Babesia Arrives in the Mid-Atlantic Region

A recent study published in the Journal of Medical Entomology has shown that the Babesia parasite has rapidly spread throughout the mid-Atlantic region.

Researchers wrote that, to our knowledge, this is the first report of B. microti and B. burgdorferi-positive I. keiransi from Virginia and the first report of B. burgdorferi-positive I. keiransi from Delaware.

This poses a significant health risk to people in communities where the disease was previously considered rare. Humans enter the cycle when bitten by infected ticks.

According to the U.S. CDC, Babesiosis, caused by microscopic parasites that infect red blood cells, can range from asymptomatic to severe illness, particularly in immunocompromised individuals.

The research published on April 22, 2025, highlights an increasing number of locally acquired human cases and the detection of Babesia microti, the primary causative agent of human babesiosis, in blacklegged and Ixodes keiransi ticks.

Little is known about the prevalence of Babesia worldwide, says the CDC, but little is known about its prevalence in malaria-endemic countries, where misidentification as Plasmodium probably occurs. In Europe, most reported cases are due to B. divergens and occur in splenectomized patients.

In the United States, B. microti is the agent most frequently identified (Northeast and Midwest) and can occur in nonsplenectomized individuals.

This study highlighted an unfortunate issue for healthcare providers.

Jurisdictions in the southern mid-Atlantic region should expect babesiosis cases, Lyme disease, and anaplasmosis coinfections during the summer of 2025, and healthcare providers should consider these tick-borne infections as part of the differential diagnosis.

As of May 11, 2025, no approved vaccines are available for these diseases. However, a Lyme disease vaccine has progressed in a phase 3 clinical study.