New vectors of Rift Valley fever in West Africa.

After an outbreak of Rift Valley fever in Southern Mauritania in 1987, entomologic studies were conducted in a bordering region in Sénégal from 1991 to 1996 to identify the sylvatic vectors of Rift Valley fever virus. The virus was isolated from the floodwater mosquitoes Aedes vexans and Ae. ochraceus. In 1974 and 1983, the virus had been isolated from Ae. dalzieli. Although these vectors differ from the main vectors in East and South Africa, they use the same type of breeding sites and also feed on cattle and sheep. Although enzootic vectors have now been identified in West Africa, the factors causing outbreaks remain unclear

Effect of Parainfluenza Virus Infection on Human Immuno-Inflammatory Genes Expression and Gene Ontology Analysis

Parainfluenza virus (PIV) causes respiratory infections with high rates of morbidity and mortality in Children and immune-deficiency patients worldwide.  The aim of this study is to detect the changes of mRNA expression of 84 human inflammatory genes and gene ontology analysis. From 90 patients only 2 gave positive IgM –PIV test. PIV infection caused over expression of 25 prominent genes (from 168 genes) affect functional pathways, ten of these genes regard as proinflammatory genes. Three genes were down-regulated; this suggests that the host-viral interaction is a cellular response against viral infection.  In conclusion: Gene ontology analysis revealed that PIV stimulated 4 different key role immunological pathways represented by cytokine-cytokine receptor interaction, NOD-like receptor signaling, Toll-like receptor signaling, and asthma pathway. The patients are mostly infected with related subtypes of PIV. These results may help in further analysis of viral-host interaction

Acute Spotted Fever Rickettsiosis among Febrile Patients, Cameroon

Although potential arthropod vectors are abundant in Cameroon, acute febrile illnesses are rarely evaluated for arboviral or rickettsial infections. Serum samples from 234 acutely febrile patients at clinics in Tiko and Buea, Cameroon, were examined for antibodies to Rickettsia africae and African alphaviruses and flaviviruses. These serum samples did not contain antibodies against typhoid, and blood malarial parasites were not detected. Serum samples of 32% contained immunoglobulin M antibodies reactive with R. africae by immunofluorescence assay and were reactive with outer membrane proteins A and B of R. africae by immunoblotting. These findings established a diagnosis of acute rickettsiosis, most likely African tick-bite fever. Hemagglutination inhibition testing of the serum samples also detected antibodies to Chikungunya virus (47%) and flaviviruses (47%). High prevalence of antibodies to arboviruses may represent a major, previously unrecognized public health problem in an area where endemic malaria and typhoid fever have been the principal diagnostic considerations

Rift Valley Fever Outbreak with East-Central African Virus Lineage in Mauritania, 2003

Phylogenetic studies demonstrated that outbreak strains belonged to the East-Central African lineage

Post-Epidemic Chikungunya Disease on Reunion Island: Course of Rheumatic Manifestations and Associated Factors over a 15-Month Period

Although the acute manifestations of Chikungunya virus (CHIKV) illness are well-documented, few data exist about the long-term rheumatic outcomes of CHIKV-infected patients. We undertook between June and September 2006 a retrospective cohort study aimed at assessing the course of late rheumatic manifestations and investigating potential risk factors associated with the persistence of these rheumatic manifestations over 15 months. 147 participants (>16 yrs) with laboratory-confirmed CHIKV disease diagnosed between March 1 and June 30, 2005, were identified through a surveillance database and interviewed by telephone. At the 15-month-period evaluation after diagnosis, 84 of 147 participants (57%) self-reported rheumatic symptoms. Of these 84 patients, 53 (63%) reported permanent trouble while 31 (37%) had recurrent symptoms. Age ≥45 years (OR = 3.9, 95% CI 1.7–9.7), severe initial joint pain (OR = 4.8, 95% CI 1.9–12.1), and presence of underlying osteoarthritis comorbidity (OR = 2.9, 95% CI 1.1–7.4) were predictors of nonrecovery. Our findings suggest that long-term CHIKV rheumatic manifestations seem to be a frequent underlying post-epidemic condition. Three independent risk factors that may aid in early recognition of patients with the highest risk of presenting prolonged CHIKV illness were identified. Such findings may be particularly useful in the development of future prevention and care strategies for this emerging virus infection

