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BackgroundHospital-acquired infections (HAIs) represent the most prevalent adverse event among patients in hospital settings. Contamination with pathogenic bacteria that are highly resistant in the hospital environment increases the risk of HAIs.ObjectiveThe antimicrobial resistance (AMR) patterns of hospital contaminants isolated from highly frequented surfaces in a tertiary hospital in Kenya.MethodsA total of 62 swabs were collected from selected surfaces, equipment, and health workers’ palms in April 2020. They were cultured and bacterial contaminants were identified using standard microbiological procedures and their AMR patterns were determined using recommended laboratory assays.ResultsOf the 62 swabs collected, 61.3% (n=38) yielded bacterial growth, from which 46 bacteria were isolated. Swab positivity varied across the departments as follows: gynecology wards (78.6%), New Born Unit (NBU) (56.2%), Pediatric ward (61.9%), and Renal Unit (45.5%). Gram negative species comprised 86.96%(n=40) while Gram positive species comprised 13.04%(n=6). Of all the 46 isolates obtained, 36.96% (n=17) were positive for the resistance markers screened. Specifically, 10.9% (n=5) showed both extended-spectrum beta-lactamases (ESBL)and carbapenem-resistant (CR) resistance, while 23.9%(n=11) were positive for ESBL production. The rest were non-resistant strains as shown by negative ESBL at 47.8% (n=22), methicillin sensitivity at 13% (n=6) and vancomycin sensitivity at 2.2% (n=1).Acinetobacterspecies which were most reported, had the highest resistance (36.84% (7/19).ConclusionThere was a high prevalence of contamination with resistant pathogenic bacteria species.Acinetobacterspecies were the most common pathogen. Interventions are needed to mitigate the problem of resistant HAI.

Background Mortality among children with acute illness in low-income and middle-income settings remains unacceptably high and the importance of post-discharge mortality is increasingly recognised. We aimed to explore the epidemiology of deaths among young children with acute illness across sub-Saharan Africa and south Asia to inform the development of interventions and improved guidelines. Methods In this prospective cohort study, we enrolled children aged 2–23 months with acute illness, stratified by nutritional status defined by anthropometry (ie, no wasting, moderate wasting, or severe wasting or kwashiorkor), who were admitted to one of nine hospitals in six countries across sub-Saharan Africa and south Asia between Nov 20, 2016, and Jan 31, 2019. We assisted sites to comply with national guidelines. Co-primary outcomes were mortality within 30 days of hospital admission and post-discharge mortality within 180 days of hospital discharge. A priori exposure domains, including demographic, clinical, and anthropometric characteristics at hospital admission and discharge, as well as child, caregiver, and household-level characteristics, were examined in regression and survival structural equation models. Findings Of 3101 children (median age 11 months [IQR 7–16]), 1120 (36·1%) had no wasting, 763 (24·6%) had moderate wasting, and 1218 (39·3%) had severe wasting or kwashiorkor. Of 350 (11·3%) deaths overall, 234 (66·9%) occurred within 30 days of hospital admission and 168 (48·0%) within 180 days of hospital discharge. 90 (53·6%) post-discharge deaths occurred at home. The proportion of children who died following discharge was relatively preserved across nutritional strata. Numerically large high-risk and low-risk groups could be disaggregated for early mortality and post-discharge mortality. Structural equation models identified direct pathways to mortality and multiple socioeconomic, clinical, and nutritional domains acting indirectly through anthropometric status. Interpretation Among diverse sites in Africa and south Asia, almost half of mortality occurs following hospital discharge. Despite being highly predictable, these deaths are not addressed in current guidelines. A fundamental shift to a child-centred, risk-based approach to inpatient and post-discharge management is needed to further reduce childhood mortality, and clinical trials of these approaches with outcomes of mortality, readmission, and cost are warranted.

