Ascariasis; transmission, clinical features, management and prevention

Introduction

It is a helminthic infection of the small intestine.

The infection can occur at all ages, but it is more commonly affects the ages of 5-9 years. The incidence is high in poor rural population and determined by local habits in the disposal of faeces.

Causative agent: Ascaris lumbricoides (large intestinal roundworm).

Mode of transmission: Man is the reservoir of infection which is spread by faecal pollution of the soil. The eggs are swallowed as a result of ingestion of polluted soil. Under Optimum conditions, eggs can remain viable in the soil for about a year.

Photo by CDC

Transmission

The infective eggs are ingested in food or from contaminated hands

Human Host

• The larvae hatch and invade the intestinal mucosa.
• It passes through systemic circulation to the lungs where it further matures within 10 to 14 days.
• It then penetrates the alveolar ascending the bronchus to the trachea.
• Getting swallowed, it becomes adult worms in small intestines.
• The eggs produced are passed in faeces.

Environment

• Eggs becomes infected in soil in about 30 to 40 days.
• Infected eggs contaminate the environment.

Signs and Symptoms

The disease is often symptom-less and the infection is discovered during other investigations. Only noticed during routine stool examination. In severe cases, the patient present;

1. Fever.
2. Intermittent abdominal pain.
3. Anorexia.
4. Restlessness in children.
5. Abdominal distention.
6. Cough caused by irritation.
7. Intestinal obstruction.
8. Physical presence of the worm in stool.

Management

Drugs used include;

• Mebendazole,
• Piperazine citrate,
• Levamisole
• Iron supplementation.

Prevention and Control

1. Treating all infected persons.
2. Provision of adequate toilet facilities e.g. latrines.
3. Wash hands with soap and running water before eating.
4. Avoid eating uncooked vegetables, green salads and fruits which may be contaminated with faecal matter.
5. Avoiding the use of untreated human faeces as fertilizers.
6. De-worming every three months.

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