Soil Transmitted Helminthiasis Overview

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Questions and Answers

What is a common method of transmission for Trichuris trichiura?

Consumption of undercooked meat

Direct blood contact with an infected individual

Ingestion of mature eggs from contaminated soil (correct)

Inhalation of contaminated air

Which of the following is NOT a complication associated with intestinal ascariasis?

Rectal prolapse

Haemorrhagic infarction of the intestine

Hyperlipidemia (correct)

Malnutrition and anemia

Which of the following symptoms is typically associated with heavy infections of Trichuris trichiura?

Facial edema

Jaundice

Chronic cough

Nausea and abdominal pain (correct)

What is the characteristic shape of Trichuris trichiura eggs?

Barrel-shaped with thick smooth shell and polar plugs Signup and view all the answers

What is the recommended treatment for infections caused by Ascaris and Trichuris?

Antihelminthic drugs like Mebendazole and Albendazole Signup and view all the answers

Which of the following soil-transmitted helminths is known to infect over 1 billion people?

Ascaris lumbricoides Signup and view all the answers

Which factor is NOT essential for the transmission of soil-transmitted helminth infections?

Access to healthcare Signup and view all the answers

What is the primary mode of transmission for Ascaris lumbricoides and Trichuris trichiura?

Ingestion of eggs from contaminated soil Signup and view all the answers

Which community type has the highest prevalence of soil-transmitted helminth infections among schooling age children?

Orang Asli Signup and view all the answers

How long does it take for roundworm eggs to mature in the soil?

2 weeks Signup and view all the answers

Which soil-transmitted helminth is primarily associated with skin penetration as a mode of infection?

Hookworms Signup and view all the answers

Which developmental requirement for soil-transmitted helminths is mentioned as crucial for their lifecycle?

Warm and moist soil Signup and view all the answers

In areas lacking latrine systems, what contaminant primarily causes soil to be polluted with helminth eggs?

Human faeces Signup and view all the answers

What is the primary mode of transmission for ascariasis?

Fecal oral route from contaminated eggs Signup and view all the answers

What type of eggs do female Ascaris lumbricoides produce in the absence of males?

Infertile eggs Signup and view all the answers

During the life cycle of Ascaris lumbricoides, where do the larvae migrate after hatching in the small intestine?

Through the liver and to the lungs Signup and view all the answers

What is the typical size range for fertilized Ascaris lumbricoides eggs?

45-75 x 35-50 um Signup and view all the answers

What complications can heavy infections of Ascaris lumbricoides cause?

Intestinal obstruction and nutritional deficiency Signup and view all the answers

Which diagnostic technique is used to identify fertilized or unfertilized eggs of Ascaris lumbricoides?

Direct fecal smear and concentration techniques Signup and view all the answers

What is a potential allergic manifestation due to larval lung migration in ascariasis?

Asthmatic attacks Signup and view all the answers

Which statement best describes the lifecycle of the Ascaris lumbricoides?

The larvae penetrate the intestinal wall and migrate to various organs before returning to the intestine. Signup and view all the answers

What is the primary method by which young children become infected with soil-transmitted helminths?

Ingesting contaminated water sources Signup and view all the answers

Which parasitic infections are known for skin penetration as a method of transmission?

Ancylostoma duodenale & Strongyloides stercoralis Signup and view all the answers

Which statement regarding the clinical manifestations of soil-transmitted helminths is true?

Moderate and high-intensity infections are linked to children. Signup and view all the answers

Which factor is NOT considered when determining the disease threshold for soil-transmitted helminth infections in children?

Geographical location Signup and view all the answers

What is a significant characteristic of soil-transmitted helminths' interaction with their hosts?

They establish chronic infections despite immune responses. Signup and view all the answers

In which population groups is preventive chemotherapy for soil-transmitted helminthiasis recommended?

High-risk adults and pregnant women Signup and view all the answers

What is the minimal duration required for soil-transmitted helminth eggs to become infective after being passed in feces?

2-3 weeks Signup and view all the answers

What was the primary finding of the World Development Report for 1993 regarding soil-transmitted helminths?

