Tick-Borne Disease Agents in Various Wildlife from Mississippi

Abstract

Because tick-borne diseases are becoming increasingly important throughout the world, monitoring their causative agents in wildlife may serve as a useful indicator of potential human exposure. We assessed the presence of known and putative zoonotic, tick-borne agents in four wildlife species in Mississippi. Animals were tested for exposure to or infection with Ehrlichia chaffeensis, Ehrlichia ewingii, Borrelia lonestari, Rickettsia spp., Anaplasma phagocytophilum, and Francisella tularensis. Whole blood and serum were tested from white-tailed deer (WTD; Odocoileus virginianus) and feral swine (Sus scrofa); serum was tested from raccoons (Procyon lotor) and opossums (Didelphis virginiana). We used polymerase chain reaction to detect all agents in blood, whereas an indirect fluorescent antibody assay was used to detect antibodies to E. chaffeensis, B. lonestari, and Rickettsia parkeri (spotted fever group rickettsiae) antigens in serum. Molecular evidence of infection with E. chaffeensis, B. lonestari, and An. phagocytophilum was detected only in WTD. Antibodies to E. chaffeensis antigen were detected in 43.9% of WTD, 32.8% of swine, 42.1% of raccoons, and 15.8% of opossums. Serologic evidence of exposure to B. lonestari antigen was found in 19.3% of WTD, 6.9% of swine, and 5.3% of raccoons, but not in opossums. Interestingly, the percent of animals with antibodies reactive to spotted fever group rickettsiae (R. parkeri antigen) was highest in raccoons (73.7%) and opossums (57.9%). These results support the role of WTD as reservoirs for E. chaffeensis, B. lonestari, and An. phagocytophilum, as well as provide additional evidence for exposure of raccoons and opossums to E. chaffeensis. Finally, we provide new data that feral swine may have antibodies to these agents. Thus, in general, these four wildlife species are exposed to tick-borne disease agents in Mississippi, suggesting that ticks carry and have the potential to transmit the agents to humans in the state.

Serological evidence of exposure to tick-borne agents in opossums (Didelphis spp.) in the state of São Paulo, Brazil

“…antibodies in opossums. Evidence of the exposure of opossums to E. chaffeensis has been reported in the USA (CASTELLAW et al, 2011). Although research into Ehrlichia spp.…”

“…Various tick species act as vectors of several pathogens, and many wild animals act as reservoirs for these agents. Therefore, rickettsiosis, ehrlichiosis, and borreliosis have been reported around the world to cause illness in animals and humans (CASTELLAW et al, 2011).…”

“…Animals seropositive to Ehrlichia chaffeensis have been reported in the United States (CASTELLAW et al, 2011). On the other hand, Lyme disease, a common zoonosis in the northern hemisphere (United States, Europe and Asia), is considered an infectious disease caused by spirochetes of the Borrelia burgdorferi sensu lato complex which is transmitted by ticks of the Ixodes ricinus complex (STEERE, 2001).…”

Gene expression profile suggests that pigs (Sus scrofa) are susceptible to Anaplasma phagocytophilum but control infection

“…has not been reported in wild boar [13,19,20], although other tick species feeding on wild boar were positive for A. phagocytophilum DNA [12]. Recently, 16S rDNA but not p44 / msp2 genotypes identical to A. phagocytophilum were found with low prevalence in wild boar in Japan [21] but a survey in Mississippi, United States, failed to detect pathogen DNA in feral pigs [22]. These results suggested that wild pigs might play a role in the epizootiology of A. phagocytophilum by serving as a natural reservoir host in some regions only.…”

Evidence of Antibodies to Spotted Fever Group Rickettsiae in Small Mammals and Quail from Mississippi

“…Rickettsia typhi is maintained by a rat-flea life cycle (Azad 1990), and has also been found in spleen tissue samples from opossums (Didelphis marsupialis; Williams et al 1992), suggesting that this opossum is a good host for proliferation of the bacterium. In Mississippi, mammals such as raccoons, opossums, cottontail rabbits, and white-tailed deer, have been shown to have antibodies to SFGR (Norment et al 1985;Castellaw et al 2011). Identifying vertebrates that are part of tick-borne agent life cycles provides important information about the ecology and epidemiology of such pathogens that is relevant to the veterinary and public health sectors.…”