Roundworm

Introduction
Roundworm infection, medically known as Ascariasis, is a parasitic disease caused by Ascaris lumbricoides, one of the most common intestinal helminths in humans. It affects an estimated 800 million to 1.2 billion people globally, particularly in tropical and subtropical regions with poor sanitation and hygiene. 

Ascariasis is classified as a soil-transmitted helminth (STH) infection, as the eggs are passed in human feces and spread through contaminated soil, food, or water. While many cases remain asymptomatic, heavy infections can lead to malnutrition, growth retardation, intestinal obstruction, and impaired cognitive development in children.

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Etiology and Transmission

• The infection is caused by ingestion of embryonated Ascaris eggs, usually through contaminated hands, vegetables, fruits, or water.

• The eggs hatch in the small intestine, releasing larvae that migrate via the bloodstream to the lungs.

• From the lungs, larvae ascend the bronchial tree, are swallowed again, and finally mature into adult worms in the small intestine.

• Each adult worm can live 1–2 years and female worms may produce up to 200,000 eggs per day, perpetuating the transmission cycle.

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Risk Factors

• Poor sanitation and open defecation

• Consumption of raw or unwashed vegetables grown in contaminated soil

• Children under the age of 10 (most vulnerable group)

• Tropical and subtropical regions (Asia, Africa, Latin America)

• Low socioeconomic conditions

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Pathophysiology

The disease progresses in two stages:

1. Larval Migration Phase

   • Symptoms arise when larvae pass through the lungs.

   • Inflammatory response may cause Löffler’s syndrome (transient pulmonary infiltrates with eosinophilia).

2. Intestinal Phase

   • Adult worms reside in the small intestine, competing for nutrients.

   • Heavy infestations cause abdominal pain, bloating, malnutrition, and intestinal obstruction.

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Clinical Features

1. Asymptomatic cases

• Most patients have no symptoms, especially with light infections.

2. Gastrointestinal symptoms

• Abdominal pain, nausea, vomiting

• Diarrhea or constipation

• Visible worms in stool or vomitus

• Malnutrition, weight loss, growth delay in children

3. Pulmonary phase symptoms

• Cough, wheezing, chest discomfort

• Fever

• Hemoptysis (in rare severe cases)

4. Complications

• Intestinal obstruction (common in children with heavy worm burden)

• Biliary or pancreatic ascariasis: worms migrate into bile ducts, gallbladder, or pancreas → cholecystitis, cholangitis, pancreatitis

• Appendicitis if worms block the appendix

• Rare systemic complications include peritonitis if the intestinal wall is perforated

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Diagnosis

• Stool microscopy: Detection of Ascaris eggs (most common method).

• Imaging:

  • Abdominal X-ray or ultrasound may show intestinal obstruction or worms.

  • CT/MRI in rare complicated cases.

• Blood tests: Eosinophilia (especially during larval migration).

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Treatment

Treatment depends on severity and complications. Most uncomplicated cases are treated with anthelmintic drugs.

First-line medications (generic names and doses):

1. Albendazole

   • Dose: 400 mg orally as a single dose

   • Mechanism: Inhibits microtubule formation in parasites, leading to immobilization and death.

   • Widely used in mass drug administration (MDA) campaigns for deworming.

2. Mebendazole

   • Dose: 100 mg orally twice daily for 3 days OR 500 mg single dose

   • Similar mechanism to albendazole.

   • Effective against multiple soil-transmitted helminths.

3. Pyrantel pamoate

   • Dose: 11 mg/kg orally (maximum 1 g) single dose

   • Mechanism: Neuromuscular blocker causing paralysis of worms, expelled via peristalsis.

   • Especially useful in pediatric patients.

Second-line/Alternative treatments:

• Ivermectin: 150–200 mcg/kg single oral dose (effective but not first-line for Ascaris alone; more common in strongyloidiasis and filariasis).

Management of complications:

• Intestinal obstruction: Nasogastric decompression, IV fluids, surgical intervention if conservative management fails.

• Biliary ascariasis: Endoscopic removal (ERCP) may be necessary.

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Prevention

• Improved sanitation (toilets, safe disposal of feces)

• Washing hands with soap and water

• Washing and cooking vegetables thoroughly

• Mass deworming programs for children in endemic areas (WHO recommends annual or biannual albendazole or mebendazole administration).

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Prognosis

• With treatment, prognosis is excellent.

• Untreated, chronic infection can lead to malnutrition, impaired growth, and life-threatening intestinal obstruction.

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Public Health Perspective

• Ascariasis is part of the Neglected Tropical Diseases (NTDs).

• WHO targets elimination of soil-transmitted helminths as a public health problem by 2030.

• Regular mass deworming campaigns in schools and rural communities have significantly reduced prevalence in many countries.