In humans, parasitic cestode infections occur in either of two forms: as mature tapeworms residing in the gastrointestinal tract or as one or more larval cysts (variously called hydatidosis, cysticercosis, coenurosis, or sparganosis) embedded in liver, lung, muscle, brain, eye,…
The trematode flatworms that infect humans include the schistosomes, which live in venules of the gastrointestinal (GI) or genitourinary tract, and other flukes, which inhabit the bile ducts, intestines, or lungs. The geographic distribution of each species of trematode parallels…
Tissue-dwelling nematode (roundworm) infections are widely distributed throughout the world. The health and socioeconomic impacts of these infections are greatest in resource-poor settings in the tropics and subtropics, although populations in temperate and industrialized regions of the world continue to…
Intestinal Nematodes More than 1 billion people are infected with intestinal nematodes worldwide. Also referred to as soil-transmitted helminths (STHs), intestinal nematodes are complex, nonsegmented, multicellular worms. Each organism is surrounded by a species-specific acellular cuticle composed of structural proteins,…
The helminthiases are among the most prevalent infections in the world and a leading cause of morbidity, particularly in low-income and resource-constrained regions. An estimated 1.5 billion persons harbor at least one species of parasitic worm. The helminths that parasitize…
During the past several decades, the association of human health and environmental problems with harmful and toxic algae has been increasingly recognized, as has awareness of the complex range of natural toxins (and toxin congeners) that can be produced by…
Coccidia Other Than Cryptosporidia Cyclospora, Cystoisospora, and Sarcocystis are coccidian parasites belonging to the phylum Apicomplexa, family Eimeriidae. Coccidian protozoan infections are well recognized but still relatively uncommon causes of diarrheal disease. Cryptosporidium parvum and Cyclospora cayetanensis, two of the…
Protozoan parasites of the genus Cryptosporidium were first identified in the stomach of mice in 1907. The species name Cryptosporidium parvum was proposed in 1912 to describe parasites identified in murine intestines. Although Cryptosporidium was linked to gastrointestinal disease in…
The first recorded mention of babesiosis is believed to date to biblical times. In the Book of Exodus, the fifth plague is described as “very grievous murrain” that fell “upon thy cattle which is in the field, upon the horses,…
Trichomonas vaginalis is the causative agent of trichomoniasis, a common cause of vaginitis. In men, it may cause urethritis but is more commonly asymptomatic. Despite being a readily diagnosed and treatable sexually transmitted disease (STD), trichomoniasis is not a reportable…