Which parasite is associated with the Maltese cross pattern inside red blood cells?

• A. Plasmodium vivax
• B. Babesia microti
• C. Plasmodium falciparum
• D. Toxoplasma gondii

Answer: (B)

The Maltese cross pattern inside red blood cells signals infection with Babesia species, most commonly Babesia microti in humans. This pattern comes from four merozoites that arrange into a tetrad within an erythrocyte during replication, producing that distinctive cross shape. Babesia is an intraerythrocytic parasite transmitted by Ixodes ticks and causes babesiosis, which can resemble malaria but lacks the hemozoin pigment and the typical malaria parasite forms. Plasmodium vivax and Plasmodium falciparum show ring forms and other stages in red cells but not a Maltese cross, and Toxoplasma gondii does not produce intracellular erythrocytic parasites.