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Bats (order: Chiroptera) are known to host a diverse range of viruses, some of which present a human public health risk. Thorough viral surveillance is therefore essential to predict and potentially mitigate zoonotic spillover. Astroviruses (family: Astroviridae) are an understudied group of viruses with a growing amount of indirect evidence for zoonotic transfer. Astroviruses have been detected in bats with significant prevalence and diversity, suggesting that bats may act as important astrovirus hosts. Most astrovirus surveillance in wild bat hosts has, to date, been restricted to single-gene PCR detection and concomitant Sanger sequencing; additionally, many bat species and many geographic regions have not yet been surveyed for astroviruses at all. Here, we use metagenomic Next Generation Sequencing (mNGS) to detect astroviruses in three species of Madagascar fruit bats, Eidolon dupreanum, Pteropus rufus, and Rousettus madagascariensis. We detect numerous partial sequences from all three species and one near-full length astrovirus sequence from Rousettus madagascariensis, which we use to characterize the evolutionary history of astroviruses both within bats and the broader mammalian clade, Mamastrovirus. Taken together, applications of mNGS implicate bats as important astrovirus hosts and demonstrate novel patterns of bat astrovirus evolutionary history, particularly in the Southwest Indian Ocean region.
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Infecções por Astroviridae , Astroviridae , Quirópteros , Metagenômica , Filogenia , Animais , Quirópteros/virologia , Astroviridae/genética , Astroviridae/isolamento & purificação , Astroviridae/classificação , Infecções por Astroviridae/veterinária , Infecções por Astroviridae/virologia , Infecções por Astroviridae/epidemiologia , Sequenciamento de Nucleotídeos em Larga Escala , Madagáscar , Genoma Viral/genética , Análise de Sequência de DNARESUMO
A Rift Valley fever (RVF) outbreak occurred in at least five regions of Madagascar in 2021. The aim of this study was to provide an overview of the richness, abundance, ecology, and trophic preferences of mosquitoes in the Mananjary district and to investigate the distribution of mosquitoes that were RT-PCR-positive for RVFV. Three localities were prospected from 26 April to 4 May 2021, using light traps, BG-Sentinel traps baited with an artificial human odor, Muirhead-Thomson pit traps, and indoor pyrethroid spray catches. A total of 2806 mosquitoes belonging to at least 26 species were collected. Of 512 monospecific pools of mosquitoes tested with real-time RT-PCR, RVFV was detected in 37 pools representing 10 mosquito species. The RVFV-positive species were as follows: Aedes albopictus, Ae. argenteopunctatus, Anopheles coustani, An. gambiae s.l., An. mascarensis, An. squamosus/cydippis, Culex antennatus, Cx. decens, Cx. Tritaeniorhynchus, and Uranotaenia spp. Of the 450 tested engorged females, 78.7% had taken a blood meal on humans, 92.9% on cattle, and 71.6% had taken mixed (human-cattle) blood meals. This investigation suggests the potential role of mosquitoes in RVFV transmission within this epizootic/epidemic context and that the human populations at the three study sites were highly exposed to mosquitoes. Therefore, the use of impregnated mosquito nets as an appropriate prevention method is recommended.
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An epizootic of rift valley fever (RVF) was suspected on 21 February 2021 in various districts of Madagascar, with a lab confirmation on 1 April 2021. A cross-sectional survey aiming to detect cases of RVF in humans and to study the circulation of rift valley fever virus (RVFV) in animals was conducted from 22 April to 4 May 2021 in the district of Mananjary. Blood samples from cattle and humans were tested using serological and molecular techniques. In cattle, the circulation of RVFV was confirmed between 5 February and 4 May 2021. The positivity rates of anti-RVFV IgG and IgM were 60% and 40%, respectively. In humans, the circulation of RVFV was observed from 1 April to 5 May 2021. The positivity rate of RVFV was estimated to be 11.7% by combining the results of the molecular and serological approaches. Of the 103 individuals who agreed to participate in the survey, 3 were determined to be positive by RT-PCR, and 10 had anti-RVFV IgM. Among them, one was positive for both. Given that previous studies have reported the circulation of RVFV during inter-epidemic periods and the occurrence of outbreaks due to imported RVFV in Madagascar, our findings suggest the importance of strengthening RVF surveillance from a "One Health" perspective by conducting syndromic and risk-based surveillance at the national and regional levels.
