Ascaris lumbricoides, Nematoda, nematode, Ascaris.
Roundworms are almost worldwide in distribution and highest prevalence is in tropical and subtropical regions and areas with inadequate sanitation. They are abundant in the surface layers of soils and can occur at all ages, but are more prevalent in the five to nine years’ age group. The incidence is higher in poor rural populations.
Symptoms of a roundworm infection depend upon the severity of the infection. A few worms in your intestines may not produce any symptoms at all or just mild abdominal pain. Ten to twenty worms may go unnoticed except in a routine stool examination. The commonest complaint is vague abdominal pain. The patient may experience listlessness, weight loss, anorexia, distended abdomen, intermittent loose stool and occasional vomiting. Most symptoms are due to the physical presence of the parasitic worm. In heavy infections, however, abdominal cramps occur, and occasionally a mass of worms can block the intestines, causing pain, vomiting and bloating. Adult worms also can block other parts of the digestive tract such as the appendix, bile duct or pancreatic duct, causing similar symptoms. During the pulmonary stage when the larvae are migrating through the lungs, there may be a brief period of fever, cough, wheezing, dyspnea, sub-sternal discomfort and sometimes asthma.
Diagnosis is based on identification of eggs (40 to 70 micrometers by 35 to 50 micrometers) in the stool. Ascaris produces such an abundance of eggs that they often can be seen when stool samples are examined under a microscope. Less commonly, an adult worm may be passed in the stool or may crawl up the throat and try to exit through the mouth or nose. Ascaris larvae may be identified in sputum or phlegm coughed up during the pulmonary stage.
Infection usually begins when soil containing eggs gets on to your hands. If you eat or touch your mouth before washing your hands, the eggs can get into your mouth and be swallowed. The eggs may also get into your body in food that has been contaminated with human waste. The eggs thus swallowed hatch in the small intestine, become larvae and swim through the bloodstream to the lungs and then to the throat, where they are swallowed. Back in the stomach and small intestine, the larvae become adults, mate, and produce new eggs. The entire cycle, from eggs being swallowed to new eggs being produced, takes about two to three months. Although Ascaris worms are found in people of all ages, children are most likely to be heavily infected.
Adult worms live in the lumen of the small intestine. A female may produce approximately 200,000 eggs per day, which are passed with the feces. Unfertilized eggs may be ingested but are not infectious. Fertile eggs embryonate and become infectious after eighteen days to several weeks depending on the environmental conditions (optimum: moist, warm, shaded soil). After infectious eggs are swallowed, the larvae hatch, invade the intestinal mucosa, and are carried via the portal, then systemic circulation to the lungs. The larvae mature further in the lungs (ten to fourteen days), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed. Upon reaching the small intestine, they develop into adult worms. Between two and three months are required from ingestion of the infectious eggs to oviposition by the adult female. Adult worms can live one to two years.
Of course yes, especially in areas where there are poor hygiene and sanitation practices.
Doctors may prescribe several different oral medications to treat ascariasis. If the intestine is blocked, surgery may be necessary. If the pulmonary stage is severe, corticosteroids may be prescribed to lessen the symptoms. Mebendazole, 200 mg, for adults and 100 mg for children, for three days is effective. Talk to your doctor for more information and appropriate dosages and intervals.
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