Pathophysiology
Ascaris lumbricoides is the largest intestinal nematode in humans, measuring 15-35 cm in adulthood. Infection starts with ingestion of embryonated (infective) eggs in feces-contaminated soil or food. Eggs hatch, usually in the small intestine, releasing larvae that penetrate the intestinal wall. Larvae migrate through the portal veins to the pulmonary vascular beds and alveoli, usually 1-2 weeks after infection, where they may cause cough and wheezing. After climbing the respiratory tract and being swallowed, they mature, copulate, and lay eggs in the intestine. Adult worms may live in the gut for 6-24 months, where large numbers can cause partial or complete bowel obstruction, or they may migrate into the appendix, hepatobiliary system, pancreatic ducts, or rarely the kidneys or brain. From egg ingestion to new egg passage takes about nine weeks, with an additional three weeks for egg molting before the eggs can infect a new host.
Statistics and Incidences
Intestinal nematode infections affect one fourth to one-third of the world's population, and Ascaris lumbricoides is the most common. In the United States, about 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 carrying Ascaris suum is thought to occur; children aged 2-10 years are more heavily infected there and elsewhere. Worldwide, a 2022 systematic review estimated about 732 million people infected (roughly 11% global prevalence), down from older estimates near 1 billion, with prevalence in endemic regions ranging from a few percent up to nearly 30% in parts of Melanesia (Global Prevalence of Ascaris Infection, 2010 to 2021). Complication rates run 11-67%, with intestinal and biliary tract obstruction the most common serious sequelae. Though often asymptomatic, A. lumbricoides causes an estimated 730,000 cases of bowel obstruction annually, 11,000 of them fatal. In one series of pregnant patients in Bangladesh, biliary ascariasis accounted for a plurality (28%) of nonobstetric causes of acute abdomen. No racial predilection is known, though a genetic predisposition was described in families from Nepal. Male children are thought to be infected more often, owing to a greater tendency to eat soil.
Clinical Manifestations
Most patients are asymptomatic. Symptoms split into early (larval migration) and late (mechanical effects). In the early phase (4-16 days after egg ingestion), larval migration through the lungs produces respiratory symptoms, classically eosinophilic pneumonia (Löffler syndrome): fever, nonproductive cough, dyspnea, wheezing. In the late phase (6-8 weeks after egg ingestion), GI symptoms reflect high parasite loads: passage of worms (from mouth, nares, anus), diffuse or epigastric abdominal pain, nausea, vomiting, pharyngeal globus, "tingling throat," frequent throat clearing, and dry cough.
Assessment and Diagnostic Findings
A CBC may show eosinophilia. Sputum analysis may reveal larvae or Charcot-Leyden crystals (crystalloid collections of eosinophilic proteins). Stool exam is typically normal in the absence of prior infection (during the first 40 days); in the adult phase it shows characteristic eggs, and since adult females lay about 200,000 eggs per day, identification is straightforward. Chest radiography may show patchy infiltrates of eosinophilic pneumonia. Abdominal radiography may show bowel obstruction (air-fluid levels) or the "cigar bundle" appearance of a worm bolus. On CT, Ascaris worms appear as linear or cylindrical filling defects with contrast, or as groups or masses (sometimes whirled). Ultrasonography is recommended by some as the initial imaging choice, especially when pancreatobiliary involvement is suspected, and point-of-care ultrasonography (POCUS) has been used for diagnosis.
Medical Management
Treatment splits by phase: early (larval migration) and established (adult phase). Benzimidazoles are the mainstay for symptomatic and asymptomatic infection; they are poorly absorbed, so human toxicity is low while they act directly on worms, with albendazole and mebendazole the most common members. Bowel obstruction is managed with IV hydration, nasogastric suctioning, electrolyte monitoring, and laparotomy if conservative measures fail; colonoscopy and EGD may help remove obstructing worm masses.