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Introduction: In Madagascar, rabies is endemic and a notifiable disease. The objective of this mixed study was to understand the challenges faced by the Veterinary Health Officers (VHOs) in the current rabies surveillance system in Madagascar. Methods: A survey was conducted from mid-April to the end of July 2021 during which all officially-listed VHOs (N = 150) were contacted by phone at least twice. Participants, representative of the 22 regions of Madagascar, were interviewed by phone based on a semi-structured questionnaire on (1) their knowledge of rabies epidemiology in their area of activities, (2) the occurrence of human and animal rabies and the species affected in the region where they work, (3) the factors that might influence rabies surveillance depending on (a) their activities and area of operation, (b) the socio-cultural aspects of local communities, and (c) the general organization of animal rabies surveillance. Results: The majority (80/90) of VHOs declared having been informed of at least one suspected or confirmed case of human and/or animal rabies in their area of activity during their work as VHOs: at least once a month for 11 of them, at least once a year for 40 and with undetermined frequency for 29. Several obstacles hinder the surveillance of rabies resulting in under-reporting. The lack of funds to access suspect animals, collect, pack and ship samples in compliance with biosecurity measures and the cold chain, was mentioned as a major obstacle to surveillance. The second barrier is socio-cultural: in many large coastal regions, dogs are taboo and VHOs fear rejection by the community if they treat dogs. Discussion and conclusion: While the general population requires information on the rabies situation in Madagascar and on how to proceed in the event of a bite, veterinarians and decision-makers need to be fully aware of an evidence-based approach to rabies surveillance, prevention and control. Communication between the human and animal health sectors should be improved. Politicians need to be persuaded of the importance of funding to eliminate rabies in Madagascar. The adoption, in early 2023, of a national strategic plan for rabies control is a first step in this direction.
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Bats (order: Chiroptera ) are known to host a diverse range of viruses, some of which present a public health risk. Thorough viral surveillance is therefore essential to predict and potentially mitigate zoonotic spillover. Astroviruses (family: Astroviridae ) are an understudied group of viruses with a growing amount of indirect evidence for zoonotic transfer. Astroviruses have been detected in bats with significant prevalence and diversity, suggesting that bats may act as important astrovirus hosts. Most astrovirus surveillance in wild bat hosts has, to date, been restricted to single-gene PCR detection and concomitant Sanger sequencing; additionally, many bat species and many geographic regions have not yet been surveyed for astroviruses at all. Here, we use metagenomic Next Generation Sequencing (mNGS) to detect astroviruses in three species of Madagascar fruit bats, Eidolon dupreanum, Pteropus rufus, and Rousettus madagascariensis . We detect numerous partial sequences from all three species and one near-full length astrovirus sequence from Rousettus madagascariensis , which we use to characterize the evolutionary history of astroviruses both within bats and the broader mammalian clade, Mamastrovirus . Taken together, applications of mNGS implicate bats as important astrovirus hosts and demonstrate novel patterns of bat astrovirus evolutionary history, particularly in the Southwest Indian Ocean region.
