Biomedical Engineering Reference
In-Depth Information
larvae are carried through the portal system to the capillaries of the liver,
where they mature to adults. The adults lay their eggs in the liver. This leads
to liver fibrosis. If the parasite burden is high, cirrhosis may eventually
develop. The parasite infects a wide range of animals, but rats are the most
likely source of human infections. When an infected rat dies, its body
decomposes, and eggs within the liver are released to the soil, where the life
cycle resumes.
Trichuris trichiura is called the human whipworm, named for its tightly
wound, thick segment, from which a straight, thinner segment extends (i.e.,
handle and whip). The disease caused by Trichuris trichiura is trichiuriasis.
Humans are the natural primary host for the organism. No secondary host is
involved. Ingested eggs hatch in the small intestine, and larvae mature in the
large intestine. The mature worms, which can live up to five years, anchor in
the colonic mucosa and release eggs that pass out of the colon with feces.
Eggs in the soil contaminate food, and the life cycle resumes.
The degree of morbidity is determined by the number of parasitic worms.
Heavy infections can produce bloody diarrhea, anemia, and even rectal pro-
lapse (from the aggregate weight of worms the rectum). Trichiuriasis often
accompanies other parasitic infections, in the same individual.
Infectious species:
Anisakis simplex complex (anisakiasis)
Pseudoterranova decipiens (anisakiasis)
Ascaris lumbricoides (ascariasis, ascaris pneumonitis)
Baylisascaris procyonis
(baylisascariasis,
larva migrans with brain
involvement)
Toxocara canis, the dog roundworm (toxocariasis, visceral larva migrans,
ocularis larva migrans)
Toxocara cati,orTococara mystax, or the feline roundworm (toxocaria-
sis, visceral larva migrans, ocularis larva migrans)
Dioctophyme renale (giant kidney worm infection)
Enterobius vermicularis, also called pinworm in the USA and as thread-
worm in the United Kingdom, or sometimes as seatworm (enterobiasis or
oxyuriasis)
Strongyloides stercoralis, known as threadworm in USA and pinworm in
United Kingdom (strongyloidiasis)
Ancylostoma duodenale (hookworm, along with Necator americanus)
Necator americanus (hookworm, along with Ancylostoma duodenale)
Angiostrongylus cantonensis (angiostrongyliasis)
Angiostrongylus costaricensis (abdominal angiostrongyliasis,
intestinal
angiostrongyliasis)
Angiostrongylus mackerrasae (eosinophilic meningitis)
Trichostrongylus orientalis (trichostrongyliasis, trichostrongylosis)
Dracunculus medinensis (dracunculiasis, guinea worm disease)
