore, we evaluated the effect of incubation temperatures ranging from 14°C to 30°C on infection and dissemination rates for Culex tarsalis and Aedes taeniorhynchus allowed to feed on hamsters infected with RVFV. Engorged mosquitoes were randomly allocated to cages and placed in incubators maintained at 14°C, 18°C, 22°C, 26°C, or 30°C. Although infection rates detected in Cx. tarsalis increased with increasing holding temperature, holding temperature had no effect on infection rates detected in Ae. taeniorhynchus. However, for both species, the percentage of mosquitoes with a disseminated infection after specific extrinsic incubation periods (4, 7, 10, 14, 17, or 21 days) increased with increasing incubation holding temperature, even after adjusting for the apparent increase in infection rate in Cx. tarsalis. The effects of environmental factors, such as ambient temperature, need to be taken into account when developing models for viral persistence and spread in nature.

Rift Valley fever virus (RVFV) causes Rift Valley fever (RVF), resulting in morbidity and mortality in humans and ruminants. Evidence of transboundary outbreaks means that RVFV remains a threat to human health and livestock industries in countries that are free from the disease. To enhance surveillance capability, methods for detection of RVFV are required. The generation of reagents suitable for the detection of RVFV antigen in formalin-fixed, paraffin-embedded tissues from infected animals have been developed and are described herein. Recombinant nucleoprotein (rNP) was expressed in Escherichia coli and purified using immobilized metal ion affinity chromatography. Purified rNP was used as an immunogen to produce anti-NP polyclonal antisera in rabbits for use in detection of RVFV NP in experimentally infected animals by immunohistochemistry. Antisera raised in rabbits against rNP were able to recognize viral NP antigen in fixed infected Vero cell pellets and sheep liver. Therefore, the methods and reagents described herein are useful in assays for detection of RVFV infections in animals, for research and surveillance purposes.

Rift Valley Fever (RVF) is an acute infectious zoonotic arthropod-born viral disease, affecting many species of animals and it causes great economic losses in animal wealth and has a zoonotic implication. Eradication of mosquito and vaccination is an important and best method for preventing and controlling the disease. This study was applied for the preparation and evaluation of Rift Valley Fever inactivated vaccine in a lyophilized form that is reconstituted at the time of inoculation using saponin that acts as an adjuvant. The prepared vaccine was proved to be sterile and safe. ED50 Potency test of the prepared vaccine in mice gave 0.0010 ED50/ML (permissible limit less than 0.02/ml). Sheep were vaccinated with 1ml S\C of the prepared lyophilized inactivated RVF vaccine and another group was vaccinated S|C with 1ml of Aluminum hydroxide inactivated RVF vaccine. The immune response of different vaccinated sheep groups was evaluated using SNT and ELISA. The Prepared lyophilized inactivated RVF vaccine gave protective NI at the second-week post-vaccination (2.1 and 0.286 OD) , then reach to peak at the 4th week (3.28 and 0.343OD) then began to decline till ten months (1.8 and 0.241 OD), while the Aluminum hydroxide inactivated RVF vaccine gave protective NI at the second-week post-vaccination (1.7 and 0.277 OD) then reach to its NI peak at the 4th week (3.13 and 0.312 OD) then began to decline till ten months (1.73 and 0.228 OD). From the obtained results, it was found that the prepared lyophilized inactivated RVF vaccine was safe, potent and gave approximately similar immune response as aluminum hydroxide inactivated RVF vaccine but it is better as it reduces time and effort consuming during vaccine production.

In 2018, a large outbreak of Rift Valley fever (RVF)–like illness in cattle in Rwanda and surrounding countries was reported. From this outbreak, sera samples from 157 cows and 28 goats suspected to be cases of RVF were tested to confirm or determine the etiology of the disease. Specifically, the hypothesis that orthobunyaviruses—Bunyamwera virus (BUNV), Batai virus (BATV), and Ngari virus (NRIV)—were co-circulating and contributed to RVF-like disease was tested. Using reverse transcriptase-polymerase chain reaction (RT-PCR), RVFV RNA was detected in approximately 30% of acutely ill animals, but in all cases of hemorrhagic disease. Seven cows with experienced abortion had positive amplification and visualization by gel electrophoresis of all three segments of either BUNV or BATV, and three of these were suggested to be coinfected with BUNV and BATV. On sequencing, five of these seven cows were conclusively positive for BUNV. However, in several other animals, sequencing was successful for some but not all segments of targeted viruses BUNV and BATV. In addition, there was evidence of RVFV–orthobunyavirus coinfection, through RT-PCR/gel electrophoresis and subsequent Sanger sequencing. In no cases were we able to definitely identify the specific coinfecting viral species. This is the first time evidence for orthobunyavirus circulation has been molecularly confirmed in Rwanda. Furthermore, RT-PCR results suggest that BUNV and BATV may coinfect cattle and that RVFV-infected animals may be coinfected with other orthobunyaviruses. Finally, we confirm that BUNV and, perhaps, other orthobunyaviruses were co-circulating with RVFV and contributed to the burden of disease attributed to RVFV in Rwanda.

