[PPT] - Helminthology Nematodes Nematodes Helminthology Hookworm PowerPoint Presentation

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Helminthology Helminthology – – Nematodes Nematodes Hookworm Hookworm

Terry L Terry L Dwelle Dwelle MD MPHTM MD MPHTM

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Classification of Nematodes Classification of Nematodes

Subclass Subclass Order Order (suborder) (suborder) Superfamily Superfamily Genus and Species Genus and Species Probable Probable prevalence in prevalence in man man

Secernentea Secernentea Strongylida Strongylida Ankylostomatoidea Ankylostomatoidea Ankylostoma Ankylostoma douodenale douodenale 716 million 716 million Necator Necator americanus americanus A A caninum caninum Thousands Thousands A A braziliense braziliense Thousands Thousands A A ceylanicum ceylanicum Rare Rare Ternidens Ternidens diminutus diminutus Thousands Thousands Oesophagostomum Oesophagostomum apiostomum apiostomum Rare Rare Syngamus Syngamus laryngeus laryngeus Rare Rare

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General Information General Information

► ►Two major species;

Two major species; Ankylostoma Ankylostoma duodenale duodenale (old world), (old world), Necator Necator Americanus Americanus (new (new world) world)

► ►Others; A

Others; A caninum caninum, A , A braziliense braziliense, A , A ceylanicum ceylanicum

► ►Prevalence

Prevalence – – Africa, Asia, Central America, Africa, Asia, Central America, South America, Caribbean Islands, SE US South America, Caribbean Islands, SE US

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General Recognition Features General Recognition Features

► ► Size

Size

Necator

Necator americanis americanis – – male 7 male 7-

9 mm, female 10

9 mm, female 10-

18 mm

18 mm

Ankylostoma

Ankylostoma duodenale duodenale – – male 8 male 8-

11 mm, female 10

11 mm, female 10-

15

15 mm mm

► ► Structure

Structure

NA has a fused

NA has a fused copulatory copulatory spicule spicule vs vs AD AD

AD totally dorsally flexed. NA is dorsally flexed but with

AD totally dorsally flexed. NA is dorsally flexed but with a ventral flex near the head a ventral flex near the head

Two sets of reproductive organs

Two sets of reproductive organs

Distinctive mouth parts

Distinctive mouth parts

Copulatory

Copulatory bursa ray patterns are distinctive bursa ray patterns are distinctive

► ► Eggs

Eggs

Thin shelled

Thin shelled

60

60-

75 um X 35

75 um X 35-

40 um

40 um

4 to 8 cells

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General Recognition Features General Recognition Features

► ► Structure

Structure

NA has a fused

NA has a fused copulatory copulatory spicule spicule vs vs AD AD

AD totally dorsally flexed. NA is

AD totally dorsally flexed. NA is dorsally flexed but with a ventral dorsally flexed but with a ventral flex near the head flex near the head

Two sets of reproductive organs

Two sets of reproductive organs

Copulatory

Copulatory bursa ray patterns are bursa ray patterns are distinctive for male worms distinctive for male worms

From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1621

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General Recognition Features General Recognition Features

From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1622

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General Recognition Features General Recognition Features

A Duodenale N Americanus A Caninum A Ceylanicum

From a Color Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers, pp 148-149

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General Recognition Features General Recognition Features

From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1621-1622

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General Recognition Features General Recognition Features

From a Color Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers, pp 148-149

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General Recognition Features General Recognition Features

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Life Cycle Life Cycle

► ►Definitive host

Definitive host – – man man

► ►Stage leaving the body

Stage leaving the body – – fertile eggs fertile eggs

► ►Infectious stage for the definitive host

Infectious stage for the definitive host – – L3 L3 larvae larvae

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Prepatency Prepatency and Incubation Period and Incubation Period

► ►Prepatency

Prepatency – – 8 8-

12 weeks

12 weeks

► ►Incubation period

Incubation period – – 4 4-

12 weeks

12 weeks

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Life Cycle Life Cycle

L3 Filariform Larvae Skin Blood Lungs Largnx Esophagus Small Intestine Eggs Soil L1 rhabdiform Larvae

loose, sandy 24-48 hours Penetrates skin within a few minutes 6 – 10 days 5000/day NA, 20,000/day AD AD 5-7w, NA 4-6w Rhabditis like esophagus Life span 5-10 years

GI

Meat Breast Milk

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Life Cycle Life Cycle

L3 Filariform Larvae Skin Blood Lungs Largnx Esophagus Small Intestine Eggs Soil L1 rhabdiform Larvae

loose, sandy 24-48 hours Penetrates skin within a few minutes 6 – 10 days 5000/day NA, 20,000/day AD Rhabditis like esophagus Life span 5-15 years

GI

Meat Breast Milk

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Signs and Symptoms Signs and Symptoms

► ► Ground itch due to

Ground itch due to vesiculation vesiculation and and pustulation pustulation at at the entry site the entry site

Exposed portions of the body usually the soles of the

Exposed portions of the body usually the soles of the feet or hands feet or hands

