DIAGNOSIS AND EPIDEMIOLOGY OF MICROSPORIDIA INFECTIONS IN HUMANS

Microsporidia are single-celled, obligately intracellular parasites that are considered a cause of emerging and opportunistic infections in humans. The most common symptoms associated with microsporidiosis are persistent and self-limiting diarrhea in immune-deficient and immune-competent individuals, respectively. Species of microsporidia that infect humans also infect a wide range of animals which raises a concern for zoonotic transmission. Microsporidian spores are environmentally resistant and have been identified in various water sources, also raising a concern for water- and food-borne transmission. Microsporidia can be detected in patient specimens such as urine, feces, and tissue biopsies by staining with calcofluor white, concentrated trichrome, Gram, or immunofluorescent antibody but species identification usually requires detection by PCR-based techniques. Improved diagnostic methods are being used to address the epidemiology of microsporidiosis and recent studies indicate that individuals most at risk for infection include persons with AIDS, immune-suppressed organ transplant recipients, malnourished children, travelers, and the elderly. Risk factors have included eating undercooked meat and exposure to water through recreational or occupational exposure or through drinking water. Strategies, therefore, are being developed to identify and remove or disinfect species of microsporidia present in water sources that pose a risk for transmission to humans and animals.