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Rabies is endemic in Madagascar and a neglected disease. The aim of this study was to summarize human and animal rabies surveillance activities in Madagascar from 2011 to 2021. Samples from terrestrial mammals and humans were tested for rabies virus infection using direct fluorescent antibody, RT-PCR and virus isolation by the National Reference Laboratory (NRL) for rabies at the Institut Pasteur de Madagascar. Among 964 animal and 47 human samples tested, 66.7 and 70.2% were positive, respectively. The NRL received these suspect rabies samples from 48 of 114 districts of Madagascar. Most of them were submitted from the district of the capital city Antananarivo (26.3%) and mainly from its region Analamanga (68.9%). Animal samples were mainly from dogs (83%), cats (9.5%) and cattle (5.8%). Pigs, lemurs, goats accounted for less than 1%. During the 11 years of surveillance, 48 human skin and/or brain biopsy samples were received from 20 districts, mainly from Antananarivo and its surroundings (N = 13), Toamasina and its surroundings (N = 8) and Moramanga (N = 6). The high positivity rate for all species and the non-homogeneous spatial distribution of samples suggests substantial underreporting of rabies cases. There is a clear need to better understand the reasons for underreporting and prioritize rabies surveillance, prevention and control in Madagascar, with improvements in budget, education and infrastructure. A joint animal and human health rabies control program including vaccination of at least 70% of the dog population, is needed to achieve the goal of eliminating dog-transmitted human rabies by 2030 from Madagascar.
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The diversity and circulation of arboviruses are not much studied in Madagascar. The fact is that arboviral emergences are rarely detected. The existing surveillance system primarily relies on serological detection and records only a few human infections annually. The city of Mahajanga, however, experienced a confirmed dengue fever epidemic in 2020 and 2021. This study aimed to characterize and analyze the virome of mosquitoes collected in Mahajanga, near patients with dengue-like syndromes to detect known and unknown viruses as well as investigate the factors contributing to the relative low circulation of arboviruses in the area. A total of 4280 mosquitoes representing at least 12 species from the Aedes, Anopheles, and Culex genera were collected during the dry and the rainy seasons from three sites, following an urbanization gradient. The virome analysis of 2192 female mosquitoes identified a diverse range of viral families and genera and revealed different patterns that are signatures of the influence of the mosquito genus or the season of collection on the composition and abundance of the virome. Despite the absence of known human or veterinary arboviruses, the identification and characterization of viral families, genera, and species in the mosquito virome contribute to our understanding of viral ecology and diversity within mosquito populations in Madagascar. This study serves as a foundation for ongoing surveillance efforts and provides a basis for the development of preventive strategies against various mosquito-borne viral diseases, including known arboviruses.
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Environmental Enteric Dysfunction (EED) is an associate driver of stunting in poor settings, and intestinal infections indirectly contribute to the pathophysiology underlying EED. Our work aimed at assessing whether enteric viral carriage is determinant to stunting. A total of 464 healthy and asymptomatic children, aged 2 to 5 years, were recruited, and classified as non-stunted, moderately stunted, or severely stunted. Among the recruited children, 329 stool samples were obtained and screened for enteric and non-enteric viruses by real-time polymerase chain reaction. We statistically tested for the associations between enteric viral and potential risk factors. Approximately 51.7% of the stool samples were positive for at least one virus and 40.7% were positive for non-enteric adenoviruses. No statistical difference was observed between virus prevalence and the growth status of the children. We did not find any statistically significant association between viral infection and most of the socio-demographic risk factors studied, except for having an inadequate food quality score or an over-nourished mother. In addition, being positive for Ascaris lumbricoides was identified as a protective factor against viral infection. In conclusion, we did not find evidence of a direct link between stunting and enteropathogenic viral carriage in our population.
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INTRODUCTION: COVID-19-associated mortality remains difficult to estimate in sub-Saharan Africa because of the lack of comprehensive systems of death registration. Based on death registers referring to the capital city of Madagascar, we sought to estimate the excess mortality during the COVID-19 pandemic and calculate the loss of life expectancy. METHODS: Death records between 2016 and 2021 were used to estimate weekly excess mortality during the pandemic period. To infer its synchrony with circulation of SARS-CoV-2, a cross-wavelet analysis was performed. Life expectancy loss due to the COVID-19 pandemic was calculated by projecting mortality rates using the Lee and Carter model and extrapolating the prepandemic trends (1990-2019). Differences in life expectancy at birth were disaggregated by cause of death. RESULTS: Peaks of excess mortality in 2020-21 were associated with waves of COVID-19. Estimates of all-cause excess mortality were 38.5 and 64.9 per 100 000 inhabitants in 2020 and 2021, respectively, with excess mortality reaching ≥50% over 6 weeks. In 2021, we quantified a drop of 0.8 and 1.0 years in the life expectancy for men and women, respectively attributable to increased risks of death beyond the age of 60 years. CONCLUSION: We observed high excess mortality during the pandemic period, in particular around the peaks of SARS-CoV-2 circulation in Antananarivo. Our study highlights the need to implement death registration systems in low-income countries to document true toll of a pandemic.
