New research has shed light on the origins of a fungal infection which is one of the major causes of death from AIDS-related illnesses. The study, published on April 28, 2011, in the journal PLoS Pathogens, shows how the more virulent forms of Cryptococcus neoformans evolved and spread out of Africa and into Asia. Cryptococcus neoformans is a species of often highly aggressive fungi. One particular strain of the fungus – known as Cryptococcus neoformas varietygrubii (Cng) – causes meningitis amongst patients with compromised immune systems following HIV infection. There are believed to be up to a million cases of cryptococcal meningitis each year, resulting in over 600,000 deaths. Infection with the fungus, which invades the central nervous system, is treated with a life-long therapy of antifungal drugs, which can have highly unpleasant side effects. Sitali Simwami and Dr. Matthew Fisher from Imperial College London, together with colleagues from St Georges, University of London, Naresuan University, Thailand, and the CBS Fungal Biodiversity Centre, The Netherlands, used genetic sequencing techniques to compare the genetic diversity of Cng in 183 samples taken from the clinic and the environment in Thailand against the 77 samples from a global database. Thailand has an emerging HIV epidemic and nearly one in five HIV-infected patients is affected by cryptococcal infection. "Cryptococcal meningitis kills hundreds of thousands of people each year, almost as many as malaria, yet gets little attention," explains Dr. Fisher. "We know very little about where it originated from and how it evolved. If we can track its evolution and diversity, then we can begin to understand where the pathogen originates from, how it infects people, and how it adapts to become more – or less – virulent.
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