Oesophagostomum overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Oesophagostomum species are free-living nematodes of the family Strongyloidae. These worms occur in Africa, Brazil, China, Indonesia and the Philippines. The majority of human infection with Oesophagostomum is localized to northern Togo and Ghana. Because the eggs may be indistinguishable from those of the hookworms (which are widely distributed and can also rarely cause helminthomas), the species causing human helminthomas are rarely identified with accuracy.Oesophagostomum, especially O. bifurcum, are common parasites of livestock and animals like goats, pigs, and non-human primates, although it seems that humans are increasingly becoming favorable hosts as well. The disease they cause, oesophagostomiasis, is known for the nodule formation it causes in the intestines of its infected hosts, which can lead to more serious problems such as dysentery. Although the routes of human infection have yet to be elucidated sufficiently, it is believed that transmission occurs through oral-fecal means, with infected humans unknowingly ingesting soil containing the infectious filariform larvae.
Oesophagostomum infection is largely localized to northern Togo and Ghana in western Africa where it is a serious public health problem. Because it is so localized research on intervention measures and the implementation of effective public health interventions have been lacking. In recent years, however, there have been advances in the diagnosis of Oesophagostomum infection with PCR assays and ultrasound and recent interventions involving mass treatment with albendazole shows promise for controlling and possibly eliminating Oesophagostomum infection in northern Togo and Ghana.
Classification
Oesophagostomum is part of the phylum Nematoda. This phylum is composed of five orders: Ascaridida, Enoplida, Oxyurida, Spirurida, Strongylida, and Rhabditida.[1] Strongylida has three superfamilies: Ancyclostomatoidea, Trichostrongyloidea, andStrongylidea. Oesophagostomum lie within the Strongyloidae.[2]
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.[3]
Differential Diagnosis
Oesophagostomum needs to be differentiated from common misdiagnosis which include carcinoma, appendicitis, amebiasis, and tuberculosis.[4]
Diagnosis
Laboratory Findings
A definitive diagnosis of Oesophagostomum infection is traditionally done by demonstrating the presence of the larval or young adult forms in nodules of the intestinal wall via surgical examination of tissue. The larvae usually found in tissues can be 500 nanometers or longer in length.[5] With microscopy, one can identify the larvae based on the presence of somatic musculature divided into four quarters, along with a multinucleated intestine as well as an immature reproductive system.
Echocardiography or Ultrasound
Recent advances have allowed for less invasive and more accurate methods of diagnosis by ultrasonographic imaging.
Treatment
Surgery
In the case of formation of abscesses or fistulae arising from Dapaong tumors, incision and drainage is performed, followed by a regimen of albendazole and antibiotic treatment.[6]
Primary Prevention
Given that infective Oesophagostomum larvae are most likely transmitted via oral-fecal routes, sufficiently cleaning and cooking meat and vegetables, as well as boiling all consumed water or only using potable water would help to complement a mass treatment program. Factors like religion, family size and wealth do not suffice in explaining the unique epidemiology of Oesophagostomum; geographic and geological factors must be explored in more detail.[7]
References
- ↑ John, David T., Krotoski, Wojciech A. and Markell, Edward K. Markell and Voge's Medical Parasitology. St. Louis: Saunders Elsevier, 2006. 9th ed.
- ↑ Wooten, Darcy. “Oesophagostomum.” 5 Feb 2009 <http://www.stanford.edu/class/humbio103/ParaSites2002/oesophagostomiasis/Intro.html>.
- ↑ “GIDEON Infectious Diseases - Diseases.” GIDEON Infectious Disease Database. 5 Feb 2009. <http://web.gideononline.com/web/epidemiology/index.php?gdn_form=ZGlzZWFzZT0xMTY1MA==>.
- ↑ Sun, Tsieh. Parasitic Disorders: Pathology, Diagnosis, and Management. Baltimore: William and Wilkins, 1999. 2nd ed.
- ↑ 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. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006.<https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.
- ↑ Ziem, J.B. “Controlling human oesophagostomiasis in northern Ghana.” (Doctoral thesis) Leiden University. 2006. <https://openaccess.leidenuniv.nl/dspace/handle/1887/4917?mode=more>.