Rift valley fever is an arthropod-born, multispecies zoonotic viral disease. Control of RVF disease depends mainly on vector control and vaccination of susceptible animals. The present work aims to detect the correlation between Rift Valley Fever Virus (RVFV) neutralizing antibody titers in vaccinated sheep using Serum Neutralization test as in vitro test and effective dose fifty in vaccinated mice as in vivo potency test and determine if they can be alternative to each other. In this work,17 inactivated RVFV vaccine batches were evaluated, applying SNT for serum samples of vaccinated sheep and ED50 in vaccinated mice. The two models of tests showed compatible results, where the same 14 vaccine batches showed satisfactory results [(SNT >1.5) and (ED50 less than 0.02)], while the other three batches revealed unsatisfactory results in both two tests. Statistical analysis of results using Wilcoxon’s test was (0.0001), indicating a significant correlation between the tests so it could be recommended to depend on SNT instead of mice inoculation in the evaluation of RVF vaccine to reduce the numbers of animals being used and to avoid the possible public health hazard.

L’épizoo-épidémie de la Fièvre de la Vallée du Rift (FVR), survenue suite à une pluviométrie marquée par de fortes précipitations dans la région de Tahoua frontalière au département d’Ingal qui accueille l’événement de la cure salée chaque année, a engendré de nombreuses pertes en vies humaines. Au niveau du secteur animal, l’impact économique et sanitaire est également considérable, compte-tenu des lourdes pertes engendrées dans le cheptel. Ces pertes sont une forte mortalité chez les jeunes, des taux d’avortements élevés chez les femelles gravides et une baisse de la productivité des élevages touchés. Afin d’évaluer la séroprévalence de la FVR chez les ruminants de la région, des échantillons de sérums prélevés lors du seromonitoring des campagnes de vaccination contre la peste des petits ruminants et la péripneumonie contagieuse des bovidés financé par le Projet Régional d’Appui au Pastoralisme au Sahel (PRAPS) en février 2017, ont été analysés pour la détection d’anticorps du virus de la FVR au moyen du test ELISA de compétition. Les séroprévalences obtenues chez les espèces étudiées sont assez élevées chez les bovins (30,62%) et les caprins (18,40%), suivies de celle des ovins qui est de 14,90%.Les résultats sérologiques répartis dans les communes montrent que les bovins de Ibohaman et Tassara sont significativement les plus affectés avec une prévalence de 50,00% chacune (P=0,00224). Par contre, chez les petits ruminants, les communes de Tchintabaraden et Abalak ont significativement les prévalences les plus élevées tant chez les ovins (22,07% et 40,90%) que chez les caprins (8,69% et 37,21%).Toutefois, il n’y a pas de différence significative entre les prévalences d’infection des ovins et caprins pour chaque commune. Les résultats révèlent que la prévalence est plus élevée chez les mâles que chez les femelles (32,35±11,11 contre 18,49±3,43), mais la différence n’est pas significative. En somme, la mise en place d’une stratégie privilégiant l’approche « One Health » est nécessaire pour une lutte efficace contre la FVR, mais aussi la nécessité d’études entomologiques complémentairesMots clés: Sérologie, c-ELISA, Fièvre de la vallée de Rift, Bovins, Ovins, Caprins. English Title: Rift valley fever seroprevalence in domestic ruminants in Tahoua region/NigerThe epizoo-epidemic outbreak of Rift Valley Fever (RVF) that occurred following a heavy rainfall in the region of Tahoua, along the border of Ingal’s department that hosts every year, the salt cure event has caused considerable human deaths. Considerable economic and health losses were reported in livestock sector. These losses include high mortality in young animals, high abortion rates in pregnant females and decrease productivity in affected farms. To assess the seroprevalence of RVF of ruminants from that region, sera samples collected in February 2017, for the Seromonitoring of vaccination campaigns against Peste des Petits Ruminants (PPR) and Contagious Bovine Peri Pneumonia (CBPP), Supported by the Regional Project for Pastoralism in the Sahel (PRAPS), were tested for antibodies against RVF virus using the competitive ELISA test. The seroprevalence of RVF in the studied species, reveal a high prevalence in cattle (30.62%) and goats (18.40%) followed by sheep (14.90%).Cattle, from Ibohaman and Tassara are significantly affected with a prevalence of 50.00% each (P=0.00224) compared to other districts. Small ruminants from the districts of Tchintabaraden and Abalak have significantly the highest prevalence both in sheep (22.07% and 40.90%) and goats (8.69% and 37.21%). However, there is no significant difference between the prevalence of infection of sheep and goats in each district. Seroprevalence is higher in males than females (32.35±11.11) versus (18.49±3.43), with no significant difference between the two species. Based on the above results, for effective control of RVF it, is necessary to implement a one heath approach in the country couple with additional entomological investigations.Keywords: Serology, c-ELISA, Rift Valley Fever, Cattle, Sheep, Goats.