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COVID-19 , Mortalidade , Infecções Respiratórias , Feminino , Humanos , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Causas de Morte , COVID-19/epidemiologia , Madagáscar/epidemiologia , Pandemias , SARS-CoV-2 , Mortalidade/tendências , Saúde Pública , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/virologia , Surtos de DoençasRESUMO
The geographic and evolutionary origins of the SARS-CoV-2 Omicron variant (BA.1), which was first detected mid-November 2021 in Southern Africa, remain unknown. We tested 13,097 COVID-19 patients sampled between mid-2021 to early 2022 from 22 African countries for BA.1 by real-time RT-PCR. By November-December 2021, BA.1 had replaced the Delta variant in all African sub-regions following a South-North gradient, with a peak Rt of 4.1. Polymerase chain reaction and near-full genome sequencing data revealed genetically diverse Omicron ancestors already existed across Africa by August 2021. Mutations, altering viral tropism, replication and immune escape, gradually accumulated in the spike gene. Omicron ancestors were therefore present in several African countries months before Omicron dominated transmission. These data also indicate that travel bans are ineffective in the face of undetected and widespread infection.
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The genus Henipavirus (family Paramyxoviridae) currently comprises seven viruses, four of which have demonstrated prior evidence of zoonotic capacity. These include the biosafety level 4 agents Hendra (HeV) and Nipah (NiV) viruses, which circulate naturally in pteropodid fruit bats. Here, we describe and characterize Angavokely virus (AngV), a divergent henipavirus identified in urine samples from wild, Madagascar fruit bats. We report the nearly complete 16,740-nucleotide genome of AngV, which encodes the six major henipavirus structural proteins (nucleocapsid, phosphoprotein, matrix, fusion, glycoprotein, and L polymerase). Within the phosphoprotein (P) gene, we identify an alternative start codon encoding the AngV C protein and a putative mRNA editing site where the insertion of one or two guanine residues encodes, respectively, additional V and W proteins. In other paramyxovirus systems, C, V, and W are accessory proteins involved in antagonism of host immune responses during infection. Phylogenetic analysis suggests that AngV is ancestral to all four previously described bat henipaviruses-HeV, NiV, Cedar virus (CedV), and Ghanaian bat virus (GhV)-but evolved more recently than rodent- and shrew-derived henipaviruses, Mojiang (MojV), Gamak (GAKV), and Daeryong (DARV) viruses. Predictive structure-based alignments suggest that AngV is unlikely to bind ephrin receptors, which mediate cell entry for all other known bat henipaviruses. Identification of the AngV receptor is needed to clarify the virus's potential host range. The presence of V and W proteins in the AngV genome suggest that the virus could be pathogenic following zoonotic spillover. IMPORTANCE Henipaviruses include highly pathogenic emerging zoonotic viruses, derived from bat, rodent, and shrew reservoirs. Bat-borne Hendra (HeV) and Nipah (NiV) are the most well-known henipaviruses, for which no effective antivirals or vaccines for humans have been described. Here, we report the discovery and characterization of a novel henipavirus, Angavokely virus (AngV), isolated from wild fruit bats in Madagascar. Genomic characterization of AngV reveals all major features associated with pathogenicity in other henipaviruses, suggesting that AngV could be pathogenic following spillover to human hosts. Our work suggests that AngV is an ancestral bat henipavirus that likely uses viral entry pathways distinct from those previously described for HeV and NiV. In Madagascar, bats are consumed as a source of human food, presenting opportunities for cross-species transmission. Characterization of novel henipaviruses and documentation of their pathogenic and zoonotic potential are essential to predicting and preventing the emergence of future zoonoses that cause pandemics.
