Description, Causes and Risk Factors:
Infection with nematode parasites of the genus Oesophagostomum
Oesophagostomiasis is a parasitic disease transmitted by species of worms falling under the family Strongylidae. 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.
The life-cycle of Oesophagostomum can usually be completed in less than 60 days.
Transmission of Oesophagostomum is believed to be oral-fecal for both humans and animals, largely because percutaneous infection with Oesophagostomum has never been reported. It is unclear whether or not parasite transmission is specifically waterborne, foodborne, or both. Regardless, introduction of the stage three infective larvae is necessary for human infection. Much about the biological mechanism of transmission is still unknown. It is possible that there are behavioral factors or unique soil conditions that facilitate larval development and are not found outside the current endemic areas.
Oesophagostomiasis is generally classified as a zoonotic disease, which is an infectious disease that can be transmitted between animals and humans. This has been called into question recently, as recent research has found that human-to-human transmission is possible.
Oesophagostomum infection is largely localized to northern Togo and Ghana in western Africa; there, it is a serious public health problem, but since it is so localized, research on intervention measures and the implementation of effective public health interventions has 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 AlbenzaTM shows promise for controlling and possibly eliminating Oesophagostomum infection in northern Togo and Ghana.
Protruding abdominal masses.
Lower right quadrant pain.
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.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 a reproductive system.
Laboratory methods are of little use for Oesophagostomum diagnosis. It is virtually impossible to make a diagnosis based on microscopy of stool samples alone, as Oesophagostomum eggs cannot be differentiated from hookworm eggs, which are often found in Oesophagostomum endemic areas.The only way to differentiate between the two species of eggs is to perform coproculture, which allows eggs to develop to their stage three larvae, although this is both time consuming and unreliable. Immunoassay tests like ELISA that monitoring for increases in IgG4 antibodies can indicate tissue invasion by Oesophagostomum.
Recent advances, however, have allowed for less invasive and more accurate methods of diagnosis. Using genetic markers in ribosomal DNA, the researchers developed PCR assays to selectively amplify O. bifurcum DNA from human fecal samples. These assays achieved Sensitivityratings of 94.6% and Specificityof 100%, suggesting that the PCR method could be a viable alternative to the long-standing methods of diagnosis as well as an opportunity to reveal more about the epidemiology of oesophagostomiasis.
The typical adult therapy for oesophagostomiasis is a single 400 mg dose of AlbenzaTM (200 mg for children) or CombantrinTM. AlbenzaTM works by binding to the free beta tubulin, which inhibits tubulin polymerization. This results in the inhibition of glucose uptake by the Oesophagostomum. AlbenzaTM and CombantrinTM at these doses have cure rates of 85% and 59-82%, respectively. Excision of Oesophagostomum larvae from nodules has been shown to have a curative effect on the patient but is invasive and more resource intensive than chemotherapy.
In the case of formation of abscesses or fistulae arising, incision and drainage is performed, followed by a regimen of AlbenzaTM and antibiotic treatment.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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