Study suggests ELISA may widen detection of Cytauxzoon exposure: full analysis

A newly published study adds a potentially important diagnostic wrinkle to feline cytauxzoonosis surveillance: in healthy cats from Oklahoma, Arkansas, and Missouri, ELISA detected substantially more Cytauxzoon felis exposure than qPCR detected circulating parasite DNA. The study, published April 28, 2026, in Veterinary Sciences, compared an indirect ELISA with probe-based qPCR and found that 248 cats, or 35.37% of those tested, were ELISA-positive but qPCR-negative. The authors say that pattern likely reflects cats that developed specific antibodies despite having no detectable parasitemia at sampling. (mdpi.com)

That matters because C. felis remains one of the most consequential tick-borne infections in cats in the U.S., especially across the southern, south-central, and mid-Atlantic regions. Acute disease can be highly fatal, but not every exposed cat dies. Reviews of the disease note that some cats survive acute infection and remain chronically infected, while others may be exposed without developing overt illness. The parasite was first reported in domestic cats in Missouri in 1976, and its recognized range has expanded over time. (mdpi.com)

The new paper builds on a longer line of work from the same regional disease ecology. In a 2015 prevalence study of healthy cats from enzootic parts of Arkansas, Missouri, and Oklahoma, investigators found C. felis DNA in 56 of 902 cats, for an overall prevalence of 6.2%, with state-level prevalence of 15.3% in Arkansas, 12.9% in Missouri, and 3.4% in Oklahoma. That study was important because it showed clinically normal cats in high-incidence areas can carry the parasite, and it argued that domestic cats may have a larger role in transmission than once assumed. (parasitesandvectors.biomedcentral.com)

The new ELISA-versus-qPCR comparison pushes that idea further by suggesting exposure is more widespread than DNA-based screening alone shows. Based on the article abstract, the study enrolled healthy pet and free-ranging cats and paired biologic samples with demographic data. The central finding was not just that ELISA picked up more positives than qPCR, but that the discordant ELISA-positive/qPCR-negative group was large. That suggests serology may better capture prior exposure, resolved infection, intermittent parasitemia, or infections below qPCR detection thresholds. That last point is an inference from the testing pattern rather than a direct conclusion that every ELISA-positive cat remains infectious. (mdpi.com)

Expert background from Oklahoma State University and prior reviews helps explain why this is clinically relevant. OSU has described cytauxzoonosis as an acute, frequently fatal disease in cats and has emphasized year-round tick prevention for cats with outdoor access. The broader literature also shows domestic cats are not simply dead-end hosts: experimental and field evidence cited in prior studies indicates chronically infected cats can act as competent reservoirs, alongside bobcats, for tick-mediated transmission. (news.okstate.edu)

Why it matters: For veterinarians, the study is a reminder that a negative qPCR in a healthy cat does not necessarily mean no meaningful C. felis history. In endemic areas, this has implications for how clinicians interpret screening results, counsel pet parents about outdoor risk, and think about population-level surveillance in shelter, community-cat, and mixed indoor-outdoor cat populations. It also sharpens the distinction between tests that detect current circulating DNA and tests that detect an immune response to exposure. If ELISA is validated further, it could become a useful complement to qPCR when the clinical question is exposure history rather than confirmation of acute parasitemia. (mdpi.com)

There are still important caveats. Seropositivity alone does not establish active infection, infectiousness to ticks, or protection from future disease. And because acaricide options for cats remain more limited than for dogs, prevention still hinges on consistent tick control, especially in regions where Amblyomma americanum and Dermacentor variabilis overlap with feline exposure risk. Prior work has linked disease occurrence to those vectors and to environmental interfaces such as wooded or edge habitats. (parasitesandvectors.biomedcentral.com)

What to watch: The next step will be whether follow-on studies define how ELISA status correlates with chronic carrier state, seasonality, geography, and transmission risk, and whether diagnostic guidance in endemic regions begins to position serology and qPCR as complementary rather than competing tools. (mdpi.com)