Ascariasis: Transmission and Prevention.

Ascariasis is a parasitosis of the small intestine caused by one of two worm nematodes (family Ascarididae): Ascaris lumbricoides Linnaeus, 1758, which typically infects humans, and A. suum Goeze, 1782, which is generally found in pigs. The two species are morphologically very similar and both can cause cross infections in each of the hosts.

A. lumbricoides is the largest intestinal nematode of man. The female worms are larger than the males and can measure 40 cm in length and 6 mm in diameter. They are white or pink and are tapered at both ends.

Classification of Ascaris lumbricoides:

Domain – Eukarya

Phylum – Nematoda

Order – Asaridida

Family – Ascaridoidea

Genus – Ascaris

Species – lumbricoides

Transmission of Ascariasis

Ascariasis is transmitted by accidental ingestion of ascaris eggs through contaminated food, water or soil. Once the eggs are swallowed, they are passed into the intestine where they hatch into larvae. The larvae migrate through the body and into the bloodstream where they can cause severe coughing and wheezing.

The larvae are eventually swallowed and return to the small intestine where they mature and lay eggs sometimes up to 240,000 per day. Ascaris eggs are passed into the feces and incubate in the soil for a minimum of two weeks before the cycle begins again.

Causes of Ascariasis

You can become infected with ascariasis after accidentally ingesting the eggs of the lumbricoidesroundworm.

The eggs can be found in soil contaminated by human feces or uncooked food contaminated by soil that contains roundworm eggs.

Children often become infected when they put their hands in their mouths after playing in contaminated soil, according to WHO. Ascariasis can also be passed directly from person-to-person.

Risk factors of Ascariasis

• Warm tropical or sub-tropical climates
• Rural or overcrowded living areas with poor sanitation
• Lack of modern hygiene and sanitation infrastructure
• Farming practices utilizing improperly treated wastewater or human feces as fertilizer
• Young children ages 3 – 8 years
• Exposure to an environment where dirt might be ingested
• Clinical manifestations of Ascariasis

Many people have few or no symptoms. Often the first symptom is live worms being passed in the stool or occasionally from the mouth, anus or nose.

Roundworms in your lungs can cause:

Coughing or gagging

Wheezing or shortness of breath

Aspiration pneumonia, rarely

Blood in mucous

Chest discomfort

Fever

Roundworms in your intestines can cause:

Nausea

Vomiting

Irregular stools or diarrhea

Intestinal blockage, which causes severe pain and vomiting

Loss of appetite

Visible worms in the stool

Abdominal discomfort or pain

Weight loss

Growth impairment in children due to malabsorption

Malnutrition, anemia and impaired physical growth, particularly in children

Prevention of Ascariasis

The best strategies for preventing ascariasis include

Washing hands thoroughly with soap and water before handling food

Washing, peeling, and/or cooking all raw vegetables and fruits before eating, particularly those that have been grown in areas where human feces is used as fertilizer

Not defecating outdoors

Effective sewage disposal systems can help prevent this infection from spreading.

Drinking only bottled water and avoiding raw fruits and vegetables unless you’re able to wash and peel them yourself when you’re in places without modern sanitation.