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Search Results: 1 - 10 of 16 matches for " Mirdad Kazanji "
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Human T-cell Lymphotropic Virus types I and II (HTLV-I/II) in French Guiana: clinical and molecular epidemiology
Kazanji, Mirdad;Gessain, Antoine;
Cadernos de Saúde Pública , 2003, DOI: 10.1590/S0102-311X2003000500002
Abstract: we review here the epidemiological studies performed by our group on human retrovirus htlv-i and htlv-ii infections and the associated diseases in french guiana since 1984. french guiana is an overseas french administrative district located between brazil and surinam. its population is characterized by a large variety of ethnic groups, including several populations of african origin and various populations of amerindian origin. several epidemiological studies of large samples of pregnant women and in remote villages showed that htlv-i is highly endemic in this area but is restricted to groups of african origin, especially the noir-marrons. in this endemic population, the results of segregation analysis in a genetic epidemiological study were consistent with the presence of a dominant major gene predisposing to htlv-i infection, especially in children. in contrast, htlv-ii infection appears to be rare in french guiana, having been found in only a few individuals of brazilian origin. from a molecular point of view, the htlv-i strains present in the noir-marrons, creoles and amerindians appear to originate from africa, as they belong to the large cosmopolitan molecular subtype a.
Human T-cell Lymphotropic Virus types I and II (HTLV-I/II) in French Guiana: clinical and molecular epidemiology
Kazanji Mirdad,Gessain Antoine
Cadernos de Saúde Pública , 2003,
Abstract: We review here the epidemiological studies performed by our group on human retrovirus HTLV-I and HTLV-II infections and the associated diseases in French Guiana since 1984. French Guiana is an overseas French administrative district located between Brazil and Surinam. Its population is characterized by a large variety of ethnic groups, including several populations of African origin and various populations of Amerindian origin. Several epidemiological studies of large samples of pregnant women and in remote villages showed that HTLV-I is highly endemic in this area but is restricted to groups of African origin, especially the Noir-Marrons. In this endemic population, the results of segregation analysis in a genetic epidemiological study were consistent with the presence of a dominant major gene predisposing to HTLV-I infection, especially in children. In contrast, HTLV-II infection appears to be rare in French Guiana, having been found in only a few individuals of Brazilian origin. From a molecular point of view, the HTLV-I strains present in the Noir-Marrons, Creoles and Amerindians appear to originate from Africa, as they belong to the large cosmopolitan molecular subtype A.
Hepatitis E virus is highly prevalent among pregnant women in Gabon, central Africa, with different patterns between rural and urban areas
Mélanie Caron, Mirdad Kazanji
Virology Journal , 2008, DOI: 10.1186/1743-422x-5-158
Abstract: Hepatitis E virus (HEV) is an enterically transmitted pathogen and is responsible for recent large-scale epidemics of hepatitis around the world, as reported recently in Uganda http://www.promedmail.org webcite, where more than 7500 cases were registered in 1 year [1]. HEV induces self-limiting or acute hepatitis, and the severity can varied from no symptoms to fulminating infection [2]. HEV infections have not been known to become chronic [2]; however, recently, persistent HEV infection, with chronic hepatitis and cirrhosis, has been reported in patients with reduced immune surveillance induced by chemotherapy or post-transplant immune suppression [3,4]. The average mortality rate from HEV infection is 1–4%, principally among adolescents and young adults, but it is still not clear that the severity is age-dependent. For unknown reasons, the mortality rate is higher among pregnant women, especially during the third trimester [5]. In Sudan, a case:fatality ratio of 17.8% was found in an outbreak in Darfur, with a ratio of 31.1% among pregnant women [6].In endemic areas, which include Africa, Asia and the Middle East, HEV outbreaks are waterborne, whereas in non-endemic areas such as Europe, Japan and the USA, sporadic cases of acute hepatitis are usually due to zoonotic foodborne transmission [7]. Bloodborne and perinatal transmission could also occur, but ingestion of fecally-contaminated water remains the main route of HEV transmission. Many HEV outbreaks have been observed in Africa, such as in Ethiopia and Somalia in 1988–1989, Djibouti in 1993, Morocco in 1994, Chad and Sudan in 2004–2005, the Democratic Republic of the Congo in 2006 and Uganda in 2007–2008 [1,8-12]. In the absence of outbreaks, the HEV prevalence in rural populations was 4.4% in Ghana, 14.0% in Burundi, 15.3% in South Africa and 67.7% in Egypt, with a seroprevalence of up to 84.3% among pregnant women [13-16]. There appear to be considerable differences in exposure to HEV in endemic areas.Few d
Acute risk for hepatitis E virus infection among HIV-1-positive pregnant women in central Africa
Caron Mélanie,Bouscaillou Julie,Kazanji Mirdad
Virology Journal , 2012, DOI: 10.1186/1743-422x-9-254
Abstract: Background Hepatitis E virus (HEV), an enterically transmitted pathogen, is highly endemic in several African countries. Pregnant women are at particularly high risk for acute or severe hepatitis E. In Gabon, a central African country, the prevalence of antibodies to HEV among pregnant women is 14.1%. Recent studies have demonstrated unusual patterns of hepatitis E (chronic hepatitis, cirrhosis) among immunodeficient patients. Findings We investigated the prevalence of antibodies to HEV among pregnant women infected with HIV-1 or HTLV-1 in Gabon. Of 243 samples collected, 183 were positive for HIV-1 and 60 for HTLV-1; 16 women (6.6%) had IgG antibodies to HEV. The seroprevalence was higher among HIV-1-infected women (7.1%) than HTLV-1-infected women (5.0%). Moreover, the HIV-1 viral load was significantly increased (p ≤ 0.02) among women with past-HEV exposure (1.3E+05 vs 5.7E+04 copies per ml), whereas no difference was found in HTLV-1 proviral load (9.0E+01 vs 1.1E+03 copies per ml). Conclusions These data provide evidence that HIV-1-infected women are at risk for acute or severe infection if they are exposed to HEV during pregnancy, with an increased viral load.
