1.1 Background of the study
Microsporidia are single-celled, obligate intracellular parasites that were recently reclassified from protozoa to fungi. Microsporidia are a group of intracellular parasites which have attracted the interest of parasitologists for over 100 years. The first species, Nosemabombycis, was discovered in the middle of the 19th century as the cause of silkworm disease (i.e., pepper disease, pebrine disease), which nearly destroyed the silkworm industry in Southern Europe (Didier,2005; Franzen,2008).More than 1,400 microsporidian species have been described in both invertebrate and vertebrate hosts. Only eight genera and 15 species of microsporidia have been associated with human infections.
The first report on human microsporidia infection was in 1959 and described the case of a 9-year-old Japanese boy who presented with disseminated microsporidiosis associated with fever, headache, vomiting,and spastic convulsions, (Matsubayashet al.,1959). Interest in this group of parasites started with the development of the AIDS pandemic around the world in 1980’s. In 1985, a new species Enterocytozoonbieneusi was found in an HIV-infected patient. Since then,species of microsporidia have been recognized worldwideas etiologic agents of opportunistic infections. The clinical course of microsporidiosis depends on the immune status of the patient and the site of infection. The groups at risk constitute people with HIV/AIDS, organ transplant recipients being treated with immunosuppressive drugs, travellers,children and the elderly, (Didier, 2000; Garcia, 2002;Rabodonirina, 2003; Wichro, 2005; Dworkin, 2007; Galvan, 2011).
Two microsporodia Enterocytozoonbieneusi and Encephalitozoonintestinalis have been identified as possible causes of diarrhoeal illness in HIV-infected patients, (Moura et al.,1993; Kotler, 1995).Over 40 million people are living with HIV/AIDS, the majority (more than 25 million) of whom live in sub-Saharan Africa. Up to 2.4 million deaths were recorded worldwide in 2005, (Akinbo et al.,2009).
People in the advanced stages of HIV infection are vulnerable to secondary infections and malignancies that are generally termed as opportunistic infections as they take the advantage of the opportunity offered by a weakened immune system, (Saidu, et al.,2009). In HIV/AIDS positive patients, the most clinical manifestation is chronic diarrhoea and wasting due to enteric infection, (UNIADS 1998).This parasite is commonly observed in HIV-infected patients with CD4 Lymphocytes count of less than 50cells/mm3 who complain of chronic diarrhoea, nausea, malabsorption and severe weight loss but asymptomatic infection have also been reported in immunocompetent persons,(Sak et al.,2011).
Microsporidiosisis a neglected tropical disease that is associated with chronic diarrhoea especially in persons living with HIV/AIDS, and in other immune-compromised individuals (elderly, organ transplant individuals, travellers). In developing countries like Nigeria, there has not been any serious efforts toward the eradication of Microsporidiosis. Infection rate of Microsporodiosis is on the increase in tropical and subtropical countries due to lack of health hygiene, access to public health centres, and knowledge of the disease. In Nigeria detection of microsporidia is not routinely performed in clinical practice, there is therefore dearth of information concerning Microsporidia in respect to prevalence, diagnosis, treatment and control.