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International audience; Zika virus (ZIKV) is an arthropod-borne RNA virus (arbovirus), belonging to the Spondweni serogroup. ZIKV was first described in Africa in 1947 and remained sporadic until Micronesia outbreak in 2007, which was followed by outbreaks in the Pacific Islands, Latin America, and the Caribbean. Subsequent to the epidemics, ZIKV revealed its severity as virus was sexually transmissible, and it was associated with serious fetal and neurological complications. ZIKV originated from Africa; however, little is known about the epidemiology of the virus in African populations. Following a recent study in Cameroon that evidenced low ZIKV epidemiology associated with a presumptive (peri-)sylvatic transmission, we performed a seroepidemiological study in Republic of the Congo, neighbor of Cameroon. To accomplish this, 386 serum specimens from volunteer blood donors collected in 2011 from rural and urban areas of Republic of the Congo were tested with ZIKV-specific methodology; primary screening with anti-NS1 ZIKV IgG ELISA followed by confirmation with cytopathic effect (CPE)-based virus neutralization test (VNT). ZIKV seropositivity was determined as low as 1.8%, varying slightly between urban and rural areas (1.7% and 3.6%). These results demonstrate that the majority of the population of Republic of the Congo is immunologically naïve against ZIKV with a presumptive (peri-)sylvatic transmission cycle, which emphasizes the importance of surveillance studies in Africa.

Introduction: Viral hepatitis B is the most formidable and confusing of all viral hepatitis, given its cirrhogenic and carcinogenic potential. The objective of the study is to characterize the molecular profile of hepatitis virus B in northern Congo. Materials and Methods: This was a descriptive and cross-sectional study that was carried out between January and September 2014, that is 9 months, in the establishments of the National Center for Blood Transfusion (CNTS) of the 4 departments of the north of the Congo. Epidemiological, serological and molecular variables (HBsAg, HBV DNA, genotypes and subtypes) were studied. The HBs antigen was searched by rapid test and confirmed by ELISA. For all positive donors, conventional and specific gene extraction and amplification techniques were performed for the identification of genotypes and subtypes from the serum. Results: A total of 892 donors were included. The average age was 35.36 ± 12.36 years with extremes ranging from 18 to 65 years old. The sex ratio (M/F) was 3.3. The prevalence of HBV was 8.6%. The viral DNA of HBV was amplified in 83.1%. Four genotypes were found: E (40.6%), A (3.1%), B (3.1%) and C (1.6%). Two cases of co-infection were identified: E/A (15.6%) and B/C (1.6%). Subgenotypes A1, B2 and C1 were highlighted. Conclusion: The prevalence of HBV is high, HBV infection remains a major public health problem for blood donors in Congo. Genotypes E, A, B, C as well as subtypes A1, B2, C1 have been identified in northern Congo.

Objectif Caracteriser le profil moleculaire du VHB dans les zones de forte endemicite du Congo.

Background Ebola and Marburg viruses (family Filoviridae, genera Ebolavirus and Marburgvirus) cause haemorrhagic fevers in humans, often associated with high mortality rates. The presence of antibodies to Ebola virus (EBOV) and Marburg virus (MARV) has been reported in some African countries in individuals without a history of haemorrhagic fever. In this study, we present a MARV and EBOV seroprevalence study conducted amongst blood donors in the Republic of Congo and the analysis of risk factors for contact with EBOV. Methodology and Findings In 2011, we conducted a MARV and EBOV seroprevalence study amongst 809 blood donors recruited in rural (75; 9.3%) and urban (734; 90.7%) areas of the Republic of Congo. Serum titres of IgG antibodies to MARV and EBOV were assessed by indirect double-immunofluorescence microscopy. MARV seroprevalence was 0.5% (4 in 809) without any identified risk factors. Prevalence of IgG to EBOV was 2.5%, peaking at 4% in rural areas and in Pointe Noire. Independent risk factors identified by multivariate analysis were contact with bats and exposure to birds. Conclusions/Significance This MARV and EBOV serological survey performed in the Republic of Congo identifies a probable role for environmental determinants of exposure to EBOV. It highlights the requirement for extending our understanding of the ecological and epidemiological risk of bats (previously identified as a potential ecological reservoir) and birds as vectors of EBOV to humans, and characterising the protection potentially afforded by EBOV-specific antibodies as detected in blood donors., Author Summary Ebola and Marburg viruses cause haemorrhagic fevers often fatal to humans. Here, we looked for antibodies to Ebola and Marburg viruses (i.e., markers of previous contact with these viruses) in Congolese blood donors with no previous history of haemorrhagic fever. We found serologic evidence for contact with Marburg and Ebola viruses in 0.5% and 2.5% of blood donors, respectively. The circulation of Marburg virus occurs at a very low rate without any identified risk factor. In contrast, prevalence to Ebola virus was peaking at 4% in rural areas and in Pointe Noire city. Importantly, we identified that contacts with bats and birds constituted two independent environmental determinants of exposure. This study confirms that contact with Ebola virus is not infrequent in Congo and can occur in the absence of haemorrhagic fever. It highlights the requirement for further investigating the role of bats and birds in the ecological cycle of Ebola, and for determining whether asymptomatic contact with Ebola virus can provide subsequent protection against severe forms of the Ebola disease.