Introduction: Many acutely ill children in low- and middle-income settings have a high risk of mortality both during and after hospitalisation despite guideline-based care. Understanding the biological mechanisms underpinning mortality may suggest optimal pathways to target for interventions to further reduce mortality. The Childhood Acute Illness and Nutrition (CHAIN) Network (www.chainnnetwork.org) Nested Case-Cohort Study (CNCC) aims to investigate biological mechanisms leading to inpatient and post-discharge mortality through an integrated multi-omic approach. Methods and analysis; The CNCC comprises a subset of participants from the CHAIN cohort (1278/3101 hospitalised participants, including 350 children who died and 658 survivors, and 270/1140 well community children of similar age and household location) from nine sites in six countries across sub-Saharan Africa and South Asia. Systemic proteome, metabolome, lipidome, lipopolysaccharides, haemoglobin variants, toxins, pathogens, intestinal microbiome and biomarkers of enteropathy will be determined. Computational systems biology analysis will include machine learning and multivariate predictive modelling with stacked generalization approaches accounting for the different characteristics of each biological modality. This systems approach is anticipated to yield mechanistic insights, show interactions and behaviours of the components of biological entities, and help develop interventions to reduce mortality among acutely ill children. Ethics and dissemination. The CHAIN Network cohort and CNCC was approved by institutional review boards of all partner sites. Results will be published in open access, peer reviewed scientific journals and presented to academic and policy stakeholders. Data will be made publicly available, including uploading to recognised omics databases. Trial registration NCT03208725.

Background Antimicrobial resistance (AMR) poses a major threat to human health around the world. Previous publications have estimated the effect of AMR on incidence, deaths, hospital length of stay, and health-care costs for specific pathogen–drug combinations in select locations. To our knowledge, this study presents the most comprehensive estimates of AMR burden to date. Methods We estimated deaths and disability-adjusted life-years (DALYs) attributable to and associated with bacterial AMR for 23 pathogens and 88 pathogen–drug combinations in 204 countries and territories in 2019. We obtained data from systematic literature reviews, hospital systems, surveillance systems, and other sources, covering 471 million individual records or isolates and 7585 study-location-years. We used predictive statistical modelling to produce estimates of AMR burden for all locations, including for locations with no data. Our approach can be divided into five broad components: number of deaths where infection played a role, proportion of infectious deaths attributable to a given infectious syndrome, proportion of infectious syndrome deaths attributable to a given pathogen, the percentage of a given pathogen resistant to an antibiotic of interest, and the excess risk of death or duration of an infection associated with this resistance. Using these components, we estimated disease burden based on two counterfactuals: deaths attributable to AMR (based on an alternative scenario in which all drug-resistant infections were replaced by drug-susceptible infections), and deaths associated with AMR (based on an alternative scenario in which all drug-resistant infections were replaced by no infection). We generated 95% uncertainty intervals (UIs) for final estimates as the 25th and 975th ordered values across 1000 posterior draws, and models were cross-validated for out-of-sample predictive validity. We present final estimates aggregated to the global and regional level. Findings On the basis of our predictive statistical models, there were an estimated 4·95 million (3·62–6·57) deaths associated with bacterial AMR in 2019, including 1·27 million (95% UI 0·911–1·71) deaths attributable to bacterial AMR. At the regional level, we estimated the all-age death rate attributable to resistance to be highest in western sub-Saharan Africa, at 27·3 deaths per 100 000 (20·9–35·3), and lowest in Australasia, at 6·5 deaths (4·3–9·4) per 100 000. Lower respiratory infections accounted for more than 1·5 million deaths associated with resistance in 2019, making it the most burdensome infectious syndrome. The six leading pathogens for deaths associated with resistance (Escherichia coli, followed by Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa) were responsible for 929 000 (660 000–1 270 000) deaths attributable to AMR and 3·57 million (2·62–4·78) deaths associated with AMR in 2019. One pathogen–drug combination, meticillin-resistant S aureus, caused more than 100 000 deaths attributable to AMR in 2019, while six more each caused 50 000–100 000 deaths: multidrug-resistant excluding extensively drug-resistant tuberculosis, third-generation cephalosporin-resistant E coli, carbapenem-resistant A baumannii, fluoroquinolone-resistant E coli, carbapenem-resistant K pneumoniae, and third-generation cephalosporin-resistant K pneumoniae. Interpretation To our knowledge, this study provides the first comprehensive assessment of the global burden of AMR, as well as an evaluation of the availability of data. AMR is a leading cause of death around the world, with the highest burdens in low-resource settings. Understanding the burden of AMR and the leading pathogen–drug combinations contributing to it is crucial to making informed and location-specific policy decisions, particularly about infection prevention and control programmes, access to essential antibiotics, and research and development of new vaccines and antibiotics. There are serious data gaps in many low-income settings, emphasising the need to expand microbiology laboratory capacity and data collection systems to improve our understanding of this important human health threat. Funding Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Health and Social Care using UK aid funding managed by the Fleming Fund.

