Exploring the Ecologic Basis for Extreme Susceptibility of Pallas' Cats (Otocolobus Manul) to Fatal Toxoplasmosis

Abstract

Recent efforts by North American zoos to establish a genetically viable captive population of Pallas' cats (Otocolobus manul) have been compromised by high newborn mortality (ϳ60%), primarily because of toxoplasmosis. The basis for this extreme susceptibility to toxoplasmosis is unknown. In the present study, the general health status of wild Pallas' cats in Mongolia was evaluated, including assessment of basal hematologic parameters and fecal corticoid metabolite concentrations. The prevalence of exposure to Toxoplasma gondii in Mongolian Pallas' cats, local domestic cats, and prey species also was determined based on serology and/or polymerase chain reaction analysis. Biologic samples (blood, feces, and/or brain tissue) were obtained from 15 wild Pallas' cats, 15 domestic cats, and 45 prey animals (rodents and pikas) captured in Mongolia during the summers of 2000 and 2001. Comparative data were obtained from nine captive Pallas' cats maintained in North American zoos. Based on physical examinations, complete blood counts, and blood chemistry analyses, only minor differences were observed in the general health status of wild and captive Pallas' cats. Fecal cortisol metabolite concentrations did not differ (PϾ0.05) between populations, indicating that Pallas' cats in captivity and in the wild have similar basal adrenocortical activity. A pronounced difference (PϽ0.01) in seroprevalence to T. gondii was observed between populations. Whereas all captive Pallas' cats exhibited elevated immunoglobulin titers (IgGϾ2,048) to T. gondii, only two of 15 (13%) wild Pallas' cats were seropositive, with both cats having lower IgG titers (Ͻ1,024). Furthermore, no evidence of exposure to this parasite was found in any of the Mongolian domestic cats or prey species. These findings suggest that wild Pallas' cats have minimal opportunity for exposure to T. gondii in their natural habitat and, typically, do not become infected with this parasite until being brought into captivity. Accordingly, maintenance of a viable captive population may require implementing effective strategies to prevent exposure of immunologically naive Pallas' cats to T. gondii and to reduce parasite transmission between seropositive females and their highly susceptible offspring.

DETECTION OF SEASONAL WEIGHT LOSS AND A SEROLOGIC SURVEY OF POTENTIAL PATHOGENS IN WILD PALLAS' CATS (FELIS[OTOCOLOBUS]MANUL) OF THE DAURIAN STEPPE, RUSSIA

“…First, a small percentage (13%) of Pallas' cats had detectable antibodies to Toxoplasma (Table 2), similar to results of Brown et al (2002) on Mongolian Pallas' cats, where 2 of 15 cats (13%) were positive. Thus, our results confirm the low frequency of T. gondii in wild Pallas' cats in different habitats.…”

“…Captive breeding of Pallas' cats has been successful; however, there are no persistent captive populations because kitten survival is low (,40%;Swanson 1999;Kenny et al 2002) because of susceptibility to Toxoplasma gondii (Dubey et al 1988;Basso et al 2005). Brown et al (2002) showed that prevalence of antibodies to T. gondii was 13% in wild cats in Mongolia, but 100% in cats in captivity.…”

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…In fact, wild Pallas' cats have minimal opportunity for exposure to T. gondii in their isolated natural habitat in Central Asia and, typically, do not become infected with this parasite until being brought into captivity. This could explain their extreme susceptibility to toxoplasmosis [132], which could threaten conservation programs devoted to this species [133]. Although no specific case has been documented in the wild, T. gondii may threaten local wild-living populations, for example when new human settlements come in contact with isolated endangered populations.…”

First record and molecular identification ofToxocara catiin a Pallas’ catOtocolobus manulfrom Kyrgyzstan

“…Given the Pallas' cat's habitat of uplands, steppe and semi-desert regions, human population density in its distribution range is very low. While in the Pallas' cats Russian distribution range, sheepherders and cattle farms keep domestic cats as companion animals, this is not the case in other parts of its range (in Mongolia for example; Brown et al, 2005). Given that the Pallas' cats themselves only occur at low densities, it appears unlikely that the parasite generally has a high prevalence in this newly discovered defi nitive host.…”

“…Given the decline of wild Pallas' cats, knowledge of the general health status of wild population may be important in a conservation context. For example, while toxoplasmosis leads to high mortality rates of new-borns in captive populations, exposure to Toxoplasma gondii appears to be minimal in the wild (Brown et al, 2005). Here, we present the fi rst record of a T. cati infestation observed in a Pallas' cat sampled in Kyrgyzstan.…”