Transmission: oral – fecal route or undercooked meat
Several species parasitize humans after being consumed in under prepared meat such as
pork ( Taenia solium ),
beef ( T. saginata ), 12 m (40 ft);
fish ( Diphyllobothrium spp.),
or in food prepared in conditions of poor hygiene.
Other species grow up to over 30 m (100 ft).
Taenia solium pork tapeworm
Class Trematoda (flukes)
Liver Fluke - parasitize and live in the liver bile ducts of cattle and sheep, sometimes humans as well.
Fascioloides magna – Large American Liver Fluke (deer) Fasciola hepatica - Liver fluke (sheep, cattle, humans)
Fasciola hepatica Liver fluke
P. Nematoda (roundworms)
“ tube within a tube”
Sexual reproduction with separate genders (dioecious)
Have a primary and sometimes secondary host with a parasitic relationship.
Necator Americanus (hookworm)
Parasitic nematode that lives in the small intestine of its host (dog, cat, or human).
N. americanus predominates in the Americas, Sub-Saharan Africa, Southeast Asia, China, and Indonesia.
Hookworms are thought to infect more than 600 million people worldwide.
Enterobius vermicularis (pinworm)
common human intestinal parasite, especially in children
Dracunculus medinensis (guinea worm) Transmitted by drinking water that contains water fleas infected by the parasite.
Humans become infected by drinking unfiltered water containing copepods (small crustaceans) which are infected with larvae of D. medinensis .
Following ingestion, the copepods die and release the larvae, which penetrate the host stomach and intestinal wall and enter the abdominal cavity and retroperitoneal space .
After maturation into adults and copulation, the male worms die and the females (length: 70 to 120 cm) migrate in the subcutaneous tissues towards the skin surface .
Approximately one year after infection, the female worm induces a blister on the skin, generally on the distal lower extremity, which ruptures.
When this lesion comes into contact with water, a contact that the patient seeks to relieve the local discomfort, the female worm emerges and releases larvae .
The larvae are ingested by a copepod and after two weeks (and two molts) have developed into infective larvae. Ingestion of the copepods closes the cycle .
Current Information from WHO
In the mid 1980s, the parasitic infection was widespread in 20 countries worldwide, 16 of which were in Africa, with more than 3.5 million people infected. In 2010, fewer than 1800 cases were reported. Only four African countries, namely Chad, Ethiopia, Mali and South Sudan, are still reporting cases, with the majority of cases occuring in South Sudan.
According to the World Heath Organization, 1 in every 4 people on Earth has roundworms living inside them (and its mainly people in North America and Europe).
ragworms – segmented marine worms
earthworms – segmented earth worms
leeches – segmented sucker worms
P. Annelida – ragworms, earthworms and leeches
Over 17,000 species
Closed circulatory system and heart (w/ oxygen carrying pigment)
Brain and nervous system
Some have compound or camera eyes to form images
Still respire through the skin
Some are hermaphrodites, others are male when young and female when mature.