parasites- extra Flashcards
two types of parasite
helminths and protozoa
helminths consist of
nematodes, trematodes, cestodes
nematodes
roundworms
trematodes
flukes
cestodes
tapeworms
what type of infection
intestinal or systemic
most common intestinal nematode (flatworm)
Ascaris lumbricoides and hookworms
most common tissue-dwelling nematode (flatworm)
wucheria bancrofti
most common cestodes (flukes)
echinococcus granulosis
most common tremadoes (round worm)
schistose mansoni
example of a parasite disease
schistosomiasis
vector of schistosomiasis
water snail
how many species of schistosomes
6
how many people affected by schistosomiasis
> 200 million
where does schistosome infection occur
fresh water contaminated with motile, fork tailed cercariae
life cycle of schistosomes
- eggs hatch to yield motile MIRACIDIA
- MIRICIDIA infect snails
- MIRICIDIA mature and multiple to release infectious CERCARIAE
Free swimming Cercariae strucuturee
fork tailed, with long body and head (sperm with fork tail)
when the cercariae wants to penetrate hosts skin
cercariae shed their tail and use proteases and mucalr action of oral suckers to penetrate
after penetrator cercariae become
immature shistosomula
schistosomula migrate via
the circulation to reach the liver microcirculation where they mature
schistosoumula mature to
schistosomes
do worms multiply in host
no
- adult
females reside intimately within a canal in
the ventral body of the male
pairs migrate
against the portal venous blood flow (GI to the liver) to release eggs into the veins draining the bladder and intestines
what do eggs elicit
a granulomatous inflammatory
response that is believed to assist their
transit into the intestines or bladder, and
excretion from the body in the stool or
urine respectively
