Definition The Pathogens Cestode parasites are members of the animal kingdom, subphylum Cestoda. The organisms are characterized by several life cycle stages, which typically develop in distinct hosts. The adult stage is the tapeworm, which is acquired by ingestion of…
Babesiosis Babesiosis is a tick-borne, malaria-like disease caused by sporozoan parasites of the genus Babesia that infect red blood cells. Epidemiology With few exceptions, Babesia spp are transmitted by ixodid ticks. Thus, wherever humans are intensely exposed to hard-bodied ticks,…
Definition Amebiasis is due to infection with the enteric protozoan parasite Entamoeba histolytica . Amebiasis can cause asymptomatic colonization, diarrhea, dysentery, and colitis. It also can spread extraintestinally to cause liver and rarely brain abscess ( Fig. 323-1 ). The…
Definition Giardia lamblia ( Giardia duodenalis, Giardia intestinalis ) is a ubiquitous, small intestinal protozoan parasite of humans and other mammals. It is the most common parasitic infection of the gastrointestinal tract in the United States as well as worldwide,…
Definition Cryptosporidiosis is the disease in humans and animals caused by protozoal parasites of the genus Cryptosporidium (phylum Apicomplexa). Cryptosporidium spp are major waterborne parasites worldwide, and more than 20 species have been documented to infect humans. The Pathogen The…
Definition Toxoplasmosis refers to symptomatic disease, whereas T. gondii infection refers to latent, asymptomatic disease. Toxoplasma gondii is a ubiquitous protozoan parasite. Although felids are T. gondii ’s only definitive host (i.e., where parasitic sexual reproduction occurs), the parasite’s intermediate…
Definition Leishmaniasis, which is caused by protozoan parasites of the genus Leishmania, is generally transmitted between mammalian hosts by female phlebotomine sandflies. The parasite exists as an extracellular flagellated form, the promastigote, in the gut of the female sandfly, and…
Definition Chagas disease, or American trypanosomiasis, is caused by the protozoan parasite Trypanosoma cruzi . The terms Chagas disease , American trypanosomiasis , and T. cruzi infection are synonyms. The Pathogen Several dozen species are included in the genus Trypanosoma…
Definition Human African trypanosomiasis, commonly known as sleeping sickness, is a vector-borne parasitic disease transmitted to humans and animals by the bite of the tsetse fly (genus Glossina ). Infection is caused by protozoa of the genus Trypanosoma and species…
Definition Malaria is caused by infection with protozoan parasites of the genus Plasmodium, all of which are transmitted by bites of infected anopheline mosquitoes. Malaria is typically characterized by an acute febrile illness, with parasites infecting large numbers of erythrocytes,…