UMass researchers discover new tick-borne bacteria strain

Researchers at the University of Massachusetts Amherst have identified a new strain of bacteria in rabbit ticks across Maine that could cause spotted fevers. This group of diseases includes Pacific Coast tick fever and the potentially deadly Rocky Mountain spotted fever.

The discovery came during a survey of ticks in New England backyards, led by staff from Project Is Tick Control Helping, or ITCH. Stephen Rich, a microbiologist at UMass Amherst and co-author of the study, said it was surprising to find rabbit ticks because they are considered rare in New England.

" When we tested them, we were also surprised to find that they have a germ that's very similar to the germ that's associated with Rocky Mountain spotted fever," Rich said. It's one of the most dangerous illnesses in this disease group.

The researchers emphasized there is no immediate risk to humans because rabbit ticks typically bite birds and small mammals, not people. The finding doesn't suggest people need to change their behavior, said Rich.

However, "if it's in the environment, and it's being transmitted, there's a possibility that it could get into a tick that does feed on a person," Rich said.

The study's authors said more research is needed to determine whether the newly identified bacteria strain causes illness in animals or humans. Their research was published online and in the May issue of the journal Ticks and Tick-borne Diseases.

Nine cases of Rocky Mountain spotted fever were reported in Massachusetts from 1995-2017, according to the state's Department of Public Health. Nationwide, the U.S. Centers for Disease Control and Prevention report thousands of cases each year, with the highest concentration occurring in southern states.

Common symptoms include fever, headache and nausea, followed by a rash. Rocky Mountain spotted fever can be life-threatening without prompt treatment, typically with antibiotics.

The research team collected 296 rabbit ticks from nine counties in Maine. More than 6% of the sample tested positive for the new strain, indicating this wasn't a one-off situation, Rich said.

The discovery adds to scientists' understanding of the diseases ticks can carry, said Goudarz Molaei, a research scientist at the Connecticut Agricultural Experiment Station who was not involved with the study.

But he said it's still unclear whether the finding reflects advances in genetic testing for bacteria or a change in how ticks carry and transmit disease. Of the 18 recognized tick pathogens, more than 40% have been discovered since 1980.

Nonetheless, the study should serve as a reminder that ticks are becoming more common in New England, Molaei said, which creates more opportunities for disease-carrying ticks to bite humans.

Molaei surveys ticks in Connecticut, where he said he's noticed more invasions of tick species typically found in southern states. New England is experiencing warmer temperatures due to climate change, and that is expanding the range of species like the Gulf Coast tick, which can carry a form of spotted fever, he said.

Gulf Coast ticks are not established in Massachusetts, but "it's only a matter of time" before they make their way to the commonwealth, Molaei said.

Warmer temperatures also mean native tick species are active year-round, like the deer ticks that can carry Lyme disease. New England states report the highest annual rates of Lyme disease in the country, according to the CDC.

" In recent years because of warming temperature in the region, we can no longer call [one period] tick activity season. It seems that ticks are active year-round," Molaei said. " As long as the temperature stays above freezing, these ticks are active, and they can bite."

Reports of tick-borne illnesses typically spike during warmer summer months. Public health officials recommend checking yourself, pets and children for ticks at least once a day. When going outside, they recommend sticking to clear paths and the centers of hiking trails.

"We have to learn how to live with ticks," Molaei said. "And that requires some practice. That requires some changes to our lifestyle to enjoy nature but also protect ourselves and our loved ones."