Background: Chikungunya is an Aedes -borne disease characterised by febrile arthralgia and responsible for massive outbreaks. We present a prospective clinical cohort study and a retrospective serological study relating to a CHIK outbreak, in the Republic of Congo in 2011. Methodology and Findings: We analysed 317 suspected cases, of which 308 (97.2%) lived in the city of Brazzaville (66.6% in the South area). Amongst them, 37 (11.7%) were CHIKV+ve patients (i.e., biologically confirmed by a real-time RT-PCR assay), of whom 36 (97.3%) had fever, 22 (66.7%) myalgia and 32 (86.5%) arthralgia. All tested negative for dengue. The distribution of incident cases within Brazzaville districts was compared with CHIKV seroprevalence before the outbreak (34.4% in 517 blood donors), providing evidence for previous circulation of CHIKV. We applied a CHIK clinical score to 126 patients recruited within the two first day of illness (including 28 CHIKV+ves (22.2%)) with sensitivity (78.6%) and specificity (72.4%) values comparing with those of the referent study in Reunion Island. The negative predictive value was high (92%), but the positive predictive value (45%) indicate poor potential contribution to medical practice to identify CHIKV+ve patients in low prevalence outbreaks. However, the score allowed a slightly more accurate follow-up of the evolution of the outbreak than the criterion "fever+arthralgia". The complete sequencing of a Congolase isolate (Brazza_MRS1) demonstrated belonging to the East/Central/South African lineage and was further used for producing a robust genome-scale CHIKV phylogenetic analysis. Conclusions/Significance: We describe the first Chikungunya outbreak declared in the Republic of Congo. The seroprevalence study conducted amongst blood donors before outbreak provided evidence for previous CHIKV circulation. We suggest that a more systematic survey of the entomological situation and of arbovirus circulation is necessary in Central Africa for better understanding the environmental, microbiological and sociological determinants of emergence.

Half of AIDS dementia cases are associated with HIV-encephalitis or myelin pallor. Another half die with no HIV-related neuropathological changes. Previous observations suggest that cerebral dysfunction may result from more subtle cellular interactions, and that some of them may be mediated by cell adhesion molecules. In the present study the expression by astrocytes and endothelial cells of intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) was analysed as a function of the neuropathological diagnosis, the density of astrogliosis and of HIV-1 positive cells, and of the mental status. Twelve AIDS cases, without focal brain lesion, eight of whom were demented. were selected from a prospective study. They were compared with six control cases with multiple sclerosis, and with six control patients without neurological disease. ICAM-1 and VCAM-1 expression was localized by immunofluorescence and confocal microscopy. HIV protein gp41 1 was detected by immunohistochemistry on adjacent sections. Endothelial expression of ICAM-1 and VCAM-1 was significantly up-regulated in all AIDS patients. VCAM-1 only was related to myelin pallor. The density of VCAM-1 or ICAM-1 positive astrocytes increased in demented AIDS patients, independently of the neuropathological findings or the density of gp41 positive cells. Expression of cell adhesion molecules, together with other secondary mechanisms such as secretion of cytokines may play a role in the pathogenesis of white matter lesions leading to HIV-1-associated cognitive changes.

