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April 23, 2021 – If you’ve never heard of cytauxzoonosis, a life-threatening, tick-transmitted infection of cats, you’re not alone. This rare, often-fatal disease caused by the blood parasite Cytauxzoon felis was relatively unknown outside the southeastern United States until roughly 20 years ago when the disease began spreading to new areas.

Morris Animal Foundation has funded 10 studies in the last 15 years to address this growing crisis. Two newly funded studies aim to develop new systems for studying C. felis in the laboratory. The complex life cycle of C. felis makes studying the parasite difficult, and discovery of new diagnostic tests or drug therapies nearly impossible.

Dr. Craig Miller, an immunopathologist at Oklahoma State University, is conducting one of these new studies, hoping to establish new tick and feline cell culture systems.

“It’s difficult to test potential treatments or answer basic biological questions without a viable system,” said Dr. Miller, noting that success would be a major advance for studying this unusual, but important, parasite of cats, and could potentially lead to better treatments for this deadly disease.

C. felis passes through several different stages as it moves between cats (including bobcats, its natural host) and ticks. Transmitted via tick bites, the parasite enters the host’s white blood cells which swell as the parasite matures. These enlarged cells block small blood vessels primarily in the liver, lung, spleen and lymph nodes, cutting off blood supply, setting off a spiral of inflammation, organ damage and often death.

The infected white blood cells eventually burst and parasites are released into the host’s bloodstream, infecting red blood cells. In cats that survive, the infected red cells are ingested by feeding ticks, starting the cycle of transmission again.