Epidemiological investigation of a clinical case of Q fever in the Brazilian Amazon.

The bacterium Coxiella burnetii, responsible for causing Q fever in humans and coxiellosis in animals, is globally distributed, with the exception of New Zealand. In Brazil, is a neglected zoonosis, with scarce information, and with the number of reported cases in humans and animals is certainly underestimated, being considered an important neglected zoonosis. The present study aimed to evaluate, through an epidemiological investigation, a farm located in Belterra, Pará, Brazil, where a recent human case of Q fever occurred, considered the first recognized in the Amazon region of Brazil. After the clinical confirmation of persistent Q fever in the patient, blood samples were collected from 2 dogs, 5 cattle, 2 horses, and 22 goats living on the farm, as well as ticks found on cattle and horses (46 in total). Indirect Immunofluorescence Assay (IFA) show two dogs and three goats seropositive for C. burnetii, demonstrating their roles as sentinels and potential reservoirs and environmental spreaders. One goat had high endpoint titer (1024) to C. burnetii phase II antigen, indicating recent infection. Although no C. burnetii DNA was detected in ticks from livestock, we amplified DNA of Coxiella-like endosymbiont from the cattle tick Rhipicephalus microplus. The results of this study contribute to a better understanding of the ecology of hosts, ticks, and C. burnetii under natural and anthropogenic environmental conditions and how human activities can affect the distribution of this important pathogen.