Ascariasis
- caused by Ascaris lumbricoides, a soil-transmitted large nematode
- The average life of the adult parasite is 1y, after which it dies, and is spontaneously eliminated. Adult worms do not multiply in the human host
- Infection occurs if host ingests eggs found in stool-contaminated soil.
- Once in the duodenum, larvae are released and enter the circulation via the enteric mucosa
- larvae reach liver via the portal vein and then the lungs within the 1st week. Mature in alveoli > expectorate larvae > ingested > mature to worms in GIT in 20/7
Clinical
- usually asymptomatic
- symptoms can include abdominal pain, bloating, nausea, vomiting, anorexia, intermittent diarrhoea.
- If significant larval load in lung - pneumonitis and eosinophilia can be seen (Loeffler syndrome). Symptoms include wheezing, dyspnea, cough, hemoptysis, and fever.
- In superinfection, adult worms can migrate to tubular structures like the biliary and pancreatic system causing cholecystitis, cholangitis, pancreatitis, small bowel obstruction, volvulus, appendicitis, and intussusception.
- Children are more susceptible to complications than adults.
Management
- dosage for children and adults is the same
- Albendazole 400 mg as a single dose is usually the drug of choice
- Mebendazole 100mg bd for 3/7 is 2nd choice (1st in UK). Single 500mg dose also possible
- pregnancy - piperazine 50 mg/kg/day for 5/7 (Mebendazole not proven to be harmful)