Babesiosis

Definition

A malaria-like parasitic disease of mammals caused by intraerythrocytic protozoans in the order Piroplasmida (phylum Apicomplexa), especially Babesia and Theileria species, transmitted primarily by ixodid ticks. In humans, infection occurs mainly in the Northeastern and Midwestern United States and parts of Europe during warm months, often co-occurring with Lyme disease and other tick-borne pathogens. In domestic animals, babesiosis causes significant morbidity and mortality; in cattle it is known as Texas cattle fever or redwater. Transmission also occurs via blood transfusion and congenitally.

Etymology

From New Latin Babesia (genus name, honoring Romanian pathologist Victor Babeș) + -osis (disease condition)

Example

In the northeastern United States, Ixodes scapularis ticks frequently transmit both Babesia microti and Borrelia burgdorferi, causing concurrent babesiosis and Lyme disease in humans; clinical presentation of babesiosis ranges from asymptomatic to severe hemolytic anemia with fever and fatigue.

Synonyms

• Piroplasmosis

Related Terms

• tick-borne disease
• Ixodes
• Babesia
• Theileria
• Lyme disease
• vector-borne pathogen
• apicomplexan
• hemoparasite
• Zoonosis

Usage Notes

The term encompasses disease caused by any piroplasmid, though Babesia species predominate in human and veterinary medicine. Specialists distinguish babesiosis from malaria by parasite morphology (absent pigment, tetrad 'Maltese cross' forms in B. microti), vector (ticks vs. mosquitoes), and geographic patterns. Co-infection with Lyme disease is clinically significant because it may exacerbate symptoms or complicate diagnosis. In veterinary contexts, 'redwater' and 'Texas cattle fever' refer specifically to bovine babesiosis.