Lab diagnosis of Ascaris lumbricoides
a. Detection of Parasite
- In the case of heavy infection, the adult worm is possible to find in stool or sputum of the patient by the naked eye.
- Barium meal may reveal the presence of an adult worm in the small intestine.
- A plain abdominal film may reveal masses of worms in gas-filled loops of bowel in patients with intestinal obstruction.
- Pancreaticobiliary worms can be detected by ultrasound (more than 50% sensitive) and endoscopic retrograde cholangiopancreatography (ERCP; 90% sensitive.
- In the early stages of infection, when migrating larvae cause Loeffler’s syndrome, the diagnosis may be made by demonstrating the larvae in sputum, or more often in gastric washings.
- Eosinophilia may be present, especially during the larval migration through the lungs which supports the diagnosis. At this
stage, no eggs are seen in feces.
- Chest X-ray may show patchy pulmonary infiltrates.
Specimen: stool, bile
- The saline emulsion of stool is examined microscopically for the presence of eggs. Both fertilized and unfertilized eggs are usually present.
- If very few eggs are present the diagnosis may be easily missed so the concentration technique will increase the yield of diagnosis through microscopy.
- Eggs may be demonstrative in the bile obtained by duodenal aspirates.
c. Blood examination
- A complete blood count may show eosinophilia in the early stage of invasion.
d. Serological Tests
- Ascaris antibody can be detected by Indirect hemagglutination (IHA), Immunofluorescence antibody (IFA), Enzyme-linked immunosorbent assay (ELISA)
- Serodiagnosis is helpful in extraintestinal ascariasis like Loeffler’s syndrome.
Treatments of Ascaris lumbricoides
- Anti-parasite medications are the first line of treatment against ascariasis. The most common are:
- Albendazole (400 mg orally once),
- Ivermectin (150–200 mcg/kg once).
- Mebendazole (100 mg orally twice daily for 3 days or 500 mg orally once).
- These medications, taken for one to three days, kill the adult worms. Side effects include mild abdominal pain or diarrhea.
- Pregnant women may take pyrantel palmoate (11 mg/kg once; maximum 1 g).
- Partial intestinal obstruction should be managed with nasogastric suction, intravenous fluid administration, and the installation of piperazine through the nasogastric tube.
- Complete obstruction requires immediate surgical intervention.
Prophylaxis of Ascaris lumbricoides
- Ascariasis can be eliminated by preventing fecal contamination of soil. The Ascaris egg is highly resistant. Therefore, the use of night soil as manure will lead to the spreading of the infection, unless the destruction of the eggs is ensured by proper composting.
- Treatment of vegetables and other garden crops with water containing iodine 200 ppm for 15 minutes kills the eggs and larvae of
Ascaris and other helminths.
- Avoid eating raw vegetables.
- Improvement of personal hygiene.
- Treatment of infected persons especially the children.
References and Sources
- Abhay R. Satoskar. Medical Parasitology. 1st edition. CRC Press.
- Sougata Ghosh. Paniker’s Textbook of Medical Parasitology. 8th edition. Jaypee Brothers Medical Pub.
- 2% – https://www.essaysauce.com/science-essays/parasitology/
- 1% – https://www.researchgate.net/publication/5531734_Biliary_parasites_Diagnostic_and_therapeutic_strategies
- 1% – https://www.phaa.com/human-intestinal-worms-types-symptoms-pictures.htm
- 1% – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1255313/
- 1% – https://iliveok.com/health/intestinal-obstruction_79243i15938.html
- 1% – http://fungusfocus.com/html/most_common_parasitic_drugs.htm
2 thoughts on “Ascaris lumbricoides- Lab Diagnosis, Treatments, Prophylaxis”
Regarding the dosage of Ivermectin noted as 150–200 mg/kg once, Ivermectin is typically dosed in Micrograms, not Milligrams. Also, a single dose may kill the adult worms, since medications cannot kill parasite eggs, unless the dose is repeated after an off period of several days to allow eggs to hatch, the infection will just return. The female worm excretes a hormone to prevent all eggs from hatching at once, so when you kill the adult females, the missing hormone will then allow more eggs to begin hatching,, resulting in a new group of adult worms which will need to be eliminated. A routine of dosing for one to three days with days off periods to allow egg hatching, is the only way to kill the entire population within the body.
Thank you for the correction. The page has been updated with the correct medications.