The genus Phlebovirus contains about 70 named viruses, distributed widely in Europe, Africa, Central Asia, and the Americas. These viruses are currently classified into 10 species by the International Committee on Taxonomy of Viruses (ICTV): Bujaru phlebovirus, Candiru phlebovirus, Chilibre phlebovirus, Frijoles phlebovirus, Punta Torro phlebovirus, Rift Valley fever phlebovirus, Salehabad phlebovirus, Sandfly fever Naples phlebovirus, Mukawa phlebovirus, and Uukuniemi phlebovirus. In addition, at least 32 unclassified strains are associated with this genus.1 Phleboviruses have a genome comprising three segments of negative sense, single-stranded RNA. The large segment (L) encodes the viral RNA-dependent RNA polymerase, the medium segment (M) encodes the structural glycopolyproteins, and the small segment (S) has an ambisense strategy encoding the nucleoprotein (NP) in the negative sense and the nonstructural small (NSs) protein in the positive sense.2 Phleboviruses are largely transmitted by sand flies; Phlebotomus species in the Old World or Nyssomyia (previously Lutzomyia) species in the New World.3 However, some viruses in this genus are transmitted by mosquitoes, Culicoides, and ticks. Many phleboviruses have been associated with human and animal disease. Pathogenic strains include Rift Valley fever, Toscana, Candiru, Sandfly fever Naples, Sandfly fever Sicilian, and severe fever with thrombocytopenia syndrome viruses.4 Recent discoveries of Sandfly fever Turkey,5 Heartland,6 Hunter Island Group,7 Fermo,8 and Malsoor9 viruses highlight the extent to which the diversity and public or animal health impact of phleboviruses are still unknown and likely underestimated. Despite their public health impact, some phlebovirus species remain characterized solely by serological techniques. Given the many recent discoveries, genetic characterization of historically identified phleboviruses is important for the development of diagnostic and surveillance tools, and evolutionary insights into the ever-growing breadth of recognized phleboviruses. Here, we describe the complete sequences of two phlebovirus species complexes, and three previously unclassified phleboviruses isolated in the Americas.

Background: Sudan has often faced outbreaks of malaria, the life-threatening waterborne disease. In 2019, the country experienced an outbreak of six different infectious diseases, i.e., cholera, chikungunya, dengue fever, diphtheria, malaria, and Rift Valley fever. Objectives: The aim of this study was to perform an epidemiological descriptive analysis of data of these disease outbreaks to determine the spatial and temporal patterns of outbreaks and to estimate the magnitude of the diseases. Methods: The data consisted of the number of cases and deaths due to disease outbreaks of cholera, chikungunya, dengue fever, diphtheria, malaria, and Rift Valley fever. We analyzed the reports of an investigation conducted by the World Health Organization and the Federal Ministry of Health, Sudan. Descriptive statistics and case fatality rate (CFR) were used in this study. Results: The frequency of disease occurrence was as follows: cholera (344 cases), chikungunya (308 cases), dengue fever (4236 cases), diphtheria (105 cases), malaria (5,188,135 cases) and River Valley fever (567 cases). The CFRs for cholera, chikungunya, are diphtheria were 4.3%, 2.05%, and 9.5%, respectively. The mortality rate of malaria was 0.0013. The states most affected by outbreaks of these diseases in Sudan were the western states. Women were at a higher risk for all diseases, except River Valley fever. Conclusions: This study highlights the patterns of the outbreak of these diseases in Sudan and provides a basis for future scientific research.

Rift Valley Fever (RVF) is an acute infectious zoonotic arthropod - born viral disease, affecting many species of animals with causing great economic losses in animal wealth. Vaccination of susceptible animals with RVF vaccines are an important factor for controlling the disease. This study was applied to improve the locally produced vaccine by using Montanide Gel 01™ as an adjuvant in comparison with Aluminium Hydroxide inactivated RVF vaccine, through evaluating the humeral, cellular immune response and the duration of immunity in sheep vaccinated with the prepared vaccines. The antibody titre in the group vaccinated with one dose of Montanide Gel 01TM inactivated RVF vaccine reached the protective level at the 7th-day post-vaccination and stayed within the protective level till the end of the 11th month, while in the group vaccinated with 2 doses, the antibody titre stayed within the protective level till the end of 13th month in sheep vaccinated with the same vaccine. These results revealed that the best vaccine is 20% Montanide Gel 01TM inactivated RVF vaccine (2 doses) as it gave a higher level of antibody throughout the experiment compared with that of other vaccinated groups. Also, the results of cell-mediated immune response showed that: (i) The cell proliferation expressed by optical density showed early significance in sheep vaccinated by Montanide Gel 01TM inactivated RVF vaccine and a slight elevation in sheep vaccinated by Aluminium Hydroxide inactivated RVF vaccine. (ii) The phagocytic activity expressed by phagocytic percentage and phagocytic index showed early significant in sheep vaccinated with Montanide Gel 01TM inactivated RVF vaccine and a slight elevation in sheep vaccinated by Aluminium hydroxide inactivated RVF vaccine. Also, high levels of IL-6 and IL-12 gene expression were detected in sheep vaccinated with Montanide Gel 01TM inactivated RVF vaccine as shown by RT-PCR. All the previous data showed that the Montanide Gel 01TM was highly immunogenic than Aluminium Hydroxide beside that Montanide Gel 01TM inactivated RVF vaccine induces rapid onset immunological response with a long duration which recommended for emergency vaccination.

