Xavier Pourrut

Human Ebola Outbreak Resulting from Direct Exposure to Fruit Bats in Luebo, Democratic Republic of Congo, 2007

Twelve years after the Kikwit Ebola outbreak in 1995, Ebola virus reemerged in the Occidental Kasaï province of the Democratic Republic of Congo (DRC) between May and November 2007, affecting more than 260 humans and causing 186 deaths. During this latter outbreak we conducted several epidemiological investigations to identify the underlying ecological conditions and animal sources. Qualitative social and environmental data were collected through interviews with villagers and by direct observation. The local populations reported no unusual morbidity or mortality among wild or domestic animals, but they described a massive annual fruit bat migration toward the southeast, up the Lulua River. Migrating bats settled in the outbreak area for several weeks, between April and May, nestling in the numerous fruit trees in Ndongo and Koumelele islands as well as in palm trees of a largely abandoned plantation. They were massively hunted by villagers, for whom they represented a major source of protein. By tracing back the initial human-human transmission events, we were able to show that, in May, the putative first human victim bought freshly killed bats from hunters to eat. We were able to reconstruct the likely initial human-human transmission events that preceded the outbreak. This study provides the most likely sequence of events linking a human Ebola outbreak to exposure to fruit bats, a putative virus reservoir. These findings support the suspected role of bats in the natural cycle of Ebola virus and indicate that the massive seasonal fruit bat migrations should be taken into account in operational Ebola risk maps and seasonal alerts in the DRC.

Marburg virus infection detected in a common African bat.

Marburg and Ebola viruses can cause large hemorrhagic fever (HF) outbreaks with high case fatality (80–90%) in human and great apes. Identification of the natural reservoir of these viruses is one of the most important topics in this field and a fundamental key to understanding their natural history. Despite the discovery of this virus family almost 40 years ago, the search for the natural reservoir of these lethal pathogens remains an enigma despite numerous ecological studies. Here, we report the discovery of Marburg virus in a common species of fruit bat (Rousettus aegyptiacus) in Gabon as shown by finding virus-specific RNA and IgG antibody in individual bats. These Marburg virus positive bats represent the first naturally infected non-primate animals identified. Furthermore, this is the first report of Marburg virus being present in this area of Africa, thus extending the known range of the virus. These data imply that more areas are at risk for MHF outbreaks than previously realized and correspond well with a recently published report in which three species of fruit bats were demonstrated to be likely reservoirs for Ebola virus.

Risk to Human Health from a Plethora of Simian Immunodeficiency Viruses in Primate Bushmeat

To assess human exposure to Simian immunodeficiency virus (SIV) in west central Africa, we looked for SIV infection in 788 monkeys that were hunted in the rainforests of Cameroon for bushmeat or kept as pets. Serologic reactivity suggesting SIV infection was found in 13 of 16 primate species, including 4 not previously known to harbor SIV. Overall, 131 sera (16.6%) reacted strongly and an additional 34 (4.3%) reacted weakly with HIV antigens. Molecular analysis identified five new phylogenetic SIV lineages. These data document for the first time that a substantial proportion of wild monkeys in Cameroon are SIV infected and that humans who hunt and handle bushmeat are exposed to a plethora of genetically highly divergent viruses.

Large serological survey showing cocirculation of Ebola and Marburg viruses in Gabonese bat populations, and a high seroprevalence of both viruses in Rousettus aegyptiacus

BackgroundEbola and Marburg viruses cause highly lethal hemorrhagic fevers in humans. Recently, bats of multiple species have been identified as possible natural hosts of Zaire ebolavirus (ZEBOV) in Gabon and Republic of Congo, and also of marburgvirus (MARV) in Gabon and Democratic Republic of Congo.MethodsWe tested 2147 bats belonging to at least nine species sampled between 2003 and 2008 in three regions of Gabon and in the Ebola epidemic region of north Congo for IgG antibodies specific for ZEBOV and MARV.ResultsOverall, IgG antibodies to ZEBOV and MARV were found in 4% and 1% of bats, respectively. ZEBOV-specific antibodies were found in six bat species (Epomops franqueti, Hypsignathus monstrosus, Myonycteris torquata, Micropteropus pusillus, Mops condylurus and Rousettus aegyptiacus), while MARV-specific antibodies were only found in Rousettus aegyptiacus and Hypsignathus monstrosus. The prevalence of MARV-specific IgG was significantly higher in R. aegyptiacus members captured inside caves than elsewhere. No significant difference in prevalence was found according to age or gender. A higher prevalence of ZEBOV-specific IgG was found in pregnant females than in non pregnant females.ConclusionThese findings confirm that ZEBOV and MARV co-circulate in Gabon, the only country where bats infected by each virus have been found. IgG antibodies to both viruses were detected only in Rousettus aegyptiacus, suggesting that this bat species may be involved in the natural cycle of both Marburg and Ebola viruses. The presence of MARV in Gabon indicates a potential risk for a first human outbreak. Disease surveillance should be enhanced in areas near caves.

