Clinical and Therapeutic Aspects of Cryptococcal Meningitis in West Africa

Abstract

Cryptococcus meningitis is the most severe form of cryptococcal infections that infects the brain parenchyma and sub-arachnoid space. It often progresses to fatal disease states when it goes untreated. The clinical presentation and disease course of cryptococcal infection is partially marked by changes that occur as a result of certain medical conditions including, use of glucocorticoids or other immunosuppressive drugs, diabetes, as well as the immune status of the host (Chuck, 1989; Dismukes, 1988). Mostly, the disease affects people with a compromised immune system and is found in people with advanced HIV infection and AIDS, with the major burden in South-East Asia and Africa (Mwaba, 2001; Maher, 1994; Moosa, 1997). The infection itself is caused by inhalation of a yeast-like round fungus with a polysaccharide capsule, known as Cryptococcal neoformans, and disseminates from the lungs. This fungus is the only pathogenic species of the genus Cryptococcus. Based on the capsule components four serotypes of C. neoformans (A, B, C and D) have been isolated, and the species is divided into two forms. Each serotype has different epidemiologic and pathogenic profile and their presence suggests an environmentally unfriendly atmosphere for people with a defective T cell function. Consequently, the common forms of C. neoformans that affect humans in Europe and parts of US is C. neoformans var neoformans, whereas in tropical areas such as the Far East, Africa and Australia, C. neoformans var gattii is the common form of cryptococcal infection (Gari-Toussaint,1996). C. neoformans var gattii is also thought to be ecologically resident on Eucalyptus trees (Ellis, 1990). An outbreak of Cryptococcosis in healthy humans and animals in Vancouver Island, Canada, and the subsequent isolation of C. neoformans var gattii in Washington and Oregon in the US, have now led to the understanding that this species is not restricted to tropical and sub-tropical climates alone (Datta, 2009). Rather it has a wider geographic distribution and can also thrive in temperate climates, as well as on species of trees other than Eucalyptus (Datta, 2009). Estimates indicate that worldwide, the burden of human cryptococcal infections ranges between 2 to 30 % and most infected patients have HIV/AIDS (Bicanic, 2006; French, 2002). An observation in the US in 1990 showed an increase to 5000 cases of cryptococcal meningitis infection in AIDS patients, compared to 300 cases in 1980 where half of these cases were