Search

Madagascar's lemur populations are declining in dwindling habitats due to anthropogenic expansion and changing climatic conditions. Gastrointestinal parasites can be important indicators to assess the health status of threatened species. However, parasites, hosts and the environment are connected in complex interactions. The present study aimed to disentangle the impact of seasonal and several host-specific factors (sex, species, age, reproductive status, and body mass) on endoparasitism in two small-bodied, co-occurring lemur species ( Microcebus murinus and Microcebus ravelobensis ) in the Ankarafantsika National Park. Helminth prevalence and egg shedding intensity was investigated via copromicroscopic examination of 810 fecal samples that were obtained from 178 individuals across an 11-month period with a longitudinal approach via repeated captures in a 30.6 ha forest area. Both mouse lemur hosts shed seven morphologically distinct egg types (assigned to Subulura baeri , unidentified Enterobiinae, Spirura sp., Lemuricola sp., two Hymenolepididae spp., one unidentified ascarid). Postmortem examination of two deceased individuals enabled assignment of adult worms to egg morphotypes of S. baeri , Spirura sp. and one Hymenolepididae sp., supported by molecular analysis. A significant seasonal variation was observed in the occurrence of the three most common helminth species S . baeri (total prevalence 71%), unidentified Enterobiinae (46%) and Spirura sp. (38%), with a higher likelihood of infection with advancing dry season. Neither host species, sex nor reproductive status had a significant effect on gastrointestinal helminth infections. Host body mass showed pronounced seasonal changes but did not differ significantly between infected and non-infected individuals. The pathogenic effects of gastrointestinal helminths therefore likely remained within compensable limits in the studied mouse lemur populations. Our findings highlight the prominent influence of seasonal changes on helminth communities. The results of combined morphologic and genetic approaches can furthermore help to overcome limitations of parasite identification via copromicroscopy by linking egg morphology to DNA sequences., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Sucking lice live in intimate association with their hosts and often display a high degree of host specificity. The present study investigated sucking lice of the genus Lemurpediculus from six mouse lemur ( Microcebus ) and two dwarf lemur ( Cheirogaleus ) species endemic to the island of Madagascar, considered a biodiversity hotspot. Louse phylogenetic trees were created based on cytochrome C oxidase subunit I (COI), elongation factor 1α (EF1α) and internal transcribed spacer 1 (ITS1) sequences. While clustering according to host species was generally observed for COI and ITS1, suggesting high host specificity of the examined lice, EF1α sequences alone did not distinguish between lice of different Microcebus species, possibly due to rather recent divergence. As bootstrap support for basal tree structure was rather low, further data are necessary to resolve the evolutionary history of louse-mouse lemur associations. Three new species of sucking lice are described: Lemurpediculus zimmermanni sp. Nov. From Microcebus ravelobensis , Lemurpediculus gerpi sp.nov. from Microcebus gerpi , and Lemurpediculus tsimanampesotsae sp. nov. from Microcebus griseorufus . These new species are compared with all known congeneric species and identifying features are illustrated for all known species of Lemurpediculus ., Competing Interests: None., (© 2023 The Authors.)

The dynamic relationship of vector-borne parasites, arthropod vectors and their hosts is prone to change under the influence of climate change, global integration, shifting demographics and deforestation. It is therefore essential to better understand parasitism in wildlife populations, including parasites transmitted by blood-feeding vectors, and explore host range and heterogeneity of parasitic infections. We investigated Giemsa stained blood smears of two sympatric Malagasy primate species ( Microcebus murinus : 184 samples from 69 individuals and M. ravelobensis : 264 samples from 91 individuals) for blood-stage parasites and tested for a potential influence of host species, sex, body mass and sampling month on blood-stage parasite prevalence and infection intensity. No protozoan parasites were detected in either host species. A host-specific difference was observed in filarial nematode infections, with higher risk of infection in M. murinus (prevalence 30.43%), than in M. ravelobensis (prevalence 6.59%), which may be explained by differences in host behavior and/or immune competence, linked to the period of host-parasite coevolution. Neither sex nor sampling month influenced infection prevalence or intensity significantly. We did not observe a negative effect of microfilarial infections on host fitness when taking body mass as a proxy. Our results support the hypothesis of a long-term evolutionary adaptation of hosts and parasites, leading to persistent infection with low morbidity. Morphological and molecular analyses indicate the finding of a new species, " Lemurfilaria lemuris ". Genetic analysis furthermore showed >99% sequence identity with microfilariae described from a sympatric, larger-bodied lemur species of a different genus, suggesting low host-specificity of the detected filariae and pathogen transmission across genus boundaries. Findings contribute to a more comprehensive picture of vector-borne diseases of Malagasy lemurs.

Non-human primates of South-East Asia remain under-studied concerning parasite epidemiology and co-infection patterns. Simultaneously, efforts in conservation demand knowledge of parasite abundance and biodiversity in threatened species. The Endangered proboscis monkey, Nasalis larvatus , a primate flagship species for conservation in Borneo, was investigated in the present study. Habitat loss and fragmentation are among the greatest threats to bachelor and harem groups of this folivorous colobine. Designed as a follow-up study, prevalence and co-infection status of intestinal parasites from N. larvatus in a protected area in Malaysian Borneo were analyzed from fecal samples using a flotation method. For the first time, the intestinal parasite co-infection patterns were examined using quantitative analyses. Overall, 92.3% of fecal samples (N = 652) were positive for helminth eggs. Five helminth groups were detected: (1) trichurids (82.7% prevalence) including Trichuris spp. (82.1%) and Anatrichosoma spp. (1.4%), (2) strongyles (58.9%) including Trichostrongylus spp. (48.5%) and Oesophagostomum/Ternidens spp. (22.8%), (3) Strongyloides fuelleborni (32.7%), (4) Ascaris lumbricoides (8.6%), and (5) Enterobius spp. (5.5%). On average, an individual was co-infected with two different groups. Significant positive associations were found for co-infections of trichurids with strongyles and S. fuelleborni as well as S. fuelleborni with A. lumbricoides and strongyles. This study shows a high prevalence of various gastrointestinal helminths with potential transmission pathways primarily related to soil and with zoonotic relevance in wild proboscis monkeys in their remaining natural habitats. Observed positive associations of trichurids with strongyles and Strongyloides spp. may result from the high prevalence of trichurids. Similarly, positive associations between Strongyloides and Ascaris were found, both of which typically occur predominantly in juvenile hosts. These findings should be considered when proposing conservation actions in altered habitats nearby human settlements and when managing captive populations.