ObjectivesMortality during acute illness among children in low- and middle-income settings remain unacceptably high and there is increasing recognition of the importance of post-discharge mortality. A comprehensive understanding of pathways underlying mortality among acutely ill children is needed to develop interventions and improve guidelines. We aimed to determine the incidence, timing and contributions of proximal and underlying exposures for mortality among acutely ill young children from admission to hospital until 6 months after discharge in sub-Saharan Africa and South Asia in the context of guideline-based care.DesignA prospective stratified cohort study recruiting acutely ill children at admission to hospital with follow up until 180 days after discharge from hospital (November 2016-July 2019).SettingNine urban and rural hospitals in sub-Saharan Africa and South Asia across a range of facility levels, and local prevalences of HIV and malaria.ParticipantsInclusion criteria were age 2-23 months, admission to hospital with acute, non-traumatic medical illness and stratified into three groups by anthropometry. Children were excluded if currently receiving pulmonary resuscitation, had a known condition requiring surgery within 6 months or known terminal illness with death expected within 6 months.Main outcome measuresAcute mortality occurring within 30-days from admission; post-discharge mortality within 180-days from discharge; characteristics with direct and indirect associations with mortality within a multi-level a priori framework including demographic, clinical, anthropometric characteristics at admission and discharge from hospital, and pre-existing child-, caregiver- and household-level characteristics.ResultsOf 3101 participants (median age 11 months), 1218 were severely wasted/kwashiorkor, 763 moderately wasted and 1120 were not wasted. Of 350 deaths, 182 (52%) occurred during index admission, 234 (67%) within 30-days of admission and 168 (48%) within 180-days post-discharge. Ninety (54%) post-discharge deaths occurred at home. The ratio of inpatient to post-discharge mortality was consistent across anthropometric strata and sites. Large high and low risk groups could be disaggregated for both early and post-discharge mortality. Structural equation models identified direct pathways to mortality and multiple socioeconomic, clinical and nutritional domains acting indirectly through anthropometric status.ConclusionsAmong diverse sites in Africa and South Asia, almost half of mortality occurs post-discharge. Despite being highly predictable, these deaths are not addressed in current guidelines. A fundamental shift to a risk-based approach to inpatient and post-discharge management is needed to further reduce childhood mortality and clinical trials of these approaches with outcomes of mortality, readmission and cost are warranted.Trial RegistrationClinicalTrials.gov: NCT03208725

