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Ancylostoma Duodenale andNecator Americanus
By Marquetta Valdez
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Some Facts.
Hookworms infect an estimated 1 billionpeople worldwide, mostly in tropical andsub-tropical climates
A. duodenale and N. americanus are thetwo hookworms that infect humans
A. duodenale is found in southern Europe,northern Africa, India, China, the MiddleEast, and the Americas
N. americanus can be found in thesoutheastern U.S. and Australia
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Life Cycle and Reproduction
Eggs are passed in the feces and hatch intorhabditiform larvae in about 48 hours in thefeces or in the soil
A. duodenale N. americanus
Eggs are generally 57-76 m by 35-47
m and areoval shaped
with a thin shell
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Rhabditiform Larvae (wet mount)
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Life cycle continued
Juveniles feed on feces for about 3 daysthen molt into 2nd stage juveniles
They molt again 5-10 days later intofilariform larvae. Can survive 3-4 weeksoutside host.
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Life Cycle
Worms molt again two more times toreach maturity
A. duodenale adult males measure 8-11mm
with females being 10-13mm
N. americanus adult males measure 7-9mmand females measure 9-11mm
Adult worms copulate and eggs appear in
the feces in about 6 weeks (females canproduce sever thousand eggs in one day)
Cycle starts over again and adults live 1-2years
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Life Cycle
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Transmission
Filariform juveniles wait in soil orfeces and wave back and forth to
increase chances of finding a host Filariforms then penetrate the skin
(usually hands or feet)
Children, elderly people and peoplewhowork about contaminated soilare at high risk
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Pathogenic Effects
Asymptomatic until worms have alreadystarted multiplying
Symptoms include: Irritation of skin at site of penetration
Iron-deficiency anemia Abdominal pain Diarrhea Loss of appetite Weight loss
Tiredness Difficulty breathing Cardiomegaly Irregular heartbeat Extreme cases include stunted growth and
mental retardation
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Diagnosis
Stool samples showing eggs oractual worms
Watching for symptoms
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Control and Treatment
Scientist are trying to develop avaccine
In some countries, infections arenttreated because they are socommon
Drugs of choice are Albendazole,
Mebendazole, and Pyrantel Pamoate
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Prevention
Wear shoes
Monitor the disposal of humans
feces
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Works Cited
"Hookworm Image Library." Division ofParasitic Diseases. Center for DiseaseControl. 29 Sept. 2006
. "Hookworm Infection Fact Sheet."
Parasitic Disease Infection. Center forDisease Control. 3 Oct. 2006.
"Hookworm." Parasites and Health.Center for Disease Control. 29 Sept. 2006.