In 2012, Tigray orthohantavirus was discovered in Ethiopia, but its seasonal infection in small mammals, and whether it poses a risk to humans was unknown. The occurrence of small mammals, rodents and shrews, in human inhabitations in northern Ethiopia is affected by season and presence of stone bunds. We sampled small mammals in two seasons from low- and high-density stone bund fields adjacent to houses and community-protected semi-natural habitats in Atsbi and Hagere Selam, where Tigray orthohantavirus was first discovered. We collected blood samples from both small mammals and residents using filter paper. The presence of orthohantavirus-reactive antibodies in blood was then analyzed using immunofluorescence assay (human samples) and enzyme linked immunosorbent assays (small mammal samples) with Puumala orthohantavirus as antigen. Viral RNA was detected by RT-PCR using small mammal blood samples. Total orthohantavirus prevalence (antibodies or virus RNA) in the small mammals was 3.37%. The positive animals were three Stenocephalemys albipes rats (prevalence in this species = 13.04%). The low prevalence made it impossible to determine whether season and stone bunds were associated with orthohantavirus prevalence in the small mammals. In humans, we report the first detection of orthohantavirus-reactive IgG antibodies in Ethiopia (seroprevalence = 5.26%). S. albipes lives in close proximity to humans, likely increasing the risk of zoonotic transmission.
- MeSH
- Hantavirus Infections epidemiology immunology transmission MeSH
- Orthohantavirus genetics immunology MeSH
- Immunoglobulin G blood MeSH
- Rats MeSH
- Humans MeSH
- Rodent Diseases immunology transmission virology MeSH
- Prevalence MeSH
- Antibodies, Viral blood MeSH
- Cross-Sectional Studies MeSH
- Risk Factors MeSH
- RNA, Viral genetics MeSH
- Rural Population MeSH
- Disease Reservoirs virology MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Ethiopia MeSH
Hepatitis C virus (HCV; genus Hepacivirus) represents a major public health problem, infecting about three per cent of the human population. Because no animal reservoir carrying closely related hepaciviruses has been identified, the zoonotic origins of HCV still remain unresolved. Motivated by recent findings of divergent hepaciviruses in rodents and a plausible African origin of HCV genotypes, we have screened a large collection of small mammals samples from seven sub-Saharan African countries. Out of 4,303 samples screened, eighty were found positive for the presence of hepaciviruses in twenty-nine different host species. We, here, report fifty-six novel genomes that considerably increase the diversity of three divergent rodent hepacivirus lineages. Furthermore, we provide strong evidence for hepacivirus co-infections in rodents, which were exclusively found in four sampled species of brush-furred mice. We also detect evidence of recombination within specific host lineages. Our study expands the available hepacivirus genomic data and contributes insights into the relatively deep evolutionary history of these pathogens in rodents. Overall, our results emphasize the importance of rodents as a potential hepacivirus reservoir and as models for investigating HCV infection dynamics.
- Publication type
- Journal Article MeSH
A key aim in wildlife disease ecology is to understand how host and parasite characteristics influence parasite transmission and persistence. Variation in host population density can have strong impacts on transmission and outbreaks, and theory predicts particular transmission-density patterns depending on how parasites are transmitted between individuals. Here, we present the results of a study on the dynamics of Morogoro arenavirus in a population of multimammate mice (Mastomys natalensis). This widespread African rodent, which is also the reservoir host of Lassa arenavirus in West Africa, is known for its strong seasonal density fluctuations driven by food availability. We investigated to what degree virus transmission changes with host population density and how the virus might be able to persist during periods of low host density. A seven-year capture-mark-recapture study was conducted in Tanzania where rodents were trapped monthly and screened for the presence of antibodies against Morogoro virus. Observed seasonal seroprevalence patterns were compared with those generated by mathematical transmission models to test different hypotheses regarding the degree of density dependence and the role of chronically infected individuals. We observed that Morogoro virus seroprevalence correlates positively with host density with a lag of 1-4 months. Model results suggest that the observed seasonal seroprevalence dynamics can be best explained by a combination of vertical and horizontal transmission and that a small number of animals need to be infected chronically to ensure viral persistence. Transmission dynamics and viral persistence were best explained by the existence of both acutely and chronically infected individuals and by seasonally changing transmission rates. Due to the presence of chronically infected rodents, rodent control is unlikely to be a feasible approach for eliminating arenaviruses such as Lassa virus from Mastomys populations.
