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.

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Platyhelminthes

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

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 artesunate can 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 artesunate can 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

Blood fluke that is sexually dimorphic. Males and females attach permanently with the male resting in a crevice of the female.

Cestoda: Tapeworms.

Diphyllobothrium latum

Freshwater fish tapeworm that is native to Scandinavia, Russia, and the Baltics but can also be found in Peru, Chile, Uganda, and Japan. The longest human tapeworm. Has two bothria on the scolex. Proglottids are wider than they are long, so this species is classified as a broad tapeworm. Can cause B12 deficiency and anemia. Praziquantel and niclosamide can be used to treat it.

Diphyllobothrium pacificum

Saltwater fish tapeworm that is similar to Diphyllobothrium latum. Mostly common in Peru.

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.

Planaria

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

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Nematoda

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.

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.

Ancylostoma duodenale

Old World hookworm that infects the small intestine. Mostly common in Europe, Africa, and Asia. Spreads from skin (of feet) to blood to lungs to small intestines. Can cause iron deficiency anemia. Has four fang-like teeth.

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.

Caenorhabditis elegans

A model species for biological 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.

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. Can be removed by wrapping the worm around a stick and rotating the stick slowly as to not break the worm.

Enterobius vermicularis

Pinworm or threadworm of humans that infects the intestines. The most common helminth in the United States. They molt four times during their life cycle. Male worms die and are passed through feces, and female worms remain in the intestine to continue parasitizing before laying eggs at the anus.

Heterorhabditis

A genus of beneficial nematodes that are obligate parasites of insects. They can be used as biological control of pest insects.

Loa loa

Eye worm that causes a neglected tropical disease. Most common in West and Central Africa and is transmitted from Chrysops horsefly / deerfly bites. Mostly asymptomatic infection for years or decades. Live in peripheral blood during the daytime and migrate to lungs at nighttime. Can surface at the sclera of eyes for up to one week and can also surface in other areas such as the penis, testes, nipples, kidneys, and heart. Ivermectin can be used to treat it, but it can cause neurological effects in the hosts. Diethylcarbamazine is the treatment recommended by the CDC.

Necator americanus

New World hookworm that infects the small intestine. Mostly common in tropical areas. Spreads from skin (of feet) to lymph nodes to small intestines. Can cause iron deficiency anemia. Has two rounded "buck teeth".

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Acanthocephala

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.

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Annelids

A phyla of segmented worms including earthworms and leeches.