Rift Valley Fever (RVF) is a viral zoonosis that primarily affects animals but also has the capacity to infect humans. The disease also results in significant economic losses due to death and abortion among RVF-infected livestock. A lateral flow device (LFD) was developed for the rapid detection of IgG and IgM anti-RVF antibodies in infected and vaccinated ovine sera. The conjugated RVF antigen with nano-gold was used as a detector antigen and was laid on a conjugated pad. The staphylococcal protein A was used as the capture complex (antibodies IgG-antigen conjugated with nanogold) at the first test line of device and anti-IgM antibodies were used as the capture complex (antibodies IgM-antigen conjugated with nanogold) at the second test line of device. When compared with RVF specific ELISA, The sensitivity, specificity, and accuracy of developed LFD for detection of IgG were found to be 88.2, 96.9 and 94.0%, respectively, while the same for detection of IgM was found to be 100, 96, and 96%, respectively.

One of the mosquito-borne zoonotic diseases is the Rift Valley fever virus (RVFV). Currently, there is no completely licensed vaccine that can be used to vaccinate animals or humans outside endemic areas. The aim of this work was to use the RVFV glycoprotein (Gn) and the subunit B of cholera toxin (CTB) at gene level and build up fused recombinant vaccine. The gene of CTB was joined to the gene Gn to work as an adjuvant in the resulting fusion protein. The designed merged genes (CTB-Gn) was tested for restriction sites, open reading frames, expected fusion protein tertiary structure and antigenicity using computer software. The insert sequence was submitted to the BioProject (GenBank). The insert was subcloned into the pQE-31 expression plasmid. The target recombinant protein (rCTB-Gn) was expressed in M15 bacteria, purified and identified by protein gel electrophoresis. The insert got the accession No: PRJNA386723. Analysis of the designed rCTB-Gn protein revealed that it had the right 3D structure, immunogenic and at the correct molecular weight. The presence of the CTB in the proposed vaccine will augment its immunogenicity. Doses and protection levels of the vaccine need to be manipulated. Keywords: RVFV, Adjuvant, CTB, Subunit vaccine, Recombinant vaccine

BackgroundRift Valley Fever (RVF) is a viral disease caused by the Rift Valley Fever virus and spread mainly by the Aedes and Culex mosquito species. The disease primarily infects domestic animals such as sheep, goats, and cattle, resulting in a spectrum of clinical outcomes including morbidity, massive storm abortions, and neonatal fatalities. RVF outbreaks are closely linked to above-average rainfall and flooding, which create an ideal environment for mosquitos to breed, multiply, and transmit the virus to animals. The outcomes of human RVF infection range from self-limiting febrile illness to potentially fatal hemorrhagic diatheses and miscarriage in pregnant women. Collectively, the economic losses due to the zoonotic RVF disease is immense.MethodsUsing the Weighted Gene Co-expression Network Analysis (WGCNA) package, RNA-Seq data generated from five healthy Bos taurus steer calves aged 4-6 months was obtained from the Gene Expression Omnibus (GEO) database (Accession number GSE71417). The data was utilized to construct a gene co-expression network. Enriched modules containing genes potentially involved in RVF infection progression were identified. Moreover, using the Multiple Expectation Maximizations for Motif Elicitation (MEME) suite, consensus regulatory motifs of enriched gene clusters were deciphered and the most abundant putative regulatory motif in each enriched module unveiled by comparative analysis with publicly available motifs using the TOMTOM motif comparison tool. The potential roles of the identified regulatory motifs were inferred by literature mining.ResultsThe constructed gene co-expression network revealed thirty-three (33) modules, nine of which were enriched for Gene Ontology terms linked to RVF pathogenesis. Functional enrichment in two (red and turquoise) of the nine modules was significant. ASH1-like histone lysine methyltransferase and Astrotactin were the hub genes for the red and turquoise modules respectively. ASH1-like histone lysine methyltransferase gene is involved in chromatin epigenetic modification while Astrotactin is a vertebrate-specific gene that plays an important role in neurodevelopment. Additionally, consensus regulatory motifs located on the 3' end of genes in each enriched module was identified.ConclusionsIn this study, we have developed a gene co-expression network that has aided in the unveiling of functionally related genes, intramodular hub genes, and immunity genes potentially involved in RVF pathogenesis. The discovery of functional genes with putative critical roles in the establishment of RVF infection establishment will contribute to the understanding of the molecular mechanism of RVF pathogenesis. Importantly, the putative regulatory motifs identified are plausible targets for RVF drug and vaccine development.

