Researchers identify new Rickettsia species in dogs

November 09, 2020

Researchers at North Carolina State University have identified a new species of Rickettsia bacteria that may cause significant disease in dogs and humans. This new yet unnamed species, initially identified in three dogs, is part of the spotted-fever group Rickettsia which includes Rickettsia rickettsii, the bacteria that cause Rocky Mountain Spotted Fever (RMSF).

Rickettsia pathogens are categorized into four groups; of those, spotted-fever group Rickettsia (which are transmitted by ticks) is the most commonly known and contains the most identified species. There are more than 25 species of tick-borne, spotted-fever group Rickettsia species worldwide, with R. rickettsii being one of the most virulent and dangerous.

For dogs, R. rickettsii is the only known spotted fever group Rickettsia that causes clinical disease in North America. Symptoms of RMSF in dogs and people are similar, including fever, lethargy, weight loss and symptoms related to vascular inflammation, like swelling, rash and pain.

In 2018 and 2019, three dogs from three different states (Tennessee, Illinois and Oklahoma) with exposure to ticks and RMSF-associated symptoms had blood samples taken, to test them for R. rickettsii. While the samples reacted positively to antibody tests for R. rickettsii, when researchers at NC State utilized polymerase chain reaction (PCR) to amplify the pathogen's DNA from the samples, the DNA they retrieved was only 95% similar to R. rickettsii.

"Often, antibodies from other spotted fever group Rickettsia will cross-react in antibody tests for RMSF," says Barbara Qurollo, associate research professor at NC State and corresponding author of a paper describing the work. "So to be sure what we're dealing with, we also look at the genetic information via PCR and that's how we found that this is a new organism."

The initial PCR work led Qurollo and James Wilson, a PCR technician at NC State and first author of the study, to pursue the new bacteria further. They performed additional PCRs to amplify different genes and examined five different regions of the bacteria's DNA, comparing it to the sequenced DNA from other spotted fever group Rickettsia. They also performed a phylogenetic tree analysis, which allowed them to place the new Rickettsia firmly within the spotted fever group.

Before naming this new Rickettsia species, Qurollo and colleagues want to culture the organism, which would allow for better characterization of the new species. Culturing Rickettsia species from small amounts of a clinical sample has been difficult to do thus far.

"We're going to continue looking for this Rickettsia species, determine its geographical range and try to better characterize it - it's a slow process, but high on our radar," Qurollo says. "So far in 2020 we've detected this new Rickettsia species in four more dogs residing in the southeastern and midwestern U.S. We're also asking veterinarians to collect the ticks associated with dogs who show symptoms when possible, and we're collaborating with researchers in Oklahoma to collect ticks in the environment for testing. This will help us determine what tick species may be transmitting this particular bacteria.

"Another question we would like to answer is whether this new Rickettsia species also infects people. Dogs are great sentinels for tick-borne diseases - they have high rates of exposure to ticks and the ability to become infected with many of the same tick-borne pathogens that infect people. We hope to take a 'One Health' approach to this new pathogen and collaborate with scientists in human medicine as well."
-end-
The work appears in Emerging Infectious Diseases. The PCR work was performed at NC State's Vector Borne Disease Diagnostics Lab, in the College of Veterinary Medicine.

Note to editors:
An abstract follows.

"A Novel Rickettsia species Infecting Dogs in the United States"

DOI: 10.3201/eid2612.200272

Authors: James M. Wilson, Edward B. Breitschwerdt, Nicholas B. Juhasz, Henry S. Marr, Barbara Qurollo, North Carolina State University; Joao Felipe de Brito Galvao, VCA Arboretum View Animal Hospital, Downers Grove, IL; Carmela L. Pratt, Oklahoma Veterinary Specialists, Tulsa, OK
Published: Online in Emerging Infectious Diseases

Abstract:
In 2018 and 2019, three dogs with febrile illness and hematological abnormalities were infected with a novel Rickettsia sp. All dogs were R. rickettsii seroreactive and identical Rickettsia DNA sequences were amplified from blood samples. By multi-locus phylogenetic analysis the Rickettsia sp. was related to human Rickettsia pathogens.

North Carolina State University

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.