BackgroundMalnutrition increases risk of acquiring infections but clinical characteristics and hospital outcomes among children in low resource settings with high rates of antimicrobial resistance have not been clearly described.AimOur main aim was to ascertain prevalence of bacteraemia in hospitalised children at Queen Elizabeth Central Hospital, Malawi.MethodsWe conducted a secondary analysis of a prospective study of children who had a blood culture collected during hospitalisation.ResultsOut of 175 children who had blood cultures collected during hospitalisation, 75 had severe acute malnutrition (SAM), 31 moderate acute malnutrition (MAM), and 69 no acute malnutrition (NAM). Twelve (7%) had bacteraemia (8 SAM, 1 MAM, 3 NAM) and seventeen (10%) died (14 SAM, 2 MAM, 1 NAM). Fever, vomiting and convulsions were least common in SAM (69%, 37%, 1%) compared to MAM (90%, 81%, 10%) and NAM (99%, 46%, 29%; pSalmonella Typhimurium (31%) and Escherichia coli (23%). High rates of bacterial resistance were noted to gentamicin (58%), a first-line antibiotic, and ceftriaxone (33%), a second-line antibiotic.ConclusionsMortality and bacteraemia rates are highest in hospitalised children with SAM. Despite this, SAM children do not present with typical clinical features, including fever, vomiting and convulsions. Given the high rate of antimicrobial resistance in this setting, a high index of infection clinical suspicion, awareness of local susceptibility patterns and evidence-based antibiotic guidelines are needed to optimise clinical care and antimicrobial stewardship.Lay SummaryMalnutrition increases the risk of having an infection but symptoms and hospital outcomes among children with malnutrition, in countries like Malawi with high rates of antimicrobial resistance, have not been clearly described. This study describes a study of children who had a blood culture collected during admission to Queen Elizabeth Central Hospital, Malawi. Of 175 children who had blood cultures collected, 12 (7%) had a bacteria found (‘bactaeriemia’) and 17 (10%) died. Fever, vomiting and convulsions were significantly less common in severe malnutrition compared to children with moderate malnutrition and those with no malnutrition. Mortality was significantly higher in those with bacteraemia than without. High rates of bacterial resistance were noted to first- and second-line antibiotics. Mortality and bacteraemia rates are highest in hospitalised children with SAM even though they do not present with typical features of bacteraemia.

Background Yellow fever, Dengue, West Nile and Zika viruses are re-emerging mosquito-borne Flaviviruses of public health concern. However, the extent of human exposure to these viruses and associated disease burden in Kenya and Africa at large remains unknown. We assessed the seroprevalence of Yellow fever and other Flaviviruses in human populations in West Pokot and Turkana Counties of Kenya. These areas border Uganda, South Sudan and Ethiopia where recent outbreaks of Yellow fever and Dengue have been reported, with possibility of spillover to Kenya. Methodology Human serum samples collected through a cross-sectional survey in West Pokot and Turkana Counties were screened for neutralizing antibodies to Yellow fever, Dengue-2, West Nile and Zika virus using the Plaque Reduction Neutralization Test (PRNT). Seroprevalence was compared by county, site and important human demographic characteristics. Adjusted odds ratios (aOR) were estimated using Firth logistic regression model. Results Of 877 samples tested, 127 neutralized with at least one of the four flaviviruses (14.5, 95% CI 12.3–17.0%), with a higher proportion in Turkana (21.1%, n = 87/413) than in West Pokot (8.6%, n = 40/464). Zika virus seroprevalence was significantly higher in West Pokot (7.11%) than in Turkana County (0.24%; χ2 P

We describe a novel virus, designated Ntepes virus (NPV), isolated from sand flies in Kenya. NPV has the characteristic phlebovirus trisegmented genome architecture and is related to, but distinct from, Gabek Forest phlebovirus. Diverse cell cultures derived from wildlife, livestock, and humans were susceptible to NPV, with pronounced permissiveness in swine and rodent cells. NPV infection of newborn mice caused rapid and fatal illness. Permissiveness for NPV replication in sand fly cells, but not mosquito cells, suggests a vector-specific adaptation. Specific neutralizing antibodies were found in 13.9% (26/187) of human serum samples taken at the site of isolation of NPV as well as a disparate site in northeastern Kenya, suggesting a wide distribution. We identify a novel human-infecting arbovirus and highlight the importance of rural areas in tropical Africa for arbovirus surveillance as well as extending arbovirus surveillance to include hematophagous arthropods other than mosquitoes.

