Ascaris lumbricoides is a nematode (roundworm) which inhabits the intestines of humans.
Risk factors
- Eating unwashed fruit and vegetables
- Low socio-economic class and poor sanitation are also risk factors for infection.
- Walk on bare foot
Presentation
- Adult worms usually cause no symptoms if localised to the intestinal lumen.
- Infestation may cause impaired growth in children.
- Heavy infestations may cause abdominal pain, nausea, vomiting, anorexia, diarrhoea, malabsorption, weight loss, anal itching and intestinal obstruction.
- Migrating adult worms may cause symptomatic occlusion of the biliary tract or oral expulsion.
- Larval migration may cause cough, dyspnoea, haemoptysis and eosinophilic pneumonitis (Löffler’s syndrome).
Investigations
- Diagnosis is usually made by identifying eggs in a stool sample.
- FBC may reveal eosinophilia or anaemia.
- LFTs may reveal liver damage or low protein state.
- Specific investigations such as ultrasound, X-ray, amylase level, lung function tests and exploratory surgery may be required depending on the site of infestation.
- Endoscopic retrograde cholangiopancreatography may be useful if biliary tree involvement is suspected.
Management
- Advise the patient to wash his or her hands thoroughly after using the toilet or changing nappies, and before eating or preparing food.
- Drug treatment:
- Albendazole or Mebendazole is effective and generally considered to be the drug of choice.
- Surgical intervention may be required to treat abdominal complications.
Complications
Chronic infestation with A. lumbricoides may be associated with a poor nutritional state, anaemia, failure to thrive and impaired cognition, particularly in children. Nutritional deficiencies and anaemia may be caused by heavy worm loads, especially in people in developing countries where nutritional status is often marginal.
Other possible complications include:
- Intestinal: intussusception, perforation, appendicitis, peritonitis, volvulus
- Pancreatitis, cholangitis, jaundice, liver abscesses
- Respiratory tract obstruction
Prevention
- Infection can be avoided by scrupulous attention to personal hygiene and the careful washing of all fruit and vegetables.
- Improved sanitation in developing countries is associated with a reduced risk of transmission of helminthiases to humans.