Study compares qPCR and ELISA for Cytauxzoon felis in cats

A newly published Veterinary Sciences study adds nuance to how veterinarians may think about detecting Cytauxzoon felis in apparently healthy cats in the south-central U.S. The Oklahoma State University-led team evaluated both probe-based qPCR and an indirect IgG ELISA in 100 client-owned cats from Arkansas, Missouri, and Oklahoma, aiming to compare evidence of active infection versus prior exposure in an endemic region where bobcat fever remains a serious clinical threat. (pmc.ncbi.nlm.nih.gov)

That question matters because C. felis has long been framed mainly as an acute, often fatal disease, but the epidemiology has become more complicated. Cytauxzoonosis is transmitted primarily by the lone star tick, and most U.S. cases are reported in the south-central and southeastern states, typically during the main tick season from March through September. At the same time, earlier research has shown that some cats survive infection and remain chronically infected, potentially contributing to ongoing transmission. (news.okstate.edu)

The new paper specifically set out to compare healthy pet cats and free-range cats using two different tools: qPCR for parasite DNA and IgG ELISA for antibody evidence of exposure. According to the study summary, samples from client-owned cats were collected by veterinary personnel from April 2024 through August 2024 in Arkansas, Oklahoma, and Missouri. The authors reported that lifestyle was significantly associated with ELISA detection, but not with qPCR detection, suggesting serology may surface a broader exposure history than molecular testing alone. (pmc.ncbi.nlm.nih.gov)

The findings fit with a broader body of regional surveillance work. A 2014 study in healthy cats from enzootic areas of Arkansas, Missouri, and Oklahoma reported an overall C. felis infection prevalence of 6.2%, with state-level prevalence estimates of 15.5% in Arkansas, 12.9% in Missouri, and 3.4% in Oklahoma. In eastern Kansas, a later qPCR-based study found a much higher carrier prevalence of 25.8% in asymptomatic cats, with significant seasonal variation and the highest detection in fall and spring. Together, those studies suggest that silent infection or exposure in outwardly healthy cats is not rare in some endemic settings, even if the clinical disease remains the main trigger for testing in practice. (pmc.ncbi.nlm.nih.gov)

Industry and expert commentary around cytauxzoonosis continues to center on prevention and fast recognition rather than routine broad screening, but the surveillance implications are getting harder to ignore. CAPC says subclinical infection prevalence in U.S. domestic cats ranges from 0% to 25.8%, and notes that piroplasms may appear on blood smears one to three weeks after infection. In a recent dvm360 interview, parasitologist Susan Little, DVM, PhD, emphasized that year-round systemic tick control is important in high-pressure regions, including the Southeast and south-central states where lone star ticks are abundant. Oklahoma State has also continued to stress year-round tick prevention for both indoor and outdoor cats in endemic areas. (capcvet.org)

Why it matters: For veterinary teams, this study is less about replacing one test with another than about sharpening what each result means. qPCR is still the better fit for identifying current infection, especially when acute disease is on the table, while IgG ELISA may help reveal prior exposure patterns that matter for surveillance, population studies, and risk communication. In practical terms, that could affect how clinicians talk with pet parents about outdoor access, tick exposure, prior illness history, and why a clinically normal cat in an endemic area may still be epidemiologically relevant. (pmc.ncbi.nlm.nih.gov)

The paper also lands amid ongoing concern about bobcat fever in Oklahoma and neighboring states, where clinicians report persistent seasonal pressure and narrow treatment windows. Oklahoma State has noted that untreated cytauxzoonosis can kill within days of symptom onset, and that atovaquone plus azithromycin with supportive care improved survival in a 2013 study to about 60%. That backdrop helps explain why better understanding of asymptomatic infection matters: the disease remains severe, but the reservoir picture is broader than acute cases alone. (news.okstate.edu)

What to watch: The next step is whether additional validation studies translate this paired-testing approach into clinical guidance, reference-lab offerings, or regional surveillance protocols, particularly in endemic states where veterinarians are already balancing acute diagnosis, prevention messaging, and the possibility of chronically infected carrier cats. (pmc.ncbi.nlm.nih.gov)