Primary Distribution: Worldwide.
Primary Distribution: Worldwide. With an estimated one billion infected persons worldwide, ascariasis is the most common human helminthic infection (Kazura, 2000).
Agent and Vector: Ascaris lumbricoides (nematode or roundworm) eggs are ingested via water, food, or hands contaminated with human feces. Eggs or larvae of the ascarids of dogs or cats (Toxocara spp.) may be ingested by children or the larvae may pass through the skin. After passage in stool, eggs mature and become infective in 5-10 days; and may remain so for up to two years (Centers for Disease Control [CDC], 1999; Kazura, 2000).
Incubation: 1-6 months
Clinical Findings and Treatment
Signs and Symptoms: Transient respiratory symptoms of pneumonitis with productive coughing (sometimes slight hemoptysis), wheezing, pulmonary infiltrates, and fever occur after the eggs hatch in the small intestine and the larvae travel to the respiratory system. Gastrointestinal symptoms include most commonly vague and/or colicky abdominal; and also nausea and vomiting, with vomitus sometimes bile-stained and sometimes containing worms. Steatorrhea and diminished vitamin A absorption also may occur. The adult worms may be more than 20 cm. in length, hence are easily seen in stool. Worms may also emerge from the nose or mouth as a result of coughing or vomiting (CDC, 1999; Goldsmith, 1999; Kazura, 2000)
Complications: Children are more likely than adults to have complications, which, with heavy worm burdens, may include hiatal hernia, duodenal ulcer, bowel obstruction, perforation, appendicitis, pancreatitis, cholecystitis, cholangitis, obstructive jaundice, diverticulitis, invasion of other organ systems, malnutrition, and stunted growth.
Common Laboratory Findings: Eosinophils (30-50%) are elevated during the pulmonary phase, but not in the intestinal phase. Diagnosis: Visualization and description of the worms establishes diagnosis. Microscopic exam of direct fecal smear shows eggs or ova. Diagnosis of pulmonary ascariasis is primarily on the basis of clinical data. Chest radiographs may show patchy, ill-defined transitory asymmetric infiltations (Loffler's syndrome). With bowel obstruction, abdominal radiographic examination (with or without barium) shows worms, especially in large air-filled bowel loops (Goldsmith, 1999; Kazura, 2000).
Differential Diagnosis: Pulmonary: asthma, pneumonia, aspergillosis, strongyloidiasis, hookworm, or other parasitic infections. The intestinal phase may resemble a variety of gastrointestinal problems (also see complications above). Postprandial dyspepsia may appear as duodenal ulcar, hiatal hernia, pancreatic or gall bladder disease (Goldsmilth, 1999).
Treatment: There is no effective treatment for the pulmonary phase. The intestinal phase is treated with albendazole 400 mg po in a single dose for light infections and a daily dose for three days for heavier infections. Pyrantel pamoate 10 mg/kg po (maximum 1 gram) in a single dose OR mebendazole 100 mg po bid for 3 days OR mebendazole 500 mg po in one dose are also effective for both children and adults. A benefit of using albendazole or mebendazole is that these also are effective treatment of hookworm and whipworm infections. Infections complicated by biliary or intestinal obstruction may be treated with piperazine 50-75 mg/kg (maximum 3.5 grams) po qd (before or after breakfast) for two days. For severe infections, piperazine treatment may be repeated after one week. Rarely, obstruction requires surgery. After treatment, stools should be checked every two weeks and if necessary, the patient re-treated until there are no more ascarids. There is some disagreement about treatment during pregnancy. Albendazole and mebendazole are category C drugs, hence are not recommended in pregnancy or for nursing mothers. Goldsmith (1999) recommends treatment of ascariasis only after the first trimester.
Notes From the Field Ascaries, hookworm, whip worm, and pin worm can all be minimized by swallowing crushed sun dried papaya seeds. The adult dosage is one tablespoon of the seed powder in a glass of sugar water once a week for two weeks. The pediatric dose is one teaspoon of seed powder in a glass of water once a week for two weeks. The sugar water is only to make the bitter powder more palatable. Roberts has seen several villages in Africa reduce their helminthic infections by 33% using only papaya seeds as a treatment. Swallowing two tablespoons of fresh seeds prevents the worms from burrowing into the intestinal wall and is a preventive measure (Sohni, Kaimal, & Bhatt 1995; Tona, Kambu, Ngimbi, Cimanga, & Vlietinck, 1998).
Authors: Charles Kemp, FNP & Amy Roberts, FNP
Centers for Disease Control and Prevention. (1999). How to prevent transmission of intestinal roundworms from pets to people. Retrieved January 9, 2000, from the World Wide Web: http://www.cdc.gov/ncidod/diseases/roundwrm/roundwrm.htm.
Goldsmith, R.S. (1999). Infectious diseases: Protozoal and helminthic. In L.M. Tierney, S.J. McPhee, & M.A. Papadakis (Eds.), Current medical diagnosis & treatment (38th ed.) (pp.1353-1417). Stamford Connecticut: Appleton & Lange.
Kazura, J.W. (2000). Ascariasis (Ascaris lumbricoides). In R. Behrman, R. Kliegman, & H. Jenson (Eds.). Nelson textbook of pediatrics (16th ed.) (pp. 1064-1065). Philadelphia: W.B. Saunders Company.
Rosenblatt, J.E. (1999). Antiparasitic agents. Mayo Clinic Proceedings. 74(11), 1161-1175.
Sohni, Y., Kaimal, P., & Bhatt, R. (1995). The antiamoebic effect of a crude drug formulation of herbal extracts against Entamoeba histolytica in vitro and in vivo. Journal of Ethnopharmacology, 19(1), 29-32.
Tona, L., Kambu, K., Ngimbi, N., Cimanga, K., & Vlietinck, A. (1998). Antiamoebic and phytochemical screening of some Congolese medicinal plants. Journal of Ethnopharmacology, 61(1), 57-65.