Background Zoonotic diseases pose a significant threat to human, animal, and environmental health. The Economic Community of West African States (ECOWAS) has endured a significant burden of zoonotic disease impacts. To address zoonotic disease threats in ECOWAS, a One Health Zoonotic Disease Prioritization (OHZDP) was conducted over five days in December 2018 to prioritize zoonotic diseases of greatest regional concern and develop next steps for addressing these priority zoonoses through a regional, multisectoral, One Health approach. Methods The OHZDP Process uses a mixed methods prioritization process developed by the United States Centers for Disease Control and Prevention. During the OHZDP workshop, representatives from human, animal, and environmental health ministries from all 15 ECOWAS Member States used a transparent and equal process to prioritize endemic and emerging zoonotic diseases of greatest regional concern that should be jointly addressed by One Health ministries and other partners. After the priority zoonotic diseases were identified, participants discussed recommendations and further regional actions to address the priority zoonoses and advance One Health in the region. Results ECOWAS Member States agreed upon a list of seven priority zoonotic diseases for the region – Anthrax, Rabies, Ebola and other viral hemorrhagic fevers (for example, Marburg fever, Lassa fever, Rift Valley fever, Crimean-Congo Hemorrhagic fever), zoonotic influenzas, zoonotic tuberculosis, Trypanosomiasis, and Yellow fever. Participants developed recommendations and further regional actions that could be taken, using a One Health approach to address the priority zoonotic diseases in thematic areas including One Health collaboration and coordination, surveillance and laboratory, response and preparedness, prevention and control, workforce development, and research. Conclusions ECOWAS was the first region to use the OHZDP Process to prioritize zoonotic disease of greatest concern. With identified priority zoonotic diseases for the region, ECOWAS Member States can collaborate more effectively to address zoonotic diseases threats across the region using a One Health approach. Strengthening national and regional level multisectoral, One Health Coordination Mechanisms will allow ECOWAS Member States to advance One Health and have the biggest impact on improving health outcomes for both people and animals living in a shared environment.

The mosquito-borne Rift Valley fever (RVF) is a prioritised disease that has been listed by the World Health Organization for urgent research and development of counteraction. Rift Valley fever virus (RVFV) can cause a cytopathogenic effect in the infected cell and induce hyperimmune responses that contribute to pathogenesis. In livestock, the consequences of RVFV infection vary from mild symptoms to abortion. In humans, 1–3% of patients with RVFV infection develop severe disease, manifested as, for example, haemorrhagic fever, encephalitis or blindness. RVFV infection has also been associated with miscarriage in humans. During pregnancy, there should be a balance between pro-inflammatory and anti-inflammatory mediators to create a protective environment for the placenta and foetus. Many viruses are capable of penetrating that protective environment and infecting the foetal–maternal unit, possibly via the trophoblasts in the placenta, with potentially severe consequences. Whether it is the viral infection per se, the immune response, or both that contribute to the pathogenesis of miscarriage remains unknown. To investigate how RVFV could contribute to pathogenesis during pregnancy, we infected two human trophoblast cell lines, A3 and Jar, representing normal and transformed human villous trophoblasts, respectively. They were infected with two RVFV variants (wild-type RVFV and RVFV with a deleted NSs protein), and the infection kinetics and 15 different cytokines were analysed. The trophoblast cell lines were infected by both RVFV variants and infection caused upregulation of messenger RNA (mRNA) expression for interferon (IFN) types I–III and inflammatory cytokines, combined with cell line-specific mRNA expression of transforming growth factor (TGF)-β1 and interleukin (IL)-10. When comparing the two RVFV variants, we found that infection with RVFV lacking NSs function caused a hyper-IFN response and inflammatory response, while the wild-type RVFV suppressed the IFN I and inflammatory response. The induction of certain cytokines by RVFV infection could potentially lead to teratogenic effects that disrupt foetal and placental developmental pathways, leading to birth defects and other pregnancy complications, such as miscarriage.

International audience; Rift Valley fever (RVF) is a major emerging arboviral disease with a complex epidemiological cycle. RVF virus (RVFV) is transmitted by mosquito vectors to ruminants, causing epizootics, and then from animals to humans, triggering epidemics. During its cycle, RVFV infects a wide range of hosts, but the associated pathogenesis has yet to be elucidated. RVFV displays a predominant hepatic tropism, but also has a multicellular tropism inducing physiopathological effects in several tissues. However, there is variability between species in terms of physiopathology : a common clinical picture is found (severe hepatitis, hemorrhages, leukopenia), but certain forms are mainly found in humans (neurological and ocular damage) or in ruminant herds (waves of abortions). Although the molecular mechanisms involved are still poorly understood, it seems that early inflammatory response is related to the severity of the pathology. A better understanding of the pathogenesis of RVFV seems essential, especially since no specific treatment exists to date.; La fièvre de la vallée du Rift (FVR) est une arbovirose émergente majeure possédant un cycle de transmission complexe. Le virus de la FVR (RVFV) est transmis aux élevages de ruminants par des moustiques vecteurs, provoquant des épizooties, puis de l’animal à l’Homme, déclenchant alors des épidémies. Au cours de son cycle, le RVFV infecte une large gamme d’hôtes, la pathogenèse associée soulevant de nombreuses questions. Malgré un tropisme principalement hépatique, le RVFV a également un tropisme multicellulaire induisant un effet physiopathologique dans de nombreux tissus. Un tableau clinique commun est habituellement retrouvé (hépatite sévère, hémorragies, leucopénie) mais une variabilité interspécifique a également été décrite. Ainsi, certaines formes sont principalement retrouvées chez l’Homme (atteintes neurologiques et oculaires) ou dans les élevages de ruminants (vagues d’avortements). Bien que les mécanismes moléculaires impliqués soient encore mal connus, il semblerait que la sévérité de la pathologie soit liée à la réponse inflammatoire précoce. De même, la pathogenèse du RVFV semble être soumise à de nombreux facteurs responsables d’une variabilité inter-individuelle importante dans la sévérité de l’infection. Devant l’absence de traitement spécifique, il semble primordial de mieux comprendre la pathogenèse du RVFV.