Clinical Forms of Chikungunya in Gabon, 2010

Chikungunya fever (CHIK) is a disease caused by a virus transmitted to humans by infected mosquitos. The virus is responsible for multiple outbreaks in tropical and temperate areas worldwide, and is now a global concern. Clinical and biological features of the disease are poorly described, especially in Africa, where the disease is neglected because it is considered benign. During a recent CHIK outbreak that occurred in southeast Gabon, we prospectively studied clinical and biological features of 270 virologically confirmed cases. Fever and arthralgias were the predominant symptoms. Furthermore, variable and distinct clinical pictures including pure febrile, pure arthralgic and unusual forms (neither fever nor arthralgias) were detected. No severe forms or deaths were reported. These findings suggest that, during CHIK epidemics, some patients may not have classical symptoms (fever and arthralgias). Local surveillance is needed to detect any changes in the pathogenicity of this virus

Acute Arboviral Infections in Guinea, West Africa, 2006

Acute febrile illnesses comprise the majority of the human disease burden in sub-Saharan Africa. We hypothesized that arboviruses comprised a considerable proportion of undiagnosed febrile illnesses in Guinea and sought to determine the frequency of arboviral disease in two hospitals there. Using a standard case definition, 47 suspected cases were detected in approximately 4 months. Immunoglobulin M antibody capture enzyme-linked immunosorbent assays and plaque-reduction neutralization assays revealed that 63% (30/47) of patients were infected with arboviruses, including 11 West Nile, 2 yellow fever, 1 dengue, 8 chikungunya, and 5 Tahyna infections. Except for yellow fever, these are the first reported cases of human disease from these viruses in Guinea and the first reported cases of symptomatic Tahyna infection in Africa. These results strongly suggest that arboviruses circulate and are common causes of disease in Guinea. Improving surveillance and laboratory capacity for arbovirus diagnoses will be integral to understanding the burden posed by these agents in the region

Séminaire international sur la fièvre jaune en Afrique : actes

WHO Collaborating Centers, or (by default) designated national laboratories, intervene at two levels in the surveillance of yellow fever : (1) upstream, through knowledge and analysis of risk factors linked to vectors and populations, including : collection of entomological data (surveillance of the sylvatic cycle, Kédougou, Senegal), measuring the risk of an outbreak in urban areas (quantity of larvae of #Aedes aegypti$), measuring the national immunity to yellow fever among human populations, developing and reflecting on the capacity to respond at a national level, and advising at the national level on strategies to control yellow fever ; and (2) downstream by furnishing an adapted, rapid response for the diagnosis of suspected cases of yellow fever including : detecting of specific IgM through immunocapture, following-up with virological or molecular (RT-PCR) confirmation, making available transportation and techniques of appropriate preparation of laboratory samples, accepting some of the expenses linked to epidemics, adapting of the surveillance system (based on a case definition). Yellow fever surveillance must be incorporated into the national system of detection and declaration of infectious diseases, but owing to its unique epidemiological aspects, which includes the possiblity of vaccination, a rapid and adapted response means being prepared. (Résumé d'auteur

Vertical transmission of the yellow fever virus by Aedes aegypti (Diptera, Culicidae) : dynamics of infection in F1 adult progeny of orally infected females

Vertical transmission of yellow fever virus from orally infected females to their progeny was experimentally demonstrated in 2 #Aedes aegypti$ colonies from the Dakar and Koungheul regions in Senegal. A total of 10350 F1 adult mosquito progeny were tested. The overall vertical transmission rate was 0.97%, with no significant difference between the Dakar and Koungheul colonies. The infection rates were significantly higher in females (1.15%) than in males (0.74%) in both colonies. The virus was not isolated from the progeny of the first oviposition cycle (OVC1). The true infection rates were 0.27% and 1.99%, respectively, for the OVC2 and OVC3 progeny in the Dakar colony, and 1.1% and 1.48%, respectively, for the OVC2 and OVC3 progeny in the Koungheul colony. The infection rates increased with extrinsic incubation in both male and female offspring of the two colonies, reaching 5.2% in 20-day-old OVC3 female progeny in the Dakar colony. The epidemiologic consequences of these results are discussed. (Résumé d'auteur

Phlébotomes du Sénégal (Diptera - Psychodidae) : peuplement et dynamique des populations de la région de Mont-Rolland

Quatorze espèces de Phlébotomes ont été capturées dans la communauté rurale de Mont-Rolland. Les espèces les plus abondantes sont respectivement : #Sergentomyia dubia$(35,9$ (27,7%) et #S. buxtoni$(24,5$ constitue 99,6% des récoltes contre seulement 0,4% pour le genre #Phlebotomus. L'ensemble du peuplement a présenté un maximum d'abondance en février. Les habitats préférentiels des Phlébotomes sont, dans l'ordre d'abondance d'individus capturés les trous d'arbres, les termitières et les terriers. #S. dubia est l'espèce dominante dans les trous d'arbres. Elle est remplacée par #S. buxtoni dans les termitières et par #S. schwetzi dans les terriers. (Résumé d'auteur