What are other Names for this Condition? (Also known as/Synonyms)

• Dapaong Tumor
• Kounkoul
• Esophagostomiasis

What is Oesophagostomiasis? (Definition/Background Information)

• Oesophagostomiasis is a parasitic worm infection brought on by several species of nematodes (roundworms) belonging to the genus Oesophagostomum, of which Oesophagostomum bifurcum (or O. bifurcum) affects humans the most
• Humans and other mammals are known to act as definitive hosts for the parasite, allowing the infection to last for years at a time. This parasite is found in warmer climates, such as the tropics, or other regions that are favorable for hatching of parasite eggs. Most clinical cases are reported from Ghana and Togo (two countries in Africa)
• O. bifurcum is primarily a monkey parasite, and therefore, areas with monkey populations often report a higher frequency of Oesophagostomiasis. Additionally, livestock, such as pigs, sheep, and goats, can also carry the infection
• Poor hygienic standards and warm climates pose an increased risk for contracting the disease, which is transmitted via contaminated soil/feces
• Some common symptoms of this infection are pain in the lower right abdomen, presence of nodules, or distention of abdominal organs. Complications from the disease may severely affect the gastrointestinal tract and result in bowel obstruction and perforation
• The outcome is guarded, in case the affected individuals do not have access to proper treatment, which is mostly the case in the endemic regions. The outcome also depends on when intervention is sought. If it is sought prior to conditions worsening beyond recovery, the outcome may be poor. Young children, specifically, have a lower survival rate once infected

Who gets Oesophagostomiasis? (Age and Sex Distribution)

• The parasite, Oesophagostomum spp., is reported from regions of the world warm, tropical climates conducive to hatching of its eggs
• Oesophagostomiasis can develop in individuals of any age, gender, racial or ethnic group
• Most clinical cases of infection are reported from Ghana and Togo, two west African countries, where the infection is a public health concern
• There are a few cases of infection reported from Malaysia, Indonesia, Brazil, Uganda, and French Guiana as well

What are the Risk Factors for Oesophagostomiasis? (Predisposing Factors)

The following are some known risk factors for contracting Oesophagostomiasis, specifically for those living in:

• Areas of poverty, and poor hygiene conditions 
• Areas indigenous to monkey populations, whose feces may contaminate the soil, where food is grown, or where human activity is present
• Farms and other places where livestock, such as pigs and cattle, are raised
• Tropical (warm and humid) climates

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Oesophagostomiasis? (Etiology)

Oesophagostomiasis is caused by the nematode (or roundworm) of the Oesophagostomum genus. The major method of transmission is believed to be the fecal-oral route.

• O. bifurcum is the most common species associated with human cases of Oesophagostomiasis, and is primarily found in monkeys (which are hosts for the parasite)
• The infected hosts pass parasitic eggs via their feces, and the larvae develop in the soil/environment to become infective. The parasite infection takes about a month to produce eggs in the feces
• Once the infective larvae are ingested, they enter the gut of the new host, where they mature into adult parasites and release eggs

What are the Signs And Symptoms of Oesophagostomiasis?

There are no definitive or isolated set of signs and symptoms observed for Oesophagostomiasis, as the pathology may differ among the affected individuals. Some common symptoms of the disease may include:

• Low-grade fever
• Abdominal pain in the lower right side
• Nodules in abdominal organs
• Presence of large masses in the lower right side of abdomen 

Some uncommon symptoms may include: 

• Loss of appetite 
• Dysentery (diarrhea mixed with blood) 
• Vomiting
• Weight loss
• Formation of nodules under the skin

In rare cases, the intestines may be perforated, and the parasite may migrate into other organs, such as the skin, where tender or painful subcutaneous nodules/masses may form. 

How is Oesophagostomiasis Diagnosed?

