Oesophagostomum pathophysiology: Difference between revisions
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For non-human hosts, the life cycle of ''Oesophagostomum'' begins with the passing of eggs in the animal feces. From there the eggs develop into stage one larvae. These larvae then spend 6–7 days in the environment developing into stage two and then infectious stage three larvae.<ref>Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006. <https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.</ref> Infection begins with the ingestion of soil contaminated with stage three larvae. After ingestion the larvae end up in the small intestine, unsheathing and penetrating the intestinal wall to form nodules. The resulting adult worms that remain in the intestinal lumen copulate; the eggs from the female are then deposited in the feces. Females usually lay around 5,000 eggs per day, which is on par with reproductive rates of other nematodes within Strongyloidea.<ref name="Krepel, H P 1992">Krepel, H P, and A M Polderman. “Egg production of Oesophagostomum bifurcum, a locally common parasite of humans in Togo.” The American Journal of Tropical Medicine and Hygiene 46.4 (1992): 469-72.</ref> | For non-human hosts, the life cycle of ''Oesophagostomum'' begins with the passing of eggs in the animal feces. From there the eggs develop into stage one larvae. These larvae then spend 6–7 days in the environment developing into stage two and then infectious stage three larvae.<ref>Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006. <https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.</ref> Infection begins with the ingestion of soil contaminated with stage three larvae. After ingestion the larvae end up in the small intestine, unsheathing and penetrating the intestinal wall to form nodules. The resulting adult worms that remain in the intestinal lumen copulate; the eggs from the female are then deposited in the feces. Females usually lay around 5,000 eggs per day, which is on par with reproductive rates of other nematodes within Strongyloidea.<ref name="Krepel, H P 1992">Krepel, H P, and A M Polderman. “Egg production of Oesophagostomum bifurcum, a locally common parasite of humans in Togo.” The American Journal of Tropical Medicine and Hygiene 46.4 (1992): 469-72.</ref> | ||
For human hosts, the life cycle is very similar to that of ''Oesophagostomum'' in animals. It begins when an animal reservoir defecates into the soil, leaving feces infested with eggs that develop into rhabitiform larvae.<ref>Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006.<https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.</ref> These larve then develop into stage two and then infectious stage three larvae in the environment over the course of 6–7 days. Human infection occurs when soil or water containing the third-stage larvae is ingested, presumably via contaminated meat obtained from infected livestock or crops with contaminated soil. Once ingested, the filariform larvae migrate to the submucosa of the small or large intestine, then to the lumen of the colon. The developing worms then penetrate the intestinal tissues, causing nodular lesion formation in the intestines and colon; it is in these nodules that the larvae mature to stage four larvae. | For human hosts, the life cycle is very similar to that of ''Oesophagostomum'' in animals. It begins when an animal reservoir defecates into the soil, leaving feces infested with eggs that develop into rhabitiform larvae.<ref>Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006.<https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.</ref> These larve then develop into stage two and then infectious stage three larvae in the environment over the course of 6–7 days. Human infection occurs when soil or water containing the third-stage larvae is ingested, presumably via contaminated meat obtained from infected livestock or crops with contaminated soil. Once ingested, the filariform larvae migrate to the submucosa of the small or large intestine, then to the lumen of the colon. The developing worms then penetrate the intestinal tissues, causing nodular lesion formation in the intestines and colon; it is in these nodules that the larvae mature to stage four larvae. These larvae may then emerge from their nodules and migrate back to the intestinal lumen, where they mature into adults. But many larvae often do not complete development and remain in their colon nodules, as humans are generally unsuitable hosts for ''Oesophagostomum''. The instances where''Oesophagostomum''have completed development in humans seem to be dependent on certain environmental and host factors that have yet to be identified.<ref name="Ziem, J.B. 2006">Ziem, J.B. et al. “Impact of repeated mass treatment on human Oesophagostomum and hookworm infections in northern Ghana.” Tropical Medicine & International Health: TM & IH 11.11 (2006): 1764-72.</ref> | ||
==References== | ==References== | ||
Revision as of 14:24, 5 December 2012
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Oesophagostomum pathophysiology On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Pathophysiology
In oesophagostomiasis, larvae can invade the colon wall, potentially causing two pervading types of nodular pathology. Multinodular disease is characterized by the formation of many tiny nodular lesions containing worms and pus along the colon wall. About 15% of patients have this form of oesophagostomiasis.[1] Nodules themselves are usually not a problem, but they can give rise to further complications, such as bowel obstruction, peritonitis and intestinal volvulus. In rare cases serious disease can occur including emaciation, fluid in the pericardium, cardiomegaly, hepatosplenomegaly, perisplenitis, and enlargement of the appendix.
Single-nodular disease, more commonly known as Dapaong disease, is characterized by the development of a single mass that develops throughout the colon wall. This is the most common form of oesophagostomiasis, affecting 85% of patients.[2] This nodule can instigate intense tissue reactions that result in the formation of painful projecting masses.
Life Cycle
For non-human hosts, the life cycle of Oesophagostomum begins with the passing of eggs in the animal feces. From there the eggs develop into stage one larvae. These larvae then spend 6–7 days in the environment developing into stage two and then infectious stage three larvae.[3] Infection begins with the ingestion of soil contaminated with stage three larvae. After ingestion the larvae end up in the small intestine, unsheathing and penetrating the intestinal wall to form nodules. The resulting adult worms that remain in the intestinal lumen copulate; the eggs from the female are then deposited in the feces. Females usually lay around 5,000 eggs per day, which is on par with reproductive rates of other nematodes within Strongyloidea.[4]
For human hosts, the life cycle is very similar to that of Oesophagostomum in animals. It begins when an animal reservoir defecates into the soil, leaving feces infested with eggs that develop into rhabitiform larvae.[5] These larve then develop into stage two and then infectious stage three larvae in the environment over the course of 6–7 days. Human infection occurs when soil or water containing the third-stage larvae is ingested, presumably via contaminated meat obtained from infected livestock or crops with contaminated soil. Once ingested, the filariform larvae migrate to the submucosa of the small or large intestine, then to the lumen of the colon. The developing worms then penetrate the intestinal tissues, causing nodular lesion formation in the intestines and colon; it is in these nodules that the larvae mature to stage four larvae. These larvae may then emerge from their nodules and migrate back to the intestinal lumen, where they mature into adults. But many larvae often do not complete development and remain in their colon nodules, as humans are generally unsuitable hosts for Oesophagostomum. The instances whereOesophagostomumhave completed development in humans seem to be dependent on certain environmental and host factors that have yet to be identified.[6]
References
- ↑ “GIDEON Infectious Diseases - Diseases.” GIDEON Infectious Disease Database. 5 Feb 2009. <http://web.gideononline.com/web/epidemiology/index.php?gdn_form=ZGlzZWFzZT0xMTY1MA==>.
- ↑ “GIDEON Infectious Diseases - Diseases.” GIDEON Infectious Disease Database. 5 Feb 2009.<http://web.gideononline.com/web/epidemiology/index.php?gdn_form=ZGlzZWFzZT0xMTY1MA==>.
- ↑ Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006. <https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.
- ↑ Krepel, H P, and A M Polderman. “Egg production of Oesophagostomum bifurcum, a locally common parasite of humans in Togo.” The American Journal of Tropical Medicine and Hygiene 46.4 (1992): 469-72.
- ↑ Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006.<https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.
- ↑ Ziem, J.B. et al. “Impact of repeated mass treatment on human Oesophagostomum and hookworm infections in northern Ghana.” Tropical Medicine & International Health: TM & IH 11.11 (2006): 1764-72.