A Potentially Life-Threatening Disease Caused by Ticks Is Expanding to New Parts of America Babesiosis typically occurs in the Northeast and the Upper Midwest, but new research suggests it’s emerging in the mid-Atlantic region including Delaware, Maryland and Virginia Most babesiosis infections are caused by blacklegged ticks, also known as deer ticks. U.S. Centers for Disease Control and Prevention Babesiosis is a rare, tick-borne disease caused by a parasite that attacks the red blood cells and can lead to flu-like symptoms such as fever, body aches and fatigue. In North America, babesiosis typically occurs in the Northeast and the Upper Midwest. But the parasite’s range seems to be expanding into the mid-Atlantic, according to a new paper published last month in the Journal of Medical Entomology. Scientists are urging health care providers in Virginia, Maryland and Delaware to be on the lookout for symptoms of the disease, which is easiest to treat when it’s caught early. “Health care providers should consider babesiosis in the differential diagnosis for patients with [fever-causing] illness, particularly during peak tick-activity seasons,” says lead author Ellen Stromdahl, an entomologist with the United States Army Public Health Center, in a statement. Babesiosis is caused by a microscopic parasite called Babesia microti, which lives in the blood of rodents like shrews, chipmunks and mice. When ticks bite those animals, then bite humans, the parasite hitches a ride to a new host. (Though much less common, it’s also possible for humans to become infected from blood transfusions.) Once inside the human body, B. microti begins destroying red blood cells. Many individuals with babesiosis have no symptoms and do not feel sick, according to the U.S. Centers for Disease Control and Prevention. But others may experience fever, chills, sweats, headaches, body aches, loss of appetite, nausea and fatigue. If left untreated, extreme cases of the disease can progress to organ failure and, eventually, death. Asymptomatic cases usually do not require treatment. The illness is particularly dangerous for individuals over the age of 50, as well as those with weakened immune systems and other serious health conditions. Doctors can treat babesiosis with a combination of antibiotics and antiparasitic medications, as well as blood transfusions if necessary—but they have to know to test for it first. That’s why the researchers want their new study to serve as an “early warning” for medical professionals in the mid-Atlantic, Stromdahl tells the Baltimore Banner’s Meredith Cohn. Stromdahl decided to take a close look at B. microti in the mid-Atlantic region after a friend came down with the disease in 2023 in Virginia—a state where infections were incredibly rare. Working with public health officials and other researchers, Stromdahl collected 1,310 blacklegged ticks, also known as deer ticks, from across Delaware, Maryland and Virginia. The team found B. microti in ticks from all three states. The overall incidence rate was low—just 2.7 percent of the ticks harbored the parasites—but the researchers say the findings are still cause for concern. About half of the ticks that were infected with B. microti were also carrying the bacteria that causes Lyme disease in humans, Borrelia burgdorferi. Scientists are still investigating the connection between coinfections of B. microti and B. burgdorferi. But the findings suggest doctors in the mid-Atlantic should start watching for both, the researchers write in the paper. “Babesia infection seems to spread where Lyme infection is already present,” says Shannon LaDeau, a disease ecologist at the Cary Institute of Ecosystem Studies who was not involved with the research, to Grist’s Zoya Teirstein. Researchers found the rare infections of locally acquired babesiosis in the mid-Atlantic were clustered around the city of Baltimore and on the Delmarva Peninsula between 2009 and 2023. Stromdahl et al. / Journal of Medical Entomology, 2025 The scientists also investigated the few human cases of babesiosis that have been reported in the mid-Atlantic region. Many were clustered around two locations: the city of Baltimore and the Delmarva Peninsula, the landmass that separates the Chesapeake Bay from the Atlantic Ocean and includes parts of Delaware, Maryland and Virginia. Even in these “hot spots,” babesiosis is rare. Maryland reported 29 infections in 2023, for example, and some of them might have been acquired in other areas, per the Baltimore Banner. But researchers fear the infection has been overlooked or misdiagnosed, since physicians haven’t had a reason to check for it. “There are not many cases, but we think it’s the tip of the iceberg,” Stromdahl tells the Baltimore Banner. What’s to blame for the parasite’s spread? Scientists say it’s likely a combination of factors. Warmer temperatures caused by climate change—especially during the winter—have allowed ticks and their host rodents to proliferate, reports Grist. Wetter weather is probably contributing to their success, too. Additionally, reforestation efforts have supported an overpopulation of white-tailed deer. The ungulates don’t carry the parasite themselves, but they do transport ticks across long distances. Suburban expansion also means humans are now spending more time in areas where ticks live. Blacklegged ticks, which cause most babesiosis infections, dwell in wooded, brushy and grassy habitats, per Live Science’s Emily Cooke. “The findings underscore the need for increased surveillance, public awareness and preventive measures against tick-borne diseases in the mid-Atlantic region,” says Stromdahl in the statement. Get the latest stories in your inbox every weekday. Source: https://www.smithsonianmag.com/smart-news/a-potentially-life-threatening-disease-caused-by-ticks-is-expanding-to-new-parts-of-america-180986605/ #potentially #lifethreatening #disease #caused #ticks #expanding #new #parts #america