John D. Toft

Bio: John D. Toft is an academic researcher. The author has contributed to research in topics: Secondary infection. The author has an hindex of 1, co-authored 1 publications receiving 44 citations.

The Pathoparasitology of Nonhuman Primates: A Review

Abstract: Most people who have had more than cursory experience in the husbandry of nonhuman primate colonies will agree that parasitism is one of the most common disease entities that affects these animals. Numerous protozoal and metazoal genera have been described as infecting the members of all major nonhuman primate groups. Many of these are considered to be nonpathogenic, or at least their detrimental effects upon the host have yet to be eludicated. A large number, however, can produce lesions that result in serious debilitation and can create opportunities for secondary infections that may be fatal. This process appears to be exacerbated by the stress of capture and confinement.

Habituating the great apes: The disease risks

Abstract: All six great apes, gorillas Gorilla gorilla and G. beringei , chimpanzees Pan troglodytes and P. paniscus , and orang-utans Pongo pygmaeus and P. abelii , are categorized as Endangered on the 2000 IUCN Red List and face many threats to their continued existence in the wild. These threats include loss of habitat to settlement, logging and agriculture, illegal hunting for bushmeat and traditional medicine, the live ape trade, civil unrest and infectious diseases. The great apes are highly susceptible to many human diseases, some of which can be fatal while others can cause marked morbidity. There is increasing evidence that diseases can be transmitted from humans to free-living habituated apes, sometimes with serious consequences. If protective measures are not improved, ape populations that are frequently in close contact with people will eventually be affected by the inadvertent transmission of human diseases. This paper describes the risks, sources and circumstances of infectious disease transmission from humans to great apes during and consequent upon habituation for tourism and research. A major problem is that the regulations that protect habituated apes from the transmission of disease from people are often poorly enforced. Suggestions are made for improving the enforcement of existing regulations governing ape-based tourism, and for minimizing the risk of disease transmission between humans, both local people and international visitors, and the great apes.

Prevalence and Intensity of Intestinal Parasites in Mantled Howling Monkeys (Alouatta palliata) in Northeastern Costa Rica: Implications for Conservation Biology

Abstract: I examined the prevalence and intensity of intestinal parasitic infections in a population of mantled howling monkeys (Alouatta palliata) at La Selva Biological Reserve, a rainforest in northeastern Costa Rica. I collected fresh fecal samples from individual bowler monkeys from two focal troops from October 1991 through October 1992. The presence of parasite ova and larvae in samples was determined by using a formalin-ethyl acetate sedimentation technique. Three types of endoparasites were found: (1) a roundworm, Parabronema sp., (2) a physalopterid roundworm, species undetermined, and (3) a fluke, species undetermined. No differences were found in the prevalence of parasitic infections between sexes or troops. No statistical differences were found between the sexes for the intensity of infection. The troop that lived along the river showed a statistically significant higher intensity of nematode infection than the troop that lived mostly in primary forest. Parabronema sp. was found only from individuals in the river group. The prevalence of parasitic infection observed in howlers at La Selva (100%) is higher than has been reported for bowlers in a dry deciduous forest at La Pacifica, Costa Rica (47%). Microclimatic factors, ranging patterns, and home-range size are identified as important variables that may affect parasitic infections of howler populations. Data from this study suggest that narrow corridor designs may be inappropriate for conservation of primates and possibly other species of arboreal animals.

Parasites of Wild Howlers (Alouatta spp.)

Abstract: A literature review of howler parasites provides the basis for an overview of the ecological significance of parasite surveys in primates. Within this framework, we have added insights into the interactions between primate hosts and their parasites from a long-term study in Costa Rica. We collected fecal samples from mantled howlers (Alouatta palliata) over a 9-year period (1986–1994 inclusive) and analyzed them for parasite eggs, larvae, cysts, and oocysts. We found many misperceptions inherent in the typical methodology of primate parasite surveys and in the reporting of the findings. Our work in Costa Rica suggests that a snapshot effect occurs with most surveys. A static view does not reflect the dynamic and changing ecological interaction between host and parasite. We describe some problems with parasite data analyses that emphasize the need for long-term longitudinal surveys in wild primate groups.

Bioactive properties of plant species ingested by chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, Uganda

Abstract: We examined the biological activities of a selected sample (84 crude extracts) of 24 species eaten by wild chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, western Uganda, to assess their potential chemotherapeutic values. Antibacterial, antimalarial, and/or antileishmania activities were observed in some crude extracts, and five of these extracts showed a significant cytotoxicity against humantumor cells. Active compounds isolated from three plant parts occasionally ingested by chimpanzees (Diospyros abyssinica (Ebenaceae) bark, Uvariopsis congensis (Annonaceae) leaves, and Trichilia rubescens (Meliaceae) leaves) showed highly significant medicinal properties. Two novel antiparasitic limonoids were isolated Trichilia rubescens and their molecular structures were determined. In addition to elucidating the natural equilibrium maintained between hosts and pathogens, our investigation of the diet of wild chimpanzees may serve as a guideline to discovering plants with bioactive properties that should bepreserved from destruction because of their health maintenance value for great ape populations