They cause significant disease burden in children of developing countries. Signup and view all the answers

Study Notes

Soil Transmitted Helminthiasis (STH)

STH are a group of parasitic nematode worms that cause human infection
They are transmitted through contact with parasite eggs or larvae that thrive in warm, moist soil of tropical and subtropical countries
STH is one of the most common infections worldwide, affecting primarily deprived communities
Children are most commonly affected
Climate, poverty, and inadequate water supplies and sanitation significantly impact transmission

Types of Soil-Transmitted Helminths

Roundworms (Ascaris lumbricoides): infects over 1 billion people
Whipworms (Trichuris trichiura): infects 795 million people
Hookworms (Necator americanus & Ancylostoma duodenale): infects 740 million people
Other types include Strongyloides stercoralis

Transmission

Infection occurs through ingestion of eggs from contaminated soil or active penetration of the skin by larvae in the soil.
Soil must be warm and moist for the eggs to mature (2–4 weeks depending on the worm type)
Common sources of transmission include:
- Contaminated water
- Vegetables not properly cooked, washed, or peeled
- Children playing in contaminated soil and putting their hands in their mouths
Feces containing eggs contaminates the soil
No direct person-to-person transmission

Epidemiology

Climate plays a significant role in transmission requiring adequate moisture and warmth
Poverty and inadequate sanitation are also critical determinants
STH species commonly co-endemic in areas with these conditions
High infection rates occur in sub-Saharan Africa, the Americas, China, and East Asia

Prevalence in Different Communities

Prevalence rates vary depending on community type
Urban slums have the highest prevalence (68.7%)
Rural/estate communities have a moderate prevalence (67.2%)
Orang Asli communities have a high prevalence (77.8%)

Clinical Manifestations

Most STH infections are asymptomatic (5-10 worms)
Heavy infections might cause nutritional deficiency, abdominal pain, diarrhea, weight loss, and intestinal obstruction in children
Lung migration of larvae may result in allergic manifestations like asthma, or pulmonary signs (Loeffler's syndrome)
Migrations of adult worms may cause blockage of bile ducts, gallbladder, liver, appendicitis, and ectopic lesions

Diagnosis

Identification of fertilised or unfertilised eggs in human feces using direct fecal smears, concentration techniques (e.g., Kato Katz technique), and other methods

Pathology

The intensity of host reactions depends on the worm burden
Lung migration of larvae can cause pulmonary signs, and allergies like asthma or urticaria.
Intestinal ascariasis causes competition for food leading to malnutrition, anemia, fluid retention, and intestinal obstruction

Prevention and Treatment

Control strategy involves treating once or twice annually, targeting preschool and school-aged children, women of childbearing age, lactating women, and high-risk adults in certain occupations (e.g., tea-pickers, miners)
Treatment relies on antihelminthic drugs (Mebendazole, Albendazole)
Personal hygiene, proper sanitation, and avoidance of using feces as fertilizer are also critical preventative measures.

Ascaris lumbricoides

Largest intestinal roundworm causing ascariasis
Adult female (20-35cm), male (10-25cm)
Fertilised egg is broadly oval (45-75 x 35-50 µm)
Thick shell with brown bile-stained, mammilated outer covering (albumin layer)
Inside vitelline layer
Infertile: more elongated (80-90 µm), prominent mammilations, disorganised globular internal contents

Trichuris trichiura

Also known as whipworms
Long slender, threadlike anterior portion, thicker posterior portion resembling a whip handle
Adult worm 30-50 mm, with a coiled tail in the male having the spicule
Eggs are oval (barrel-shaped), bile-stained, with a thick smooth shell and a prominent polar plug at each end
Egg measures 45-55µm x 20-23µm

Life Cycle of Ascaris lumbricoides

Eggs are ingested and develop in the small intestine
Larvae penetrate intestinal walls and migrate to lungs
Larvae are coughed up, swallowed, and mature in the small intestine
Fertilized eggs are passed in the feces.

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Description

This quiz explores Soil Transmitted Helminthiasis (STH), a significant group of parasitic infections affecting predominantly children in tropical and subtropical regions. Understand the types of helminths, their transmission routes, and the socio-economic factors influencing these infections. Test your knowledge on this global health issue affecting vulnerable communities.