Background: Good Clinical Laboratory Practice (GCLP) is a standard that helps ensure the quality and reliability of research data through principles of Good Laboratory Practice (GLP) and Good Clinical Practice (GCP). The implementation of GCLP includes careful documentation of procedures, competencies and safety measures. Implementation of GCLP is influenced by existing resources and quality systems, thus laboratories in low- and middle-income countries may face additional challenges. Methods: This paper describes implementation of Good Clinical Laboratory Practice (GCLP) at the Kenya Medical Research Institute-Center for Microbiology Research (KEMRI-CMR) as part of a quality system to support medical research. This study employed assessment, twinning (institutional mentorship) model, conducting relevant training workshops and Kaizen 5S approaches to implement an effective quality management system using GCLP standard. This was achieved through a collaboration between the KEMRI/Wellcome Trust Research Programme (KWTRP) and KEMRI-CMR. The aim was compliance and continuous monitoring to meet international GCLP standards in a way that could be replicated in other research organizations. Results: Following a baseline assessment in March 2017, training, mentorship and a cycle of quality audit and corrective action using a Kaizen 5S approach (sorting, setting in order, shining, standardizing and sustaining) was established. Laboratory personnel were trained in writing standard operating procedures and analytical plans, microbiological techniques, and good documentation practice. Mid-term and exit assessments demonstrated significant declines in non-conformances across all GCLP elements. KEMRI-CMR achieved GCLP accreditation in May 2018 by Qualogy Ltd (UK). Conclusions: Involving all the laboratory personnel in implementation of quality management system processes is critical to success. An institutional mentorship (twinning) approach shows potential for future collaborations between accredited and non-accredited organizations to accelerate the implementation of high-quality management systems and continuous improvement.

Introduction Multiple outbreaks of Rift Valley Fever (RVF) with devastating effects have occurred in East Africa. These outbreaks cause disease in both livestock and humans and affect poor households most severely. Communities living in areas practicing nomadic livestock movement may be at higher risk of infection. This study sought to i) determine the human exposure to Rift Valley fever virus (RVFV) in populations living within nomadic animal movement routes in Kenya; and ii) identify risk factors for RVFV infection in these communities. Methods A cross-sectional descriptive study design was used. Samples were collected from the year 2014 to 2015 in a community-based sampling exercise involving healthy individuals aged ≥18 years from Isiolo, Tana River, and Garissa counties. In total, 1210 samples were screened by ELISA for the presence of immunoglobulin IgM and IgG antibodies against RVFV. Positive results were confirmed by plaque reduction neutralization test. Results Overall, IgM and IgG prevalence for all sites combined was 1.4% (95% CI 0.8–2.3%) and 36.4% (95% CI 33.8–39.2%), respectively. Isiolo County recorded a non-significant higher IgG prevalence of 38.8% than Garissa 35.9% and Tana River 32.2% (Chi square = 2.5, df = 2, p = 0.287). Males were significantly at higher risk of infection by RVFV than females (OR = 1.67, 95% CI 1.17–2.39, p, Author summary Rift Valley fever (RVF) is a neglected mosquito-borne zoonotic disease that causes major outbreaks and economic harm to human and ruminants health leading to increased poverty within affected communities. RVF is caused by RVF virus (RVFV) affecting humans and a wide range of ruminants. The virus is transmitted through bites from mosquitoes and exposure to blood, body fluids, or tissues of infected ruminants. It was first isolated in Kenya in 1930 and several outbreaks have been recorded in many countries in sub-Saharan Africa. We studied pastoralist communities living along livestock migratory routes. Migratory livestock do move long distances in search of water and pasture and may be at higher risk of exposure to RVFV. We also determined risk factors for RVFV infection by studying age, gender, contact with animals through birthing, and occupation. Prevention and control of RVFV infection can target significant risk factors to prevent spread and re-occurrence of outbreaks.

