Assessment of Domestic Goats as Models for Experimental and Natural Infection with the North American Isolate of Rickettsia slovaca

Abstract

Rickettsia slovaca is a tick-borne human pathogen that is associated with scalp eschars and neck lymphadenopathy known as tick-borne lymphadenopathy (TIBOLA) or Dermacentor-borne necrosis erythema and lymphadenopathy (DEBONEL). Originally, R. slovaca was described in Eastern Europe, but since recognition of its pathogenicity, human cases have been reported throughout Europe. European vertebrate reservoirs of R. slovaca remain unknown, but feral swine and domestic goats have been found infected or seropositive for this pathogen. Recently, a rickettsial pathogen identical to R. slovaca was identified in, and isolated from, the American dog tick, Dermacentor variabilis. In previous experimental studies, this organism was found infectious to guinea pigs and transovarially transmissible in ticks. In this study, domestic goats (Capra hircus) were experimentally inoculated with the North American isolate of this R. slovaca-like agent to assess their reservoir competence–the ability to acquire the pathogens and maintain transmission between infected and uninfected ticks. Goats were susceptible to infection as demonstrated by detection of the pathogen in skin biopsies and multiple internal tissues, but the only clinical sign of illness was transient fever noted in three out of four goats, and reactive lymphoid hyperplasia. On average, less than 5% of uninfected ticks acquired the pathogen while feeding upon infected goats. Although domestic goats are susceptible to the newly described North American isolate of R. slovaca, they are likely to play a minor role in the natural transmission cycle of this pathogen. Our results suggest that goats do not propagate the North American isolate of R. slovaca in peridomestic environments and clinical diagnosis of infection could be difficult due to the brevity and mildness of clinical signs. Further research is needed to elucidate the natural transmission cycle of R. slovaca both in Europe and North America, as well as to identify a more suitable laboratory model.

Topography of coronary arteries and their ramifications in the goat

“…The similarity of organ size between goats and humans makes these animals widely used. They are used in human medicine in research such as cardiac, orthopedic, model for infectious diseases or many others (Shiraishi et al 2012;Chen et al 2015;Zhang et al 2015;Lukovsky-Akhsanov et al 2016;Du et al 2018;Vandersteene et al 2018).…”

Neglected aspects of tick-borne rickettsioses

“…Rickettsial transmission to feeding ticks was also demonstrated, in the Americas, in opossums, lagomorphs, capybaras, small rodents ( R. rickettsii ) [ 40 – 44 ] and goats (North American isolate of R. slovaca ) [ 45 ]. In Europe, Heylen et al [ 46 ] showed that experimentally infected great tits ( Parus major ) transmit R. helvetica to feeding I. ricinus and facilitate co-feeding.…”