Pathogen exposure varies widely among sympatric populations of wild and domestic felids

Carver, S., Bevins, S. N., Lappin, M. R., Boydston, E. E., Lyren, L. M., Alldredge, M. W., Logan K.A., Sweanor, L.L., Riley, S.P.D., Klein Serieys, L.E., Fisher, R.N., Vickers,T.W., Boyce, W.M., McBride, R., Cunningham, M.C., Jennings, M., Lewis, J.S., Lunn, T. Crooks, K.R. & VandeWoude, S. (2015). Pathogen exposure varies widely among sympatric populations of wild and domestic felids across the United States. Ecological Applications.
Understanding how landscape, host, and pathogen traits contribute to disease exposure requires systematic evaluations of pathogens within and among host species and geographic regions. The relative importance of these attributes is critical for management of wildlife and mitigating domestic animal and human disease, particularly given rapid ecological changes, such as urbanization. We screened >1,000 samples from sympatric populations of puma (Puma concolor), bobcat (Lynx rufus) and domestic cat (Felis catus) across urban gradients in six sites, representing three regions, in North America for exposure to a representative suite of bacterial, protozoal and viral pathogens (Bartonella sp., Toxoplasma gondii, feline herpesvirus-1, feline panleukopenea virus, feline calicivirus, feline immunodeficiency virus). We evaluated prevalence within each species, and examined host trait and land cover determinants of exposure-providing an unprecedented analysis of factors relating to potential for infections in domesticated and wild felids. Prevalence differed among host species (highest for puma and lowest for domestic cat) and was greater for indirectly transmitted pathogens. Sex was inconsistently predictive of exposure to directly transmitted pathogens only, and age infrequently predictive of both direct and indirectly transmitted pathogens. Determinants of pathogen exposure were widely divergent between the wild felid species. For puma, suburban landuse predicted increased exposure to Bartonella sp. in southern California, and FHV-1 exposure increased near urban edges in Florida. This may suggest inter-specific transmission with domestic cats via flea vectors (California) and direct contact (Florida) around urban boundaries. Bobcats captured near urban areas had increased exposure to T. gondii in Florida, suggesting an urban source of prey. Bobcats captured near urban areas in Colorado and Florida had higher FIV exposure, possibly suggesting increased intra-specific interactions through pile-up of home ranges. Beyond these regional and pathogen specific relationships, proximity to the wildland urban interface did not generally increase the probability of disease exposure in wild or domestic felids, emphasizing the importance of local ecological determinants. Indeed, pathogen exposure was often negatively associated with the wildland urban interface for all felids. Our analyses suggest cross-species pathogen transmission events around this interface may be infrequent, but followed by self-sustaining propagation within the new host species.

Effects of FPL on a feral cat population

van Rensburg P.J.J., Skinner J. D. & van Aarde R. J. (1987) Effects of feline panleucopaenia on the population characteristics of feral cats on Marion Island. Journal of Applied Ecology, 24, 63-73.

(I) This paper evaluates the effects ofthe artificial introduction offcline panleucopaenia (FPL) as a primary control measure ofa feral cat population on the sub-Antarctic Marion Island (46º54'S,37º45'E). 

(2) The population decreased from an estimated 3409 cats in 1977 (introduction of control factor) to 615 (S.E. = 107) cats during 1982, suggesting an annual rate of decrease of 29%. 

(3) Litter size decreased and the age structure changed significantly because ofa decrease in subadult numbers. Age specific mortality rates were higher but followed the same pattern as in 1975 because there were fewer subadults but the same age structure of adults. 

(4) The intrinsic rate ofincrease, as suggested by the survival and fecundity schedules of the: population, was higher in 1975 owing to a greater proportion of adults and a higher fecundity in age class II. 

(5) Antibody titres of FPL were lower in 1982 than in 1978 which illustrates that FPL did affect the cat population but is no longer spreading effectively. FPL was independent of feline herpes (FVR), an endemic disease of the cat population. and FPL was, therefore, directly responsible for the decrease in cat population density. 

(6) During 1982 the cat population showed a decrease of 8% year-I, whieh indicates stabilizing of the negative growth rate. This observation was supported by lower titres of FPL. 

Transmision modes for FPLV

Berthier, K., M. Langlais, P. Auger, & D. Pontier. 2000. Dynamics of a feline virus with two transmission modes within exponentially growing host populations. Proceedings of the Royal Society, Biological Sciences, 267(1457): 2049–2056.

Feline panleucopenia virus (FPLV) was introduced in 1977 on Marion Island (in the southern Indian Ocean) with the aim of eradicating the cat population and provoked a huge decrease in the host population within six years. The virus can be transmitted either directly through contacts between infected and healthy cats or indirectly between a healthy cat and the contaminated environment: a specific feature of the virus is its high rate of survival outside the host. In this paper, a model was designed in order to take these two modes of transmission into account. The results showed that a mass-action incidence assumption was more appropriate than a proportionate mixing one in describing the dynamics of direct transmission. Under certain conditions the virus was able to control the host population at a low density. The indirect transmission acted as a reservoir supplying the host population with a low but sufficient density of infected individuals which allowed the virus to persist. The dynamics of the infection were more affected by the demographic parameters of the healthy hosts than by the epidemiological ones. Thus, demographic parameters should be precisely measured in field studies in order to obtain accurate predictions. The predicted results of our model were in good agreement with observations.