Ascaris lumbricoidesSamuel Perry

TaxonomyKingdom Animalia

Phylum NematodaClass Secernentea Order Ascaridida

Family AscarididaeGenus AscarisSpecies lumbricoides

IntroductionAscaris lumbricoidesLargest and most common roundworm in

humans.Ranges worldwide but concentrated in tropical

and subtropical areas.Over 1 billion infected worldwide. Rare in the

United States.Oldest eggs are over 24,000 years old found in

fossilized feces.Definitive host – HumansIntermediate host – None

MorphologyMales are more slender, and rarely reach

over 30 cm. Females are broader and can reach lengths of 35 cm.

Both are milky white or pinkish and have circular striations on their cuticle.

Ascaris lumbricoides have three prominent lips on their anterior end.

Life Cycle

Quick Review – Listening?Is this parasite common? In the US?How large is this parasite?What animal is the definitive host?

EggsExcessive heat and dryness may kill them.Remain viable in favorable conditions for

long periods.Bleach does not kill them.

Fertile

Infertile

SymptomsAscariasis – disease caused by infection of

Ascaris.Generally a benign infection at low numbers.May develop pneumonitis with large amounts

of larval migration.Asthma attacks may also accompany a larger

infection.Heavy infections may create bowel

obstructions and other issues. Warning - Distrubing

SymptomsWorms may exit body through the anus, and

in more severe infections, they may exit through the mouth or nose.

DiagnosisDetection of eggs in the feces is key. With the

large amount of eggs being laid, this is relatively easy.

Detection of larvae in the sputum or in gastric washing.

Many of those infected wake to find worms exiting through their anus, nose, or mouth. They may simply find a worm in their underpants, or on their pillow in the morning.

TreatmentAscarides will be effective. Mebendezole is the drug of choice.

PreventionProper disposal of human waste/good

sanitation.Safe control of use or no use of night soilWash hands after handling soil.