An 85-year-old man, actively infected with Babesia microti and Ehrlichia ch
affeensis, presented with fatigue and thrombocytopenia. He developed rhabdo
myolysis and multiple organ failure, which led to death 6 days after initia
l presentation. To our knowledge, concurrent acute disease due to these 2 o
rganisms has not been reported previously, although serologic studies have
shown that some patients acquire both infections in life.