You are in: eMedicine Specialties > Emergency Medicine > INFECTIOUS DISEASES Ascaris LumbricoidesArticle Last Updated: Feb 14, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 9
  Author: Aaron Laskey, MD, Staff Physician, Department of Emergency Medicine, New York University Aaron Laskey is a member of the following medical societies: American Academy of Emergency Medicine Coauthor(s): Ugo Anthony Ezenkwele, MD, MPH, Assistant Professor, Assistant Professor of Emergency Medicine, Department of Emergency Medicine, New York University School of Medicine/Bellevue Hospital Center; Eric L Weiss, MD, DTM&H, Director of Stanford Travel Medicine, Medical Director of Stanford Lifeflight, Assistant Professor, Departments of Emergency Medicine and Infectious Diseases, Stanford University School of Medicine Editors: Mark Louden, MD, FACEP, Assistant Medical Director, Emergency Department, Duke Raleigh Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jon Mark Hirshon, MD, MPH, Associate Professor, Department of Emergency Medicine, University of Maryland School of Medicine; John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center; Jonathan Adler, MD, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital; Division of Emergency Medicine, Harvard Medical School Author and Editor Disclosure Synonyms and related keywords: Ascaris lumbricoides, A lumbricoides, roundworm, intestinal roundworm, human parasite, nematode infection, ascariasis, malnutrition, iron-deficiency anemia, bowel obstruction, Ascaris suum, eosinophilic pneumonia, Löffler syndrome INTRODUCTIONSection 2 of 9
  BackgroundIntestinal nematode infections affect one fourth to one third of the world's population. Of these, the intestinal roundworm Ascaris lumbricoides is the most common. While the vast majority of these cases are asymptomatic, infected persons may present with pulmonary or gastrointestinal complaints. Ascariasis predominates in areas of poor sanitation and is associated with malnutrition, iron-deficiency anemia, and impairments of growth and cognition. PathophysiologyA lumbricoides is the largest of the intestinal nematodes affecting humans, measuring 15-35 cm in length. Infection begins with the ingestion of embryonated (infective) eggs in feces-contaminated soil. Once ingested, eggs hatch, releasing small larvae that penetrate the intestinal wall. Larvae migrate to the pulmonary bed via the portal veins, during which time they may cause pulmonary symptoms (eg, cough, wheezing). After migrating up the respiratory tract and being swallowed, they mature, copulate, and lay eggs in the intestines. Adult worms may live in the gut for 6-24 months, where they can cause partial or complete bowel obstruction in large numbers, or they can migrate into the appendix, hepatobiliary system, or pancreatic ducts. From egg ingestion to new egg passage takes approximately 9 weeks, with an additional 3 weeks needed for egg molting before they are capable of infecting a new host. FrequencyUnited StatesIn the United States, approximately 4 million people are believed to be infected. High-risk groups include international travelers, recent immigrants (especially from Latin America and Asia), refugees, and international adoptees. Ascariasis is indigenous to the rural southeast, where cross-infection by pigs with the nematode Ascaris suum is thought to occur. InternationalWorldwide, 1.4 billion people are infected with A lumbricoides, with prevalence among developing countries as low as 4% in Mafia Island, Zanzibar, to as high as 90% in some areas of Indonesia. Local practices (eg, termite mound–eating in Kenya) may predispose to ascariasis in some populations. Mortality/MorbidityThe rate of complications secondary to ascariasis ranges from 11-67%, with intestinal and biliary tract obstruction representing the most common serious sequelae. Although infection with A lumbricoides is rarely fatal, it is responsible for an estimated 8,000-100,000 deaths annually, mainly in children. RaceNo racial predilection is known. A genetic predisposition has been described in a study of families from Nepal. SexMale children are thought to be infected more frequently, owing to a greater propensity to eat soil. AgeChildren, because of their habits (eg, directly or indirectly consuming soil), are more commonly and more heavily infected than adults. Neonates may be infected by transplacental infection. CLINICALSection 3 of 9
HistoryMost patients are asymptomatic. When symptoms occur, they are divided in 2 categories: early (larval migration) and late (mechanical effects).