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Quirópteros , Genoma Viral , Infecções por Henipavirus , Henipavirus , Vírus Nipah , Animais , Quirópteros/genética , Genoma Viral/genética , Glicoproteínas/genética , Henipavirus/classificação , Henipavirus/genética , Infecções por Henipavirus/virologia , Humanos , Madagáscar , Vírus Nipah/genética , Filogenia , Urina/virologia , Zoonoses/genéticaRESUMO
The first documented chikungunya virus (CHIKV) outbreak in Lao People's Democratic Republic (Lao PDR) occurred in 2012-2013. Since then, several imported and a few autochthonous cases were identified by the national arbovirus surveillance network. The present study aimed to summarize the main genetic features of the CHIKV strains detected in Lao PDR between 2014 and 2020. Samples from Lao patients presenting symptoms compatible with a CHIKV infection were centralized in Vientiane Capital city for real-time RT-PCR screening. Molecular epidemiology was performed by sequencing the E2-6K-E1 region. From 2014 to 2020, two Asian lineage isolates (e.g. French Polynesia; Indonesia), one ECSA-IOL lineage isolate (e.g. Thailand) and one unclassified (e.g. Myanmar) were imported in Vientiane Capital city. Sequences from the autochthonous cases recorded in the Central and Southern parts of the country between July and September 2020 belonged to the ECSA-IOL lineage and clustered with CHIKV strains recently detected in neighboring countries. These results demonstrate the multiple CHIKV introductions in Lao PDR since 2014 and provide evidence for sporadic and time-limited circulation of CHIKV in the country. Even if the circulation of CHIKV seems to be geographically and temporally limited in Lao PDR, the development of international tourism and trade may cause future outbreaks of CHIKV in the country and at the regional level.
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Febre de Chikungunya , Vírus Chikungunya , Febre de Chikungunya/epidemiologia , Vírus Chikungunya/genética , Surtos de Doenças , Humanos , Laos/epidemiologia , FilogeniaRESUMO
The animal reservoir of SARS-CoV-2 is unknown despite reports of SARS-CoV-2-related viruses in Asian Rhinolophus bats1-4, including the closest virus from R. affinis, RaTG13 (refs. 5,6), and pangolins7-9. SARS-CoV-2 has a mosaic genome, to which different progenitors contribute. The spike sequence determines the binding affinity and accessibility of its receptor-binding domain to the cellular angiotensin-converting enzyme 2 (ACE2) receptor and is responsible for host range10-12. SARS-CoV-2 progenitor bat viruses genetically close to SARS-CoV-2 and able to enter human cells through a human ACE2 (hACE2) pathway have not yet been identified, although they would be key in understanding the origin of the epidemic. Here we show that such viruses circulate in cave bats living in the limestone karstic terrain in northern Laos, in the Indochinese peninsula. We found that the receptor-binding domains of these viruses differ from that of SARS-CoV-2 by only one or two residues at the interface with ACE2, bind more efficiently to the hACE2 protein than that of the SARS-CoV-2 strain isolated in Wuhan from early human cases, and mediate hACE2-dependent entry and replication in human cells, which is inhibited by antibodies that neutralize SARS-CoV-2. None of these bat viruses contains a furin cleavage site in the spike protein. Our findings therefore indicate that bat-borne SARS-CoV-2-like viruses that are potentially infectious for humans circulate in Rhinolophus spp. in the Indochinese peninsula.
