Soil – Transmitted Helminthiasis ( STH )ocw.usu.ac.id/course/download/111-GROWTH-AND... ·...

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Dewi Masyithah/Par/2004

Soil – Transmitted Helminthiasis ( STH )

• nematode infections

• transmitted via soil medium either

1. Ingestion of embryonated eggs

2. Skin penetration by infective larvae

• refers to these helminths:

Ascaris lumbricoidesTrichuris trichiura

HookwormsStrongyloides stercoralis

Toxocara spp.

Common

STH

agents


Epidemiological situation

Worldwide distribution. Frequencies of infection:

Ascariasis 1,000 million

Trichuriasis 900 million

Hookworms 500 million

Enterobiasis 400 million

Strongyloidiasis 100 million

Taeniasis 70 million

Reported In 150

out of 208 countries

In highly endemic areas, prevalence as high as 60-80%;

in Latin America they affect between 20-30% of general

population

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Infections STH associated with:

• Poverty and poor condition

• Inadequate sanitation and water supplies

• Soil quality and climate

• Poor personal and environmental hygiene

• Poor health awareness


Habitat of STH in host

Large intestine

Small intestine

Trichuris trichiura

Ascaris lumbricoides

Hookworms

Strongyloides

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Morphology of adult STH

Large, cylinder, tapers at both

ends

Size 200-400 mm x 2-3 mm

Long, slender, coiled

posterior (male) and

whip-like

Size 30-50 mm

Tiny, short

Size 5-13 mm

Ascaris Trichuris Hookworms


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Ascariasis

Etiology: Ascaris lumbricoides ( roundworm )

Habitat : small intestine, especially jejunum and upper ileum


Life cycle of

Ascaris

lumbricoides

Infective stage

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Clinical presentations

Migration of

larvae in

circulation �

respiratory tree

Adult worms in

small intestine

• Loeffler’s syndrome

• inflammation in brain,

heart, kidneys, spinal

cord

• blockage

• malnutrition

• allergy

• ectopic

(wanderlust)


Pathology caused by Ascaris lumbricoides

• malnutrition due to absorption of nutrients in small intestine as

food passes.

• majority symptomless

• intestinal obstruction followed by infarction and gangrene

• acute and chronic inflammation with infiltrations by eosinophils,

histiocytes and mononuclear cells at sites of ectopic ascariasis

• granuloma formation around ova in tissues

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• Malnutrition due to Ascariasis:

One adult worm: 0.14 g carbohydrate daily

0.035 g protein daily

One gram of rice contains ± 0.8 g carbohydrate.

We assume ± 4 adult worm in human body for example.

Indonesian people: ± 200 million; ± 560 million adult

worm.

We will lose carbohydrate: ± 76,440 Kg of rice.

One gram of meat contains 0.18 g protein.

One adult worm absorb ~ 424 cows (á 200 Kg).


Diagnosis

Adult worm out of body openings

Larvae std 3rd in sputum

Eggs in feces – fertilized / unfertilized

Serology for extraintestinal ascariasis (?)

Control

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Ways to improve………..

A. Short term:

Mass anti-helminthic drug administration.

Ideal condition 0f

helminthic drugs:1. Cheap

2. Available3. Less additional effect4. Broad spectrum5. Germicidal & larvacidal6. Single dose

Treatment:

- Pyrantel pamoate 10

mg/kg stat dose.

- Mebendazole 500mg daily

- Piperazine citrate 75 mg/kg

x 2 days

- Albendazole 400 mg stat

dose


1 Improve sanitation: providing proper toilet

B: Long term:

1

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Health education

Ways to improve ……

2


Health education

Ways to improve ……

2

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Trichiuriasis

Etiology: Trichiuris trichiura ( whipworm )

(trichuris = hairtail; trichocephalus = hairhead)

Habitat: large intestine, especially cecum and vermiform appendix


Adult Trichuris

Female

- larger

- whip-like

Male

- coiled

posterior

Anterior end

3/5 body length

Posterior end

2/5 body length

Contain intestine, reproductive organs

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Trichuris eggs

Eggs in fresh feces

- barrel shaped

- mucus plugs at both ends

- unsegmented ovum

Eggs in external environment

- similar characteristics

- embryonated larva inside!


Life cycle of

Trichuris trichiura

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• LOW

• anemia

• bloody diarrhea

• malnutrition

• anorectal prolapse

• 2nd bacterial / protozoal infections


Pathology caused in Trichuriasis

Anterior portion of worm embedded in intestinal mucosa of large

intestine and cause petechial hemorrhages � anemia

Breaks and lesions in mucosa predispose to secondary bacterial

and protozoan infections

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Diagnosis

� stool FEME (Formalin Ether Microscopic Examination)

– barrel shaped eggs, adult worms, Charcot-Leyden

crystals

� High eosinophilia in peripheral blood film

� sigmoidoscopy – see adult worm

Treatment

Anti-helminthic agents


Ancylostomiasis (Uncinariasis)

Etiology: Ancylostoma duodenale

Necator americanusHookworms

of man

Distribution

Prevalence of Necator > Ancylostoma, according to geographical

areas, but more often overlap. 2nd or 3rd commonest helminthic

infection after ascariasis.

Infection with Ancylostoma more severe!

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Prevalence of hookworm disease in the world


Rhabditiform larva Filariform larva

Hookworm larvae

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Hookworm eggs

Oval, 65 x 40 um

Colorless, transparent hyaline

membrane

Segmented ovum with 4 blastomers

Clear space between egg and ovum

Not infective in freshly passed stool

Similar forms between two species

Both polar ends are blunt


Life cycle of hookworms

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Life cycle of

hookworms


As filariform larva

penetrates skin

- skin rash, red, itchy

- creeping eruption

As larvae migrates

through circulation

� respiratory tree

- fever, cough,

wheezingeosinophilia

Adult worms

- absorb blood,

nutrients

- iron def. anemia

- diarrhea

- hypoproteinemia


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Pathology caused by Hookworms

� Blood sucking action of adult worms causes chronic blood

loss due to punctate hemorrhages in jejunal mucosa, where

hookworms lodge and predispose to bacterial infections;

-A.duodenale: o.15 ml/day

-N.americanus: 0.03-0.05 ml/day

� Reduced protein intake causes bone marrow suppression

�Malabsorption of Vit B12 and folic acid

�Intestinal villi atrophy, blunting and fusion which impairs

absorption

�Allergic reactions in lungs due to migration of larva

�Cognitive


Diagnosis

Eggs with segmented ovum in feces

Rhabditiform larvae in old feces

Treatment

Anti-helminthic agents :

-Albendazole : 400 mg, single dose

-Pirantel pamoate : 5-10 mg/kg BB, single dose

-Mebendazole :- 500 mg single dose or

2x100 mg for 3 days

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