Simian Foamy Virus in Non-Human Primates and Cross-Species Transmission to Humans in Gabon: An Emerging Zoonotic Disease in Central Africa?
Augustin Mouinga-Ondémé,Mirdad Kazanji
Viruses , 2013, DOI: 10.3390/v5061536
Abstract: It is now known that all human retroviruses have a non-human primate counterpart. It has been reported that the presence of these retroviruses in humans is the result of interspecies transmission. Several authors have described the passage of a simian retrovirus, simian foamy virus (SFV), from primates to humans. To better understand this retroviral “zoonosis” in natural settings, we evaluated the presence of SFV in both captive and wild non-human primates and in humans at high risk, such as hunters and people bitten by a non-human primate, in Gabon, central Africa. A high prevalence of SFV was found in blood samples from non-human primates and in bush meat collected across the country. Mandrills were found to be highly infected with two distinct strains of SFV, depending on their geographical location. Furthermore, samples collected from hunters and non-human primate laboratory workers showed clear, extensive cross-species transmission of SFV. People who had been bitten by mandrills, gorillas and chimpanzees had persistent SFV infection with low genetic drift. Thus, SFV is presumed to be transmitted from non-human primates mainly through severe bites, involving contact between infected saliva and blood. In this review, we summarize and discuss our five-year observations on the prevalence and dissemination of SFV in humans and non-human primates in Gabon.
New Strain of Simian Immunodeficiency Virus Identified in Wild-Born Chimpanzees from Central Africa
Sandrine Souquière, Maria Makuwa, Bettina Sallé, Mirdad Kazanji
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044298
Abstract: Studies of primate lentiviruses continue to provide information about the evolution of simian immunodeficiency viruses (SIVs) and the origin and emergence of HIV since chimpanzees in west–central Africa (Pan troglodytes troglodytes) were recognized as the reservoir of SIVcpzPtt viruses, which have been related phylogenetically to HIV-1. Using in-house peptide ELISAs to study SIV prevalence, we tested 104 wild-born captive chimpanzees from Gabon and Congo. We identified two new cases of SIVcpz infection in Gabon and characterized a new SIVcpz strain, SIVcpzPtt-Gab4. The complete sequence (9093 bp) was obtained by a PCR-based ‘genome walking’ approach to generate 17 overlapping fragments. Phylogenetic analyses of separated genes (gag, pol-vif and env-nef) showed that SIVcpzPtt-Gab4 is closely related to SIVcpzPtt-Gab1 and SIVcpzPtt-Gab2. No significant variation in viral load was observed during 3 years of follow-up, but a significantly lower CD4+ T cells count was found in infected than in uninfected chimpanzees (p<0.05). No clinical symptoms of SIV infection were observed in the SIV-positive chimpanzees. Further field studies with non-invasive methods are needed to determine the prevalence, geographic distribution, species association, and natural history of SIVcpz strains in the chimpanzee habitat in Gabon.
