About Ascaris Lumbricoides

Ascaris lumbricoides, human roundworm, infects approximately 25 percent of the world's population. Commonly called the giant roundworm, these parasites use humans as their primary host. These parasites prevail in areas of poor sanitation and human waste fertilization. Also, poor socio-economic classes prove vulnerable to these parasites because of malnutrition, anemia and impaired growth. The highest rates occur in China, Southeast Asia and African coastal regions.

Life Cycle

• Ascaris eggs dwell in human feces-contaminated soil, and swallowing the eggs causes infection. Fingers, water and food tainted with infected soil carry the eggs to the mouth, where ingestion occurs. Larvae hatch and penetrate intestinal walls, infecting the blood. They travel through the blood and into the lungs. They crawl up the respiratory tract and are swallowed again. During this second trip into the digestive system, they attach and mature in the intestines, releasing more eggs into the environment.

Symptoms

• Symptoms of this parasite appear according to its location in the human body. Circulating larvae may cause fever. Larval migration to the lungs causes symptoms such as coughing, shortness of breath and bloody sputum. Once the worms mature in the intestine, they may cause abdominal pain, vomiting, bowel obstruction and other intestinal symptoms. Because of the large size of these worms, 13 to 35 centimeters, slowed growth and bowel obstruction are possible in young children.

Diagnosis and Treatment

• Diagnosis of Ascaris lumbricoides involves microscopic examination of patient feces. Identification of typical eggs proves infection. Occasionally, larvae and adults appear in feces making diagnosis simple for physicians. Additional tests may include abdominal x-rays and endoscopic exams. Usually, treatment involves one to three days of medication that paralyzes or kills the worms. Typical medications include albendazole or mebendazole. Follow-up fecal exams confirm parasitic removal.

Complications

• As with any disease, complications may occur. Larval migration, to areas other than lungs, may cause problems in the body's skin, brain or eyes. Large numbers of worms can form intestinal blockages or biliary (gall bladder) blockages. Removing blockages usually requires endoscopy or surgery. In long-lasting infections or re-infection, asthmatic allergies may develop, and infested children commonly appear malnourished, anemic and learning impaired. All treatments include parasitic removal.

Prevention/Solution

• Good hygiene and sanitation prevents Ascaris lumbricoides infections. Because the eggs inhabit the soil, keeping the contaminated soil off hands and out of food and water is imperative. Careful washing of hands and food is necessary, especially if soil is fertilized with sewage. Also, younger children in higher numbers increases infection potential because of risky hand-to-mouth behaviors. High-risk areas may require routine treatment with deworming medications.