Soil Transmitted Helminthiasis [Parasitology]

Soil Transmitted Helminthiasis

1AHS/Parasitologi/FKUSU

Refference

1. Roberts L, Janovy Jr J. Gerald D. Schmidt & Larry S. Roberts’ Foundations of Parasitology. 7th ed. McGraw Hill. New York. 2005 : 397-99, 417-24, 431-5

2. Brooker S, Bundy DAP, Soil Transmitted Helminths (Geohelminths). In : Cook GC, Zumla AI (ed). Manson’s Tropical Disease. 22nd ed. Saunders Elsevier. 2009 : 1517-40

3. World Health Organization. Preventive Chemotherapy in Human Helminthiasis : Coordinated Use of Anthelminthic Drugs in Control Intervensions : A Manual for Health Professionals and Programme Managers. Geneva, Switzerland : World Health Organization; 2006

4. World Health Organization. Weekly Epidemiological Record : Soil- Transmitted Helminthiasis : Estimates of The Number of Children Needing Preventive Chemotherapy and Number Treated . Geneva, Switzerland : World Health Organization; 2011

5. Hotez PJ, Brooker S, Bethony JM, et al. Hookworm Infection. The New England Journal of Medicine. 2004; 351 : 799-807

AHS/Parasitologi/FKUSU 2

References

• Agents of the disease• Pathology• Diagnosis • Prevention


Soil Transmitted HelminthiasisLearning Objective

Soil Transmitted HelminthiasisGeneral

o Nematode infections

o Transmitted via soil medium either :

1. Ingestion of embryonated eggs

2. Skin penetration by infective larvae


o Etiology :• Ascaris lumbricoides• Trichuris trichiura• Hookworms• Strongyloides stercoralis• Toxocara spp.


Common STH agents


o Infections STH associated with:• Poverty and poor condition• Crowded living conditions,

combined with lack of access to health care and low levels of education (poor personal and health awareness)

• Soil quality and climate• Inadequate water supply and

poor environmental sanitation



Soil Transmitted HelminthiasisGlobal Estimation


o Etiology : Ascaris lumbricoides (roundworm)o Habitat : small intestine, especially jejunum

and upper ileumo One of the most common & widespread human

infection, about 1 billion people worldwide

AscariasisGeneral


Ascaris lumbricoidesMorfology

Adult Ascaris lumbricoides




corticated

decorticated

Egg of A. lumbricoides

Fertilized Unfertilized



Infectious corticated

Egg of A. lumbricoides

AscariasisLife Cycle

Infective stage: fertilized eggDiagnostic stage: egg & adult in fecesRoute of infection: ingestion


o Majority symptomlesso May be caused by migrating larvae or adult

worms

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AscariasisPathology

AHS/Parasitologi/FKUSU

Migrating Larvae

AscariasisPathology

• When juveniles break out of lung cappilaries into the respiratoric system → small hemorrhage

• Segments of 4th stage larvae can be seen in the bronchioles associated with infiltration with PMN and eosinophil with scattered Charcot-Leyden crystals and radiological pulmonary infiltration → Ascaris pneumonitis (Löffler’s pneumonia)


• Ascaris pneumonitis (Löffler’s pneumonia): fever, cough, sputum, wheeze, skin rash, eosinophilia, and radiological pulmonary infiltration.

• Larvae may wander into the brain, eye, causing granulomas.

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AscariasisPathology


• Adult can cause physiological abnormalities in the small intestine → malabsorbtion of nutrients and micronutrients, malnutrition, growth failure and cognitive impairments

• Intestinal ascariasis → GI discomfort, colic and vomiting are quite common

AscariasisPathology

Adult worms


• The commonest complication of ascariasis among children below 10 years is small-bowel obstruction

• Heavy infection can cause intestinal colic, fatal intestinal blockage

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AscariasisPathology


• Wandering worms:– may reach liver, billiary tract,

appendix and oesophagus – acute and chronic inflammation

with infiltrations by eosinophils, histiocytes and mononuclear cells at sites of ectopic ascariasis

– granuloma formation around ova in tissues

AscariasisPathology


We assume ± 6 adult worm in human body for example.Indonesian people: ± 220 million; prevalence 60% → ± 792

million adult worms.One adult worm absorbs 0.14g carbohydrate daily and

0.035g protein dailyOne gram of rice contains ± 0.8g carbohydrateWe will lose carbohydrate: ± 110.880 Kg/ daily ≈ 110 tons of

rice/dayOne gram of meat contains 0.19g proteinWe will lose protein: ± 145.895 kg/day ≈ 729 cows (á 200 Kg)

Ascariasis

o Adult worm out of body openings

o Larvae std 4th in sputum

o Eggs in feces – fertilized/unfertilized

o Eosinophilia

o Serology (?)

