Over 340 parasitic species infect over 3 billion people all over the globe, with variable morbidity and mortality. The Tropics constitute the main reservoir of infection with highest clinical impact, owing to favorable ecological factors. The acquisition of infection, clinical severity and outcome of a parasitic disease depend on innate and acquired host immunity as well as the parasite's own immune response against the host when infection is established. Organ transplant recipients may acquire significant parasitic disease in three ways: transmission with the graft; de-novo infection or activation of dormant infection as a consequence of immunosuppression. Malaria, Trypanosoma, Toxoplasma and Leishmania are the principal parasites that may be transmitted with bone marrow, kidney or liver homografts, and microsporidia with xenotransplants. De-novo infection with malaria and kala-azar may occur in immunocompromised travelers visiting in endemic areas, while immunocompromised natives are subject to superinfection with different strains of endemic parasites, reinfection with schistosomiasis or, rare primary infections as canthameba. The list of parasites that may be reactivated in the immunocompromised host includes Giardiasis, Balantidiasis, Stroglyloidiasis, Capillariais, Malaria Chaga's disease and Kala-azar. The broad clinical syndromes of parasitic infection in transplant recipients include prolonged pyrexia, lower gastrointestinal symptoms, bronchopneumonia and meningoencepahalitis. Specific syndromes include the hematological manifestations of Malaria, myocarditis in Chaga's disease, acute renal failure in Malaria and Leishmaniasis, and the typical skin lesions of Chaga's and cutaneous Leishmaniasis. Many antiparasitic drugs have the potential of gastrointestinal, hepatic, renal and hematological toxicity, and may interact with the metabolism of immunosuppressive agents. It is recommended that transplant clinicians must
have a high index of suspicion of parasitic infections as an important transmission threat, as well as a potential cause of significant post-transplant morbidity.