Rift Valley fever virus (RVFV) is an arbovirus found throughout Africa. It causes disease that is typically mild and self-limiting; however, some infected individuals experience severe manifestations, including hepatitis, encephalitis, or even death. Reports of RVFV encephalitis are notable among immunosuppressed individuals, suggesting a role for adaptive immunity in preventing this severe complication. This phenomenon has been modeled in C57BL/6 mice depleted of CD4 T cells prior to infection with DelNSs RVFV (RVFV containing a deletion of nonstructural protein NSs), resulting in late-onset encephalitis accompanied by high levels of viral RNA in the brain in 30% of animals. In this study, we sought to define the specific type(s) of CD4 T cells that mediate protection from RVFV encephalitis. The viral epitopes targeted by CD4 and CD8 T cells were defined in C57BL/6 mice, and tetramers for both CD4 and CD8 T cells were generated. RVFV-specific CD8 T cells were expanded and of a cytotoxic and proliferating phenotype in the liver following infection. RVFV-specific CD4 T cells were identified in the liver and spleen following infection and phenotyped as largely Th1 or Tfh subtypes. Knockout mice lacking various aspects of pathways important in Th1 and Tfh development and function were used to demonstrate that T-bet, CD40, CD40L, and major histocompatibility complex class II (MHC-II) mediated protection from RVFV encephalitis, while gamma interferon (IFN-γ) and interleukin-12 (IL-12) were dispensable. Virus-specific antibody responses correlated with protection from encephalitis in all mouse strains, suggesting that Tfh/B cell interactions modulate clinical outcome in this model. IMPORTANCE The prevention of RVFV encephalitis requires intact adaptive immunity. In this study, we developed reagents to detect RVFV-specific T cells and provide evidence for Tfh cells and CD40/CD40L interactions as critical mediators of this protection.

The epidemiology of Rift Valley fever virus (RVFV) and Crimean-Congo hemorrhagic fever virus (CCHFV) in Jordan is unknown. Our investigation showed 3% of 989 tested dairy cattle, sheep, and goats were RVFV seropositive and 14% were CCHFV seropositive. Ongoing surveillance is needed to assess risk to humans and protect public health.

Rift Valley fever (RVF) is a viral, vector-borne, zoonotic disease. The relative contributions of livestock species to RVFV transmission has not been previously quantified. To estimate their potential to transmit the virus over the course of their infection, we 1) fitted a within-host model to viral RNA and infectious virus measures, obtained daily from infected lambs, calves, and young goats, 2) estimated the relationship between vertebrate host infectious titers and probability to infect mosquitoes, and 3) estimated the net infectiousness of each host species over the duration of their infectious periods, taking into account different survival outcomes for lambs. Our results indicate that the efficiency of viral replication, along with the lifespan of infectious particles, could be sources of heterogeneity between hosts. For similar infectious titers, we found that infection rates in Aedes spp. vectors were significantly higher than in Culex spp. vectors. Consequently, for Aedes infections, we estimated the net infectiousness of lambs to be 2.93 (median) and 3.65 times higher than that of calves and goats, respectively. Among lambs, individuals which eventually died from the infection were 1.93 times more infectious than lambs recovering. Beyond infectiousness, the relative contributions of host species to transmission depend on local ecological factors, including relative abundances and vector host-feeding preferences. Quantifying these contributions will ultimately help design efficient, targeted, surveillance and vaccination strategies.

Background Rift Valley Fever (RVF) outbreaks in livestock have had a detrimental impact on livestock trade, animal breeding, and productivity. Routine evaluation and data analysis of surveillance systems ensure that health events are efficiently and effectively monitored. This study evaluated Kenya Livestock and Wildlife Surveillance System (KLWSS) and characterized RVF cases reported for Narok County. Methods We evaluated KLWSS from January 2018 to December 2019 using CDC guidelines for evaluating surveillance systems. Attributes of simplicity, flexibility, data quality, acceptability, representativeness, timeliness, stability, sensitivity, and predictive value positive were examined. A retrospective review of RVF surveillance data for Narok County was performed. Demographic and clinical variables were assessed. Data were cleaned in Ms. Excel and descriptive analysis was done using Epi Info 7. Categorical variables were summarized using frequencies and proportions while continuous variables were summarized using measures of central tendency and dispersion. Study authorization was granted by the Directorate of Veterinary Services. Results System was simple in structure and operation, accommodated upgrading of its application, data quality performance was 69.8%, stakeholder’s participation rate was 80% with 842 reports coming from six sub-counties and 30 wards. The median time between event occurrence and event reporting was two days (range one to six days). The system had been operational since 2018 with no reports of any unscheduled outages and downtimes. Suspected cases of RVF reported were 11% (95/842) of the reported cases. The livestock species affected were cattle 56% (53/95) and Sheep 44% (42/95). About 96% (91/95) of the suspected cases were in mixed livestock production systems. The common syndrome was abortions 74% (95/129) with Loita ward recording 97% (92/95) suspected RVF cases. All suspected cases were reported in March 2018. Conclusions The KLWSS system was found to be stable but with below-par performance in data quality. Improvement in data quality is required to ensure that the surveillance system is efficient and effective.

