Attempted Experimental Infection of Domestic Goats withEhrlichia chaffeensis

Abstract

Although white-tailed deer (WTD; Odocoileus virginianus ) are considered the primary natural reservoir host for Ehrlichia chaffeensis, the causative agent of human monocytotropic ehrlichiosis, the potential role of other vertebrates as reservoir hosts has not been fully explored. Because domestic goats are naturally infected in areas where E. chaffeensis is endemic in deer, we evaluated the susceptibility of domestic goats to experimental infection with E. chaffeensis. A total of 12 goats were inoculated with E. chaffeensis (15B-WTD-GA or Ark strain)-infected DH82 cells by one of three routes: intravenously, subcutaneously, or intradermally. White-tailed deer simultaneously inoculated with the same dose, route, and inoculum served as positive controls; additional goats and WTD were included as negative controls. Evidence of E. chaffeensis infection was evaluated in all animals by indirect fluorescent antibody assay, PCR, and cell culture isolation techniques. All goats exposed to E. chaffeensis seroconverted by 14 days post-infection (DPI), and E. chaffeensis was isolated from one goat on 3 DPI; however, molecular or cell culture evidence of active infection was not detected in goats later than 3 DPI. White-tailed deer exhibited serologic and molecular evidence of E. chaffeensis infection throughout both trials, and E. chaffeensis was reisolated in cell culture from all infected WTD on numerous days post-infection. Our results suggest that despite the occurrence of natural infection in goats, this animal may not be susceptible to experimental infection and thus may not serve as a suitable model of E. chaffeensis reservoir host infection.

Predominance of Ehrlichia ewingii in Missouri Dogs

“…A closely related species, E. chaffeensis, was subsequently identified as the cause of human monocytic ehrlichiosis (1). E. chaffeensis has also been detected in dogs (12), coyotes (21), goats (13), and deer (3,10). Another closely related species, E. ewingii, was initially recognized as the cause of granulocytic ehrlichiosis in dogs (15) and was recently found to cause some cases of granulocytic ehrlichiosis in humans (7).…”

Ehrlichiosis and related infections

“…In goats from E chaffeensis-endemic areas, seropositivity has been identified, and the organism has been detected in blood samples via nucleic acid detection tests and bacteriologic culture. 64 European strains of A phagocytophilum cause a febrile illness in sheep and cattle known as tick-borne fever. 65 The pathogen also infects a wide variety of wildlife in Europe, including rodents and cervids.…”

Human Ehrlichioses and Rickettsioses in Cameroon

“…Earlier reports revealed E. canis, E. chaffeensis, and E. ewingii in R. sanguineus ticks collected from 51 dogs from different localities in Cameroon (Figure 2), suggesting that dogs could be a reservoir for E. chaffeensis and that R. sanguineus is the probable vector (Ndip et al, 2007). In the United States, the white-tailed deer (Odocoileus virginianus) has been recognised as the primary natural reservoir of E. chaffeensis (Dugan et al, 2000). However, animals such as goats, dogs, and coyotes have also been identified as reservoirs which could play a limited role in the transmission of the pathogen to humans (Breitschwerdt et al, 1998;Dugan et al, 2000;Kocan et al, 2000).…”

“…In the United States, the white-tailed deer (Odocoileus virginianus) has been recognised as the primary natural reservoir of E. chaffeensis (Dugan et al, 2000). However, animals such as goats, dogs, and coyotes have also been identified as reservoirs which could play a limited role in the transmission of the pathogen to humans (Breitschwerdt et al, 1998;Dugan et al, 2000;Kocan et al, 2000). Unlike rickettsial species, ehrlichial species are not transmitted trans-ovarially (ie., larvae are uninfected) suggesting that the pathogen is maintained transstadially after the infection is acquired (Ismail et al, 2010).…”