Identification and distribution of pathogens coinfecting with Brucella spp., Coxiella burnetii and Rift Valley fever virus in humans, livestock and wildlife

Abstract

Zoonotic diseases, such as brucellosis, Q fever and Rift Valley fever (RVF) caused by Brucella spp., Coxiella burnetii and RVF virus, respectively, can have devastating effects on human, livestock, and wildlife health and cause economic hardship due to morbidity and mortality in livestock. Coinfection with multiple pathogens can lead to more

severe disease outcomes and altered transmission dynamics. These three pathogens

can alter host immune responses likely leading to increased morbidity, mortality and

pathogen transmission during coinfection. Developing countries, such as those commonly afflicted by outbreaks of brucellosis, Q fever and RVF, have high disease burden and thus common coinfections. A literature survey provided information on case

reports and studies investigating coinfections involving the three focal diseases. Fifty

five studies were collected demonstrating coinfections of Brucella spp., C. burnetii or

RVFV with 50 different pathogens, of which 64% were zoonotic. While the literature

search criteria involved ‘coinfection’, only 24/55 studies showed coinfections with direct pathogen detection methods (microbiology, PCR and antigen test), while the rest

only reported detection of antibodies against multiple pathogens, which only indicate

a history of co- exposure, not concurrent infection. These studies lack the ability to

test whether coinfection leads to changes in morbidity, mortality or transmission dynamics. We describe considerations and methods for identifying ongoing coinfections

to address this critical blind spot in disease risk management.