Bovine Babesiosis (Piroplasmosis, Texas Fever, Redwater, Tick Fever)

Etiology and Transmission. Bovine babesiosis may be caused by either Babesia bovis or B. bigemina. These are protozoan parasites that infect red blood cells. Morphology of the two parasites within red blood cells is different and helps to distinguish the two.

Photo of red cells parasitized by B. bigemina. Note pear-shaped bodies within erythrocyte (arrows).

B. bovis and B. bigemina are transmitted by Boophilus ticks, primarily Boophilus annulatus (How can I identify Boophilus?). Babesia can survive for several generations.

Geography. Both B. bovis and B. bigemina were eradicated from the U.S through an extensive and successful campaign to get rid of all Boophilus ticks (Boophilus ticks are one-host ticks - eradication of a three-host tick would be considerably more problematic!)

Both diseases are present in many parts of Latin America and there is continuing concern that they may be re-introduced through infected ticks coming into the U.S from Mexico.

What are these USDA employees doing on horseback?

Clinical Signs. Clinical disease caused by the two babesia are basically similar, but B. bovis tends to cause more severe problems.

Hmmmm, this could be Babesiosis! (Ernst Bosch, 1872; “A Serious Case”)

Initial signs include: high fever (41.5 C or 106.7 F), icterus, self-isolation from the herd, and depression. Infected cattle may stand with an arched back, and have dyspnea and/or tachycardia. Mucous membranes are initially reddened but then as erythrocyte lysis and anemia become more pronounced, there is pallor. In the terminal stages the urine is dark red to brown in color because of the presence of free hemoglobin.