New Invasive Tick Species in Connecticut Found to Carry Potentially Deadly Bacteria

An invasive tick species has been identified in Connecticut that carries bacteria capable of causing ehrlichiosis in humans, raising health concerns as the species continues its spread across the state. The longhorned tick, an emerging invasive species in the region, has now been found to harbor the bacteria responsible for ehrlichiosis, a bacterial infection that can lead to serious illness. Although rare in Connecticut, cases of ehrlichiosis have increased significantly over recent years, with reported cases rising from just 142 between 2001 and 2019 to over 2,000 between 2019 and 2023, according to the Connecticut Agriculture Experiment Station (CAES). Dr. Goudarz Molaei, a state entomologist, noted that this detection is particularly alarming because previously, ehrlichiosis was primarily associated with lone star ticks. The fact that it has now been found in longhorned ticks, which do not require mating to reproduce, suggests a potential for rapid population expansion and increased risk of disease transmission.

Longhorned ticks reproduce via parthenogenesis, allowing a single female to produce viable eggs and establish a new population independently. This reproductive capability increases the threat of the species spreading quickly across more regions. Molaei emphasized that this reproductive trait is rare among ticks in the U.S., making this species particularly noteworthy. A rise in ehrlichiosis cases is anticipated, as the bacteria can cause severe health complications if untreated, including organ damage, neurological issues, and death. While antibiotics are effective treatments, there is currently no vaccine available.

Originally native to tropical areas of Asia, the longhorned tick was first detected in the United States in 2017 and has since expanded into at least 21 states, primarily in the eastern and northeastern regions. The species was first reported in Connecticut in 2018 and has now been found in counties such as Fairfield and New Haven. The tick’s ability to transmit multiple pathogens, including those responsible for Lyme disease, anaplasmosis, babesiosis, and Bourbon virus disease, raises additional concerns. What makes this tick particularly dangerous is its ability to feed intermittently and detach from hosts, increasing the likelihood of transmitting pathogens.

Deer often serve as reservoirs for Ehrlichia bacteria, and the longhorned tick feeds on white-tailed deer, further facilitating the spread of the bacteria. As climate change progresses, experts expect the range of this tick to extend further northward into New England and Canada, potentially heightening the risk of tick-borne diseases across wider regions. Although the tick population in Connecticut remains somewhat localized, its spread trajectory warrants close monitoring to mitigate future health risks.

This discovery underlines the importance of tick surveillance and public awareness about tick-borne diseases. Protective measures, such as using tick repellents and checking for ticks after outdoor activities, remain essential for reducing infection risk.

Source: https://medicalxpress.com/news/2025-05-emerging-species-ct-rare-bacteria.html