The importance of hand washing.
A: The most common parasitic worms that infest Filipinos are roundworms, notably ascaris, whipworm, hookworm and pinworm. These parasites impair the nutritional status of their human hosts and cause a number of other health problems.
Ascaris (Ascaris lumbricoides) is the most widespread roundworm globally. Experts estimate that 25 percent of the world's population and 70 percent of Filipinos plays host to the worm.
An ascaris looks like an earthworm, but it is slightly smaller and is white, not brown, in color. It resides in the small intestines where it feeds on digested food. The female lays as many as 200,000 microscopic eggs a day that are discharged with the feces. The eggs must undergo development in the soil for at least two weeks before they can be infective. Infective eggs gain entry to our body when we ingest soil, food or water that contains the eggs, which occurs when we fail to wash our hands before eating or when we partake of contaminated salads and other raw foods.
Ingested ascaris eggs hatch and grow within the body. The mature worms get to reside and mate in the small intestine.
A small number of ascaris in the intestines usually produce no symptoms. But in heavy infestations, colic, abdominal pain, and coughing out, vomiting or passing out of worms through the nose can occur.
Ascaris can produce nutritional deficiencies. They can also trigger life-threatening conditions by migrating from the intestines into the bile duct, liver, appendix and other organs; or by wrapping around each other to form a solid ball that then obstructs the intestine.
Whipworms (Trichuris trichiuria) are small (3.5 to 5 cm long), flesh-colored worms that reside in the large intestine. They are almost as common as ascaris.
The female whipworm lays 5,000-7,000 eggs a day that pass out with the stool. These eggs, like those of the ascaris, need to incubate in the soil before becoming infective.
Whipworms are transmitted to humans the same way as ascaris. After the eggs are ingested, they hatch,then the worms migrate to the large intestine where they mature.
Symptoms of whipworm infection, which occurs in heavy infestation, include abdominal pain, chronic diarrhea, anemia, bleeding, weight lost and rectal prolapse.
Hookworms, on the other hand, are slightly smaller than whipworms. They attach themselves by their mouths to the wall of the small intestine where they feed on blood. The female lays thousands of eggs per day that pass out with the stool. In the soil, the eggs hatch into larvae. The larvae gain entry to the human body by penetrating the skin, which occurs when a person walks barefooted or sits on contaminated soil. On gaining entry into the human body, the larvae mature and get to reside in the small intestine.
Hookworm infection can result in anemia, which, in children could lead to stunting of growth and even heart failure.
Pinworms (Enterobius vermicularis), meanwhile, are very thin and tiny (two to 13mm) white worms that reside in the large intestine where they feed on digested food. The female deposits its eggs in the area around the anus from where the eggs can contaminate beddings, clothes, etc. Pinworms get transmitted by ingestion of the eggs, which are infective as soon as they are laid. After ingestion, the eggs hatch and the worms migrate into the large intestine.
Pinworm infection produces no symptoms aside from itching in and around the anal area and disturbed sleep, and, in girls, vaginal itching and irritation.
The drugs currently available for roundworms are very effective and relatively safe. Most are to be taken as a single dose. However, re-infection occurs very often. In endemic areas, experts recommend deworming of all children, and even adults, once or twice a year
The best way to prevent roundworm infection is by proper disposal of human waste (i.e., use of water-sealed or similar toilets). Other very effective preventive measures include: washing of hands with soap and water after defecating and before eating; thorough washing in running water of vegetables and other foods that are eaten raw; and, avoidance of walking barefooted.
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