Pearls Babesia: An Emerging Infectious Threat in Transfusion Medicine

Babesiosis is an emerging zoonosis caused by protozoan parasites of the genus Babesia. The disease is endemic primarily in the Northeast and upper Midwestern United States. The genus Babesia comprises multiple species of apicomplexan parasites that infect red cells of many vertebrate hosts. Babesia divide and replicate in the hosts ’ red blood cells and are called piroplasms due to their pear-shaped appearance within the RBCs (Figure 1). They are transmitted by ixodid tick vectors as they feed on a blood meal from the host [1]. Babesiosis has long been recognized as an economically important disease of cattle, but only in the last 40 years has Babesia been recognized as an important pathogen in man. The majority of cases in the United States are caused by B. microti and occur in the Northeast and upper Midwest [2]. A small number of infections caused by B. duncani and B. duncani–lik