Biology subjects

Soarimalala, V.

Publications and source records attributed to Soarimalala, V..

3 recordsLinked to original sources

bioRxiv2023

Effect of habitat degradation on hantavirus infection among introduced and endemic small mammals of Madagascar

Hantaviruses are globally distributed zoonotic pathogens capable of causing fatal disease in humans. Rodents and other small mammals are the typical reservoirs of hantaviruses, though the particular host varies regionally. Addressing the risk of hantavirus spillover from animal reservoirs to humans requires identifying the local mammal reservoirs and the predictors of infection in those animals, such as their population density and habitat characteristics. We screened native and non-native small mammals and bats in northeastern Madagascar for hantavirus infection to investigate the influence of habitat, including effects of human land use on viral prevalence. We trapped 227 bats and 1663 small mammals over 5 successive years in and around Marojejy National Park across a range of habitat types including villages, agricultural fields, regrowth areas, and secondary and semi-intact forests. Animals sampled included endemic tenrecs (Tenrecidae), rodents (Nesomyidae) and bats (6 families), along with non-native rodents (Muridae) and shrews (Soricidae). A hantavirus closely related to the previously described Anjozorobe virus infected 9.5% of Rattus rattus sampled. We did not detect hantaviruses in any other species. Habitat degradation had a complex impact on hantavirus prevalence in our study system: more intensive land use increase the abundance of R. rattus. The average body size of individuals varied between agricultural and non-agricultural land-use types, which in turn affected infection prevalence. Smaller R.rattus had lower probability of infection and were captured more commonly in villages and forests. Thus, infection prevalence was highest in agricultural areas. These findings provide new insights to the gradients of hantavirus exposure risk for humans in areas undergoing rapid land use transformations associated with agricultural practices.

zoology↗

bioRxiv2022

The macroevolutionary impact of recent and imminent mammal extinctions on Madagascar

Madagascars biota has suffered recent extinctions and many of its unique species are threatened. However, the severity of recent and potential extinctions in a global evolutionary context is unquantified. We compiled a phylogenetic dataset for the complete non-marine mammalian biota of Madagascar and estimated natural rates of extinction, colonization, and speciation. We measured how long it would take to restore Madagascars mammalian biodiversity under these rates, the "evolutionary return time" (ERT). We show the loss of currently threatened Malagasy mammal species would have a much deeper long-term impact than all the extinctions since human arrival to the island. A return from current to pre-human diversity would take 1.6 million years (Myr) for bats, and 2.9 Myr for non-volant mammals. However, if species currently classified as threatened go extinct, the ERT rises to 2.9 Myr for bats and 23 Myr for non-volant mammals. The evolutionary history currently under threat on Madagascar is much greater than on other islands, suggesting an extinction wave with deep evolutionary impact is imminent unless immediate conservation actions are taken.

evolutionary biology↗

bioRxiv2021

Co-evolution of Leptospira and Tenrecidae (Afrotheria) on Madagascar

Leptospirosis is a bacterial zoonosis caused by pathogenic Leptospira that are maintained in the kidney lumen of infected animals acting as reservoirs and contaminating the environment via infected urine. The investigation of leptospirosis through a One Health framework has been stimulated by notable genetic diversity of pathogenic Leptospira together with a high infection prevalence in certain animal reservoirs. Studies of Madagascars native mammal fauna have revealed a diversity of Leptospira with high levels of host-specificity. Native rodents, tenrecids, and bats shelter several distinct lineages and species of Leptospira, some of which have also been detected in acute human cases. Specifically, Leptospira mayottensis, first discovered in humans on Mayotte, an island neighboring Madagascar, was subsequently identified in a few species of Malagasy tenrecids, an endemic family of small mammals. Distinct L. mayottensis lineages were identified in shrew tenrecs (Microgale cowani and Nesogale dobsoni) on Madagascar, and later in spiny tenrecs (Tenrec ecaudatus) on Mayotte. These findings suggest that L. mayottensis (i) has co-radiated with tenrecids on Madagascar, and (ii) has recently emerged in human populations on Mayotte following the introduction of T. ecaudatus from Madagascar. Hitherto, L. mayottensis has not been detected in spiny tenrecs on Madagascar. In the present study, we broaden the investigation of Malagasy tenrecids and describe the presence of L. mayottensis in Malagasy T. ecaudatus and M. thomasi. These results confirm the hypothesis that L. mayottensis was introduced to Mayotte, presumably via T. ecaudatus, and provide additional data on the co-radiation of Leptospira and Tenrecidae.

evolutionary biology↗