Vector-borne emerging and re-emerging diseases pose considerable public health problem worldwide. Some of these diseases are emerging and/or re-emerging at increasing rates and appeared in new regions in the past two decades. Studies emphasized that the interactions among pathogens, hosts, and the environment play a key role for the emergence or re-emergence of these diseases. Furthermore, social and demographic factors such as human population growth, urbanization, globalization, trade exchange and travel and close interactions with livestock have significantly been linked with the emergence and/or re-emergence of vector-borne diseases. Other studies emphasize the ongoing evolution of pathogens, proliferation of reservoir populations, and antimicrobial drug use to be the principal exacerbating forces for emergence and re-emergence of vector-borne infectious diseases. Still other studies equivocally claim that climate change has been associated with appearance and resurgence of vector-borne infectious diseases. Despite the fact that many important emerging and re-emerging vector-borne infectious diseases are becoming better controlled, our success in stopping the many new appearing and resurging vector-borne infectious diseases that may happen in the future seems to be uncertain. Hence, this paper reviews and synthesizes the existing literature to explore global patterns of emerging and re-emerging vector-borne infections and the challenges for their control. It also attempts to give insights to the epidemiological profile of major vector-borne diseases including Zika fever, dengue, West Nile fever, Crimean-Congo hemorrhagic fever, Chikungunya, Yellow fever, and Rift Valley fever.

Rift Valley fever (RVF) is an emerging mosquito-borne zoonosis that threatens public health and animal agriculture in the endemic areas causing devastating epizootics characterized by abortion storms and high mortalities, especially in newborn animals. A cross-sectional study was conducted to determine the seroprevalence and investigate risk factors associated with exposure to the virus in camels slaughtered in Maiduguri abattoir, Borno state of Nigeria. Camels presented for slaughtered were sampled and data on age, sex, source or origin, utility, presence of post mortem lesions, body weights and body condition score were collected. Blood samples were collected and sera were harvested and stored at -20°C until tested. The sera were tested using a commercial ELISA kit based on the manufacturer's instructions. The overall seroprevalence in the study was 20.7% (95% CI, 13.6 – 30.0). The analysis showed no significant differences between presence of antibodies and variables that included the sex of camels (c2=0.015, df = 1, p = 0.904) and presence of post mortem lesion on the carcass (c2=0.009, df = 1, p = 0.925). There were significant differences between presence of antibodies and three variables that included the age (c2= 4.89, df = 1, p = 0.027), the source (c2= 7.077, df = 2, p = 0.029) and the main utility (c2= 8.057, df = 3, p = 0.045) of the camels. It was concluded that camels presented for slaughter at the Maiduguri abattoir have evidence of exposure to the RVF virus and may be means of transmission of the virus. Regular monitoring and control of transboundary animal movements were recommended in the study area.

Discovered in 1931, Rift Valley fever virus (RVFV) is an arbovirus that causes disease in humans and livestock. In humans, disease ranges from a self-limiting febrile illness to a more severe hepatitis or encephalitis. There are currently no licensed human therapeutics for RVFV disease. Given the recent advances in the use of monoclonal antibodies (MAbs) for treating infectious disease, a panel of anti-RVFV Gn glycoprotein MAbs was developed and characterized. RVFV MAbs spanned a range of neutralizing abilities and mapped to distinct epitopes along Gn. The contribution of Fc effector functions in providing MAb-mediated protection from RVFV was assessed. IgG2a version MAbs had increased capacity to induce effector functions and conferred better protection from RVFV challenge in a lethal mouse model than IgG1 version MAbs. Overall, this study shows that Fc-mediated functions are a critical component of humoral protection from RVFV. IMPORTANCE Rift Valley fever virus (RVFV) is a mosquito-borne virus found throughout Africa and into the Middle East. It has a substantial disease burden; in areas of endemicity, up to 60% of adults are seropositive. With a case fatality rate of up to 3% and the ability to cause hemorrhagic fever and encephalitis, RVFV poses a serious threat to human health. Despite the known human disease burden and the fact that it is a NIAID category A priority pathogen and a WHO priority disease for research and development, there are no vaccines or therapeutics available for RVF. In this study, we developed and characterized a panel of monoclonal antibodies against the RVFV surface glycoprotein, Gn. We then demonstrated therapeutic efficacy in the prevention of RVF in vivo in an otherwise lethal mouse model. Finally, we revealed a role for Fc-mediated function in augmenting the protection provided by these antibodies.