Introduction: Arboviruses cause emerging and re-emerging infections affecting humans and animals. They are spread primarily by blood-sucking insects such as mosquitoes, ticks, midges, and sandflies. Changes in climate, ecology, demographic, land-use patterns, and increasing global travel have been linked to an upsurge in arboviral disease. Outbreaks occur periodically followed by persistent low-level circulation. Aim: This study was undertaken to determine the seroepidemiology of selected arboviruses among febrile patients in selected lake/river basins of Kenya. Methods: Using a hospital-based cross-sectional descriptive survey, febrile patients were recruited and their serum samples tested for exposure to immunoglobulin M (IgM) and IgG antibodies against Crimean–Congo hemorrhagic fever virus (CCHFV), Rift Valley fever virus (RVFV), West Nile virus (WNV), and chikungunya virus (CHIKV). Samples positive for CHIKV and WNV were further confirmed by the plaque reduction neutralization test (PRNT). Results: Of the 379 samples examined, 176 were IgG positive for at least one of these arboviruses (46.4%, 95% confidence interval [CI] 41.4–51.5%). Virus-specific prevalence for CCHF, RVF, WN, and CHIK was 25.6%, 19.5%, 12.4%, and 2.6%, respectively. These prevalences varied significantly with geographical site (p

Background Rift Valley fever (RVF) is a mosquito-borne viral zoonosis of ruminants and humans that causes outbreaks in Africa and the Arabian Peninsula with significant public health and economic consequences. Humans become infected through mosquito bites and contact with infected livestock. The virus is maintained between outbreaks through vertically infected eggs of the primary vectors of Aedes species which emerge following rains with extensive flooding. Infected female mosquitoes initiate transmission among nearby animals, which amplifies virus, thereby infecting more mosquitoes and moving the virus beyond the initial point of emergence. With each successive outbreak, RVF has been found to expand its geographic distribution to new areas, possibly driven by available vectors. The aim of the present study was to determine if RVF virus (RVFV) transmission risk in two different ecological zones in Kenya could be assessed by looking at the species composition, abundance and distribution of key primary and secondary vector species and the level of virus activity. Methodology Mosquitoes were trapped during short and long rainy seasons in 2014 and 2015 using CO2 baited CDC light traps in two counties which differ in RVF epidemic risk levels(high risk Tana-River and low risk Isiolo),cryo-preserved in liquid nitrogen, transported to the laboratory, and identified to species. Mosquito pools were analyzed for virus infection using cell culture screening and molecular analysis. Findings Over 69,000 mosquitoes were sampled and identified as 40 different species belonging to 6 genera (Aedes, Anopheles, Mansonia, Culex, Aedeomyia, Coquillettidia). The presence and abundance of Aedes mcintoshi and Aedes ochraceus, the primary mosquito vectors associated with RVFV transmission in outbreaks, varied significantly between Tana-River and Isiolo. Ae. mcintoshi was abundant in Tana-River and Isiolo but notably, Aedes ochraceus found in relatively high numbers in Tana-River (n = 1,290), was totally absent in all Isiolo sites. Fourteen virus isolates including Sindbis, Bunyamwera, and West Nile fever viruses were isolated mostly from Ae. mcintoshi sampled in Tana-River. RVFV was not detected in any of the mosquitoes. Conclusion This study presents the geographic distribution and abundance of arbovirus vectors in two Kenyan counties, which may assist with risk assessment for mosquito borne diseases., Author summary Rift Valley fever (RVF) is a mosquito-borne disease caused by the Rift Valley fever virus (RVFV) transmitted by diverse species of mosquitoes broadly classified into primary vectors and secondary vectors. Primary vectors consist of floodwater Aedes (e.g Ae. mcintoshi, Ae. ochraceus, Ae. sudanensis, Ae. dentatus etc), known to maintain the virus in their drought resistant eggs which are deposited on wet soils on low lying depressions on land, remaining viable in dry soil for variable number of years during dry periods. Following heavy persistent rains with flooding, such eggs hatch with a proportion already infected. Emerging infected adult female mosquitoes initiate transmission to nearby animals which serve as amplifiers, infecting more mosquitoes resulting in outbreaks. Another group of mosquito species, the secondary vectors, mainly from the Culex (Culex pipiens and Culex poicilipes), and other potential vectors including, Culex univittatus, Anopheles and Mansonia species may take over such breeding sites, breed in abundance and incidentally propagate RVFV transmission. Outbreaks of RFV occur at varying intensities among livestock in different counties in Kenya, and counties are classified into high, medium and low risk zones. We assessed the species composition, distribution and abundance of primary and secondary vectors in two counties; Isiolo (medium risk) and Tana-River (high risk). Striking difference in composition of primary vector species between Isiolo and Tana-River was observed suggesting that vector species composition in different regions could further be applied to assess risk of RVF outbreaks and intensity. We propose further evaluation of vector species surveillance as an additional risk assessment tool for RVFV and other mosquito borne viruses.