Concurrent chikungunya and dengue virus infections during simultaneous outbreaks, Gabon, 2007.

An outbreak of febrile illness occurred in Gabon in 2007, with 20,000 suspected cases. Chikungunya or dengue-2 virus infections were identified in 321 patients; 8 patients had documented co-infections. Aedes albopictus was identified as the principal vector for the transmission of both viruses.

Characterization of a novel simian immunodeficiency virus with a vpu gene from greater spot-nosed monkeys (Cercopithecus nictitans) provides new insights into simian/human immunodeficiency virus phylogeny

ABSTRACT In the present study, we describe a new simian immunodeficiency virus (SIV), designated SIVgsn, naturally infecting greater spot-nosed monkeys (Cercopithecus nictitans) in Cameroon. Together with SIVsyk, SIVgsn represents the second virus isolated from a monkey belonging to the Cercopithecus mitis group of the Cercopithecus genus. Full-length genome sequence analysis of two SIVgsn strains, SIVgsn-99CM71 and SIVgsn-99CM166, revealed that despite the close phylogenetic relationship of their hosts, SIVgsn was highly divergent from SIVsyk. First of all, they differ in their genomic organization. SIVgsn codes for a vpu homologue, so far a unique feature of the members of the SIVcpz/human immunodeficiency virus type 1 (HIV-1) lineage, and detailed phylogenetic analyses of various regions of the viral genome indicated that SIVgsn might be a mosaic of sequences with different evolutionary histories. SIVgsn was related to SIVsyk in Gag and part of Pol and related to SIVcpz in Env, and the middle part of the genome did not cluster significantly with any of the known SIV lineages. When comparing the two SIVgsn Env sequences with that of SIVcpz, a remarkable conservation was seen in the V3 loop, indicating a possible common origin for the envelopes of these two viruses. The habitats of the two subspecies of chimpanzees infected by SIVcpz overlap the geographic ranges of greater spot-nosed monkeys and other monkey species, allowing cross-species transmission and recombination between coinfecting viruses. The complex genomic structure of SIVgsn, the presence of a vpu gene, and its relatedness to SIVcpz in the envelope suggest a link between SIVgsn and SIVcpz and provide new insights about the origin of SIVcpz in chimpanzees.

Spatial and Temporal Patterns of Zaire ebolavirus Antibody Prevalence in the Possible Reservoir Bat Species

To characterize the distribution of Zaire ebolavirus (ZEBOV) infection within the 3 bat species (Epomops franqueti, Hypsignathus monstrosus, and Myonycteris torquata) that are possible reservoirs, we collected 1390 bats during 2003-2006 in Gabon and the Republic of the Congo. Detection of ZEBOV immunoglobulin G (IgG) in 40 specimens supports the role of these bat species as the ZEBOV reservoirs. ZEBOV IgG prevalence rates (5%) were homogeneous across epidemic and nonepidemic regions during outbreaks, indicating that infected bats may well be present in nonepidemic regions of central Africa. ZEBOV IgG prevalence decreased, significantly, to 1% after the outbreaks, suggesting that the percentage of IgG-positive bats is associated with virus transmission to other animal species and outbreak appearance. The large number of ZEBOV IgG-positive adult bats and pregnant H. monstrosus females suggests virus transmission within bat populations through fighting and sexual contact. Our study, thus, helps to describe Ebola virus circulation in bats and offers some insight into the appearance of outbreaks.

