HookwormsHookworms

Presented by: Mahamoud Ahmed & Faisal Farea

The disease induced by hookworms…The disease induced by hookworms…was never suspected to be a disease was never suspected to be a disease at all. The people who had it were at all. The people who had it were merely supposed to be lazy, and merely supposed to be lazy, and were therefore despised and made were therefore despised and made fun of, when they should have been fun of, when they should have been pitied.pitied.

---Mark Twain---Mark Twain

TaxonomyTaxonomyKingdom: animaliaKingdom: animalia

Phylum:NematodePhylum:Nematode

Class: secernenteaClass: secernentea

Order:Order: StrongiloidaeStrongiloidae

Family: AncylostomatidaeFamily: Ancylostomatidae

Genus: Necator/AncylostomaGenus: Necator/Ancylostoma

Species: A. duodenale and N. AmericanusSpecies: A. duodenale and N. Americanus

Hookworms are the voracious blood feeders of the Hookworms are the voracious blood feeders of the nematode world.nematode world.

Two principal species that infect Two principal species that infect around 900 million people on earth around 900 million people on earth are:are:

Necator americanus known as the Necator americanus known as the american killer also known the new american killer also known the new world hookworm.world hookworm.

Ancylostoma duodenale known as Ancylostoma duodenale known as the old world hookworm.the old world hookworm.

Definitive hostDefinitive hostHumanHuman No Intermediate No Intermediate

hosthost

Neactor americanusNeactor americanusN. americanus is the most N. americanus is the most common species in humans in common species in humans in most of the world. About 95% most of the world. About 95% of the hookworms in the of the hookworms in the southern United States are southern United States are this speciesthis species. . N. americanus has a pair of N. americanus has a pair of dorsal and a pair of ventral dorsal and a pair of ventral cutting plates surrounding the cutting plates surrounding the anterior margin of the bucal anterior margin of the bucal capsulecapsuleMales have bursa diagnostic Males have bursa diagnostic for the genus. The needlelike for the genus. The needlelike specules have minute barbs specules have minute barbs at their tips and are fused at their tips and are fused distally. distally.

Ancylostoma duodenaleAncylostoma duodenaleAssociated with miners Associated with miners because mines offer an ideal because mines offer an ideal habitat for egg and juvenile habitat for egg and juvenile development due to development due to constancy in temperature constancy in temperature and humidity.and humidity.

It was known to cause a It was known to cause a serious anemia in miners.serious anemia in miners.

Has two ventral plates, each Has two ventral plates, each with large teeth that are with large teeth that are fused at their bases. A pair of fused at their bases. A pair of small teeth is found in the small teeth is found in the depths of the capsule. The depths of the capsule. The needlelike specules have needlelike specules have simple tips and are never simple tips and are never fused distally. fused distally.

Bucal cavityBucal cavity

Necator amricansNecator amricans

Dorsal and ventral cutting Dorsal and ventral cutting platesplates

Ancylostoma Ancylostoma duodenaleduodenale

2 ventral plates and 2 ventral plates and two large teethtwo large teeth

Size of femaleSize of female 9-11mm9-11mm 10-1310-13Size of maleSize of male 7-9mm7-9mm 8-11mm8-11mmPosition of vulvaPosition of vulva Mid-bodyMid-body 1/3 from 1/3 from

posteriorposteriorEgg productionEgg production 9000/ day9000/ day 25000/ day25000/ dayPenetration Penetration through skinthrough skin

YesYes YesYes

LongevityLongevity 15 years15 years 5 years5 years

Comparison of hookwormsComparison of hookworms

morphologymorphology

The eggs are bluntly rounded, thin shelled, The eggs are bluntly rounded, thin shelled, and are almost indistinguishable between and are almost indistinguishable between the different species. Measuring 60 by the different species. Measuring 60 by 4040µm, µm, the eggs of Ancylostoma being the eggs of Ancylostoma being slightly larger than those of Necator.slightly larger than those of Necator.

The adult parasites The adult parasites are small cylindrical are small cylindrical worms, (Ancylostoma worms, (Ancylostoma duodenale being duodenale being slightly larger than slightly larger than Necator americanus) Necator americanus) The male worm is The male worm is equipped with a equipped with a characteristic characteristic copulatory bursa, used copulatory bursa, used to catch and hold the to catch and hold the female during mating.female during mating.

Geographic distributionGeographic distribution

A.duodenale is the indigenous A.duodenale is the indigenous hookworm of the north-temperate zone hookworm of the north-temperate zone of the eastern hemisphere. it is of the eastern hemisphere. it is confined in southern Europe, northern confined in southern Europe, northern Africa, India, China and southern Asia.Africa, India, China and southern Asia.N.americanus is the new world worm. N.americanus is the new world worm. the “American killer,” was first the “American killer,” was first discovered in Brazil and then Texas, discovered in Brazil and then Texas, but it was later found indigenous in but it was later found indigenous in Africa, India, Southeast Asia, China, Africa, India, Southeast Asia, China, and southwest Pacific islands. and southwest Pacific islands.