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COVID-19 , Quirópteros , Enzima de Conversão de Angiotensina 2 , Animais , Ásia , Cavernas , Quirópteros/virologia , Reservatórios de Doenças , Humanos , Ligação Proteica , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/químicaRESUMO
Three epidemic waves of coronavirus disease-19 (COVID-19) occurred in Madagascar from March 2020 to May 2022, with a positivity rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of 21% to 33%. Our study aimed to identify the impact of COVID-19 on the epidemiology of seasonal respiratory viruses (RVs) in Madagascar. We used two different specimen sources (SpS). First, 2987 nasopharyngeal (NP) specimens were randomly selected from symptomatic patients between March 2020 and May 2022 who tested negative for SARS-CoV-2 and were tested for 14 RVs by multiplex real-time PCR. Second, 6297 NP specimens were collected between March 2020 and May 2022 from patients visiting our sentinel sites of the influenza sentinel network. The samples were tested for influenza, respiratory syncytial virus (RSV), and SARS-CoV-2. From SpS-1, 19% (569/2987) of samples tested positive for at least one RV. Rhinovirus (6.3%, 187/2987) was the most frequently detected virus during the first two waves, whereas influenza predominated during the third. From SpS-2, influenza, SARS-CoV-2, and RSV accounted for 5.4%, 24.5%, and 39.4% of the detected viruses, respectively. During the study period, we observed three different RV circulation profiles. Certain viruses circulated sporadically, with increased activity in between waves of SARS-CoV-2. Other viruses continued to circulate regardless of the COVID-19 situation. Certain viruses were severely disrupted by the spread of SARS-CoV-2. Our findings underline the importance and necessity of maintaining an integrated disease surveillance system for the surveillance and monitoring of RVs of public health interest.
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COVID-19 , Influenza Humana , Vírus Sincicial Respiratório Humano , Infecções Respiratórias , Vírus , Humanos , COVID-19/epidemiologia , Influenza Humana/epidemiologia , SARS-CoV-2/genética , Pandemias , Madagáscar/epidemiologia , Estações do Ano , Infecções Respiratórias/epidemiologia , Vírus/genética , Vírus Sincicial Respiratório Humano/genéticaRESUMO
Since its first detection in 1979, dengue fever has been considered a major public health issue in the Lao People's Democratic Republic (PDR). Dengue virus (DENV) serotype 1 was the cause of an epidemic in 2010-2011. Between 2012 and 2020, major outbreaks due successively to DENV-3, DENV-4 and recently DENV-2 have been recorded. However, DENV-1 still co-circulated in the country over this period. Here, we summarize epidemiological and molecular data of DENV-1 between 2016 and 2020 in the Lao PDR. Our data highlight the continuous circulation of DENV-1 in the country at levels ranging from 16% to 22% among serotyping tests. In addition, the phylogenetic analysis has revealed the circulation of DENV-1 genotype I at least since 2008 with a co-circulation of different clusters. Sequence data support independent DENV-1 introductions in the Lao PDR correlated with an active circulation of this serotype at the regional level in Southeast Asia. The maintenance of DENV-1 circulation over the last ten years supports a low level of immunity against this serotype within the Lao population. Thereby, the risk of a DENV-1 epidemic cannot be ruled out in the future, and this emphasizes the importance of maintaining an integrated surveillance approach to prevent major outbreaks.
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Members of the family Herpesviridae have enveloped, spherical virions with characteristic complex structures consisting of symmetrical and non-symmetrical components. The linear, double-stranded DNA genomes of 125-241 kbp contain 70-170 genes, of which 43 have been inherited from an ancestral herpesvirus. In general, herpesviruses have coevolved with and are highly adapted to their hosts, which comprise many mammalian, avian and reptilian species. Following primary infection, they are able to establish lifelong latent infection, during which there is limited viral gene expression. Severe disease is usually observed only in the foetus, the very young, the immunocompromised or following infection of an alternative host. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Herpesviridae, which is available at ictv.global/report/herpesviridae.
