Cryptococcus

Cryptococcus neoformans is a yeast-like fungus which is found worldwide, often in soil which has been contaminated by bird excrement. It is much more common in Africa than in Europe. It usually gets into the body through the lungs, and is not spread from person to person.

About 5 to 10% of people with HIV develop illness due to Cryptococcus or cryptococcosis. This may be caused by a new infection with Cryptococcus, or by reactivation of a latent infection. People with HIV are usually considered to be at risk if their CD4 count falls below 100 cells/mm3. A survey of cryptococcosis diagnoses in four major United States centres between 1992 and 1994 showed that people diagnosed with cryptococcosis were significantly more likely to be smokers or to have a history of working outdoors.1

Cryptococcus is much more prevalent in developing countries, and a systematic review has led to the estimate that as many as 0.5 million people with HIV died of cryptococcal meningitis in 2006 due to lack of diagnosis and treatment.2

Laboratory research suggests that infection with Cryptococcus can also increase HIV replication.2

References

  1. Haijeh RA et al. Cryptococcosis: population based multistate active surveillance and risk factors in human immunodeficiency virus-infected persons. Journal of Infectious Diseases, 179: (2): 449-454, 1999
  2. Park BJ et al. Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS. AIDS, 23: 525-530, 2009