In South America, dengue is the arbovirus-transmitted disease with the highest incidence. Unlike other arboviruses, wild mammals have no confirmed role in the cycle of dengue in the neotropics, although serological studies have suggested a possible secondary amplification cycle involving mammals other than nonhuman primates. In French Guiana, where all four serotypes (DENV-1, DENV-2, DENV-3, DENV-4) are present, the disease is endemic with outbreak events. To determine whether wild mammals can be infected by DENV, rodents, marsupials, and bats were captured over several periods, from 2001 to 2007, at two sites. The first location is a secondary forest surrounded by an urban area where dengue is endemic. The second location is a forest edge site where the disease has not yet emerged. A total of 10,000 trap-nights were performed and 616 mammals were captured. RNAs representing the four DENV serotypes were detected at both sites by reverse-transcriptase polymerase chain reaction in the livers and/or sera of 92 mammals belonging to 14 out of 32 species distributed among all the orders investigated: Rodentia (33 positive/146 tested), Marsupialia (40/318), and Chiroptera (19/152). Sequence analyses of a portion of the capsid and premembrane junction revealed that mammal strains of DENV-1, DENV-2, DENV-3, and DENV-4 had only 92.6%, 89%, 95%, and 95.8% identity, respectively, with strains circulating in the human population during the same periods. Regarding DENV-2, strains related (99% identity) to those responsible for an epidemic event in humans in French Guiana concurrent to the capture sessions were also evidenced, suggesting that wild mammals in edge habitats can be infected by circulating human strains. Our results demonstrate, for the first time, that neotropical wild mammals can be infected with dengue virus. The question of whether mammals maintain DENV in enzootic cycles and can play a role in its reemergence in human populations remains to be answered.
ObjectiveTo assess the level of circulation of DENV, CHIKV, ZIKV, MAYV in French Guiana.IntroductionArboviral infections have become a significant public health problem with the emergence and re-emergence of arboviral diseases worldwide in recent decades [1-6]. Given the increasing number of cases, geographic spread, but also health, social and economic impact of arboviral outbreaks, estimating their true burden represents a crucial issue but remains a difficult task [7-10].In French Guiana, the epidemiology of arboviral diseases has been marked by the occurrence several major dengue fever (DENV) outbreaks over the past few decades, recent emergences of Chikungunya (CHKV) and Zika virus (ZIKV) and the circulation of Mayaro virus (MAYV) [11-14].MethodsTo assess antibody seroprevalence against DENV, CHIKV, ZIKV, MAYV a random 2-stage household cross-sectional survey was conducted among the general population. We enrolled 2,697 individuals aged 1-87 years from June 1 to 12 October 2017. We performed detection of DENV, CHIKV, ZIKV, MAYV IgG antibodies on collected blood samples using a microsphere immunoassay (MIA). Socio-economic data, environmental variables and exposure to mosquitoes, perceptions of the illness and risk of contracting arboviral infections were collected using a standardized questionnaire administrated to all individuals included in the survey. Cross-reactivity between same families of viruses was taking into account using seroneutralisation and modeling approaches.ResultsOverall seroprevalence rates for antibodes against DENV were 69.5% [66.4%-72.5%] and differed significantly according to age and geographical area. Seroprevalence rates of CHIKV, ZIKV and MAYV antibodies were respectively 19.3% [16.5%-22.5%], 23.1% [19.5%-27.2%] and 9.6% [8.1%-11.3%] and did not differed significantly according to gender or age.The distribution of seroprevalence rates for CHIKV, ZIKV antibodies differed from extrapolations obtained from routine surveillance systems and brings valuable information to assess the epidemic risk of future outbreaks. MAYV has been circulating in the southern part of FG, at levels that appear to be substantially higher