BY: SAMANTHA BARTLETT, DVM

A new species of tick-borne Rickettsia bacteria has been identified this fall by researchers at North Carolina State University. The species belongs to the spotted-fever group such as the Rickettsia species that causes Rocky Mountain Spotted Fever (RMSF). In 2018 and 2019, three dogs from Tennessee, Illinois and Oklahoma with a history of tick exposure exhibiting symptoms consistent with RMSF had positive antibody reactions to R. rickettsii, but PCR testing showed the DNA of the bacteria was only 95% similar to R. Rickettsia. This prompted researchers to look further and they determined this was a new species of Rickettsia bacteria. 

Symptoms of RMSF are similar in dogs and people and include fever, lethargy, swelling, rash, pain and weight loss. In 2020, the researchers have detected the new species in four more dogs. They have also asked veterinarians to collect ticks associated with dogs who have symptoms to determine which ticks are transmitting the new bacteria. 

Until more is known about this species, researchers are postponing an official name. One big question is whether this species also affects people.  Of the known Rickettsia species, three are known to cause RMSF symptoms in humans. Only one, Rickettsia rickettsii is known to cause disease in dogs. 

The researchers’ findings have been published in the December issue of the Journal of Emerging Infectious Diseases titled, “Novel Rickettsia Species Infecting Dogs, United States” by Wilson, JM et al. and can be found online at https://wwwnc.cdc.gov/eid/article/26/12/20-0272_article.