Location: Animal Parasitic Diseases LaboratoryTitle: Bobcats (Lynx rufus) are natural definitive host of Besnoitia darlingi
|VERMA, SHIV - Non ARS Employee|
|CERQUEIRA-CEZAR, CAMILA - Non ARS Employee|
|MURATA, FERNANDO - Non ARS Employee|
|LOVALLO, MATTHEW - Pennsylvania Game Commission, Bureau Of Wildlife Management|
Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2017
Publication Date: 11/15/2017
Citation: Verma, S., Cerqueira-Cezar, C., Murata, F., Lovallo, M., Dubey, J.P., Rosenthal, B.M. 2017. Bobcats (Lynx rufus) are natural definitive host of Besnoitia darlingi. Veterinary Parasitology. 248:84-89. http://doi.org/10.1016/j.vetpar.2017.10.013.
Interpretive Summary: Toxoplasma gondii is an intracellular parasite that infects up to one-quarter of humans worldwide. Although it can infect virtually any warmblooded animal, its definitive host is the cat where the sexual cycle occurs in enterocytes of the small intestine, producing microscopic, durable oocysts that are shed in feces and can remain infectious for extended periods of time in the environment. The oocysts of Toxoplasma are difficult to distinguish from its 2 close relatives Hammondia hammondi and Besnoitia darlingi. In the present study, the authors found for the first time Toxoplasma -like oocysts in feces of 2 of 25 naturally infected bob cats (Lynx rufus) from Mississippi. Detailed investigation revealed that in both instances oocysts were B. darlingi and not Toxoplasma. These results will be of interest to biologists, microbiologists, and parasitologists.
Technical Abstract: Bovine besnoitiosis, caused by Besnoitia besnoiti, is an economically important disease of cattle in many countries but its transmission remains a mystery. Wild felids are suspected to be its definitive hosts. The domestic cat (Felis catus) is known experimental definitive host for Besnoitia species of rodents. Here, we report for Besnoitia darlingi the first identification of a natural definitive host, the bobcat (Lynx rufus). Oocysts resembling Toxoplasma gondii (11.9 x 12.3 µm) were detected microscopically in the feces of two of 25 free ranging wild bobcats from Mississippi, USA. After detailed investigation, we identified these oocysts as B. darlingi and not T. gondii. The IFN-_ gene knockout (KO) mice fed oocysts from bobcats died of acute besnoitiosis and tachyzoites were found in their tissues. Oocysts were also mildly pathogenic to outbred Swiss Webster mice (SW) (Mus musculus). The SW mice fed oocysts became ill but generally survived and developed characteristic thick-walled Besnoitia tissue cysts in their muscles and brains. Two laboratory-raised domestic cats (Felis catus) excreted B. darlingi oocysts after ingesting murine tissues infected with bobcat-derived oocysts. The parasite was successfully cultivated in CV1 cells seeded with infected murine tissue homogenate. The multilocus PCR-DNA sequencing from culture derived tachyzoites confirmed the parasite as B. darlingi. Our results suggest that bobcats may be an important link in the sylvatic cycle of Besnoitia species and bioassay is needed to differentiate Toxoplasma gondii-like oocysts in feces of felids, both domestic and wild cats.