Ascariasis: Causes, Symptoms, Diagnosis, Treatment by Nurses Note

 Ascariasis

Ascaris lumbricoides is a nematode worm acquired from ingestion of contaminated soil. It has a wide geographic distribution but is most prevalent in rural tropics. The disease is relatively more common in children, who also carry higher worm loads.

Eggs hatch in the small intestine, then penetrate the intestinal wall into the portal circulation. From the liver, they are carried haematogenously to the lungs, from where they migrate up the bronchial tree and over the epiglottis back into the digestive tract. They can also migrate to ectopic sites in patients who are febrile or in whom the gastrointestinal tract has been irritated, e.g. by drugs, anaesthesia, or surgical manipulation.

Adult worms have a lifespan of 1 year, after which they are spontaneously expelled from the bowel.

Presentation of Ascariasis

Most cases are asymptomatic, although the presentation may include fever, malaise, nausea, vomiting, intestinal colic, or diarrhoea. The migratory phase can cause a hypersensitivity eosinophilic pneumonitis, with urticaria and bronchospasm (Loeffler’s syndrome), lasting on average 7–10 days. In severe disease, a large number of worms can entangle to form obstructing boluses. Depending on location, these can cause intestinal obstruction, acute appendicitis, pancreatitis, or ascending cholangitis with obstructive jaundice. The latter is often associated with multiple liver abscesses, caused by the disintegration of trapped worms or eggs and secondary bacterial infection.

Urethritis: Causes, Symptoms, Diagnosis, Management, Complication and Nursing Assessment

Investigation of Ascariasis

Blood tests

FBC is usually normal, apart from eosinophilia during the migration phase. LFTs and amylase are useful if obstruction of the biliary tree or pancreatic duct is suspected. Serology is not helpful for diagnosis.

Imaging

CXR may show transient mottling or opacities during the migratory phase but is otherwise normal. AXR is usually normal although it can show a large bolus of worms (particularly during contrast studies) or obstruction with extremely heavy loads. Ultrasound will reveal obstruction of the biliary tree and the presence of hepatic abscesses.

ERCP

This is indicated for diagnosis if there is evidence of cholangitis or pancreatitis and for the therapeutic removal of worms.

Treatment of Ascariasis

Antihelminth agents are indicated in all cases, irrespective of the presentation or worm load, as the consequences of a single episode of ectopic migration are severe. Treatment should, however, be avoided during active pulmonary migration or infection, as the risks of pneumonitis from dying worms are high. Suitable choices include:

•  Albendazole 400 mg orally, single dose.

•  Mebendazole 100 mg bd for 3 days.

•  Pyrantel pamoate 11 mg/kg (maximum total dose 1 g), single dose.

•  Piperazine salts 75 mg/kg (maximum total dose 3.5 g) once daily for 2 days.

•  These agents are unsuitable for pregnant women and children, and expert advice should be sought in such cases. 

Pyrantel pamoate and piperazine are paralysing agents and should not be used in intestinal obstruction, as they may exacerbate the blockage.

Supportive treatment is required for other complications. ERCP is indicated for cholangitis or pancreatitis. Intestinal obstruction should be managed, as described in the section on acute abdominal pain, and may require surgical intervention.

Prognosis

Medical therapy is curative in >90% patients.