Background Aedes aegypti is a competent arthropod vector of chikungunya virus (CHIKV). The rate at which the virus disseminate in the vector is limited by temperature of their environment which can be an important determinant of geographical and seasonal limits to transmission by the arthropods in the tropics. This study investigated the vector competence of Ae. aegypti for CHIKV at ambient temperature of 32 and 26 °C (Coastal and Western Kenya respectively) reared at Extrinsic Incubation Temperature (EIT) of 32 and 26 °C that resembles those in the two regions. Methods Ae. aegypti eggs were collected from coastal and Western Kenya, hatched in the insectary and reared to F1 generation. Four-day old mosquitoes were exposed to CHIKV through a membrane feeding. They were then incubated in temperatures mimicking the mean annual temperatures for Trans-Nzoia (26 °C) and Lamu (32 °C). After every 7, 10 and 13 days post infection (DPI); one third of exposed mosquitoes were sampled and assayed for virus infection and dissemination. Results The midgut infection rates (MIR) of Ae. aegypti sampled from Coastal Region was significantly (p

Background Mosquito lifespan can influence the circulation of disease causing pathogens because it affects the time available for infection and transmission. The life-cycle of mosquitoes is determined by intrinsic and environmental factors, which can include the availability of hosts and suitable resting environments that shelter mosquitoes from extreme temperature and desiccating conditions. This study determined the parity rates (an indirect measure of survival) and plant resting preference of vectors of Rift Valley fever (RVF) in northeastern Kenya. Methods Resting mosquitoes were trapped during the rainy and the dry season using a Prokopack aspirator from vegetation, whereas general adult populations were trapped using CDC light traps. At each site, sampling was conducted within a 1 km2 area, subdivided into 500 × 500 m quadrants and four 250 × 250 m sub-quadrants from which two were randomly selected as sampling units. In each sampling unit, plants were randomly selected for aspiration of mosquitoes. Only Aedes mcintoshi and Ae. ochraceus were dissected to determine parity rates while all mosquito species were used to assess plant resting preference. Results Overall, 1124 (79 %, 95 % CI = 76.8–81.1 %) mosquitoes were parous. There was no significant difference in the number of parous Ae. mcintoshi and Ae. ochraceus. Parity was higher in the rainy season than in the dry season. Daily survival rate was estimated to be 0.93 and 0.92 among Ae. ochraceus and Ae. mcintoshi, respectively. Duosperma kilimandscharicum was the most preferred plant species with the highest average capture of primary (3.64) and secondary (5.83) vectors per plant, while Gisekia africana was least preferred. Conclusion Survival rate of each of the two primary vectors of RVF reported in this study may provide an indication that these mosquitoes can potentially play important roles in the circulation of diseases in northern Kenya. Resting preference of the mosquitoes in vegetation may influence their physiology and enhance longevity. Thus, areas with such vegetation may be associated with an increased risk of transmission of arboviruses to livestock and humans.

