Ascaris
Ascaris is a topic covered in the Johns Hopkins ABX Guide.
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MICROBIOLOGY
- Ascaris lumbricoides: largest intestinal nematode (roundworm) that is a human pathogen.
- Soil-transmitted helminth
- Ova develop on warm, humid soil (about 3 wks) before becoming infective.
- Adult worms live in lumen of small intestine (up to 2 yrs).
- Ova excreted in stool.
- Soil-transmitted helminth
- Life cycle: humans ingest infective ova that hatch and release larvae. Larvae invade intestinal mucosa and travel from portal to systemic circulation to lungs in about 4 days. Larvae penetrate through alveoli, ascend the trachea, and are reingested, then mature in intestines and live for 10 to 24 months.[3]
- Ova are hardy. They can sustain freezing and live up to 6 years in moist soil. Adult female worms can produce 200,000 ova/day.
Epidemiology:
- Endemic in warm, humid areas especially where human excreta is used as fertilizer, contaminated wastewater is used for irrigation, or geophagy (deliberate/regular consumption of soil) is practiced.
- Infection most common in young, but affects all ages.
- Heavy infections can cause malnutrition.[6]
- Transmission: hand to mouth.
- Ascariasis due to A. suum is a swine-associated zoonosis.[7]
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Last updated: October 13, 2016
Citation
Spacek, Lisa A. "Ascaris." Johns Hopkins ABX Guide, The Johns Hopkins University, 2016. Johns Hopkins Guide, www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540034/all/Ascaris.
Spacek LA. Ascaris. Johns Hopkins ABX Guide. The Johns Hopkins University; 2016. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540034/all/Ascaris. Accessed September 16, 2019.
Spacek, L. A. (2016). Ascaris. In Johns Hopkins ABX Guide. Available from https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540034/all/Ascaris
Spacek LA. Ascaris [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2016. [cited 2019 September 16]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540034/all/Ascaris.
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T1 - Ascaris
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Y1 - 2016/10/13/
BT - Johns Hopkins ABX Guide
UR - https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540034/all/Ascaris
PB - The Johns Hopkins University
DB - Johns Hopkins Guide
DP - Unbound Medicine
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