A retrospective study was conducted during 32 months; from 1 May 2003 to 30 December 2005 in haematology department. The objective of the study was to assess the effectiveness of the anti retroviral therapy 157 patients receiving antiretroviral treatment for at least a twelve month-period and presenting AIDS symptoms based on revised CDC criteria were included. The average number of initial T4 lymphocytes is 133/mm3 (extremes 1 and 385) and the initial plasmatic average viral load, quantified in 96 patients is 214,000 copies (extreme 30,000 et 999,000) The initial antiretroviral combinations were as follows: ZDV or D4T + LMV + NVP (59.2%); ZDV or D4T + LMV + EFV (28.7%), ZDV or D4T + LMV + IDNV (8.9%); ZDV or D4T + DDI + NVP (3.2%). The results of the study are: observance rate during the first 12 months (84%), antiretroviral therapy taken irregularly (10.8%), early submission of therapy (5.2%), weight gain after 24 months: +18 kgs, clinical response globally positive. The immune response is characterised by an average increase of 353/mm3 of CD4 after 24 months. Among 96 patients tested, the plasmatic viral load was undetectable in 71% of cases after a 12 month-follow up. Mild adverse drug effects have been noticed, represented by cutaneous and nervous toxicity anaemia and digestive disorders due to indinavir These therapeutic results confirm the importance of the antiretroviral therapy in the improvement of the quality of life of HIV/AIDS patients but a concern remains on the possible drug resistance still not documented.

The viral C hepatitis is a disease which is often asymptomatic but with a very high risk of death. A prospective survey on multitransfused patients with a high transfusional risk has been conducted between May 1st and September 30th, 2001 in the medical services of the Hospital of Brazzaville. It deals with 252 samples of blood taken on 132 multitransfused patients and 120 control cases who have never been transfused. The screening of antibodies has been performed with ELISA technique by using 2 sensitive tests: the monolisa anti-HCV plus version 2 (Bio-Rad) and BIOTEC HCV a.b. Only monolisa is registered by AFSSAPS. The survey shows a overall seroprevalence of 13.9%: multitransfused patients: 26 out of 132 (19.7%) and control cases 9 out of 120 (7.5%). The prevalence of anti-HCV antibodies is practically similar in both series. It is low among control cases before 20 years old, but important in this same group when the patients are multitransfused. It is very significant among adult control cases, indicating the probability of other transmission modes in this age bracket. Patients suffering from hemoglobinopathy (sickle cell) and from malignant hemopathy paid an heavy toll to the virus with respectively 16.9% and 22% of prevalence even if the sampling is restricted. This results point out the necessary implementation of a systematic screening of all the main viruses before transfusion.

Half of AIDS dementia cases are associated with HIV-encephalitis or myelin pallor. Another half die with no HIV-related neuropathological changes. Previous observations suggest that cerebral dysfunction may result from more subtle cellular interactions. and that some of them may be mediated by cell adhesion molecules. In the present study the expression by astrocytes and endothelial cells of intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) was analysed as a function of the neuropathological diagnosis, the density of astrogliosis and of HIV-1 positive cells, and of the mental status. Twelve AIDS cases, without focal brain lesion, eight of whom were demented, were selected from a prospective study. They were compared with six control cases with multiple sclerosis, and with six control patients without neurological disease. ICAM-1 and VCAM-1 expression was localized by immunofluorescence and confocal microscopy. HIV protein gp41 was detected by immunohistochemistry on adjacent sections. Endothelial expression of ICAM-1 and VCAM-1 was significantly up-regulated in all AIDS patients. VCAM-1 only was related to myelin pallor. The density of VCAM-1 or ICAM-1 positive astrocytes increased in demented AIDS patients, independently of the neuropathological findings or the density of gp41 positive cells. Expression of cell adhesion molecules, together with other secondary mechanisms such as secretion of cytokines may play a role in the pathogenesis of white matter lesions leading to HIV-1-associated cognitive changes.

The authors report results of a prospective study to assess the prevalence of loiasis in populations older than 18 years in two villages of the Likouala district in the Congo: the study took place during a visit to Lopola in 2012 and to Lopola and Lombo in 2013. The prevalence rate was 20%. Loa loa carriers were treated with diethylcarbamazine citrate and celestamine.