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Genoma Viral , Herpesviridae , Animais , Evolução Molecular , Herpesviridae/classificação , Herpesviridae/genética , Herpesviridae/fisiologia , Herpesviridae/ultraestrutura , Infecções por Herpesviridae/veterinária , Infecções por Herpesviridae/virologia , Adaptação ao Hospedeiro , Vírion/química , Vírion/ultraestrutura , Latência Viral , Replicação ViralRESUMO
Rodents are important reservoirs of numerous viruses, some of which have significant impacts on public health. Ecosystem disturbances and decreased host species richness have been associated with the emergence of zoonotic diseases. In this study, we aimed at (a) characterizing the viral diversity in seven neotropical rodent species living in four types of habitats and (b) exploring how the extent of environmental disturbance influences this diversity. Through a metagenomic approach, we identified 77,767 viral sequences from spleen, kidney, and serum samples. These viral sequences were attributed to 27 viral families known to infect vertebrates, invertebrates, plants, and amoeba. Viral diversities were greater in pristine habitats compared with disturbed ones, and lowest in peri-urban areas. High viral richness was observed in savannah areas. Differences in these diversities were explained by rare viruses that were generally more frequent in pristine forest and savannah habitats. Moreover, changes in the ecology and behavior of rodent hosts, in a given habitat, such as modifications to the diet in disturbed vs. pristine forests, are major determinants of viral composition. Lastly, the phylogenetic relationships of four vertebrate-related viral families (Polyomaviridae, Flaviviridae, Togaviridae, and Phenuiviridae) highlighted the wide diversity of these viral families, and in some cases, a potential risk of transmission to humans. All these findings provide significant insights into the diversity of rodent viruses in Amazonia, and emphasize that habitats and the host's dietary ecology may drive viral diversity. Linking viral richness and abundance to the ecology of their hosts and their responses to habitat disturbance could be the starting point for a better understanding of viral emergence and for future management of ecosystems.
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Ecossistema , Variação Genética , Roedores/virologia , Vírus/classificação , Vírus/genética , Zoonoses/virologia , Animais , Ecologia , Florestas , Metagenoma , Filogenia , Zoonoses/transmissãoRESUMO
BACKGROUND: In 2020 Lao PDR had low reported COVID-19 cases but it was unclear whether this masked silent transmission. A seroprevalence study was done August - September 2020 to determine SARS-CoV-2 exposure. METHODS: Participants were from the general community (n=2433) or healthcare workers (n=666) in five provinces and bat/wildlife contacts (n=74) were from Vientiane province. ELISAs detected anti- SARS-CoV-2 Nucleoprotein (N; n=3173 tested) and Spike (S; n=1417 tested) antibodies. Double-positive samples were checked by IgM/IgG rapid tests. Controls were confirmed COVID-19 cases (n=15) and pre-COVID-19 samples (n=265). Seroprevalence for the general community was weighted to account for complex survey sample design, age and sex. FINDINGS: In pre-COVID-19 samples, 5·3%, [95% CI=3·1-8·7%] were anti-N antibody single-positive and 1·1% [0·3-3·5%] were anti-S antibody single positive. None were double positive. Anti-N and anti-S antibodies were detected in 5·2% [4·2-6·5%] and 2·1% [1·1-3·9%] of the general community, 2·0% [1·1-3·3%] and 1·4% [0·5-3·7%] of healthcare workers and 20·3% [12·6-31·0%] and 6·8% [2·8-15·3%] of bat/wildlife contacts. 0·1% [0·02-0·3%] were double positive for anti-N and anti-S antibodies (rapid test negative). INTERPRETATION: We find no evidence for significant SARS-CoV-2 circulation in Lao PDR before September 2020. This likely results from early decisive measures taken by the government, social behavior, and low population density. High anti-N /low anti-S seroprevalence in bat/wildlife contacts may indicate exposure to cross-reactive animal coronaviruses with threat of emerging novel viruses. FUNDING: Agence Française de Développement. Additional; Institut Pasteur du Laos, Institute Pasteur, Paris and Luxembourg Ministry of Foreign and European Affairs ("PaReCIDS II").