Coxiella burnetii infection presenting as fever of unknown origin: a retrospective case series from Bulgaria

Abstract

Purpose:The extent of filovirus exposure and the primary sources of ebolavirus spillover to high-risk communities remains poorly characterized. In the Bwindi region of Uganda, a hotspot of mammalian biodiversity in Africa, human livelihoods are intimately connected with wildlife, creating potential for exposure to filoviruses. Our objectives were to investigate previous exposure to filoviruses in people in the Bwindi region and characterize risk factors for past exposure, including livelihoods and interactions with wildlife.Methods & Materials: Samples from 331 febrile patients presenting to healthcare facilities near the Bwindi Impenetrable Forest, Uganda, were tested using molecular (PCR) and serological assay detection techniques. Serum was tested by Western blot utilizing recombinant glycoprotein antigens for Ebola virus (EBOV), Sudan virus (SUDV), Bundibugyo virus (BDBV) and Marburg virus. Questionnaires were used to collect demographic information, travel and medical history, and data on interactions with domestic and wild animals.Results: All patients were negative for active filovirus replication by PCR. However, several patient serum samples were reactive to SUDV (4.7%), EBOV (5.3%) and BDBV (8.9%) indicating likely previous exposure to these ebolaviruses. Direct contact with duikers was a significant risk factor associated with EBOV seropositivity (OR = 5.6; P = 0.026), while hunting primates (OR = 37.5; P = < 0.001) and contact with/or consumption of cane rats (OR = 10.7; P = 0.006) were significant risk factors for SUDV seropositivity.Conclusion: People in Southwestern Uganda have suspected previous exposure to filoviruses, particularly those with a history of wildlife contact. Identification of antibodies to ebolaviruses in humans in Bwindi likely represents previous infection with SUDV, EBOV, or BDBV or infection with serologically cross-reactive low or non-pathogenic undiscovered filoviruses that also share wildlife hosts. Our findings indicate that spillover of ebolaviruses in humans, and circulation of ebolaviruses, could be more common than previously reported. The results of this study inform ongoing surveillance efforts needed to improve our understanding of the role of wildlife in spillover of ebolaviruses, not only adding to investigations of bats as likely reservoir hosts, but also indicating that secondary spillover host species remain important sources of human infection.Purpose: Fever of unknown origin (FUO) is a perplexing medical problem. The causes for FUO are more than 200 diseases. The aim