Undetected Rift Valley fever (RVF) outbreaks are expected in endemic countries but little is known about their size or frequency. We describe a previously unreported RVF outbreak involving dairy cattle that appeared to be limited to the edge of the town of Moshi, Tanzania and occurred from May through August, 2018. The outbreak was detected retrospectively using samples collected as part of a cohort study investigating the causes of livestock abortion across northern Tanzania. A total of 14 RVF-associated cattle abortions were identified using a combination of serology and quantitative reverse transcription PCR (RT-qPCR). Milk samples from three (21%) of 14 cases were also RT-qPCR positive. Genotyping revealed circulation of RVF viruses from two lineages. The occurrence of an RVF outbreak among peri-urban dairy cattle, and evidence for RVF viral shedding in milk, highlights the potential for emerging zoonotic risks associated with the growth of urban and peri-urban livestock populations.

Background: Rift Valley Fever (RVF) is a viral hemorrhagic fever that can be fatal to humans and livestock. During June-October 2018, reported RVF cases increased sharply in eight western and central Ugandan districts. We investigated to identify the scope of the outbreak, determine risk factors, and recommend control measures.Methods: We defined a probable case as acute onset of unexplained fever with thrombocytopenia or leukopenia, plus ≥1 of: unexplained bleeding, blurred vision, or unexplained death during June–October 2018 in a resident of the affected districts. A confirmed case was a probable case with a positive PCR test for RVF. We reviewed medical records and actively searched for cases in communities. In a case-control study, we compared exposures of cases and age-, sex-, and neighbourhood-matched controls. We reviewed livestock RVF surveillance data.Results: We identified 19 cases (17 confirmed, 2 probable); 13 (68%) died. The mean age of the case-patients was 36 (range: 27-55) years. The attack rate in men (15/10,000) was 19 times higher than in women (0.78/10,000). Stratified epidemic curves indicated multiple point-source outbreaks, often following skinning/butchering livestock or eating grilled meat from livestock that had been sick or died of unknown causes (‘sick/dead livestock’). All case-patients with data (n=18) ate or butchered meat from sick/dead livestock. Of the 18 case-patients and 90 controls who participated in the case-control study, 10 case-patients (56%) and five controls (5.6%) cut or handled raw meat from sick/dead livestock (ORadj=14, 95%CI=2.8-72). RVF-seropositive livestock were identified from serum samples taken from farms where human cases had occurred.Conclusion. Human RVF outbreaks in Western and Central Uganda in 2018 were caused by contact with raw meat of sick/dead livestock. We recommended wearing protective gear during butchering, and safe handling and disposal of carcasses of sick/dead livestock. RVF surveillance data between human and livestock health sectors should be shared to facilitate early warning and detection for RVF.

Rift Valley fever (RVF) has been reported in the sub-Saharan region of Africa, Egypt and Arabian Peninsula - Yemen and Saudi Arabia, over the past 20 years and is a threat to both the animal and human populations in Tunisia. Tunisia is considered as a high-risk country for the introduction of RVF due to the informal movements of diseased animals already reported in the neighboring countries. The objective of this study was to assess the status of RVF in small ruminants and camels in Tunisia. A risk-based serological survey was conducted to evaluate the presence of RVF based on spatial qualitative risk analysis (SQRA). Samples were collected from small ruminants (sheep and goats) (n = 1,114), and camels (n = 173) samples, belonging to 18 breeders in 14 governorates between November 2017 and January 2018. Samples were tested using an RVF specific multispecies competitive ELISA. Out of the 1,287 samples tested for the presence of RVF IgG antibodies by ELISA, only one positive sample 0.07% (1/1 287) was detected but not confirmed with the virus neutralization test (VNT) used for confirmation. So far, no RVF outbreaks have been reported in Tunisia and our study confirmed the absence of RVF in livestock up to January 2018. Further investigations are needed to confirm the RVF-free status of Tunisia today., QRA methodology, Risk mapping, Survey, Tunisia, Rift valley fever, Small ruminants, Camels

The African buffalo (Syncerus caffer) is an iconic species of South African megafauna. As the farmed buffalo population expands, the potential impacts on population health and disease transmission warrant investigation. A retrospective study of skin biopsy and necropsy samples from 429 animals was performed to assess the spectrum of conditions seen in buffaloes in South Africa. Determination of the cause of death (or euthanasia) could not be made in 33.1% (136/411) of the necropsy cases submitted due to autolysis or the absence of significant lesions in the samples submitted. Infectious and parasitic diseases accounted for 53.5% (147/275) of adult fatal cases and non-infectious conditions accounted for 34.9% (96/275). Abortions and neonatal deaths made up 11.6% (32/275) of necropsy cases. Rift Valley fever, bovine viral diarrhoea, malignant catarrhal fever, tuberculosis, bacterial pneumonia, anaesthetic deaths, cachexia and hepatotoxic lesions were the most common causes of death. The range of infectious, parasitic and non-infectious diseases to which African buffaloes were susceptible was largely similar to diseases in domestic cattle which supports concerns regarding disease transmission between the two species. The similarity between diseases experienced in both species will assist wildlife veterinarians in the diagnosis and treatment of diseases in captive African buffaloes. The present study likely does not represent accurate disease prevalence data within the source population of buffaloes, and diseases such as anthrax, brucellosis and foot and mouth disease are under-represented in this study. Hepatic ductal plate abnormalities and haemorrhagic septicaemia have not, to our knowledge, been previously reported in African buffaloes.