Enterocytozoon bieneusi (Microsporidiosis) - Molecular diagnosis (PCR)


Enterocytozoon bieneusi is an obligate intracellular microorganism belonging to the phylum Microsporida, gender Encephalitozoon, currently seen in the kingdom Fungi, with a worldwide distribution. The Microsporida infect a wide range of vertebrates and invertebrates, including people, especially immunodeficient as a result of HIV infection. Enterocytozoon bieneusi species mainly affects pigs, but can affect other animals such as fish, birds, cattle and other mammals, including people. Enterocytozoon bieneusi infection causes a disease called microsporidiosis.

The life cycle of this organism involves a host where it multiplies. The infectious form of Enterocytozoon bieneusi is resistant spore can survive for a long time in the environment. Spores are uninucleate, 1.1 to 1.6 microns x 0.7 to 1.0 microns, and a polar tubule 5 to 7 volutes. Once in the host organism, Enterocytozoon bieneusi is located in the small intestine and in the epithelium of the bile ducts. Inside the body, the spore injects the infectious sporoplasm in the eukaryotic host cell through the polar tubule. Inside the cell, the sporoplasm multiplied either by binary fission or multiple fission. Microsporidia develop by Sporogony to mature spores in the cytoplasm or inside the parasitophorous vacuole. During sporogony, a thick wall around each spore, which provides resistance to adverse environmental conditions is formed. Once spores increase in number and completely colonize the cytoplasm of the host cells, the cell membrane ruptures and releases spores. These free mature spores can infect new cells, continuing the cycle.

Enterocytozoon bieneusi transmission occurs through ingestion or inhalation of spores present in contaminated water, secretions or body exudates, contaminated with fecal matter and transplacental.

Enterocytozoon infection usually causes minimal damage bieneusi. Infection of enterocytes of the small intestine by Enterocytozoon bieneusi produces vacuolation of parasitized cells, cell detachment of the villi, cytolysis and degeneration of enterocytes. Likewise, it generates villous atrophy, crypt hyperplasia and the formation of a lymphocytic infiltrate, macrophages and plasma, granulomatous response with a central portion of necrosis. Also it induces alterations in lipid and carbohydrate absorption. As a result of the process causes severe chronic diarrhea, especially in immunocompromised patients such as HIV - infected. In rare cases, the infection can spread beyond the digestive tract and cause systemic dissemination, with the invasion of the lungs, kidneys, eyes, liver and central nervous system. In all, it occurs and cytolysis granulomatous inflammatory response.


In immunocompromised individuals as people with HIV primarily infects the small intestine and can cause microsporidiosis disseminated in the gastrointestinal tract. It is considered that the immune status and the presence of other deficiencies appear to be determining factors in the risk of infection Enterocytozoon bieneusi, so, although infection can occur in immunocompetent patients, microsporidiosis most often affects immunocompromised individuals, especially AIDS patients , the elderly, diabetics, patients with transplants and malignancies.

Recommended tests for diagnosis:


The diagnosis is based on microscopic identification, antibody detection, or molecular diagnostic methods (PCR). Molecular methods (PCR), offer the advantage of providing a quick and specific diagnosis.

The diagnosis has been based on a combination of signs of neurological deficits detection of spores in affected tissues, or stool stained with fluorescent dyes, with high antibody titers. Histopathology has been the standard diagnostic method using immunohistochemical methods for diagnosis of granulomatous encephalitis with interstitial nephritis.

It is important to differentiate Encephalitozoon of Enterocytozoon because the treatments are different (Encephalitozoon can be treated with albendazole and Enterocytozoon with fumagillin).

For these reasons, molecular methods (PCR) are currently recommended.

Tests in IVAMI:


  • Molecular diagnosis (PCR), to detect DNA of Enterocytozoon bieneusi.

Recommended sample:


  • Feces.
  • Samples of other affected tissue


Preservation and shipment of sample:


  • Refrigerated (preferred) for less than 2 days.
  • Frozen: over 2 days (for molecular diagnostic tests only).


Delivery term:


  • Molecular diagnosis (PCR): 24 to 48 hours.

Cost of the test:


Consult ivami@ivami.com