FIV-positive African lions face additional health risks when parasites are along for the ride

Researchers at Oregon State University recently conducted an extensive study of feline immunodeficiency virus (FIV) in African lions. The study, published in the International Journal of Parasitology: Parasites and Wildlife, concluded that secondary infections are important in disease progression.

According to the researchers, this finding could have clinical implications for other animal and human populations affected by parasites and immunosuppressive viruses such as HIV. The team found coinfections with parasites is similar in magnitude to FIV when it comes to a lion’s overall health.

“This study demonstrated that coinfections are just as important as FIV on lion health,” said Heather Broughton, DVM, PhD, Courtesy Professor of research at Oregon State University, veterinary practitioner, and the study’s principal investigator. “We especially noted a link between the presence of gastrointestinal parasites and FIV. The parasites seem to alter the immune system in a way that drives progression of clinical diseases associated with FIV infection.”

The Oregon State team observed 195 free-ranging lions living in Kruger National Park, South Africa, as part of a larger study on lion health, behavior, and demographics. Lions were sedated and given a thorough physical examination. Blood and fecal samples were also obtained for further analysis.

The results revealed that approximately 73% of lions tested positive for FIV. The team demonstrated that FIV infection had negative effects on nutrient balance, clinical health, and immune system function. The team also found changes in hormones and behavior parameters that reflect increased aggression in FIV-positive hosts, which would facilitate virus transfer.¹

“This study shows how the interaction of different disease-causing agents affects wild animals,” said Janet Patterson-Kane, BVSc, PhD, FRCVS, Morris Animal Foundation chief scientific officer. “Studying diseases in free-ranging animals gives us a better picture of the real-world conditions that affect their health. It’s challenging, but these studies provide important information that can guide conservation of these incredible animals.”

FIV is a retrovirus that causes immunosuppression in an infected host. FIV is similar to human immunodeficiency virus (HIV) and is spread via direct contact, usually through bite and scratch wounds in lions. African lions in eastern and southern Africa have the highest prevalence of FIV infection of any wild felid, with estimates suggesting between 50% and 83% of adults affected in several areas, according to a release from Morris Animal Foundation, who funded the research.

“Lion populations can, and do, persist in the presence of FIV, and the association is old and long-standing,” said Anna Jolles, PhD, professor of epidemiology at Oregon State University, and Broughton’s fellowship mentor. “But for the individual host, it’s a slow and sly infection that subtly undermines the animal’s functioning and health at many levels. This is the first study to show that secondary infections are just as important as the presence of FIV when we look at health.”

Reference

Broughton H, Govender D, Serrano E, Shikwambana P, Jolles A. Equal contributions of feline immunodeficiency virus and coinfections to morbidity in African lions. Int J Parasitol Parasites Wildl. 2021;16:83-94. Published 2021 Aug 19. doi:10.1016/j.ijppaw.2021.07.003