Experts Warn of Chigger Bites Causing Scrub Typhus

( – Scientists at the North Carolina State University, Raleigh; University of North Carolina at Greensboro; and the Georgia Museum of Natural History recently released a report involving chiggers and the transmission of scrub typhus, a disease similar to tick-borne Rocky Mountain spotted fever. Those experts warned healthcare practitioners in the region to be on the lookout for possible human cases of the potentially deadly disease.

The Centers for Disease Control and Prevention (CDC) published the study’s results in the August edition of its peer-reviewed journal, Emerging Infectious Diseases. In 2022, researchers collected several samples of Eutrombicula chigger mites carrying Orientia spp., a bacteria related to the transmission of scrub typhus.

The scientists found the chiggers at five parks in North Carolina. They spanned the region from Morrow Mountain State Park in the state’s central region to Merchants Millpond State Park in North Carolina’s northeastern coastal area.

Kaiying Chen, the study’s principal author, told media outlets that this was the first time scientists detected the bacteria that causes scrub typhus in free-living chiggers in the United States. For that reason, researchers could not determine if the presence of those infected mites was a new phenomenon. Likewise, they could not draw any conclusions regarding the prevalence of infected chiggers.

According to the CDC, scrub typhus occurs mainly in rural areas of China, India, Indonesia, Southeast Asia, and the northern regions of Australia. Other government agencies like the Virginia Department of Health reported that the officials hadn’t detected the disease in the US except in travelers returning from infected areas overseas.

Scrub typhus isn’t spread by human-to-human contact. It is only transmitted through chigger bites. Symptoms resemble the flu and begin about 10 to 12 days after a person is bitten by an infected bug. Healthcare providers can diagnose the disease by observing symptoms or conducting tests. Scrub typhus is treated using antibiotics. However, a 2017 report published by the National Institutes of Health warned that left untreated, the disease had a fatality rate of up to 70%.

Fortunately, no cases of scrub typhus have been reported. Additionally, researchers could not determine if Orientia spp. could transmit the disease to humans. Orientia tsutsugamushi is the strain currently attributed to the disease’s spread.

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