Nematodes

Greeffiella (undescribed species) under approx. 1000x magnification

This figure was first published in 1966, describing Platycoma sudafricana from South Africa (Inglis, 1966).

The marine nematode worm Manunema kithara was discovered in Kuwait Bay in the northern Arabian Gulf.

Magnified 125X, this photomicrograph revealed the presence of a fertile Ascaris sp. egg that was found in an unstained formalin-preserved stool sample. See PHIL 411 for an example of an unfertilized Ascaris lumbricoides egg.Geographic Distribution:The most common human helminthic infection, Ascaris sp. have a worldwide distribution. Their highest prevalence is in tropical and subtropical regions, and areas with inadequate sanitation. Ascariasis occurs in rural areas of the southeastern United States.Created: 1973

This illustration depicts the life cycle of Baylisascaris procyonis, the causal agent of Baylisascariasis.Created: 2002

This photomicrograph reveals histopathologic changes indicative of the presence of the intestinal parasitic nematode (roundworm), Strongyloides stercoralis.Clinical Features:Frequently asymptomatic. Gastrointestinal symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination.Created: 1972

This is an illustration of the life cycle of Strongyloides stercoralis, the causal agent of Strongyloidiasis.Created: 2002

This diagram depicts the various stages in the life cycle of the Strongyloides stercoralis nematode.Created: 1982

The human hookworms include two nematode (roundworm) species, Ancylostoma duodenale and Necator americanus.Created: 1982

This is an illustration of the life cycle of Mansonella perstans, one of the causal agents of Filariasis.Created: 2002

This is an illustration of the life cycle of Mansonella streptocerca, one of the causal agents of Filariasis.Created: 2002

This is an illustration of the life cycle of Wuchereria bancrofti, one the causal agents of Filariasis.Created: 2003

This is an illustration of the life cycle of Loa loa, one of the causal agents of Filariasis.Created: 2003

This diagram depicts the various stages in the life cycle of the intestinal roundworm nematode Ascaris lumbricoides.Created: 1982

Depicted in this 1960 photograph were two Ascaris lumbricoides nematods, i.e., roundworms. The larger of the two was the female of the species, while the normally smaller male was on the right. Adult female worms can grow over 12 inches in length.Created: 1960

This 2007 photograph depicted Center for Disease Control/ NCZVED/DPD laboratory technician, Henry Bishop holding a mass of Ascaris lumbricoides worms, which had been passed by a child in Kenya, Africa. This nematode parasitizes the human small intestine, and is spread from human to human by the fecal-oral route. Children seem to be infected more often than adults, and though the organisms depicted here originated in Africa, the disease can be acquired in the southeastern United States.Created: 2007

This is an illustration of the life cycle of Mansonella ozzardi, one of the causal agents of Filariasis.Created: 2002

This is an illustration of the life cycle of Trichuris trichiura, the causal agent of Trichuriasis.Created: 2002

Magnified 128X, this photomicrograph revealed some of the ultrastructural features displayed by a Trichuris trichiura egg. The nematode, or roundworm, is also called the human whipworm. T. trichiura eggs are 50µm-55µm by 20µm-25µm. As is exemplified by this specimen, eggs are football-shaped, thick-shelled, and possess a pair of polar plugs at each end. Eggs are passed unembryonated in stool.Created: 1979

This diagram depicts the various stages in the life cycle of the human pinworm nematode Enterobius vermicularis.Created: 1982

This is an illustration of the life cycle of Dracunculus medinensis, the causal agent of Dracunculiasis.Created: 2002

This diagram depicts the various stages in the life cycle of the nematode Trichinella spiralis.Created: 1982

This photomicrograph reveals histopathologic changes indicative of the presence of the intestinal parasitic nematode (roundworm), Strongyloides stercoralis.Clinical Features:Frequently asymptomatic. Gastrointestinal symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination.Created: 1972

This photomicrograph reveals histopathologic changes indicative of the presence of the intestinal parasitic nematode (roundworm), Strongyloides stercoralis.Clinical Features:Frequently asymptomatic. Gastrointestinal symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination.Created: 1972