Study finds limited arbovirus seroreactivity in urban marmosets

Version 2

A newly published study in Frontiers in Veterinary Science reports limited evidence of recent arbovirus exposure in free-ranging black-tufted marmosets (Callithrix penicillata) from urban parks in Belo Horizonte, Brazil. The researchers screened animals for antibodies to chikungunya, Zika, dengue, and yellow fever, and found low-level IgM seroreactivity only for chikungunya and Zika: two of 68 marmosets were reactive for chikungunya, one of 68 for Zika, and one animal reacted to both. Overall, the paper suggests that, in this setting, detectable recent serologic response in marmosets was uncommon despite endemic human circulation of these arboviruses. (frontiersin.org)

That finding lands in the middle of a long-running One Health question in Brazil: whether urban and peri-urban nonhuman primates are merely incidental hosts for human-associated arboviruses, or whether some could contribute to longer-term maintenance or early warning surveillance. The authors place their work against Brazil’s major 2016–2019 yellow fever outbreak, which caused more than 2,000 human cases and major impacts in neotropical primates. They also note prior reports of arboviral exposure or infection in neotropical primates, including marmosets, while emphasizing that evidence has been inconsistent across regions and methods. (frontiersin.org)

The study population consisted of free-ranging black-tufted marmosets captured in urban or peri-urban areas, with seroreactive animals identified in Parque das Mangabeiras, described by the authors as Belo Horizonte’s largest park. Molecular testing was more limited than the serology: only 16 serum samples had sufficient volume for RT-PCR, all of those were negative, and the seroreactive animals were not among the PCR-tested group because no sample remained. That’s an important caveat for interpretation, because the findings point to possible prior or recent exposure, but they do not establish active infection at the time of capture. (frontiersin.org)

The paper also leans heavily into a technical limitation that veterinary readers will recognize: serologic cross-reactivity. The authors state that flaviviruses, especially Zika and dengue, can cross-react serologically, and that broader cross-reactivity with other arboviruses can further complicate interpretation. In their view, plaque reduction neutralization testing would have helped clarify which virus triggered the antibody response, particularly in the animal that reacted to both chikungunya and Zika assays. Without that confirmatory step, the results are best read as limited, putative seroreactivity rather than definitive proof of species-specific infection. (frontiersin.org)

Even so, the broader surveillance context makes the report useful. A 2026 Emerging Infectious Diseases report from CDC described nine yellow fever-positive Callithrix penicillata marmosets in São Paulo state during the 2024–2025 epizootic outbreak, with high viral loads and characteristic lesions, and concluded that these animals should be included in multispecies surveillance strategies for early detection. Earlier CDC-backed analysis also found that Callithrix primates can show lower apparent susceptibility and subtler pathology than some other New World primates, which may make surveillance interpretation more complicated rather than less important. (wwwnc.cdc.gov)

Why it matters: For veterinary professionals, especially those working in wildlife health, pathology, zoo and exotic medicine, public health, and vector-borne disease surveillance, the study reinforces that urban marmosets deserve attention even when positivity rates are low. Low seroreactivity does not rule out epidemiologic relevance; it may instead reflect timing of sampling, assay limitations, transient exposure, or species-specific immune dynamics. In practice, this supports a surveillance model that combines serology, PCR, pathology, entomology, and geographic context, rather than relying on any single test stream. It also underscores the value of veterinarians in interpreting wildlife findings for public health teams and for local communication with pet parents who may encounter free-ranging primates in shared urban environments. (frontiersin.org)

The industry reaction here is less about overt commentary than about convergence. Across recent Brazilian and international surveillance literature, the consistent message is that marmosets at the human-animal interface are worth monitoring, but the signal can be faint and method-dependent. This Frontiers report fits that pattern: it doesn’t show broad arboviral circulation in the sampled marmosets, but it does add another data point suggesting exposure can occur in urban-adapted primates living alongside dense human populations. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step will likely be studies that pair broader sampling with confirmatory neutralization assays and coordinated mosquito, primate, and human surveillance, particularly in Brazilian urban green spaces where arboviral ecology is changing fastest. (frontiersin.org)