Helminths / Worms

Since I was 10 years old, I kept a small notebook filled with information about numerous parasitic worm species as helminthology was (and still is) my special interest. This webpage will be the legacy of that.


A phyla of flatworms, including tapeworms, with only one opening (mouth and butthole are the same opening).

Vocab: Scolex (head), proboscis (elongated appendage from head), proglottid (segment), tegument (outer layer of skin).

Trematoda: Flukes.

Fasciola gigantica
Liver fluke. Snail is an intermediate host. Infect cattle, buffalo, sheep, and ruminants. Can also be ingested from raw vegetation. Closely related to and can mate with Fasciola hepatica. Triclabendazole and artesunatecan be used to treat it.
Fasciola hepatica
Liver fluke. One of the largest fluke species. Snail is an intermediate host. Transmitted from sheep and cattle to humans. Can also be ingested from raw vegetation like watercress. Closely related to and can mate with Fasciola gigantica. Triclabendazole and artesunatecan be used to treat it.
Paragonimus westermani
Japanese lung fluke. Infects humans in Eastern Asia and South America. Causes acute and chronic inflammation to the lung. Snail is an intermediate host. Reservoirs include canines, felines, rodents, pigs, and marine species. Can infect the spinal cord and cause paralysis and cause death if it infects the heart. Praziquantel is used to treat it.
Schistosoma mansoni
Blod fluke that is sexually dimorphic. Males and females attach permanently with the male resting in a crevice of the female.

Cestoda: Tapeworms.

Taenia saginata
Beef tapeworm transmitted through eating undercooked beef. Does not cause cysticercosis in humans, though it causes it in cattle. Normally asymptomatic infection. Can self fertilize because each proglottid has full sets of male and female reproductive systems. Longer than Taenia solium. Absorbs nutrients through the tegument. Praziquantel and niclosamide can be used to treat it.
Taenia solium
Pork tapeworm transmitted through eating undercooked pork. Can cause cysticercosis, even in the brain, in secondary hosting if eggs are eaten through human fecal contamination. Normally asymptomatic infection. Can self fertilize because each proglottid has full sets of male and female reproductive systems. Shorter than Taenia saginata. Praziquantel and albendazole can be used to treat it.

Monogenea: Ectoparasites of fish.

Turbellaria: Non parasitic flatworms.

A model species for biological research. Can regenerate body parts. Eyespots detect light. Move by cilia and muscle contractions.


A phyla of roundworms including common pet parasites with two openings (mouth and butthole). 1 out of 6 humans are estimated to be infected with a nematode.

Vocab: Amphid (Olfactosensory invaginations on the head), spicule (needle-like mating structure in males that facilitate transmission of sperm).

Enoplea: Ancestral class, cylindrical esophagus, simple excretory system, pocket shaped amphids, smooth, marked with lines.

Trichuris trichiura
Human whipworm that infects the large intestine. Tropical infections in Asia, Africa, and South America. Transmitted through feces and raw / unwashed fruits and vegetables. Can be treated with one dose of albendazole.

Chromadorea: Recently diverged class, bolbous esophagus, complex tubular excretory system, slit / pore / coil shaped amphids, may have rings or setae hairs.

Ascaris lumbricoides
Causes a neglected tropical disease that is transmitted through fecal matter. Eggs are very resistant to chemicals, extreme dryness, and low temperatures, and they can remail viable in soil for years. Acetic acid in vinegar will eggs on the surface of vegetables.
Ascaris summ
Pig roundworm. Possibly the same species as Ascaris lumbricoides as cross infection between pigs and humans is possible.
Dracunculus medinensis
Guinea worm. Remains endemic to some African countries, South Asia, Southwest Asia, and tropical regions. Transmit through microcrustaceans in drinking water. One of the longest nematodes in humans. They infect and live in feet of humans. Females often emerge through the skin while males might not emerge.
A genus of beneficial nematodes that are obligate parasites of insects. They can be used as biological control of pest insects.
Caenorhabditis elegans
A model species for biologicall research. Can be found in temperate soil environments. Lacks circulatory and respiratory systems. Most are hermaphrodites, and few are males (1 in 1000) which have spicules.


A parasitic phyla of thorny headed worms with spiny probosci that can turn inside out. Related to rotifers. Can infect invertebrates, fish, amphibians, birds, and mammals, though it rarely infects humans.

Macracanthorhynchus hirudinaceus
The species that caused the first known historic human infection in a child in Prague.
Moniliformis clarki
Likely to have infected a prehistoric man in Utah.
Moniliformis moniliformis
Can be found in rodents, cats, dogs, and rarely humans in Iran, Iraq, and Nigeria. The most common species to be isolated from humans. Sexually dimorphic. Absorbs nutrients through tegument since it has no digestive tract. Has a cylindrical proboscis with hooks.


A phyla of segmented worms including earthworms and leeches.