Physical
CausesSymptoms are typically associated with early larval migration, heavy intestinal burdens of adult worms, or aberrant worm migration. Worm migration may be stimulated by anesthetic agents or subtherapeutic anthelmintic treatment or by use of certain anthelmintics (eg, pyrantel pamoate). DIFFERENTIALSSection 4 of 9
Appendicitis, Acute Asthma Cholangitis Cholecystitis and Biliary Colic Hookworm Obstruction, Large Bowel Obstruction, Small Bowel Pancreatitis Strongyloides Stercoralis
|
| Drug Name | Albendazole (Albenza) |
|---|---|
| Description | Decreases ATP production in worm, causing energy depletion, immobilization, and finally death. |
| Adult Dose | 400 mg/d PO single dose; repeat in 3 wk if not cured |
| Pediatric Dose | <2 years: 200 mg/d PO single dose; repeat in 3 wk if not cured >2 years: Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | Coadministration with carbamazepine may decrease efficacy; dexamethasone and praziquantel may increase toxicity |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Discontinue use if LFT values increase significantly (resume when levels decrease to pretest values); GI symptoms (nausea, vomiting, diarrhea) or CNS symptoms (dizziness, headache, meningeal signs) may occur; granulocytopenia, thrombocytopenia, and pancytopenia have been reported |
| Drug Name | Mebendazole (Vermox) |
|---|---|
| Description | Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell. |
| Adult Dose | 100 mg PO bid on 3 consecutive days Administer second course if not cured within 3-4 wk |
| Pediatric Dose | <2 years: Not established >2 years: Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | Carbamazepine and phenytoin may decrease effects |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Adjust dose in hepatic impairment; GI symptoms (nausea, vomiting, abdominal pain, diarrhea) and CNS symptoms (headache, dizziness) are common; alopecia may be associated with high doses; rare reactions include angioedema, seizures, and agranulocytosis |
| Drug Name | Piperazine citrate |
|---|---|
| Description | Recommend for GI or biliary obstruction secondary to ascariasis; causes flaccid paralysis of the helminth by blocking response to worm muscle to acetylcholine. |
| Adult Dose | 3.5 g PO qd for 2 d |
| Pediatric Dose | 75 mg/kg PO qd for 2 d; not to exceed 3.5 g/dose |
| Contraindications | Documented hypersensitivity |
| Interactions | Coadministration with chlorpromazine may increase toxicity |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Most commonly reported reactions include GI and CNS effects; discontinue therapy if effects become significant; prolonged, repeated, or excessive therapy should be avoided because of potential neurotoxicity |
| Drug Name | Pyrantel pamoate (Antiminth) |
|---|---|
| Description | Depolarizing neuromuscular blocking agent; inhibits cholinesterases, resulting in spastic paralysis of worm. |
| Adult Dose | 11 mg/kg/dose PO as single dose; not to exceed 1 g |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; hepatic disease |
| Interactions | Pyrantel and piperazine are mutually antagonistic and should not be used concomitantly |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Caution in liver impairment, anemia, and malnutrition; GI effects, headache, insomnia, rash, tenesmus, and elevated LFT values may occur |
| Drug Name | Ivermectin (Stromectol) |
|---|---|
| Description | Binds selectively with glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, causing cell death. |
| Adult Dose | 150-200 mcg/kg PO once |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Serious reactions include Stevens-Johnson syndrome, asthma exacerbation, and vision loss (rare); common reactions include pruritus, rash, headache, myalgias, and elevated LFT values |
| Drug Name | Levamisole (Ergamisol) |
|---|---|
| Description | May inhibit worm copulation via agonism of L-subtype nicotinic acetylcholine receptors in male nematode muscles. |
| Adult Dose | 2.5 mg/kg PO once |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | Increases toxicity and serum levels of phenytoin; causes disulfiram reactions when taken with alcohol |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Agranulocytosis can occur asymptomatically |
Article Last Updated: Feb 14, 2007
