Ascaris lumbricoides
is a multicellular parasite (metazoan) that can cause infection when its ova are ingested. These ova may get into food or water from the soil. Large numbers of Ascaris may cause abdominal pain, intestinal blockage, vomiting, diarrhea, fever, and/or transient hepatitis. Diagnosis is accomplished by finding ova in the feces. Because the adult Ascaris is cylindrically
shaped, it is in the phylum Aschelminthes and the class Nematoda(roundworms). Ascaris adults may be either male or female; image 1 shows them embedded in plastic. Note the sharply curved tail on the adult male. The adult female lays eggs (ova) which are shed in the feces. Ova, which are used for diagnosis, occur in both infertile and fertile forms. Infertile ova have a narrow hyaline sheet and elongated shape while fertile ova have a thicker, wavy hyaline margin and rounded shape.
Click on each image to see the enlarged version.
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| 1. adults | 2. fertile ova 400 X | 3. fertile ova 400 X | 4. fertile ova 400 X | 5. fertile ova 1000 X |
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| 6. fertile ova 1000 X | 7. fertile ova 1000 X | 8. fertile ova 1000 X | 9. infertile ova 1000 X | 10. infertile ova 1000 X |
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