Molecular detection of Dientamoeba fragilis among children complaining of gastrointestinal disturbances

Abstract

D. fragilis is an enteric protozoan parasite that remains obscure and neglected. Studies utilizing electron microscopy and molecular phylogenetics defined it as a Trichomonad which lacks flagella. It is a pathogenic protozoan parasite which inhabits the gut and causes gastrointestinal disease in human. Because in most studies only some infected persons experience symptoms, it is possible that D. fragilis is a heterogeneous species with variants that display similar morphologies but different pathogenicities. There are two major D. fragilis genotypes, genotype 1 and genotype 2 with genotype I being the most common subtype. A great deal of controversy exists on the mode of transmission of D. fragilis. It has been postulated that E. vermicularis may serve as a vector for D. fragilis. Recently, D. fragilis DNA has been detected in E. vermicularis eggs. Moreover, they found a higher incidence of coinfection with D. fragilis and E. vermicularis than D. fragilis infections alone which further strengthening the hypothesis of D. fragilis transmission via E. vermicularis ova. A recent report described the discovery of a new cyst stage in its life cycle. It was found that fecal-oral transmission of cysts may play a role in transmission of D. fragilis yet many of the specific details remain unidentified. Globally, the prevalence rates of D. fragilis infection vary depending on the identification tool used. Using the light microscopy, the rates of infections oscillate between 0.4% and 52%. Previous studies done in Egypt reported prevalence rates between 1 and 29.8% using light microscopy and culture techniques. As regards the age distribution, numerous studies reported a higher incidence rate in children less than 18 years old.