The diagnosis of Oesophagostomiasis is made by the following tests and exams: 

• A thorough physical examination and assessment of symptoms
• Understanding the medical history of the affected individual
• Examination of stool: Although this test may be indicative of a parasite infection through the presence of eggs, it may not be conclusive. The characteristics of Oesophagostomum eggs with those of other parasites (such as Ancylostoma and Necator) may be similar
• Growing eggs in a culture dish to such a stage that the larvae are distinguishable as belonging to Oesophagostomum sp.
• Ultrasound imaging of the abdomen (nodule)
• Nodule biopsy: Surgical removal of an intact worm and identifying it as Oesophagostomum - for definitive diagnosis (often, the worm can be extracted from nodules)
• Molecular diagnosis, via polymerase chain reaction (PCR) of fecal samples, for specific ribosomal DNA regions in the parasite

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Oesophagostomiasis?

Untreated Oesophagostomiasis can lead to serious complications, such as the following:

• Formation of tumor-like nodules, which can be solitary or multiple. The nodules can be painful and cause a serious inflammatory response in the body
• Gastrointestinal perforation: A breach in the intestinal wall, leading to the release and leakage of harmful substances into the body
• Bowel obstruction, which may mimic hernia
• Peritonitis
• In serious cases, enlargement of the heart, liver, and spleen

How is Oesophagostomiasis Treated?

Treatment for Oesophagostomiasis may include one or more of the following:

• Anti-parasitic drugs
• Surgical removal of the parasite worm: Although it may result in a cure, this procedure is invasive and may give rise to surgery-associated complications (infection and anesthesia complications, among others) 
• Combination of medication and surgical procedures: Surgical removal of the worm(s) and draining of nodule(s) is undertaken in combination with prescription of antibiotic (amoxicillin) and anti-parasitic (albendazole) medications

How can Oesophagostomiasis be Prevented?

Oesophagostomiasis may be prevented by:

• Reducing exposure to soil, possibly contaminated with Oesophaogstomum larvae passed by infected hosts
• Cleaning fruits and vegetables thoroughly before consuming
• Cooking foods completely to recommended internal temperatures 
• Ensuring that preparation surfaces are clean and good practices are followed for cooking of food
• Consumption of well-cooked food and clean water 
• Limiting access and contact with animals that are prone to infection by the parasite (monkeys, cattle, sheep, goats, pigs)
• Ensuring proper maintenance of hygiene of the animal sheds/area

What is the Prognosis of Oesophagostomiasis? (Outcomes/Resolutions)

• The prognosis of Oesophagostomiasis is favorable in individuals who seek prompt medical attention and are treated in a timely manner
• If the parasite is able to perforate the intestinal wall, then surgical repair may cause minor, or temporary digestive discomfort and related problems. However, a full recovery is still possible 
• If left untreated, an individual with Oesophagostomiasis may succumb to the infection

Additional and Relevant Useful Information for Oesophagostomiasis:

The life cycle of the Oesophagostomum parasites involves the following steps:

• Eggs are passed out of the definitive host in their feces. Once into the environment, the eggs hatch into rhabditiform larvae, if the conditions are good (based on humidity and temperature parameters)
• Rhabditiform larvae is the name given to the early developmental stage of larvae, and Oesophagostomum larvae will undergo 2 molts (similar to snakes shedding their skin) to develop into a more mature form of the larvae, known as filariform larvae
• The filariform larva is infective to the hosts. Prior to this stage of development, the parasite is not considered to be completely able to infect a host
• The process of development from egg to filariform is about a few days
• The filariform larva is then ingested by a host, and the larva/worm digs itself into the large or small intestine (more specifically into the submucosal layer of the intestine) of the host
• A cyst is formed where the parasite has inserted itself. Inside the cyst, the larvae develop even further and turn into an adult
• The adult parasite migrates into the lumen of the gut and resides there, shedding eggs into the host gut, from where they are excreted out of the body through feces

Kounkoul is the term used by locals of Togo village to describe the disease.