► ► Asthma and bronchitis caused by migration of the

Asthma and bronchitis caused by migration of the larvae through the lungs larvae through the lungs

1

1-

2 weeks associated with dry cough and wheezing

2 weeks associated with dry cough and wheezing

► ► Established infection associated with hookworm

Established infection associated with hookworm disease disease

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Established Infection Established Infection

Light infection (

Light infection (< < 100 worms) 100 worms)

Mild anemia

Mild anemia

Fatique

Fatique

Lassitude

Lassitude

Digestive disturbances

Digestive disturbances

Eosinophilia

Eosinophilia

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Established Infection Established Infection

Heavy infection (

Heavy infection (> > 400 worms) 400 worms) – –

Fatique

Fatique

Lassitude

Lassitude

Eosinophilia

Eosinophilia

Epigastric

Epigastric apin apin

Perverted taste

Perverted taste – – pica, pica, geophagy geophagy

Hematochezia

Hematochezia / / melena melena

Anemia

Anemia

Edema associated with

Edema associated with hypoalbuminemia hypoalbuminemia

Heart failure

Heart failure

Hypothermia

Hypothermia

Retinal hemorrhages

Retinal hemorrhages

Irregular fever

Irregular fever

Growth failure

Growth failure

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Wakana Wakana disease disease

► ►Associated with oral infection with AD in

Associated with oral infection with AD in Japan Japan

► ►No larvae are found in the lung

No larvae are found in the lung

► ►Has cough,

Has cough, dyspnea dyspnea, , eosinophilia eosinophilia, nausea , nausea and vomiting and vomiting

► ►Seen one to several days after ingestion of

Seen one to several days after ingestion of larvae larvae

► ►Etiology is not known

Etiology is not known

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Infantile Disease Infantile Disease

► ►Mostly reported from China

Mostly reported from China

► ►Mainly caused by A

Mainly caused by A Duodenale Duodenale

► ►Transmission

Transmission – – trans trans-

mammary, laying

mammary, laying infants on infected soil, and rarely trans infants on infected soil, and rarely trans-

placental

placental

► ►Signs and symptoms

Signs and symptoms – – diarrhea, diarrhea, hematochezia hematochezia / / melena melena, anorexia, vomiting, , anorexia, vomiting, pallor, massive hemorrhage pallor, massive hemorrhage

► ►Mortality

Mortality – – 12% 12%

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Diagnosis Diagnosis

► ► Eggs in the stool

Eggs in the stool

Heavy infection

Heavy infection – – Direct stool smear with saline or Direct stool smear with saline or potassium iodide saturated with iodine potassium iodide saturated with iodine

Light infection

Light infection – – Concentration Concentration techiques techiques (Kato (Kato-

Katz,

Katz, Beaver direct smear, Stoll egg counting Beaver direct smear, Stoll egg counting techique techique) )

Late

Late prepatent prepatent period Charcot Leyden crystals and period Charcot Leyden crystals and eosinophils eosinophils may be seen in the feces similar to may be seen in the feces similar to whipworm whipworm

> 20 eggs / mg associated with anemia in NA

> 20 eggs / mg associated with anemia in NA vs vs > 5 > 5 eggs / mg with AD eggs / mg with AD

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Strongyloides stercoralis larva Hookworm Egg Trichostrongylus Egg Hookworm Capillaria Philippinensis Hookworm Trichostrongylus Hookworm Trichuris trichuria

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Treatment Treatment

Drug Drug Adult Adult Pediatric Pediatric Albendazole Albendazole 400 mg once 400 mg once 400 mg once 400 mg once Mebendazole Mebendazole 100 mg bid X 3 100 mg bid X 3 days or 500 mg days or 500 mg

nce
nce

100 mg bid X 3 100 mg bid X 3 days or 500 mg days or 500 mg

nce
nce

Pyrantel Pyrantel pamoate pamoate 11 mg/kg (max 11 mg/kg (max 1 gm) X 3 days 1 gm) X 3 days 11 mg/kg (max 11 mg/kg (max 1 gm) X 3 days 1 gm) X 3 days

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Adverse Reactions Adverse Reactions

Albendazole Albendazole Occasional: diarrhea, abdominal pain Occasional: diarrhea, abdominal pain Rare: Rare: leukopenia leukopenia, alopecia, increased , alopecia, increased serum serum transaminase transaminase levels levels Mebendazole Mebendazole Occasional: diarrhea, abdominal pain Occasional: diarrhea, abdominal pain Rare: Rare: leukopenia leukopenia, , agranulocytosis agranulocytosis, , hypospermia hypospermia Pyrantel Pyrantel pamoate pamoate Occasional: GI Occasional: GI distrubances distrubances, headache, , headache, dizziness, rash, fever dizziness, rash, fever

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Control Measures Control Measures

► ►Sanitary disposal of feces

Sanitary disposal of feces

► ►Treatment of all known infected people.

Treatment of all known infected people. Screening of high risk groups (agricultural Screening of high risk groups (agricultural workers and children) may help. workers and children) may help.