Background: Lassa fever is an acute, highly infectious viral haemorrhagic illness caused by Lassa fever virus. The reservoir is Mastomys natalensis. The disease is endemic in West African sub region causing 300,000-500,000 infections annually, with about 500 deaths. In March, 2012, we investigated a reported outbreak of Lassa fever in Taraba State, Nigeria to confirm the outbreak, determine its extent, characterize the outbreak and institute public health actions. Methods & Materials: We reviewed hospital records and used IDSR standard case definition for Lassa fever to identify and linelist cases. A suspected case was defined as “any person with severe febrile illness not responsive to the usual causes of fever in the area with or without sore-throat and at least one of the following: bloody stools, vomiting blood, bleeding into the skin and unexplained bleeding from the nose, vagina or eyes”. A standardized line-listing formwas developed to capture socio-demographic and clinical information of the cases. Various exposure factors including age, gender, occupation and contact history were examined. Results:A total of 35 caseswere recorded. Nine of 35 caseswere laboratory confirmed (25.7%). Altogether, 14 deaths were recorded giving a case fatality rate of 40%. Majority of the cases belonged to the age group 25-34 years (40%) with females constituting 51%. Most of the caseswere healthcareworkers (22.9%). The commonest presenting features were fever (85.7%), cough (28.6%), bleeding from orifices or into skin (25.7%) and headache (20%). In addition, the State’s Epidemic Management Committee was non-functional resulting in uncoordinated response to the outbreak. There were many exposure factors to Lassa fever such as over-crowding, drying of food items along high ways and bush burning and there was low index of suspicion of Lassa fever among health care workers. Conclusion: There was a confirmed outbreak of Lassa fever in Taraba State mostly affecting healthcare workers. Community sensitization and sensitization of health workers in Taraba State on Lassa fever were carried out. We recommended that the State should reactivate its Emergency Management Committee, surveillance of Lassa fever should be strengthened, Public/Health workers sensitization activities should be scaled up and records keeping should be improved.

Background West Nile virus (WNV) has a wide geographical distribution and has been associated to cause neurological disease in humans and horses. Mosquitoes are the traditional vectors for WNV; however, the virus has also been isolated from tick species in North Africa and Europe which could be a means of introduction and spread of the virus over long distances through migratory birds. Although WNV has been isolated in mosquitoes in Kenya, paucity of genetic and pathogenicity data exists. We previously reported the isolation of WNV from ticks collected from livestock and wildlife in Ijara District of Kenya, a hotspot for arbovirus activity. Here we report the full genome sequence and phylogenetic investigation of their origin and relation to strains from other regions. Methods A total of 10,488 ticks were sampled from animal hosts, classified to species and processed in pools of up to eight ticks per pool. Virus screening was performed by cell culture, RT-PCR and sequencing. Phylogenetic analysis was carried out to determine the evolutionary relationships of our isolate. Results Among other viruses, WNV was isolated from a pool of Rhipicephalus pulchellus sampled from cattle, sequenced and submitted to GenBank (Accession number: KC243146). Comparative analysis with 27 different strains revealed that our isolate belongs to lineage 1 and clustered relatively closely to isolates from North Africa and Europe, Russia and the United States. Overall, Bayesian analysis based on nucleotide sequences showed that lineage 1 strains including the Kenyan strain had diverged 200 years ago from lineage 2 strains of southern Africa. Ijara strain collected from a tick sampled on livestock was closest to another Kenyan strain and had diverged 20 years ago from strains detected in Morocco and Europe and 30 years ago from strains identified in the USA. Conclusion To our knowledge, this is the first characterized WNV strain isolated from R. pulchellus. The epidemiological role of this tick in WNV transmission and dissemination remains equivocal but presents tick verses mosquito virus transmission has been neglected. Genetic data of this strain suggest that lineage 1 strains from Africa could be dispersed through tick vectors by wild migratory birds to Europe and beyond. Electronic supplementary material The online version of this article (doi:10.1186/s13071-014-0542-2) contains supplementary material, which is available to authorized users.

Rift Valley fever virus causes an important zoonotic disease of humans and small ruminants in Eastern Africa and is spread primarily by a mosquito vector. In this region, it occurs as epizootics that typically occur at 5–15-year intervals associated with unusual rainfall events. It has hitherto been known that the virus is maintained between outbreaks in dormant eggs of the mosquito vector and this has formed the basis of understanding of the epidemiology and control strategies of the disease. We show here that seroconversion and sporadic acute disease do occur during the interepidemic periods (IEPs) in the absence of reported cases in livestock or humans. The finding indicates that previously undetected low-level virus transmission during the IEPs does occur and that epizootics may also be due to periodic expansion of mosquito vectors in the presence of both circulating virus and naïve animals.