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Ascariasis is an infection affecting the small intestine that is caused by a roundworm known as Ascaris lumbricoides. This worm is the commonest intestinal roundworm affecting man and belongs to a group of roundworms called Nematodes.
Ascariasis is common in humid atmosphere with poor sanitary conditions; hence is seen in the tropics and developing countries such as Asia, Africa and Central America affecting a quarter of the worlds population.
Ascariasis Pathophysiology and Life cycle of Ascaris lumbricoides
The larvae of ascaris lumbricoides cause pulmonary symptoms while the adult worms cause gastrointestinal, biliary and pancreatic symptoms. The ascaris eggs are first ingested and develop into larvae in the intestines. The larvae then penetrate the intestines into the blood stream where they are taken to the lungs and cause pulmonary symptoms. In the lungs, the larvae develop into adults and expectorated and ingested back into the intestines where they cause intestinal symptoms such as abdominal pains and may also cause bowel obstruction.
Ascariasis Symptoms and Signs
- Ascariasis may be asymptomatic (no symptoms) in established infections
- Adult worms in the lungs may cause irritating non-productive cough and chest pain; Ascaris pneumonia (fever, cough, and eosinophilia) can occur, a condition referred to as Leoffler’s syndrome or Lofflers pneumonia
- There may be Fever when the adult worms are in the lungs and a Chest x-ray may show evidence of pneumonitis (Leoffler’s syndrome)
- Heavy infections, especially in children are associated with non-specific symptoms such as nausea, vomiting, abdominal discomfort and anorexia (loss of appetite)
- Large bolus of worms may cause abdominal pain and small bowel obstruction
- Children may suffer from growth retardation in the presence of heavy worm infestation
Ascariasis Mode of Transmission
Ascariasis is transmitted through the feco-oral route the ascaris eggs are swallowed when contaminated water or food is consumed. The eggs then emerge into larvae in the small intestine and penetrate the intestine, gaining entry into the blood stream and are being taken into the lungs.
- Diagnosis of Ascariasis is by identification of ascaris eggs in stool using a microscope; sometimes the adult worms may emerge from the mouth or the anus.
- Barium meal and follow-through will show worms scattered in the small bowel
- Ultrasound scan may show worms in the common bile duct and pancreatic duct
- Chest X-ray may show fluffy exudates in Loefflers syndrome
- In uncomplicated cases of ascariasis, anti-spasmodic drugs can be given to relax the sphincter of Oddi so that the worm returns to the small intestine which can then be dealt with by antihelminthic drugs
- Surgical operation may be needed to remove the worms or to treat the complications caused by these worms
- The worms can also be extracted through the ampulla of Vater by Endoscopic retrograde cholangiopancreatography (ERCP)
Conservative management with anthelmintic drugs is the first line of treatment in Ascariasis even in obstruction and surgery is used as a last resort.
Drugs used for treating Ascariasis
- Mebendazole (100 mg twice daily for 3 days)
- Albendazole (single dose of 400mg)
- Pyrantel pamoate (single dose of 10mg/kg)
- Oxantel pamoate (single dose of 10mg/kg)
- Piperazine citrate (75mg/kg (max. 3.5g) single dose daily for two days)
Mebendazole and albendazole are contraindicated in pregnancy; but pyrantel pamoate and piperazine are safe.
These drugs are the best for treating ascariasis as they act by paralyzing the ascaris lumbricoides so that they can pass out through the stool. Other drugs act by causing irritation to the worms so that they can migrate out of the small intestine with the hope of being passed out through the stool but these drugs are most time fatal as the worms being still active migrate to other organs instead.
In heavy worm infestation, treatment of ascariasis with pyrantel pamoate may cause bowel obstruction as the paralyzed heavy load of worms becomes impacted in the intestines.
- Chyluria painless passage of milky white urine especially after a fatty meal that may become painful when it clots.
- Strictures of the biliary tree
- Intestinal obstruction – distal ileal obstruction due to bolus of worms
- Ascaris lumbricoides may enter the biliary tree through the ampulla of Vater and cause severe biliary pain
- Suppurative cholangitis from infestation of common bile duct
- Liver abscesses
- Ascariasis in children may cause malnutrition as the worms competes for food with the child and preventing absorption
- Empyema of the gall bladder
- Obstructive jaundice – from infestation of the common bile duct
- Acute pancreatitis when the worm lodges in the pancreatic duct
- In rare cases, the worms could cause perforation of the small bowel
- The worms may invade the appendix and cause acute signs of appendicitis
- Avoid use of human manure as fertilizer
- Properly wash vegetables, fruits and foodstuff before eating
- Practice good hygiene wash your hands properly with clean water before eating
- Only drink clean water
- Keep your environment clean