Dientamoebiasis

Dientamoebiasis
Classification and external resources
ICD-9-CM	007
DiseasesDB	32407
eMedicine	ped/563
MeSH	D004030
[]

Dientamoebiasis is a medical condition caused by infection with Dientamoeba fragilis, a single-cell parasite that infects the lower gastrointestinal tract of humans. It is an important cause of traveler's diarrhea, chronic abdominal pain, chronic fatigue, and failure to thrive in children.

Early microbiologists reported that the organism was not pathogenic, though six of the seven individuals from whom they isolated it were experiencing symptoms of dysentery. Their report, published in 1918, concluded the organism was not pathogenic because it consumed bacteria in culture, but did not appear to engulf red blood cells, as was seen in the best-known disease-causing amoeba of the time, Entamoeba histolytica. This initial report may still be contributing to the reluctance of physicians to diagnose the infection.

As many individuals are asymptomatic carriers of D. fragilis, pathogenic and nonpathogenic variants are proposed to exist. A study of D. fragilis isolates from 60 individuals with symptomatic infection in Sydney, Australia, found all were infected with the same genotype, which is the most common worldwide, but differed from the genotype first described from a North American isolate and later also detected in Europe.

It increases in conditions of crowding and poor sanitation. Rates of infection in military personnel and mental institutions are higher. The true extent of disease has yet to emerge, as most laboratories do not use techniques to adequately identify this organism. An Australian study identified a large number of patients, considered to have irritable bowel syndrome, who were actually infected with Dientamoeba fragilis.

Although D. fragilis has been described as an infection "emerging from obscurity", it has become one of the most prevalent gastrointestinal infections in industrialized countries, especially among children and young adults. A Canadian study reported a prevalence of around 10% in boys and girls aged 11–15 years, a prevalence of 11.5% in individuals aged 16–20, and a lower incidence of 0.3–1.9% in individuals over age 20.

The most commonly reported symptoms in conjunction with infection with D. fragilis include abdominal pain (69%) and diarrhea (61%). Diarrhea may be intermittent and may not be present in all cases. It is often chronic, lasting over two weeks. The degree of symptoms may vary from asymptomatic to severe, and can include weight loss, vomiting, fever, and involvement of other digestive organs.

Symptoms may be more severe in children. Additional symptoms reported have included:

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