Blood parasites other than malaria

Abstract

Although malaria is usually considered to be the most important and well-known infection, there are other organisms that also cause human infection including Babesia spp., Leishmania spp., Trypanosoma spp., and various filarial worms. Human babesiosis is an emerging tick-borne infectious disease caused by intraerythrocytic protozoan species of the genus Babesia with many clinical features similar to those of malaria. Over the last 50 years, the epidemiology of human babesiosis has changed from a few isolated cases to the establishment of endemic areas in the northeastern and midwestern United States. Episodic cases are reported in Europe, Asia, Africa, and South America. The severity of infection ranges from asymptomatic infection to fulminant disease resulting in death, particularly in immunocompromised patients. American trypanosomiasis (Chagas’ disease) is produced by Trypanosoma cruzi, which is confined to the American continent. African trypanosomiasis (sleeping sickness) is caused by T. brucei gambiense and T. brucei rhodesiense species belonging to the family Trypanozoon and is confined to the central belt of Africa. Depending on the species involved, infection with Leishmania spp. can result in cutaneous, diffuse cutaneous, mucocutaneous, or visceral disease. A large number of disease variations have been described, which makes classical disease categories confusing. In areas of endemicity, coinfection with human immunodeficiency virus (HIV) positive patients is common. Although there are over 200 species of filarial parasites, only a few infect humans. Of the known human filarial parasites, three species, Wuchereria bancrofti, Brugia malayi, and Onchocerca volvulus, account for most infections and pathological sequelae. There are 90 million people currently infected (two-thirds live in China, India, and Indonesia) with W. bancrofti, B. malayi, and B. timori. Onchocerca volvulus has infected 45–50 million people in Africa and Central and South America, of whom approximately 1 million are blind. Although malaria is usually considered to be the most important and well-known infection, there are other organisms that also cause human infection including Babesia spp., Leishmania spp., Trypanosoma spp., and various filarial worms. Human babesiosis is an emerging tick-borne infectious disease caused by intraerythrocytic protozoan species of the genus Babesia with many clinical features similar to those of malaria. Over the last 50 years, the epidemiology of human babesiosis has changed from a few isolated cases to the establishment of endemic areas in the northeastern and midwestern United States. Episodic cases are reported in Europe, Asia, Africa, and South America. The severity of infection ranges from asymptomatic infection to fulminant disease resulting in death, particularly in immunocompromised patients. American trypanosomiasis (Chagas’ disease) is produced by Trypanosoma cruzi, which is confined to the American continent. African trypanosomiasis (sleeping sickness) is caused by T. brucei gambiense and T. brucei rhodesiense species belonging to the family Trypanozoon and is confined to the central belt of Africa. Depending on the species involved, infection with Leishmania spp. can result in cutaneous, diffuse cutaneous, mucocutaneous, or visceral disease. A large number of disease variations have been described, which makes classical disease categories confusing. In areas of endemicity, coinfection with human immunodeficiency virus (HIV) positive patients is common. Although there are over 200 species of filarial parasites, only a few infect humans. Of the known human filarial parasites, three species, Wuchereria bancrofti, Brugia malayi, and Onchocerca volvulus, account for most infections and pathological sequelae. There are 90 million people currently infected (two-thirds live in China, India, and Indonesia) with W. bancrofti, B. malayi, and B. timori. Onchocerca volvulus has infected 45–50 million people in Africa and Central and South America, of whom approximately 1 million are blind.