Urban Rodents in Argentina Carry Diverse Cryptosporidium Species, Molecular Survey Finds

A molecular survey of rats and mice captured in urban and peri-urban areas of La Plata, Argentina, has found Cryptosporidium DNA in 11.8 percent of the animals tested, with five distinct parasite species or genotypes identified among the positive samples. The study, published in Acta Parasitologica, analysed 85 intestinal samples from three synanthropic rodent species: 25 brown rats (Rattus norvegicus), 16 black rats (Rattus rattus) and 44 house mice (Mus musculus). The researchers used nested PCR targeting the 18S rRNA gene for screening, and analysed the gp60 gene in selected cases to characterise the parasites further. The results point to these rodents as hosts carrying a mixture of rodent-adapted and potentially zoonotic Cryptosporidium species in settings where people and animals share space.

The overall detection rate of 10 positive samples out of 85 (95 percent confidence interval: 5.8 to 20.5 percent) concealed differences among the host species. Brown rats showed the highest positivity at 16 percent (4 of 25), followed by black rats at 12.5 percent (2 of 16) and house mice at 9.1 percent (4 of 44). Sequence analysis of the positive samples identified four isolates of C. tyzzeri, three of C. muris, one of C. ratti, one of C. occultus and one isolate assigned to Cryptosporidium sp. rat genotype IV. Several of these species are considered rodent-adapted, but the authors noted that C. tyzzeri, C. muris and C. occultus are potentially zoonotic, meaning they may have the capacity to infect humans under appropriate conditions.

Cryptosporidiosis, the disease caused by these protozoan parasites, is described in the study as a zoonotic illness with a global distribution that represents a significant public health concern worldwide. Synanthropic rodents, those living in close association with human environments, are recognised as reservoirs of these pathogens and are considered to play an important role in their dissemination and transmission. Detecting parasite DNA, however, does not by itself establish whether the animals were actively shedding infectious oocysts or whether transmission to humans occurs in these localities.

The identification of five different Cryptosporidium species or genotypes in a relatively small sample set underscores the genetic diversity of the parasite circulating among rodents in La Plata and surrounding areas. The presence of C. ratti and the rat genotype IV is consistent with rodent-associated parasite lineages, whereas the detection of species with suspected zoonotic potential raises questions about the role these animals may play in local transmission cycles. The authors emphasised that such findings support the need for integrated surveillance and control measures to better understand transmission dynamics and to reduce public health risks associated with Cryptosporidium spp. in shared urban environments.

As with any cross-sectional survey of this kind, the study has inherent limitations: the sample size was modest, the animals came from a single metropolitan region, and the confidence interval around the overall prevalence estimate is wide, spanning roughly 6 to 20 percent. The detection method identifies parasite DNA rather than viable, infectious organisms, and the study design cannot demonstrate direction of transmission between rodents and humans. Nevertheless, the work provides a molecular baseline for Cryptosporidium diversity in synanthropic rodents in Argentina and adds to evidence that common urban rats and mice carry multiple parasite species, some of which merit continued monitoring given their potential relevance to human health.

Subject of Research: Molecular detection and diversity of Cryptosporidium species in synanthropic rodents in urban Argentina

Article Title: Cryptosporidium spp. in Synanthropic Rodents: A Molecular Characterisation Study

Article References: Dellarupe, A., Steffen, K. D., De Felice, L., Fitte, B., del Rosario Robles, M., Sella, M. E., & Unzaga, J. M. (2026). Cryptosporidium spp. in Synanthropic Rodents: A Molecular Characterisation Study. Acta Parasitologica, 71(6), Article 246. https://doi.org/10.1007/s11686-026-01430-x

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01430-x

Keywords: Cryptosporidium, synanthropic rodents, zoonotic disease, molecular epidemiology, nested PCR, 18S rRNA, gp60 gene, La Plata Argentina, public health, parasitology, Synanthropic, Rodents