- MeSH
- Arenavirus immunology MeSH
- Population Density MeSH
- Arenaviridae Infections epidemiology MeSH
- Mice MeSH
- Rodent Diseases epidemiology MeSH
- Antibodies, Viral MeSH
- Seroepidemiologic Studies MeSH
- Disease Reservoirs veterinary MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Tanzania MeSH
Mastomys natalensis is widespread in sub-Saharan Africa and hosts several arenavirus species, including the pathogenic zoonotic Lassa virus in West Africa. Mitochondrial lineages sub-divide the range of M. natalensis and have been associated with cryptic structure within the species. To test specificity of arenaviruses to hosts carrying these lineages, we screened 1772 M. natalensis in a large area of Tanzania where three mitochondrial lineages meet. We detected fifty-two individuals that were positive for one of three arenaviruses: Gairo, Morogoro, and Luna virus. This is the first record of Luna virus in Tanzania. We confirmed the specificity of each arenavirus to a distinct host mitochondrial lineage except for three cases in one locality at the centre of a host hybrid zone. No arenaviruses were detected in a large part of the study area. Morogoro and Gairo virus showed differences in prevalence (Morogoro virus lower than Gairo virus) and in genetic structure (Morogoro virus more structured than Gairo virus). However, both viruses have genetic neighbourhood size estimates of the same order of magnitude as Lassa virus. While differences in arenavirus and/or host evolutionary and ecological dynamics may exist, Tanzanian arenaviruses could be suited to model Lassa virus dynamics in M. natalensis.
- Publication type
- Journal Article MeSH
Orthohantaviruses are RNA viruses that some members are known to cause severe zoonotic diseases in humans. Orthohantaviruses are hosted by rodents, soricomorphs (shrews and moles), and bats. Only two orthohantaviruses associated with murid rodents are known in Africa, Sangassou orthohantavirus (SANGV) in two species of African wood mice (Hylomyscus), and Tigray orthohantavirus (TIGV) in the Ethiopian white-footed rat (Stenocephalemys albipes). In this article, we report evidence that, like SANGV, two strains of TIGV occur in two genetically related rodent species, S. albipes and S. sp. A, occupying different elevational zones in the same mountain. Investigating the other members of the genus Stenocephalemys for TIGV could reveal the real diversity of TIGV in the genus.
- MeSH
- Species Specificity MeSH
- Phylogeny MeSH
- Hantavirus Infections epidemiology veterinary virology MeSH
- Orthohantavirus genetics MeSH
- Rodentia MeSH
- Humans MeSH
- Rodent Diseases epidemiology virology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Ethiopia MeSH
BACKGROUND: In the past decade, many new paramyxoviruses that do not belong to any of the seven established genera in the family Paramyxoviridae have been discovered. Amongst them are J-virus (JPV), Beilong virus (BeiPV) and Tailam virus (TlmPV), three paramyxovirus species found in rodents. Based on their similarities, it has been suggested that these viruses should compose a new genus, tentatively called 'Jeilongvirus'. RESULTS: Here we present the complete genomes of three newly discovered paramyxoviruses, one found in a bank vole (Myodes glareolus) from Slovenia and two in a single, co-infected Rungwe brush-furred rat (Lophuromys machangui) from Mozambique, that represent three new, separate species within the putative genus 'Jeilongvirus'. The genome organization of these viruses is similar to other paramyxoviruses, but like JPV, BeiPV and TlmPV, they possess an additional open reading frame, encoding a transmembrane protein, that is located between the F and G genes. As is the case for all Jeilongviruses, the G genes of the viruses described here are unusually large, and their encoded proteins are characterized by a remarkable amino acid composition pattern that is not seen in other paramyxoviruses, but resembles certain motifs found in Orthopneumovirus G proteins. CONCLUSIONS: The phylogenetic clustering of JPV, BeiPV and TlmPV with the viruses described here, as well as their shared features that set them apart from other paramyxoviruses, provide additional support for the recognition of the genus 'Jeilongvirus'.
- MeSH
- Phylogeny MeSH
- Genome, Viral * MeSH
- Cloning, Molecular MeSH
- Membrane Proteins genetics MeSH
- Paramyxoviridae classification genetics MeSH
- Paramyxovirinae classification genetics MeSH
- Amino Acid Sequence MeSH
- Sequence Analysis, DNA MeSH
- Viral Proteins genetics MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. When host population densities fluctuate, low levels of virulence with limited impact on the host are expected, as this should increase the likelihood of surviving periods of low host density. We examined the effects of Morogoro arenavirus on the survival and recapture probability of multimammate mice (Mastomys natalensis) using a seven-year capture-mark-recapture time series. Mastomys natalensis is the natural host of Morogoro virus and is known for its strong seasonal density fluctuations. RESULTS: Antibody presence was negatively correlated with survival probability (effect size: 5-8% per month depending on season) but positively with recapture probability (effect size: 8%). CONCLUSIONS: The small negative correlation between host survival probability and antibody presence suggests that either the virus has a negative effect on host condition, or that hosts with lower survival probability are more likely to obtain Morogoro virus infection, for example due to particular behavioural or immunological traits. The latter hypothesis is supported by the positive correlation between antibody status and recapture probability which suggests that risky behaviour might increase the probability of becoming infected.
