CDC Researchers are Investigating Mysterious Tick-Borne Disease

Two people hiking outside.
Tick-borne illnesses are common through much of the U.S. Jerry Monkman/Aurora Photos/Getty Images
  • According to a new report from the CDC, a novel bacterium was found in 4 U.S. patients who were suspected of being infected with tick-borne illnesses.
  • This is just an initial report and further research is needed. 
  • Antibiotics are the first line of treatment for these infections.
  • For safety precautions, people are advised to avoid areas that are known to be tick-infested and wear appropriate clothing to minimize risk.

The CDC recently announced the presence of novel Anaplasma bovis–like infections in humans. In the report in Emerging Infectious Diseases, health officials stated they found the A. bovis-like bacterium in 4 U.S. patients who are believed to have tick-borne diseases.

The CDC points out that multiple Anaplasma species are already known to lead to tick-borne illness in humans.

“Three recognized species (Anaplasma phagocytophilum, Anaplasma ovis, and Anaplasma bovis) and one provisionally named species (Anaplasma capra) are associated with moderately severe to severe disease in humans,” the CDC reported.

Little is known about how disease symptoms may present or how common infections with the A. bovis-like agent are in the population.

“The spectrum of disease and epidemiology associated with human infections caused by this novel A. bovis–like agent remains unknown. Presumably, human infections with this agent in the United States are uncommon, because this bacterium was detected only 4 times from 29,928 residual clinical samples,” the report noted.

Low number of cases

For the study, researchers looked at data from patients in the central and upper midwestern United States. 

“This is another anaplasma that affects humans so it’s the beginning of the story that we need to learn more about,” Dr. David Walker, Executive Director at UTMB Center for Biodefense and Emerging Infectious Disease, told Healthline. “It was only 4 samples out of 30,000 samples so it’s a low percentage.”

Dr. Charles Bailey, medical director for infection prevention at Providence Mission Hospital and Providence St. Joseph Hospital in Orange County, California, explained “This is an interesting observation but researchers admit there is a lot they don’t know about this class of bacteria. This is a very partial fingerprint when you don’t have a full set of fingerprints to compare it to. In the US there are approximately 15 illnesses carried by ticks that are pretty much the same. This might be the 16th, but the research is very preliminary and quite a narrow potential impact for the general public.”

It’s also important to note the samples that were tested in this study were between 2015 and 2017. 

“It’s a new species but those samples were from years ago, so it’s not an emerging infection that is now circulating,” said Wassim Ballan, MD, Division Chief of infectious disease, Medical Director of Antimicrobial Stewardship Program and Associate Director of the Infection Prevention Program at Phoenix Children’s.

What is A. bovis?  

A. bovis is a bacteria that primarily causes disease in mammals such as cattle, sheep and antelope. These types of mammals are called ruminants.

The condition is spread from host to host by a tick bite, Catherine Troisi, PhD, infectious disease epidemiologist with UTHealth Houston, explained. It is rarely transmitted from animals to humans although this paper reports on four cases of a tick-borne illness in humans (2 in 2015 and 2 in 2017).  

“Technology at the time didn’t allow for specific classification of the bacteria detected but it appeared to be close to A. bovis.  The current paper reports on a more detailed analysis of the bacteria found in these four cases and determined that it is similar to, but not exactly like, A. bovis strains found earlier and so there is some genetic variation,” said Troisi.  

Typical symptoms of tick-borne illnesses are fevers/chills, aches and pains, and rash. Due to the rarity of infections, the spectrum of disease and epidemiology associated with human infections caused by this novel A. bovis–like agent is not known, Troisi added.

Who is most at risk?

“The bacteria is spread by tick bites and people should take precautions to not get bit to protect themselves from Lyme Disease, babesiosis, ehrlichiosis, Rocky Mountain Spotted Fever along with other tick-borne infections,” Troisi stated. “However only four cases were found out of 29,928 samples tested so no cause to be concerned specifically about this disease.”

In addition, “it’s an Anaplasma infection, so it will fit within the same picture as other Anaplasma infections. Based on the whole species of Anaplasma, people who are immunocompromised are most at risk,” Ballan stated.


Antibiotics are prescribed to treat this disease since it is a bacterial infection.

However, “for this new species we don’t know for sure, but looking at Anaplasma as a whole there are antibiotics to treat these infections,” Ballan explained. “Doxycycline is commonly prescribed in these cases, but there are other options available as well. It’s antibiotics because it’s a bacterial infection.”


A new report from the CDC reveals that a novel Anaplasma bovis-like bacterium was found in 4 U.S. patients who were believed to be infected with tick-borne illnesses.

More research is needed to learn more about this new species.

Antibiotics are the first line of treatment for tick-borne infections.

To stay safe, doctors recommend avoiding places that are infested with ticks and wear proper clothing to reduce risk of infection.

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