Ascariasis: Clinical Manifestations, Diagnosis, Treatment And Prevention As An Intestinal Nematode Infection
How Ascaris Manifests
Clinical Manifestations Of Ascaris
Ascariasis is worldwide in distribution and is caused by the nematode Ascaris lumbricoides. In Africa, it is the most widely distributed worm.
Morphology and habitat: The worm measures 20 to 35 cm in length, the female is larger than the male. The females lay several thousand eggs every day. The eggs are elliptical, 30 to 40u X 50 to 60u in size with an outer dense mammilated shell and a smooth translucent inner shell. They are passed in feces. They become embryonate and infective in the soil in 2 to 3 weeks and they can remain viable under optimum conditions for years.
Life Cycle: Embryonated eggs are ingested with food or water and the larvae hatch out in the small intestine. They penetrate the intestinal mucosa to enter the venules or lymphatics and travel to the lungs, where they develop for about 10 days. They then enter the alveoli to be coughed up and swallowed. During the pulmonary phase, the larvae undergo four moultings and become resistant to gastric acid. The larvae grow and mature in 2 to 3 months. Lifespan of this worm is 6 to 15 months.
Pathogenesis: During the stage of larval migration, pulmonary symptoms like cough, wheezing and hemoptysis may occur (Loeffler’s syndrome) and this is a common cause of respiratory symptoms in children.
The adults ingest nutrients from the small intestines and lead to nutritional deprivation. Large number of adults may form tangled masses and obstruct the small intestines. The worm may migrate to ectopic sites like the stomach, nasal cavity, biliary tree, pancreatic ducts, respiratory passages, female genital tract or others.
Absorption of the products of living and dead worm leads to the development of allergy and toxic symptoms.
Those due to larvae: Respiratory symptoms such as cough, hemoptysis or wheezing may develop 1 to 5 days after swallowing the eggs. Eosinophilia may be present. The severity and duration of symptoms depend upon the worm-load. Visceral larva migrans may occur. The liver may be enlarged and histology may show centrilobular necrosis. Rarely larvae may reach the brain giving rise to convulsions. Other organs may also be affected.
Those due to Adult worms: Light infestations are asymptomatic. Moderate worm loads produce abdominal pain, pica, diarrhea, abdominal distension and grinding of the teeth (bruxism). Infected children have voracious appetite but they remain malnourished despite adequate intake of food. Migration of worms to biliary ducts or pancreatic ducts lead to obstruction. In heavy infection, the masses of worms may lead to intestinal obstruction and they may be palpable.
Ascaris Findings Clinically
Diagnosis, Treatment And Prevention Of Ascaris
Diagnosis And Treatment
Diagnosis: It is made from the history of passing round worms in the stool or the children may vomit round worms. Diagnosis is confirmed by demonstrating the ova in feces. In infection by male worms alone, ova may not be present in feces.
Treatment: The drug of choice at present is piperazine citrate which may be given in 2 doses- 1 teaspoonful (500 mg)/year of age to a maximum of 30 ml (3 to 5g) preferably given at bedtime for two days. Mebendazole in a dose of 100 mg twice a day for three days is a broad spectrum anthelminthic which is effective and safe. Pyrantel pamoate in a dose of 11 mg/Kg as a single dose is a suitable broad spectrum anthelmintic active against round wroms, hook worms and pin worms. Piperazine citrate should not be given in heavy infestations with complete intestinal obstruction. If the obstruction is mild and subacute, small doses of piperazine may be given with caution.
Children with intestinal obstruction are managed conservatively with intravenous fluids, gastric suction and antibiotics for 24 hours. If the mass of worms remains in the same position in the presence of severe abdominal colic and tenderness or if the general condition deteriorates as indicated by rising pulse rate and toxemia etc, operation is indicated. The worms are manipulated to break the mass without opening the intestine. Delayed surgery carries a high morbidity.
Improvement in nutritional status of children, health education, especially pertaining to personal hygiene, and environmental sanitation reduces the infection rates. Mass deworming campaigns are helpful in endemic area to reduce worm loads temporarily but reinfection within months is the rule.
© 2014 Funom Theophilus Makama