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AscariasisDiagnostic


o Etiology: Trichiuris trichiura (whipworm)o Habitat: large intestine, especially caecum and

vermiform appendixo Recent estimate suggests that T trichiura

infects 795 million people worldwide

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TrichiuriasisGeneral


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TrichiuriasisMorfology

Adult Trichuris trichiura Egg of Trichuris trichiura


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TrichiuriasisLife cycle

Infective stage: fertilized eggDiagnostic stage: Eggs in fecesRoute of infection: ingestion


o Majority symptomlesso Anterior portion of worm embedded in intestinal

mucosa of large intestine and feed on cell contents → petechial hemorrhage

o Mucosal damage may facilitate the invasion of other infections

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TrichiuriasisPathology


o In heavy infection, • The worms spread throughout the colon to

the rectum → cause hemorrhage, mucopurulent stools and symptoms of dysentery with rectal prolapse (Trichuris Dysentry Sindrome = TDS)

• Anemia, hypoproteinemia, growth retardation

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o Eggs in feces

o High eosinophilia in peripheral blood filmo Sigmoidoscopy – adult worms

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TrichiuriasisDiagnostic


AncylostomiasisGeneral

o Etiology : Ancylostoma duodenale Necator americanus

o Habitat : small intestine o Recent estimate suggest that hookworms

infect 740 million people worldwide


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AncylostomiasisMorfology

Adult Ancylostoma duodenale


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Adult Necator americanus


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Hookworm larvae

Rhabditiform larvae Filariform larvae


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Egg of Hookworm



Infective stage: Filariform larvaeDiagnostic stage: Eggs in fecesRoute of infection: normally aquired by skin penetration A.duodenale

AncylostomiasisLife Cycle

Uncommon, A duodenale can be transmitted through undercooked meat including rabbit, lamb, beef and pork (Wakana’s disease) and lactogenic during breast-feeding (infantile hookworm)

Hookworm disease manifests three main phases of pathogenesis: oThe cutaneous or invasion periodoThe migration or pulmonary phaseoIntestinal phase

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AncylostomiasisPathology


• Begins when larva penetrates the skin• Pruritic , erythematous, papular rash at the

site entry (ground itch)

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Cutaneous Phase


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• Occurs when juveniles break out of the lung capillary into alveoli and progress up bronchi to the throat

• Each sites hemorrhage slightly• Usually asimptomatic, although there may be cough

and sore throat• Pulmonary hookworm infection resembles Löffler’s

syndrome because of its association with eosinophilia in the lung.

• Hookworm pneumonitis may indicate severe infection

Pulmonary Phase


• The attachment of hookworm’s cutting organ to the intestinal mucosa and submucosa and the subsequent rupture of intestinal capillaries and arterioles → blood loss

• Hookworm produce active suction impulses 120-200 times per minute

• The secretion of anticoagulation by parasite help to maintain continous oozing of blood at the attachment site

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Intestinal Phase


• The major clinical manifestations of hookworm disease: chronic intestinal blood loss.

• Infection with A duodenale causes greater blood loss than does infection with N americanus

• Estimated blood loss per worm per day:A duodenale: 0,15 mlN americanus: 0,03 ml

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• In a very heavy infection → iron deficiency anemia, hypoproteinemia, edema, potbelly in children, delayed puberty, mental dullness, impair cognitive ability, heart failure and death

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AncylostomiasisDiagnostic

o Hookworm eggs or adult worms in feceso Rhabditiform larva cultured from eggs by

Harada-Mori methodo Serology


WHO has recommended three interventions to control morbidity due to STH infections: 1.Regular drug treatment of high-risk groups for reduction of the worm burden over time2.Health education 3.Sanitation supported by personal hygiene aimed to reducing soil contamination

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Soil Transmitted Helminthiasis Treatment and Control


The recommended drugs : 1.Albendazole (400mg) tablets given in a single dose, 2.Levamisole (40mg) tablets given in a single dose by weight (2.5mg/kg)3.Mebendazole (500mg) tablets given in a single dose;4.Pyrantel pamoate tablets given in a single dose by weight (10mg/kg)

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Regular drug treatment of high-risk groups



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Health education


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Sanitation supported by personal hygiene aimed to reducing soil contamination


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Thank You


Soil Transmitted Helminthiasis [Parasitology]

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