Ascaris lumbricoides Beth Wozney

The largest nematode to infect the human intestine..

Taxonomy Kingdom: Animalia Phylum: Nematoda Class: Rhabditea Order: Ascaridida Family Ascarididae Genus: Ascaris Species: lumbricoides

Geographic Distribution Up to ONE BILLION people wolrdwide are infected. Both tropical and temperate areas More common in tropical and subtropical In the United States? South Eastern states Children are most commonly infected

Morphology 15-35 cm long and the diameter of a lead pencil Female: straight posterior Male: curved posterior (button-hook tail)

Morphology Both male and female have three anterior lips with small, tooth-like projections.

Morphology Fertile eggs: 45-75 um by 35-50 um Thick hyaline wall around a one cell-stage embryo Brown, bile colored outer layer Decorticated: no mammillated outer coat Unfertile Eggs: up to 90 um Elongated with mass of highly refractile granules.

Life Cycle

Life Cycle Definitive host: Adult worms: Humans Live in lumen of the small intestine Female can produce 200,000 eggs/day Passed in the feces

Life Cycle Eggs: in the environment Unfertilized: not infective Fertilized: embryonate Infective after about 18 days depending on the environment Optimum: Moist, warm, shaded soil

Life Cycle Human ingests infected egg (Fecal-Oral Route) Larvae hatch inside the human host Invade intestinal mucosa: Carried through systemic circulation to the lungs Larvae mature here (10-14 days) Penetrate aleveolar walls into the throat Swallowed! Small intestine: Adults

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For Your Information… It takes 2-3 months from ingestion of the fertilized (infectious) egg to mature into the adult female. Adult worms can live 1-2 years. Sometimes, it is found concurrently with whipworm. Both are soil-transmitted helminth infections?

Pathogenesis Ascaris lumbricoides causes ascariasis: Adults: abdominal discomfort, loss of appetite, and pain Intestinal obstruction Affects growth of children Exit: mouth, tear duct, nose Fever? Invades other organs Liver abscess Peritonitis Secondary infection in the lungs Larva: Loffler syndrome Asthma, edema, pneumonitis, and eosinophilic infiltration

Diagnosis Diagnosis: The egg in a stool sample X-ray: bolus of worms Complete Blood Count: Eosinophilia Histmines Peroxidase

Treatment Mebendazole (Vermox): chewable tablet taken twice a day; minor side effects Blocks of uptake of glucose and other nutrients Pyrantel pamoate: combination of pyrantel and pamoic acid; sometimes paired with praziquantel Paralysis of helminths Albendazole: has not be approved; boradspectrum Depletes their glycogen stores No energy=death

Prevention We are making this a discussion, so put on those thinking hats!

Prevention Proper hygiene and sanitation: wash your hands!!!! Wash produce properly before consuming Bleach doesn’t work, iodine does! Dispose feces away for habitations This prevents contaminated food and water sources Use a toilet Eggs can live in the soil for 1-3 years

Epidemiology 1.5 billion infections in the world Primarily in Africa and Asia About 4 million of these are in the United States.