Dynamic Interaction between STLV-1 Proviral Load and T-Cell Response during Chronic Infection and after Immunosuppression in Non-Human Primates
Sandrine Souquière, Augustin Mouinga-Ondemé, Maria Makuwa, Olivier Hermine, Mirdad Kazanji
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006050
Abstract: We used mandrills (Mandrillus sphinx) naturally infected with simian T-cell leukemia virus type 1 (STLV-1) as a model for evaluating the influence of natural STLV-1 infection on the dynamics and evolution of the immune system during chronic infection. Furthermore, in order to evaluate the role of the immune system in controlling the infection during latency, we induced immunosuppression in the infected monkeys. We first showed that the STLV-1 proviral load was higher in males than in females and increased significantly with the duration of infection: mandrills infected for 10–6 years had a significantly higher proviral load than those infected for 2–4 years. Curiously, this observation was associated with a clear reduction in CD4+ T-cell number with age. We also found that the percentage of CD4+ T cells co-expressing the activation marker HLA-DR and the mean percentage of CD25+ in CD4+ and CD8+ T cells were significantly higher in infected than in uninfected animals. Furthermore, the STLV-1 proviral load correlated positively with T-cell activation but not with the frequency of T cells secreting interferon γ in response to Tax peptides. Lastly, we showed that, during immunosuppression in infected monkeys, the percentages of CD8+ T cells expressing HLA-DR+ and of CD4+ T cells expressing the proliferation marker Ki67 decreased significantly, although the percentage of CD8+ T cells expressing HLA-DR+ and Ki67 increased significantly by the end of treatment. Interestingly, the proviral load increased significantly after immunosuppression in the monkey with the highest load. Our study demonstrates that mandrills naturally infected with STLV-1 could be a suitable model for studying the relations between host and virus. Further studies are needed to determine whether the different compartments of the immune response during infection induce the long latency by controlling viral replication over time. Such studies would provide important information for the development of immune-based therapeutic strategies.
Temporal Patterns of Abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and Mitochondrial DNA Analysis of Ae. albopictus in the Central African Republic
Basile Kamgang,Carine Ngoagouni,Alexandre Manirakiza,Emmanuel Nakouné,Christophe Paupy,Mirdad Kazanji
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002590
Abstract: The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae). Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR), where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa.
High Prevalence of Both Humoral and Cellular Immunity to Zaire ebolavirus among Rural Populations in Gabon
Pierre Becquart,Nadia Wauquier,Tanel Mahlak?iv,Dieudonné Nkoghe,Cindy Padilla,Marc Souris,Benjamin Ollomo,Jean-Paul Gonzalez,Xavier De Lamballerie,Mirdad Kazanji,Eric M. Leroy
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009126
Abstract: To better understand Zaire ebolavirus (ZEBOV) circulation and transmission to humans, we conducted a large serological survey of rural populations in Gabon, a country characterized by both epidemic and non epidemic regions. The survey lasted three years and covered 4,349 individuals from 220 randomly selected villages, representing 10.7% of all villages in Gabon. Using a sensitive and specific ELISA method, we found a ZEBOV-specific IgG seroprevalence of 15.3% overall, the highest ever reported. The seroprevalence rate was significantly higher in forested areas (19.4%) than in other ecosystems, namely grassland (12.4%), savannah (10.5%), and lakeland (2.7%). No other risk factors for seropositivity were found. The specificity of anti-ZEBOV IgG was confirmed by Western blot in 138 individuals, and CD8 T cells from seven IgG+ individuals were shown to produce IFN-γ after ZEBOV stimulation. Together, these findings show that a large fraction of the human population living in forested areas of Gabon has both humoral and cellular immunity to ZEBOV. In the absence of identified risk factors, the high prevalence of “immune” persons suggests a common source of human exposure such as fruits contaminated by bat saliva. These findings provide significant new insights into ZEBOV circulation and human exposure, and raise important questions as to the human pathogenicity of ZEBOV and the existence of natural protective immunization.
Phylogeography, Risk Factors and Genetic History of Hepatitis C Virus in Gabon, Central Africa
Richard Njouom, Mélanie Caron, Guillaume Besson, Guy-Roger Ndong-Atome, Maria Makuwa, Régis Pouillot, Dieudonné Nkoghé, Eric Leroy, Mirdad Kazanji
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042002
Abstract: Background The epidemiological and molecular characteristics of hepatitis C virus (HCV) infection in the general population have been poorly investigated in Africa. The aim of this study was to determine the prevalence, genotype distribution and epidemic history of HCV in the Gabonese general population. Methods/Principal Findings A total of 4042 sera collected from adults in 220 villages in all nine administrative areas of the country were screened for antibodies to HCV. HCV NS5B region sequencing was performed for molecular characterization and population genetic analyses. Of 4042 tested sera, 455 (11.2%) were positive. The seroprevalence of HCV varied significantly by administrative area, with the highest rate in Ogooué-Lolo province (20.4%) and the lowest in Ogooué-Maritine province (3.7%). History of parenteral injections, past hospital admission and age over 55 years were independent risk factors for HCV infection (p<0.0001). Phylogenetic analyses showed that 91.9% of the strains were genotype 4 (HCV-4), 5.7% genotype 1 and 2.2% genotype 2. HCV-4 strains were highly heterogeneous, with more than eight subtypes; subtype 4e predominated (57.3%). Coalescence analyses indicated that subtype 4e was the oldest, with an estimated most recent common ancestor of 1702 [95% CI, 1418–1884]. The epidemic profile indicated that it spread exponentially during the first part of the 20th century, probably by iatrogenic transmission. Conclusions/Significance These results confirm the endemicity of HCV subtype 4e in Gabon and show that its spread is due to a cohort effect, with previous, possibly iatrogenic events. More extensive epidemiological studies are needed to better characterize the route of transmission and the dissemination of HCV in Gabon.
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