The Silent Threat: Cytauxzoonosis in Indiana Cats – A Conversation with Dr. Grant Burcham

In a startling revelation, recent research has uncovered a disturbing trend in Indiana, one that has cat owners and veterinarians on high alert. From 2018 to 2022, seven domestic shorthair cats in the state were diagnosed with Cytauxzoon felis, the parasite responsible for the often fatal disease known as bobcat fever. These cases mark the first confirmed instances of both acute and chronic cytauxzoonosis in Indiana, indicating a worrying expansion of this deadly tick-borne disease.

🙏 Brought to you by Boehringer Ingelheim, maker of NexGard® COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) for cats.  Learn more at: bit.ly/3X8FRMh  

To delve deeper into this pressing issue, we spoke with Dr. Grant Burcham, a veterinary diagnostician and assistant professor in comparative pathobiology at Purdue University. Dr. Burcham provided valuable insights into the findings of the recent study and the implications for feline health in Indiana.

The Rising Tide of Cytauxzoonosis

The infected cats, aged between 2 to 9 years, were spread across five counties in southwestern Indiana, highlighting the widespread nature of the threat. Typically transmitted by ticks, such as the American dog tick (Dermacentor variabilis) and the lone star tick (Amblyomma americanum), cytauxzoonosis is notoriously difficult to treat and often fatal in domestic cats.

"These cases are particularly concerning because they indicate that the disease is not just present, but spreading," Dr. Burcham explained. "The fact that we are seeing both acute and chronic forms of the disease means that it's becoming a significant health risk for cats in the region."

Clinical Signs and Diagnosis

The study highlighted several clinical signs that led to the diagnosis of cytauxzoonosis: fever, inappetence, lethargy, depression, dehydration, dyspnea, hemolytic crisis, anorexia, and icterus. Out of the seven reported cases, six cats exhibited acute symptoms, characterized by severe clinical signs and visible pathological lesions. Notably, one cat survived without showing clinical signs, suggesting potential immunity or resistance factors.

"Cytauxzoon felis is an apicomplexan parasite, primarily transmitted by the lone star tick, with the American dog tick being a less effective vector," Dr. Burcham said. "Bobcats, the natural reservoir hosts, typically experience subclinical infection, but can sometimes suffer fatal outcomes."

Diagnosing cytauxzoonosis involves identifying C. felis organisms in blood smears or tissue cytology, supported by PCR testing for definitive confirmation. Key diagnostic findings include leukopenia with toxic neutrophils, thrombocytopenia, normocytic normochromic anemia, hyperbilirubinemia, and hypoalbuminemia.

Treatment and Prevention

Effective treatment for cytauxzoonosis involves a combination of antiprotozoal medications and supportive care, such as IV fluids, nutritional support, oxygen therapy, and blood transfusions. Minimizing stress and handling is crucial for recovery. Historically, the disease had a near 100% fatality rate, but with prompt diagnosis and aggressive treatment using drugs like azithromycin and atovaquone, survival rates have improved significantly, with about 60% of treated cats surviving.

"Preventing cytauxzoonosis primarily relies on tick control and minimizing exposure to tick-infested areas," Dr. Burcham emphasized. "Using tick preventives can help protect cats from bites. Additionally, keeping cats indoors or limiting their access to areas where ticks and bobcats are prevalent can reduce the risk of infection."

The Bigger Picture

The emergence of cytauxzoonosis in Indiana represents a significant shift in the geographic spread of this disease, traditionally seen in southern states where bobcats are more common. This expansion highlights the need for increased vigilance among pet owners and veterinarians in the region.

"Understanding and awareness of the disease are crucial," Dr. Burcham noted. "Veterinarians in areas where C. felis is present must remain vigilant and consider cytauxzoonosis in cats presenting with relevant clinical signs. Early diagnosis and aggressive treatment are key to improving survival rates."

Moving Forward

As cytauxzoonosis continues to pose a lethal threat to cats in Indiana and potentially beyond, Dr. Burcham stresses the importance of ongoing research and education. "Our study emphasizes the need for considering C. felis infection in differential diagnoses for cats exhibiting related symptoms," he said. "Stay informed, proactive, and protect your feline patients from this expanding threat."

The study conducted by Dr. Burcham and his team serves as a wake-up call for the veterinary community, urging them to prioritize early detection and comprehensive treatment of cytauxzoonosis to safeguard the health and well-being of cats in Indiana and across the nation.