Association of human disturbance and gastrointestinal parasite infection of yellow baboons in western Tanzania.

Human disturbance is an ongoing threat to many wildlife species, manifesting as habitat destruction, resource overuse, or increased disease exposure, among others. With increasing human: non-human primate (NHP) encounters, NHPs are increasingly susceptible to human-introduced diseases, including those with parasitic origins. As such, epidemiology of parasitic disease is becoming an important consideration for NHP conservation strategies. To investigate the relationship between parasite infections and human disturbance we studied yellow baboons (Papio cynocephalus) living outside of national park boundaries in western Tanzania, collecting 135 fresh faecal samples from nine troops occupying areas with varying levels of human disturbance. We fixed all samples in 10% formalin and later evaluated parasite prevalence and abundance (of isotrichid ciliates and Strongylida). We identified seven protozoan and four helminth taxa. Taxa showed varied relationships with human disturbance, baboon troop size and host age. In four taxa, we found a positive association between prevalence and troop size. We also report a trend towards higher parasite prevalence of two taxa in less disturbed areas. To the contrary, high levels of human disturbance predicted increased abundance of isotrichid ciliates, although no relationship was found between disturbance and Strongylida abundance. Our results provide mixed evidence that human disturbance is associated with NHP parasite infections, highlighting the need to consider monitoring parasite infections when developing NHP conservation strategies.

Environmentally transmitted parasites: Host-jumping in a heterogeneous environment.

Groups of chronically infected reservoir-hosts contaminate resource patches by shedding a parasite׳s free-living stage. Novel-host groups visit the same patches, where they are exposed to infection. We treat arrival at patches, levels of parasite deposition, and infection of the novel host as stochastic processes, and derive the expected time elapsing until a host-jump (initial infection of a novel host) occurs. At stationarity, mean parasite densities are independent of reservoir-host group size. But within-patch parasite-density variances increase with reservoir group size. The probability of infecting a novel host declines with parasite-density variance; consequently larger reservoir groups extend the mean waiting time for host-jumping. Larger novel-host groups increase the probability of a host-jump during any single patch visit, but also reduce the total number of visits per unit time. Interaction of these effects implies that the waiting time for the first infection increases with the novel-host group size. If the reservoir-host uses resource patches in any non-uniform manner, reduced spatial overlap between host species increases the waiting time for host-jumping.

Molecular identification of Schistosoma mattheei from feces of Kinda (Papio cynocephalus kindae) and grayfoot baboons (Papio ursinus griseipes) in Zambia.

Terminal-spined Schistosoma sp. eggs were detected in several groups of baboons living in Kafue National Park in central Zambia. A total of 166 fecal samples was screened; egg prevalence overall ranged between 7% and 10%, while infection intensities were low. Formalin-fixed eggs had an average length of 144.5 microm and a breadth of 48.3 microm, but the schistosome species could not be unambiguously identified by size or morphology. We used molecular methods to definitively identify the parasite species. Parasite DNA was amplified from stools by polymerase chain reaction (PCR). Sequence analysis of fragments of the first internal transcribed spacer (ITS-1), mitochondrial 12S rDNA, NADH dehydrogenase subunit 6 (nad6), and cytochrome C oxidase subunit 1 (cox1) from 3 egg-positive samples revealed the presence of S. mattheei in these samples. This is the first molecular identification of S. mattheei from free-ranging baboons. Schistosoma mattheei is typically a parasite of bovids, but it can also infect humans. Schistosoma mattheei in baboons in Zambia may affect other wildlife species and humans that live in close proximity to baboons.

Evolution of a malaria resistance gene in wild primates.

The ecology, behaviour and genetics of our closest living relatives, the nonhuman primates, should help us to understand the evolution of our own lineage. Although a large amount of data has been amassed on primate ecology and behaviour, much less is known about the functional and evolutionary genetic aspects of primate biology, especially in wild primates. As a result, even in well-studied populations in which nongenetic factors that influence adaptively important characteristics have been identified, we have almost no understanding of the underlying genetic basis for such traits. Here, we report on the functional consequences of genetic variation at the malaria-related FY (DARC) gene in a well-studied population of yellow baboons (Papio cynocephalus) living in Amboseli National Park in Kenya. FY codes for a chemokine receptor normally expressed on the erythrocyte surface that is the known entry point for the malarial parasite Plasmodium vivax. We identified variation in the cis-regulatory region of the baboon FY gene that was associated with phenotypic variation in susceptibility to Hepatocystis, a malaria-like pathogen that is common in baboons. Genetic variation in this region also influenced gene expression in vivo in wild individuals, a result we confirmed using in vitro reporter gene assays. The patterns of genetic variation in and around this locus were also suggestive of non-neutral evolution, raising the possibility that the evolution of the FY cis-regulatory region in baboons has exhibited both mechanistic and selective parallels with the homologous region in humans. Together, our results represent the first reported association and functional characterization linking genetic variation and a complex trait in a natural population of nonhuman primates.