than those estimated from epidemiological and virological surveillance.ConclusionsSerological surveys provide the most direct measurement for defining the immunity landscape for infectious diseases, but the methodology remains difficult to implement particularly in the context of high cross-reactivity between flaviviruses or alphaviruses [15]. The development of reliable, rapid and affordable diagnosis tools and the use of innovative modeling approaches represent a significant issue concerning the ability of seroprevalence surveys to differentiate infections when multiple viruses co-circulate.References1. Bhatt S, Gething PW, Brady OJ, Messina JP, Farlow AW, Moyes CL, et al. The global distribution and burden of dengue. Nature. 2013;496: 504–507. pmid:235632662. Stanaway JD, Shepard DS, Undurraga EA, Halasa YA, Coffeng LE, Brady OJ, et al. The global burden of dengue: an analysis from the Global Burden of Disease Study 2013. Lancet Infect Dis. 2016;16: 712–723. pmid:268746193. Brathwaite Dick O, San Martín JL, Montoya RH, del Diego J, Zambrano B, Dayan GH. The history of dengue outbreaks in the Americas. Am J Trop Med Hyg. 2012;87: 584–593. pmid:230428464. Petersen LR, Jamieson DJ, Powers AM, Honein MA. Zika Virus. N Engl J Med. 2016;374: 1552–1563. pmid:270285615. Staples JE, Breiman RF, Powers AM. 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The Bunyaviridae family is currently composed of five genera, including Phlebovirus, in which several phleboviruses are associated with human diseases. Using high-throughput sequencing, we obtained and characterized one complete genome of the Arumowot virus (AMTV) isolated in 1978 from Turdus libonyanus, the Kurrichane Thrush, in the Central African Republic (CAR). The genomic segment of the new strain of AMTV isolated in the CAR had 75.4–83.5% sequence similarity and 82–98.4% amino acid similarity to the prototype sequence of AMTV. The different conserved proteins of the small (S) and large (L) segments (Nc, NSP, and RNA polymerase) showed close similarity at the amino acid level, whereas the polyprotein of the medium (M) segment was highly divergent, with 18% and 37.7%, respectively, for the prototype sequence of AMTV and the Odrenisrou virus (ODRV) isolated from Culex (Cx.) albiventris mosquitoes in the Tai forest, Ivory Coast. Phylogenetic analysis confirmed the sequence homology analysis and indicated that AMTV-CAR clustered into the Salehabad virus antigenic complex. The two closest viruses were the prototype sequences of AMTV originally isolated from Cx. antennatus mosquitoes and ODRV. These molecular data suggest the need for a deep genetic characterization of the diversity of this viral species to enhance its detection in the Central African region and to understand better its behavior and life cycle so that its potential spread to the human population can be prevented.
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.
Abstract Background. In Gabon, several Ebolavirus outbreaks have occurred exclusively in the northeastern region. We conducted a large serosurvey to identify areas and populations at risk and potential demographic, clinical, and behavioral risk factors. Methods. Blood samples and clinical and sociodemographic data were collected from 4349 adults and 362 children in a random sample of 220 villages in the 9 provinces of Gabon. An enzyme-linked immunosorbent assay was used to detect Zaire ebolavirus (ZEBOV)–specific IgG, and thin blood smears were used to detect parasites. Logistic regression was implemented using Stata software (Stata), and a probability level of <.05 was considered to be statistically significant. Results. The prevalence of ZEBOV-specific IgG was 15.3% overall, increasing to 32.4% (P< .001) in forest areas. No sociodemographic risk factors were found, but the antibody prevalence increased linearly up to 20 years of age. Chronic arthralgia and amicrofilaremia were the only factors associated with ZEBOV seropositivity. Conclusions. These findings confirm the endemicity of ZEBOV in Gabon and its link to the ecosystem. Human antibody positivity would appear to be to the result of exposure to contaminated fruits.
