Serological evidence of rickettsia, orientia, and coxiella in domestic animals from Bhutan: preliminary findings

There is no information on rickettsial diseases in domestic animals in Bhutan. This study provides preliminary serological data on exposure of domestic animals to Rickettsia, Orientia, and Coxiella. Animal sera were collected opportunistically from Bhutan and tested in the Australian Rickettsial Reference Laboratory for IgG antibodies against spotted fever group (SFG) and typhus group (TG) Rickettsia, scrub typhus group (STG), and Q fever (QF). Of the 294 animals tested, 136 (46%) showed serological evidence of past exposure to one or more rickettsiae: 106 (36%), 62 (21%), 45 (15%), and 11 (4%) being positive against SFG Rickettsia, Orientia, TG Rickettsia, and Coxiella, respectively. Dogs appeared to exhibit the highest seropositivity against SFG (55%) and TG Rickettsia (45%), horses against STG (91%), while goats were mostly positive for Coxiella (9%). Dogs also appeared to have high risk of being exposed to SFG Rickettsia (odd ratios [OR] 5.71, 95% confidence interval [CI] 3.02-10.80, p < 0.001), TG Rickettsia (OR 48.74, 95% CI 11.29-210.32, p < 0.001), and STG (OR 6.80, 95% CI 3.32-13.95, p < 0.001), but not against QF (OR 1.95, 95% CI 0.42-8.95, p = 0.390). Differences in seropositivity rates between animal species may have been significant for SFG, TG, and STG, but not for QF. The differences in the seropositivity rates of the four infections between districts appeared to be significant for TG and STG, but not for SFG and QF. The seropositivity rates of domestic animals to the four rickettsial infections were consistent with similar studies on the human population in the same areas and appear to demonstrate a high prevalence of exposure to rickettsiae in Bhutan. These preliminary findings constitute baseline data for Bhutan. The findings of this study call for an increased human-livestock sector collaboration in rickettsial diseases research aimed at developing diagnostic and therapeutic guidelines and formulating preventive and control measures through a One Health approach.