Prevalence of antibodies and cell mediated immune response against Leishmania major in feral nonhuman primates from Kenya.

In Kenya, Leishmania major is responsible for human cutaneous leishmaniasis (CL). Natural infection with L. major of a vervet monkey and experimental susceptibility of some nonhuman primates (NHPs) from Kenya has been established. However, there has been no comprehensive study of the prevalence of zoonotic CL in Kenya. And also, no investigation has been done to assess whether NHPs could be potential reservoir hosts of L. major even when the involvement of reservoir animals is obligatory in transmission of this parasite. To achieve this, wild caught Chlorocebus aethiops (Vervet monkeys n=213), Papio cynocephalus anubis (olive baboons n=101) and Cercopithecus mitis (Syke's monkeys n=64) from five geographical locations in Kenya were screened for antibodies against L. major using enzyme linked immunosorbent assay (ELISA) and Western blot (WB) analysis. From the population of C. aethiops (n=213) captured, 57 were used in lymphocyte proliferation assay. ELISA revealed a high prevalence of leishmaniasis sero conversion in olive baboons 78/101 (77.2%), vervet monkeys 129/213 (60.6%) and Sykes' monkeys 43/64 (67.2%). WB detected anti-L. major antibodies in 48.5% (49/101) of the baboons, 48% (102/213) of vervet monkeys and 37.5% (24/64) of Sykes' monkey sera. Specific proliferation of peripheral blood mononuclear cells to L. major antigen was demonstrated in 17 of the 57 (29.8%) vervet monkeys. In conclusion, the results of serological assays provide strong circumstantial evidence that CL is prevalent in five Provinces of Kenya and that Kenyan NHPs could be could be a potential reservoir hosts of L. major.

Efficacy of fenbendazole formulated in a commercial primate diet for treating specific pathogen-free baboons (Papio cynocephalus anubis) infected with Trichuris trichiura.

Trichuris trichiura is a common intestinal nematode parasite of captive baboons. We evaluated the efficacy of fenbendazole formulated in a commercial primate diet (FBZ-PD) for treating specific pathogen-free (SPF) baboons (Papio cynocephalus anubis) naturally infected with Trichuris trichiura. Twenty-nine baboons, housed indoors in 3 separate rooms, were fed FBZ-PD for 5 d, whereas 4 baboons housed in another isolated area served as untreated controls. The efficacy of FBZ-PD was measured as reduction in the number of T. trichiura eggs in host feces after treatment as determined by quantitative fecal flotation examination. All baboons that received FBZ-PD stopped shedding T. trichiura eggs by 7 d after initiation of treatment, and remained negative until at least 119 d after treatment. However, eggs of T. trichiura were present in the feces of 3 (10.3%) experimental baboons at 154 d after treatment. Untreated control baboons shed T. trichiura eggs throughout the entire study. Our results indicate that FBZ-PD was efficacious for treating SPF baboons infected with T. trichiura.

Efficacy of fenbendazole and milbemycin oxime for treating baboons (Papio cynocephalus anubis) infected with Trichuris trichiura.

We evaluated the efficacy of fenbendazole (FBZ) and milbemycin oxime (MO) in the treatment of baboons (Papio cynocephalus anubis) with naturally acquired Trichuris trichiura infection by comparing fecal egg count reduction (FECR) tests. We assigned 7 baboons, each singly housed and confirmed infected with T. trichiura, to treatment groups of FBZ (n=3) or MO (n=3), or as a control (n=1). All (100%) baboons that received FBZ stopped shedding T. trichiura eggs within 6 d of treatment, and fecal egg counts remained negative at 65 d after treatment. Although the number of T. trichiura eggs shed per gram of feces from 2 (67%) baboons decreased significantly after the second treatment with MO, this regimen never totally eliminated eggs of T. trichiura. The results of our study indicate that FBZ was more effective for treating baboons with T. trichiura than was MO.