How are parasites classified?
1) Multicellular |
2) Unicellular |
3) Ectoparasites |
What is a helminth?
Helminths are categorized as multicellular parasitic worms , which often can be seen by the naked eye. There are no known worms that are unicellular or ectoparasites . Helminth is a broad term that belong to two phyla: Platyhelminthes (flatworms) and Nematoda (round worms).
Helminths are categorized as multicellular parasitic worms , which often can be seen by the naked eye. There are no known worms that are unicellular or ectoparasites . Helminth is a broad term that belong to two phyla: Platyhelminthes (flatworms) and Nematoda (round worms).
What is the typical mode of transmission for parasitic helminths?
The mode of transmission varies with the type of worm; it may involve ingestion of eggs or larvae, penetration by larvae, bite of vectors, or ingestion of stages in the meat of intermediate hosts.
The mode of transmission varies with the type of worm; it may involve ingestion of eggs or larvae, penetration by larvae, bite of vectors, or ingestion of stages in the meat of intermediate hosts.
Phlyum: Platyhelminthes Class: Trematoda (flukes)
Trematodes are characterized by a sucker around the mouth and an additional ventral sucker that is used for locomotion and attachment to the host.
Fasciola hepatica
Mode of transmission: Consumption of uncooked vegetation (commonly watercress) or raw parasitized liver of cattle or sheep containing metacercariae. Disease: fascioliasis |
Clonorchis sinensis
Mode of transmission: Ingestion of contaminated raw, frozen, dried, salted, smoked or pickled fish. Disease: Clonorchiasis |
Schistosoma mansoni
Mode of transmission: Infection occurs when larval forms of the parasite are released by freshwater snails and penetrate the skin during contact with infested water. In the body, the larvae develop into adult schistosomes. Adult worms live in the blood vessels where the females release eggs out of the body in the faeces or urine to continue the parasite’s life-cycle. Disease: schistosomiasis |
Phlyum: Platyhelminthes Class: Cestoda (tapeworms)
Flatworms with long thin bodies composed of sacs called proglottids and a scolex that grips the intestine. Each proglottid is adapted to absorb nutrients and producing a new worm with the eggs inside.
Taenia saginata (pork tapeworm)
Mode of transmission: Ingestion of under cooked cooked contaminated pork. Disease: Taeniasis |
Taenia solium (pig tapeworm)
Mode of transmission: Ingestion of poorly under cooked contaminated pork. Disease: Taeniasis |
Dipylidium caninum (flea tapeworm)
Mode of transmission: Primarily affects cats and dogs, human infection occurs when a contaminated flea is ingested, usually occurs in young children. |
Phlyum: Nematoda
Elongated, cylindrical worms with protective cuticles, circular muscles, a complete digestive tract, and separate sexes. Divided into intestinal nematodes, and tissue nematodes
Ascaris lumbricoides (hookworm)
Mode of transmission: Infections are passed between hosts by the faecal-oral transmission of eggs containing infective larvae. 
Wuchereria bancrofti (filaria worms)
Mode of transmission: Vector born disease, transmitted through the bite of an infectious mosquito. |
Necator americanus (hookworm)
Mode of transmission: Hook-worms have direct life-cycles involving a geo-helminth stage where infective larvae in the soil actively penetrate the skin or oral mucosa of their hosts 
Trichinella spiralis (pork worms)
Mode of transmission: Consumption of raw or undercooked meat of infected animals, most commonly domestic pigs. |
Enterobius vermicularis (pinworms)
Mode of transmission: Ingestion of infectious eggs by direct anus-to-mouth transfer by fingers. This is facilitated by the perianal itch (pruritis ani) induced by the presence of pinworm eggs in the perianal folds, and commonly occurs as a result of nail biting, poor hygiene, or inadequate hand-washing. |