Pharmacologic Management
Albendazole decreases ATP production in the worm, causing energy depletion, immobilization, and death. Mebendazole kills the worm by selectively and irreversibly blocking uptake of glucose and other nutrients in the adult intestine where helminths dwell. Piperazine citrate, recommended for GI or biliary obstruction from ascariasis, causes flaccid paralysis by blocking the worm muscle's response to acetylcholine. Pyrantel pamoate, a depolarizing neuromuscular blocker, inhibits cholinesterases and produces spastic paralysis of the worm. Ivermectin binds selectively to glutamate-gated chloride channels in invertebrate nerve and muscle cells, causing cell death. Levamisole may inhibit worm copulation by agonism of L-subtype nicotinic acetylcholine receptors in male nematode muscle.
Nursing Management
Nursing Assessment
History: soil-transmitted worm infections are among the most common worldwide, concentrated in overcrowded communities with poor sanitation; most cases here are contracted abroad by travelers or migrants from endemic regions. Physical exam: general signs include fever, jaundice, cachexia, pallor, and urticaria; pulmonary signs include wheezing, rales, and diminished breath sounds; GI signs include abdominal tenderness, distention, nausea, and vomiting.
Nursing Diagnosis
Based on the assessment data, the major nursing diagnoses are: fluid volume deficit related to fluid loss secondary to diarrhea; impaired comfort and pain related to smooth muscle spasm from parasite migration in the stomach; imbalanced nutrition, less than body requirements, related to anorexia and vomiting; and hyperthermia related to decreased circulation secondary to dehydration.
Nursing Care Planning and Goals
The child will maintain fluid and electrolyte balance, lose or diminish pain, improve nutritional intake, and stay normothermic, shown by the absence of hyperthermia signs such as tachycardia, skin redness, and elevated temperature and blood pressure.
Nursing Interventions
Restore fluid and electrolyte balance: monitor I&O, watch for dehydration, give oral rehydration solution, and run IV fluids accurately. Reduce pain: assess its extent and character, apply a warm compress to the abdomen, teach distraction, and set a comfortable position. Improve nutrition: give adequate, nutritious food, weigh daily, explain why nutrition matters, and maintain oral hygiene. Maintain normothermia: teach the family why adequate intake matters, monitor I&O, check temperature and vital signs, give tepid sponge baths, and administer analgesics as indicated.
Evaluation
Goals are met when the child maintains fluid and electrolyte balance, pain is lost or diminished, nutritional intake improves, and normothermia holds, shown by the absence of hyperthermia signs such as tachycardia, skin redness, and elevated temperature and blood pressure.
Documentation Guidelines
Document individual findings including contributing factors, interactions, nature of social exchanges, and specifics of behavior; cultural and religious beliefs and expectations; the plan of care; the teaching plan; responses to interventions, teaching, and actions; and progress toward the desired outcome.
Frequently Asked Questions
What is ascariasis? Ascariasis is an intestinal infection caused by the roundworm Ascaris lumbricoides, the largest intestinal nematode in humans. People get it by ingesting infective eggs from soil, food, or water contaminated with feces.
How do you get roundworms (Ascaris)? Infection follows the soil-to-mouth route: swallowing embryonated eggs from contaminated soil, unwashed produce, or hands. It is most common where sanitation is poor, so teaching families about handwashing and food safety is central.
What are the symptoms of ascariasis? Most cases are asymptomatic. During larval migration through the lungs the worm can cause cough and wheezing, and a heavy worm burden can cause abdominal pain, malnutrition, and partial or complete bowel obstruction.
How common is ascariasis worldwide? It is among the most common soil-transmitted infections, with an estimated 732 million people infected globally as of 2021 (Global Prevalence of Ascaris Infection, 2010 to 2021). In the US it is uncommon and mostly seen in travelers and migrants from endemic areas.
How is ascariasis treated? Benzimidazole drugs such as albendazole and mebendazole are the mainstay. They are poorly absorbed, so toxicity is low while they act on the worms. Bowel obstruction may require IV hydration, nasogastric suction, and rarely surgery (Ascariasis, StatPearls).
How can ascariasis be prevented? Improved sanitation, safe disposal of human waste, handwashing, washing and peeling produce, and periodic deworming programs in endemic areas all reduce transmission.