Trichinella spiralis
is the metazoan that causes trichinosis. Trichinella infection may be acquired by ingestion of larvae in raw or undercooked pork, bear, or meat from any other carnivorous animal. The ingested larvae pass through the digestive system of the host and develop into adults. Mating of male and female adults produces larvae that travel through the circulatory system, encysting in the striated muscle. They are recognizable at this stage by their spiral arrangement. Diagnosis is confirmed by visualization of the larvae in the muscle or with antibody testing. Because the adult is cylindrically shaped, Trichinella is in the phylum Aschelminthes and the class Nematoda (roundworms). Trichinella adults are shown in images 1 and 2. Note the curved tail of the adult male. Images 3 through 10 show larvae in striated muscle.
Click on each image to see the enlarged version.
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| 1. adult male 3 X | 2. adult female 3 X | 3. larvae 100 X | 4. larvae 100 X | 5. larvae 100 X |
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| 6. larvae 100 X | 7. larvae 100 X | 8. larvae 100 X | 9. larvae 100 X | 10. larvae 100 X |
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