EAST PROVIDENCE, R.I. (WPRI) — The risk of contracting a tick-borne disease has been on the rise across the country in recent years, particularly in the Northeast.
Rhode Island has seen a sharper increase than many other states, with thousands of human cases reported each year, according to data from the Centers for Disease Control and Prevention.
Despite temperatures falling as winter approaches, the chance of contracting a viral or bacterial illness from a tick bite remains high.
Cases of tick-borne diseases in humans, particularly Lyme disease, have been increasing for decades in the United States. A new report led by the U.S. Geological Survey summarizes what’s happening in Rhode Island, from which tick species and diseases are present to the reasons behind these changes.
“Some southern tick species that can carry disease-causing pathogens have been increasing as well, potentially raising risk in the state,” said USGS ecologist and leading author Howard Ginsberg. “I hope our recent article will help alert people to the risks, so they can protect themselves from tick bites.”
Read the full article in the Rhode Island Medical Journal at http://rimed.org/rimedicaljournal/2021/11/2021-11-29-climate-ginsberg.pdf.
The major tick of concern in Rhode Island is the black-legged tick, also called the deer tick. It transmits the pathogens that can cause diseases such as Lyme, babesiosis and anaplasmosis, all of which have case counts on the rise.
In previous research, the USGS and its partners found a few significant factors that contribute to the higher infection rates from these ticks in the north. Northern black-legged ticks abundantly seek food sources, known as hosts, on top of the leaf litter and twigs where they can frequently encounter people. Research suggests that the climate may play a part in this pattern, as warmer temperatures in the south may cause ticks to stay below the leaf litter surface.
Researchers have also found that black-legged ticks in the north attach to and feed off mammals, such as rodents and shrews, that are efficient at carrying and spreading the bacteria.
Two other human-biting tick species are present in Rhode Island: the lone star tick and American dog tick.
Lone star ticks were formerly southern in distribution and have recently spread northward, including into Rhode Island. The American dog tick is present widely in the eastern U.S., and warmer temperatures may result in larger populations in the northern U.S. and Canada.
The American dog tick can transmit bacteria that cause diseases such as Rocky Mountain Spotted Fever, while the lone star tick can transmit bacteria that cause diseases such as ehrlichiosis. Also, the bite of the lone star tick can cause alpha-gal syndrome, which is an allergy to red meat and other products made from mammals. These diseases are far less common than some of those transmitted by the black-legged tick, but both species present potential implications for human health.
More research is needed to better understand the reasons for changes in tick distributions and disease occurrence, as well as what might happen in the future. There are several likely contributing factors, the report says, including climate change and alterations in land use practices that can modify where suitable habitats are available for ticks and the animals to which they attach for feeding.
Rhode Island is likely to remain in the main region experiencing Lyme and other major tick-borne diseases in the foreseeable future. Research by the USGS and partners is helping people understand and predict the spread of these diseases and determine where human health threats could occur, ultimately informing management decisions to protect communities.