- MeSH
- Survival Analysis MeSH
- Arenavirus immunology isolation & purification MeSH
- Behavior, Animal MeSH
- Arenaviridae Infections mortality veterinary MeSH
- Murinae * MeSH
- Rodent Diseases mortality virology MeSH
- Antibodies, Viral blood MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Brucellosis in cattle and humans has received world-wide research attention as a neglected and re-emerging zoonotic disease with many routes of transmission. Studies of brucellosis in Uganda have emphasized occupational exposures and also revealed variations in prevalence levels by region and cattle production systems. To date, research linking pastoralist household income from dairy production to brucellosis and its transmission risk pathways do not exist in Uganda. We assessed whether spatial differences in unit milk prices can be explained by brucellosis prevalence in cattle along a distance gradient from Lake Mburo National Park in Uganda. Semi-structured interviews administered to 366 randomly selected household heads were supplemented with serological data on brucellosis in cattle. Statistical analysis included Pearson correlation test, multiple regression and analysis of variance (ANOVA) using SPSS version 17. Serological results showed that 44% of cattle blood samples were sero-positive for brucellosis. The results obtained from interviews put the statistical mean of household reported cattle abortions at 5.39 (5.08-5.70 at 95% CI, n=366). Post-hoc analysis of variance revealed that both sero-positive cattle and reported cattle abortions significantly were much lower when moving outwards from the park boundary (p<0.05), while the price of milk increased significantly (p<0.05) along the same distance gradient. Further studies should identify public and private partnerships needed to create and strengthen good zoonotic brucellosis management practices at the nexus of wildlife and livestock in Uganda.
- MeSH
- Brucellosis epidemiology veterinary MeSH
- Livestock MeSH
- Humans MeSH
- Dairying * MeSH
- Milk economics MeSH
- Cattle Diseases epidemiology MeSH
- Prevalence MeSH
- Spatial Analysis MeSH
- Risk MeSH
- Cattle MeSH
- Pregnancy MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Cattle MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Uganda epidemiology MeSH
BACKGROUND: In order to optimize net transmission success, parasites are hypothesized to evolve towards causing minimal damage to their reservoir host while obtaining high shedding rates. For many parasite species however this paradigm has not been tested, and conflicting results have been found regarding the effect of arenaviruses on their rodent host species. The rodent Mastomys natalensis is the natural reservoir host of several arenaviruses, including Lassa virus that is known to cause Lassa haemorrhagic fever in humans. Here, we examined the effect of three arenaviruses (Gairo, Morogoro and Lassa virus) on four parameters of wild-caught Mastomys natalensis: body mass, head-body length, sexual maturity and fertility. After correcting for the effect of age, we compared these parameters between arenavirus-positive (arenavirus RNA or antibody) and negative animals using data from different field studies in Guinea (Lassa virus) and Tanzania (Morogoro and Gairo viruses). RESULTS: Although the sample sizes of our studies (1297, 749 and 259 animals respectively) were large enough to statistically detect small differences in body conditions, we did not observe any adverse effects of these viruses on Mastomys natalensis. We did find that sexual maturity was significantly positively related with Lassa virus antibody presence until a certain age, and with Gairo virus antibody presence in general. Gairo virus antibody-positive animals were also significantly heavier and larger than antibody-free animals. CONCLUSION: Together, these results suggest that the pathogenicity of arenaviruses is not severe in M. natalensis, which is likely to be an adaptation of these viruses to optimize transmission success. They also suggest that sexual behaviour might increase the probability of M. natalensis to become infected with arenaviruses.
- MeSH
- Arenavirus isolation & purification MeSH
- Disease Vectors * MeSH
- Arenaviridae Infections pathology veterinary virology MeSH
- Murinae physiology virology MeSH
- Carrier State pathology veterinary virology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Guinea MeSH
- Tanzania MeSH
Many emerging infections are RNA virus spillovers from animal reservoirs. Reservoir identification is necessary for predicting the geographic extent of infection risk, but rarely are taxonomic levels below the animal species considered as reservoir, and only key circumstances in nature and methodology allow intrinsic virus-host associations to be distinguished from simple geographic (co-)isolation. We sampled and genetically characterized in detail a contact zone of two subtaxa of the rodent Mastomys natalensis in Tanzania. We find two distinct arenaviruses, Gairo and Morogoro virus, each spatially confined to a single M. natalensis subtaxon, only co-occurring at the contact zone's centre. Inter-subtaxon hybridization at this centre and a continuum of quality habitat for M. natalensis show that both viruses have the ecological opportunity to spread into the other substaxon's range, but do not, strongly suggesting host-intrinsic barriers. Such barriers could explain why human cases of another M. natalensis-borne arenavirus, Lassa virus, are limited to West Africa.
- MeSH
- Arenavirus classification metabolism physiology MeSH
- Species Specificity MeSH
- Phylogeography MeSH
- Lassa Fever virology MeSH
- Humans MeSH
- Murinae virology MeSH
- Rodent Diseases virology MeSH
- Lassa virus physiology MeSH
- Disease Reservoirs virology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Tanzania MeSH