Question #1Question #1

The male is equipped with copulatory The male is equipped with copulatory bursa, used to catch…bursa, used to catch…

a) fooda) food

b) femaleb) female

c) preyc) prey

Life cycleLife cycle

Life cycleLife cycleEggs are passed with feces. Eggs hatch in about 48 hours Eggs are passed with feces. Eggs hatch in about 48 hours under favorable conditions such as (moist soil, protection under favorable conditions such as (moist soil, protection from direct sun rays and temperature about 25°C.from direct sun rays and temperature about 25°C.The first-stage larva feed upon bacteria in the feces about The first-stage larva feed upon bacteria in the feces about three days and then molt to second-stage larva. First and three days and then molt to second-stage larva. First and second stage larva have a rhabditiform esophagus. After 5-second stage larva have a rhabditiform esophagus. After 5-10 days they molt and become filariform third-stage larva 10 days they molt and become filariform third-stage larva that are infective.that are infective.These infective larva can survive 3-4 weeks in favorable These infective larva can survive 3-4 weeks in favorable environmental conditions. 25 -15°C at 0°C death occurs environmental conditions. 25 -15°C at 0°C death occurs rapidly. They move to the surface of the soil and wave back rapidly. They move to the surface of the soil and wave back and forth which increases the chance to contact host. When and forth which increases the chance to contact host. When they contact with the human host, the larva penetrate the they contact with the human host, the larva penetrate the skin and are carried through the veins to the heart and then skin and are carried through the veins to the heart and then to the lungs, break through into air sacs, to the trachea and to the lungs, break through into air sacs, to the trachea and are swallowed. The larva reach the small intestine, where are swallowed. The larva reach the small intestine, where they reside and mature in to adults. they reside and mature in to adults.

Hookworms have evolved strategies to evade the Hookworms have evolved strategies to evade the host’s defense system, and several of these has host’s defense system, and several of these has been discovered.been discovered.Ancylostoma spp. Secrete a neutrophil inhibition Ancylostoma spp. Secrete a neutrophil inhibition factor that interferes with activation of factor that interferes with activation of neutrophils.neutrophils.N. americanus secretes acetyl cholinesterase, N. americanus secretes acetyl cholinesterase, which inhabits gut peristalsis and possibly is an which inhabits gut peristalsis and possibly is an anti-inflammatory factor.anti-inflammatory factor.

Question #2Question #2

What conditions are required for the What conditions are required for the eggs to hatch?eggs to hatch?

Moist soil & warm temp.Moist soil & warm temp.

Symptoms/pathogenesisSymptoms/pathogenesis

Itching of skin as a result of penetration by the Itching of skin as a result of penetration by the larvae.larvae.Congestion in lungs in heavy infections.Congestion in lungs in heavy infections.Anemia due to loss of blood, particularly if diet is Anemia due to loss of blood, particularly if diet is deficient.deficient.DiarrheaDiarrheaPersons with chronic hookworm disease are Persons with chronic hookworm disease are debilitated.debilitated.Chronic heavy hookworm infection can damage Chronic heavy hookworm infection can damage the growth and development of children.the growth and development of children.Hookworm infection has been known to be fatal, Hookworm infection has been known to be fatal, particularly in infants. particularly in infants.

Hookworm infection/diseaseHookworm infection/disease

Depends on three factors.Depends on three factors.1)Number of worms present1)Number of worms present2)Species of hookworm2)Species of hookworm3)Nutritional conditions of the 3)Nutritional conditions of the infected infected person.person.In general fewer than 25 N.americanus in person In general fewer than 25 N.americanus in person will cause no symptoms. 500-1000 result in will cause no symptoms. 500-1000 result in severe symptoms, and more than 1000 may lead severe symptoms, and more than 1000 may lead fatal consequences.fatal consequences.Ancylostoma spp. Suck more blood than Ancylostoma spp. Suck more blood than N.americanus fewer worms cause greater N.americanus fewer worms cause greater disease. 100 worms cause severe symptoms.disease. 100 worms cause severe symptoms.

TransmissionTransmission

Hookworm infection is contracted from Hookworm infection is contracted from contact with soil contaminated by contact with soil contaminated by hookworm, by walking bare foot or hookworm, by walking bare foot or accidentally swallowing contaminated soil.accidentally swallowing contaminated soil.

Children are at high risk because they play Children are at high risk because they play in dirt and often go bare foot.in dirt and often go bare foot.

Hookworms can’t be spread person to Hookworms can’t be spread person to person.person.

Diagnosis/treatmentDiagnosis/treatment

Recovery of the eggs in stool Recovery of the eggs in stool samples.samples.

Mebendazole or albendazole. It Mebendazole or albendazole. It should not be given to pregnant should not be given to pregnant women.women.

Question #3Question #3

T/F hookworm infection can be T/F hookworm infection can be transmitted person to person?transmitted person to person?

FalseFalse

PreventionPrevention

Proper sanitation practices.Proper sanitation practices.

Appropriate fecal disposal.Appropriate fecal disposal.

Do not walk barefoot or contact with Do not walk barefoot or contact with bare hands in areas where bare hands in areas where hookworms is common or there are hookworms is common or there are likely to be feces in the soil or sand.likely to be feces in the soil or sand.

Questions from the articleQuestions from the articleWhich stage of larvae feed on bacteria?Which stage of larvae feed on bacteria?

Rhabditiform.Rhabditiform.

To become infective stage the To become infective stage the rhabditiform has to molt?rhabditiform has to molt?

a) 2 timesa) 2 times

b) 3 timesb) 3 times

C) 1 timeC) 1 time

d) 4 times.d) 4 times.

Cont..questions.Cont..questions.

Which part of the world the Which part of the world the N.americanus is found?N.americanus is found?

Central/south. Africa, s. Asia, Central/south. Africa, s. Asia, Australia and pacific islands. Australia and pacific islands.

Which of the worms suck more Which of the worms suck more blood?blood?

A.duodenaleA.duodenale

Works citedWorks cited

http://www.dpd.cdc.gov/DPDx/HTML/http://www.dpd.cdc.gov/DPDx/HTML/Para_Health.htmPara_Health.htm

http://www.dpd.cdc.gov/DPDx/HTML/http://www.dpd.cdc.gov/DPDx/HTML/Para_Health.htmPara_Health.htm

http://pathmicro.med.sc.edu/http://pathmicro.med.sc.edu/parasitology/nematodes.htmparasitology/nematodes.htm