Species-specific differences in Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti seroprevalence in Namibian wildlife

Anne Seltmann,Ortwin H K Aschenborn,Sonja K Heinrich,Susanne Thalwitzer,Gábor Á Czirják,Bettina Wachter,Gereon Schares

doi:10.1186/s13071-019-3871-3

Abstract

BackgroundKnowledge about parasitic infections is crucial information for animal health, particularly of free-ranging species that might come into contact with livestock and humans.MethodsWe investigated the seroprevalence of three tissue-cyst-forming apicomplexan parasites (Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti) in 506 individuals of 12 wildlife species in Namibia using in-house enzyme linked immunosorbent assays (indirect ELISAs applying purified antigens) for screening and immunoblots as confirmatory tests. We included six species of the suborder Feliformia, four species of the suborder Caniformia and two species of the suborder Ruminantia. For the two species for which we had most samples and life-history information, i.e. cheetahs (Acinonyx jubatus, n = 250) and leopards (Panthera pardus, n = 58), we investigated T. gondii seroprevalence in relation to age class, sex, sociality (solitary, mother-offspring group, independent sibling group, coalition group) and site (natural habitat vs farmland).ResultsAll but one carnivore species (bat-eared fox Otocyon megalotis, n = 4) were seropositive to T. gondii, with a seroprevalence ranging from 52.4% (131/250) in cheetahs to 93.2% (55/59) in African lions (Panthera leo). We also detected antibodies to T. gondii in 10.0% (2/20) of blue wildebeest (Connochaetes taurinus). Adult cheetahs and leopards were more likely to be seropositive to T. gondii than subadult conspecifics, whereas seroprevalence did not vary with sex, sociality and site. Furthermore, we measured antibodies to N. caninum in 15.4% (2/13) of brown hyenas (Hyaena brunnea) and 2.6% (1/39) of black-backed jackals (Canis mesomelas). Antibodies to B. besnoiti were detected in 3.4% (2/59) of African lions and 20.0% (4/20) of blue wildebeest.ConclusionsOur results demonstrate that Namibian wildlife species were exposed to apicomplexan parasites at different prevalences, depending on parasite and host species. In addition to serological work, molecular work is also needed to better understand the sylvatic cycle and the clear role of wildlife in the epidemiology of these parasites in southern Africa.

Highlights

Knowledge about parasitic infections is crucial information for animal health, of free-ranging species that might come into contact with livestock and humans
Since domestic cats are the main reservoir of T. gondii and occur in large numbers in some areas in southern Africa [25], we argue that seroprevalence will be higher in sites where humans and their domestic animals live, such as on freehold farmland and communal farmland, compared to natural habitat, such as national parks
Toxoplasma gondii antibodies In Feliformia (African lions, brown hyenas, caracals, cheetahs, leopards and spotted hyenas) and Caniformia (African wild dogs, bat-eared foxes, black-backed jackals and honey badgers), a dichotomous pattern of reactions in the TgSAG1 enzyme-linked immunosorbent assays (ELISA) was observed (Fig. 1a) and a positive cut-off was selected at an ELISA index of 0.5

Summary

Introduction

Knowledge about parasitic infections is crucial information for animal health, of free-ranging species that might come into contact with livestock and humans. The exposure of wildlife, livestock and humans to apicomplexan parasites such as Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti is high in Africa [1], complete information on the parasites and their. For carnivores and omnivores, including humans, infection with T. gondii predominantly occurs via ingestion of raw meat containing encysted bradyzoites, while for all host species transmission occurs transplacentally or via ingestion of water, feces or vegetation contaminated with sporulated oocysts derived from felid feces [2]. It is currently unknown to which extent wild felids, other than feral cats, such as cheetahs (Acinonyx jubatus) and leopards (Panthera pardus), contribute to the T. gondii life-cycle in southern Africa. The high density of wild and domestic animals in Africa living sympatrically and the lack of a clear spatial separation between livestock and wildlife might result in a high pathogen transmission between wild animals, livestock and humans [4]

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