Characterization of a Novel Simian Immunodeficiency Virus from Guereza Colobus Monkeys (Colobus guereza) in Cameroon: a New Lineage in the Nonhuman Primate Lentivirus Family

ABSTRACT Exploration of the diversity among primate lentiviruses is necessary to elucidate the origins and evolution of immunodeficiency viruses. During a serological survey in Cameroon, we screened 25 wild-born guereza colobus monkeys (Colobus guereza) and identified 7 with HIV/SIV cross-reactive antibodies. In this study, we describe a novel lentivirus, named SIVcol, prevalent in guereza colobus monkeys. Genetic analysis revealed that SIVcol was very distinct from all other known SIV/HIV isolates, with average amino acid identities of 40% for Gag, 50% for Pol, 28% for Env, and around 25% for proteins encoded by five other genes. Phylogenetic analyses confirmed that SIVcol is genetically distinct from other previously characterized primate lentiviruses and clusters independently, forming a novel lineage, the sixth in the current classification.Cercopithecidae monkeys (Old World monkeys) are subdivided into two subfamilies, the Colobinae and theCercopithecinae, and, so far, allCercopithecidae monkeys from which lentiviruses have been isolated belong to the Cercopithecinae subfamily. Therefore, SIVcol from guereza colobus monkeys (C. guereza) is the first primate lentivirus identified in the Colobinaesubfamily and the divergence of SIVcol may reflect divergence of the host lineage.

Isolates of Zaire ebolavirus from wild apes reveal genetic lineage and recombinants

Over the last 30 years, Zaire ebolavirus (ZEBOV), a virus highly pathogenic for humans and wild apes, has emerged repeatedly in Central Africa. Thus far, only a few virus isolates have been characterized genetically, all belonging to a single genetic lineage and originating exclusively from infected human patients. Here, we describe the first ZEBOV sequences isolated from great ape carcasses in the Gabon/Congo region that belong to a previously unrecognized genetic lineage. According to our estimates, this lineage, which we also encountered in the two most recent human outbreaks in the Republic of the Congo in 2003 and 2005, diverged from the previously known viruses around the time of the first documented human outbreak in 1976. These results suggest that virus spillover from the reservoir has occurred more than once, as predicted by the multiple emergence hypothesis. However, the young age of both ZEBOV lineages and the spatial and temporal sequence of outbreaks remain at odds with the idea that the virus simply emerged from a long-established and widespread reservoir population. Based on data from two ZEBOV genes, we also demonstrate, within the family Filoviridae, recombination between the two lineages. According to our estimates, this event took place between 1996 and 2001 and gave rise to a group of recombinant viruses that were responsible for a series of outbreaks in 2001–2003. The potential for recombination adds an additional level of complexity to unraveling and potentially controlling the emergence of ZEBOV in humans and wildlife species.

Identification of a New Simian Immunodeficiency Virus Lineage with a vpu Gene Present among Different Cercopithecus Monkeys (C. mona, C. cephus, and C. nictitans) from Cameroon

ABSTRACT During a large serosurvey of wild-caught primates from Cameroon, we found 2 mona monkeys (Cercopithecus mona) out of 8 and 47 mustached monkeys (Cercopithecus cephus) out of 302 with human immunodeficiency virus (HIV)-simian immunodeficiency virus (SIV) cross-reactive antibodies. In this report, we describe the full-length genome sequences of two novel SIVs, designated SIVmon-99CMCML1 and SIVmus-01CM1085, isolated from one mona (CML1) and one mustached (1085) monkey, respectively. Interestingly, these viruses displayed the same genetic organization (i.e., presence of a vpu homologue) as members of the SIVcpz-HIV type 1 lineage and SIVgsn isolated from greater spot-nosed monkeys (Cercopithecus nictitans). Phylogenetic analyses of SIVmon and SIVmus revealed that these viruses were genetically distinct from other known primate lentiviruses but were more closely related to SIVgsn all across their genomes, thus forming a monophyletic lineage within the primate lentivirus family, which we designated the SIVgsn lineage. Interestingly, mona, mustached, and greater spot-nosed monkeys are phylogenetically related species belonging to three different groups of the genus Cercopithecus, the C. mona, C. cephus, and Cercopithecus mitis groups, respectively. The presence of new viruses closely related to SIVgsn in two other species reinforces the hypothesis that a recombination event between ancestral SIVs from the family Cercopithecinae is the origin of the present SIVcpz that is widespread among the chimpanzee population.