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Sarcocystis Parasites Were Detected in 69% of Pennsylvania Coyotes

Coyote walking through open vegetation
Research: Disease, parasites & microbiology, Genetics & genomics

A study of wild canids from Pennsylvania, USA found Sarcocystis sporocysts in the intestines of 18 of 26 coyotes (Canis latrans), or 69.2%. Sarcocystis are microscopic single-celled parasites with life cycles that alternate between definitive carnivore hosts and intermediate prey or livestock hosts. Detecting sporocysts in a canid intestine shows that the animal was serving as a definitive host and could shed parasite stages; it does not by itself show that the coyote was clinically ill. The study was published on 18 June 2026 in Parasites & Vectors.

Sporocysts were found in all three canid species

The researchers examined intestinal material from 40 wild canids collected in Pennsylvania in 2024: 26 coyotes, eight red foxes (Vulpes vulpes) and six gray foxes (Urocyon cinereoargenteus). The animals had been harvested by hunters, allowing the team to analyse intestinal tissue for the parasite stages shed by definitive hosts.

Microscopy detected Sarcocystis sporocysts in 18 coyotes, three red foxes and three gray foxes. DNA amplification succeeded in only a subset of the positive animals — eight coyotes and two red foxes, but no gray foxes — so molecular species identification was limited to those successfully sequenced samples. The researchers used several genetic markers to distinguish parasite lineages where the DNA data were adequate.

Sarcocystis sporocysts in an intestinal homogenate from a Pennsylvania coyote
Sarcocystis sporocysts in intestinal material from a Pennsylvania coyote. Figure 1 from Gupta et al. (2026), CC BY 4.0.

DNA analysis revealed several parasite lineages

The molecular analyses supported the presence of multiple Sarcocystis types. These included forms related to Sarcocystis albifronsi, S. gjerdei, S. cristata/S. wenzeli and an undescribed lineage associated with ungulate hosts. The team also identified Sarcocystis cruzi, a parasite that uses cattle as intermediate hosts.

Coyotes and foxes act as definitive hosts in the life cycles of these parasites: sexual reproduction occurs in the canid intestine, and resistant sporocysts are released into the environment. Intermediate hosts become infected after ingesting the parasite stages, completing the cycle when infected tissues are later eaten by a suitable carnivore.

The authors conclude that wild canids in Pennsylvania harbour a diverse assemblage of Sarcocystis species and can contribute to environmental dissemination at the wildlife–livestock interface. The detection of cattle-associated S. cruzi is particularly relevant because infections in livestock can have economic consequences.

By combining microscopy with multi-locus DNA analysis, the study also showed why genetic methods are useful for these parasites: sporocysts from different Sarcocystis species can look very similar under the microscope, making species-level identification difficult from morphology alone.

Sources and image credit

  1. Gupta, A., Van Why, K., Brown, J. D., Rosenthal, B. M., & Dubey, J. P. (2026). Molecular characterization of Sarcocystis spp. in intestines of coyotes and foxes from Pennsylvania, USA. Parasites & Vectors, 19, 369. https://doi.org/10.1186/s13071-026-07515-wPrimary peer-reviewed open-access study. Intestinal samples from 26 coyotes, eight red foxes and six gray foxes collected in Pennsylvania in 2024 were examined by microscopy and multi-locus DNA analysis. Sarcocystis sporocysts were detected in 18 coyotes, three red foxes and three gray foxes.
  2. U.S. National Library of Medicine. (2026). Molecular characterization of Sarcocystis spp. in intestines of coyotes and foxes from Pennsylvania, USA. PubMed (PMID 42316237).Bibliographic record confirming the 2026 publication and summarising prevalence and molecular identifications.

Image: John and Karen Hollingsworth / U.S. Fish & Wildlife Service / Wikimedia Commons — coyote (Canis latrans) walking through open vegetation, 11 October 2001; representative species image, not an animal from the Pennsylvania parasite study. · Public Domain · Source

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Disease, parasites & microbiology

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