CDC Warns Against Rising Rates of Babesiosis in the Northeast

Babesiosis cases have risen significantly across the northeastern United States. A CDC report published on March 17, 2023, analyzed trends in this tickborne illness between 2011 and 2019, noting significant rises in Maine, New Hampshire, and Vermont.

Babesiosis is a parasitic infection caused by intraerythrocytic Babesia microti parasites, usually contracted through a bite from an Ixodes scapularis, a black-legged tick. However, it can also be transmitted via blood transfusion from an infected donor or through congenital transmission.

The severity of the infection can vary between patients, but it can be fatal in some cases. While some patients may be asymptomatic, symptomatic patients may experience fever, muscle pain, joint pain, and headaches. Less common symptoms include thrombocytopenia, renal failure, and acute respiratory distress syndrome.

Although the severe symptoms are less common, they are more likely to occur in immunocompromised individuals and may be deadly. The condition can easily be treated with antimicrobial medications, including azithromycin and atovaquone.

Despite the condition being identified in the US since 1969, the rise in cases recently has caused concern. According to the CDC, tickborne illness rates have risen across the US, reaching 50,856 reported incidences in 2019. Beyond that, Babesia infection rates have notably increased between 2011 and 2019.

The data collected looked at infection rates between 2011 and 2019 in Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, and Vermont, noting a significant rise.

In particular, Vermont, New Hampshire, and Main had the most significant rate increases. The number of incidences in Vermont rose from two cases in 2011 to 34 cases in 2019, a 1,602% increase. While slightly lower, rates in Maine increased by 1,422%, from 9 to 138 patients. Coming in third, Connecticut had a 372% increase, with cases increasing from 13 to 78.

“These three states should now be considered to have endemic transmission comparable to that in other high-incidence states; they have consistently identified newly acquired cases every year during 2011–2019 and documented the presence of Babesia microti in the associated tick vector,” noted the CDC in its report. “Because incidence in Northeastern states, including Maine, New Hampshire, and Vermont, is increasing, tick prevention messaging, provider education, and awareness of infection risk among travelers to these states should be emphasized.”

Although the CDC did not identify a cause for these rising rates, many experts postulate that climate change and environmental factors have caused a rise in tickborne illness. Warming temperatures have expanded these disease carriers' geographical and temporal habitats, causing increased infection risks.

In 2022, BMJ Global Health released a study noting that the global prevalence of Lyme disease, another zoonotic disease, has risen by 14.5%. As many healthcare organizations, including the AMA, emphasize the health risk associated with environmental disturbances, enforcing regulations that minimize the risk of further changes is increasingly critical.