No abstract

Human infection with the protozoan parasite Giardia duodenalis is one the most common parasitic diseases worldwide. Higher incidence rates of giardiasis have been reported from human subjects with multiple debilitating chronic conditions, including hypogammaglobulinemia and common variable immunodeficiency (CVID). In the current study, stool specimens were collected from 199 individuals diagnosed with HIV or cancer and immunocompetent subjects. The sensitivity of microscopy-based detection on fresh stool preparations, trichrome staining and stool antigen immunodetection for the diagnosis of G. duodenalis were 36%, 45.5% and 100%, respectively when compared with a highly sensitive stool-based PCR method as the gold standard. Further multilocus molecular analyses using glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) demonstrated that the AI genotype of G. duodenalis was the most prevalent, followed by the AII genotype and mixed (AI+B) infections. We concluded that stool antigen immunodetection-based immunoassays and stool-based PCR amplification had comparable sensitivity and specificity for the diagnosis of G. duodenalis infections in these populations. Stool antigen detection-based diagnostic modalities are rapid and accurate and may offer alternatives to conventional microscopy and PCR-based diagnostic methods for the diagnosis of G. duodenalis in human subjects living with HIV or cancer.

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Background and Purpose:Gastroenteritis and the clinical profile caused by Microsporidia, an opportunistic pathogen, may be severe in immunocompromised individuals, especially in AIDS patients. Conventionally, it is necessary to detect the small infective spores in stained smears. However, due to the limitations of the microscopy-based methods, several DNA-based methods such as polymerase chain reaction (PCR) have recently been developed to enhance diagnosis sensitivity. Therefore, we sought to evaluate the rate of infection in immunocompromised patients as compared with immunocompetent patients in Kerman, Iran.Materials and Methods:We collected stool samples of 199 human subjects (116 males and 83 females), aged 1 to 69 years old. They were divided into immunocompromised (i.e., AIDS [n=72] and cancer-positive patients [n=59]) and immunocompetent (n=68) groups. We comparatively examined the fecal materials using the microscopy and PCR methods.Results: The overall prevalence rate of Microsporidia infection was 10.05% (20/199). Entrocytozoon bieneusi was the only species within the Microsporidia genus that was identified in 14.5% (19/131) of the immunocompromised patients and 1.47% (1/68) of the immunocompetent individuals.Conclusion:Considering the higher prevalence rate of microsporidiosis in patients with immunodeficiency (10.03%), we suggest performing sensitive and specific techniques such as PCR for the detection of these parasites in immunocompromised patients.