Babesia microti is spreading beyond its traditional northeastern stronghold — and Texas is now on the map. A new study found the parasite in raccoons in East Texas, raising questions about emerging human risk in the South.
Previous studies in Florida revealed two distinct groups of this tick-borne parasite depending on host species — cotton rats versus raccoons.
Investigators in the current study looked for the presence of Babesia species in small and medium-sized mammals in East Texas. A total of 480 wild mammals were trapped, sampled, and screened using molecular analysis.
Babesia microti Found in Texas Raccoons
According to Modarelli, “Babesia microti was found only in raccoons within the areas sampled.” Five out of 15 raccoons (33%) tested positive for Babesia microti.
The Babesia microti strains identified in Eastern Texas resembled strains found in raccoons in the northeastern U.S. and in Florida, according to DNA sequence analysis.
And although the Centers for Disease Control and Prevention (CDC) reported 3 cases of Babesia in Texas between 2011 and 2015, the authors found no confirmed human cases in Florida or Texas at the time of the study.
First Babesia microti Study in Texas
“To our knowledge, this is the first study of its kind in Texas and it can provide baseline data for future research and surveillance studies on this group of parasites,” Modarelli writes.
“Public health agencies should still monitor for the risk of human babesiosis in this area,” the authors warn, “due to the established presence of the competent tick vector Ixodes scapularis (deer ticks).”
Why Babesia microti in Texas Matters for Patients
The presence of Babesia microti in Texas wildlife suggests the parasite’s geographic range is expanding. While human cases remain rare in the South, patients and clinicians should be aware that tick-borne co-infections — including Babesia — are no longer limited to the Northeast. Surveillance of animal reservoirs like raccoons can provide early warning signs before human cases emerge.
References
- Modarelli JJ, Westrich BJ, Milholland M, et al. Prevalence of protozoan parasites in small and medium mammals in Texas, USA. Int J Parasitol Parasites Wildl. 2020;11:229-234.
- Babesiosis Surveillance — United States, 2011–2015. Morbidity and Mortality Weekly Report (MMWR). CDC.