Co-infection with malaria parasite and HIV is an emerging public health problem in tropical areas, particularly in pregnant women, and management of the concurrent effects of these two infections is challenging. Co-trimoxazole is a sulfamide preparation used to prevent opportunistic infections in HIV-infected patients, and many studies have reported that it has significant activity against malaria. As the efficacy of intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) against malaria is decreasing, co-trimoxazole might be an alternative for preventing malaria among HIV-infected populations. The aim of this study is to compare the effectiveness of SP-IPT, which is recommended for the prevention of malaria during pregnancy in the Central African Republic, with that of a daily dose of co-trimoxazole against P. falciparum infections among HIV-infected pregnant women in Bangui, the capital of the Central African Republic. The MACOMBA study (MAternity and COntrol of Malaria-HIV co-infection in BAngui) is a multicentre open-label randomized clinical trial conducted at four maternity hospitals in Bangui. All HIV-infected pregnant women presenting for an antenatal clinic visit between the weeks 16 and 28 of amenorrhoea, with a CD4 count of more than 350 cells/mm3, will be eligible. All the women will provide written consent before being enrolled in the study and will then be randomly allocated to either SP-IPT (25 mg of sulfadoxine and 1.25 mg of pyrimethamine) or daily co-trimoxazole doses (960 mg per dose). The primary end-point is the placental malaria parasitaemia rate at delivery. Other main outcome measures include the number of malaria episodes during pregnancy, safety, and treatment compliance. Furthermore, the frequency of molecular resistance markers dhfr and dhps will be measured. In this trial, we seek to confirm whether co-trimoxazole is operationally suitable to replace SP-IPT in order to prevent malaria among pregnant women infected with HIV in the Central African Republic. ClinicalTrials.gov Identifier: NCT01746199 .
Zika virus (ZIKV) infection has been associated with complications during pregnancy. Although the presence of symptoms might be a risk factor for complication, the proportion of ZIKV-infected pregnant women with symptoms remains unknown. Following the emergence of ZIKV in French Guiana, all pregnancies in the territory were monitored by RT-PCR and/or detection of ZIKV antibodies. Follow-up data collected during pregnancy monitoring interviews were analysed from 1 February to 1 June 2016. We enrolled 3,050 pregnant women aged 14-48 years and 573 (19%) had laboratory-confirmed ZIKV infection. Rash, arthralgia, myalgia and conjunctival hyperaemia were more frequently observed in ZIKV-positive women; 23% of them (95% confidence interval (CI): 20-27) had at least one symptom compatible with ZIKV infection. Women 30 years and older were significantly more likely to have symptoms than younger women (28% vs 20%). The proportion of symptomatic infections varied from 17% in the remote interior to 35% in the urbanised population near the coast (adjusted risk ratio: 1.6; 95% CI: 1.4-1.9.). These estimates put findings on cohorts of symptomatic ZIKV-positive pregnant women into the wider context of an epidemic with mainly asymptomatic infections. The proportion of symptomatic ZIKV infections appears to vary substantially between populations.
A single-tube, multiplex, real-time PCR assay with molecular beacons was established in which various probes were used for the simultaneous detection, differentiation, and quantification of human T-cell leukemia virus types 1, 2, and 3 (HTLV-1, HTLV-2, and HTLV-3, respectively) and of simian T-cell leukemia virus types 1 and 3 (STLV-1 and STLV-3, respectively). The quantitative amplification of the standards with MT4 (HTLV-1) and C19 (HTLV-2) cell lines and a molecular clone of HTLV-3 was linear, with the simplex and multiplex methods having similar efficiencies. A maximum difference of 0.9 (mean, 0.4; range, 0.0 to 0.9) was found between threshold cycle values in single and multiplex reactions. The efficiency with each probe in the multiplex reaction was close to 100%, indicating strong linear amplification. The albumin gene was used to standardize the copy number. Comparable results for the detection and quantification of HTLV-1 were obtained with our new methods and with other real-time PCR methods described previously. With our new multiplex assay, however, we were able to detect and quantify HTLV-2 and -3 and STLV-1 and -3 in clinical specimens, with an excellent dynamic range of 10(6) to 10(0) copies per assay, which the other assays could not do. Thus, it will be possible to determine a wide range of HTLV types in both standard and clinical samples, with a detection of 1 to 10 HTLV copies in samples containing at least 100 cells. Furthermore, our system can provide evidence for multiple infections with the three HTLV types, with separate proviral load results. Our new method also could be used for epidemiological studies in Africa and in countries where HTLVs and STLVs are endemic.
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