| Popis: |
Cryptococcus neoformans and Cryptococcus gatti are yeasts that can cause severe, life-threatening infections of the lungs and brain, particularly in immunocompromised individuals. Cryptococci are opportunistic pathogens. Their natural habitat is the environment where they have evolved a series of mechanisms to resist radiation, desiccation, high temperatures, and digestion by protists such as amoebae. Infections of humans occurs following inhalation of the yeasts or their spores. The factors that enable survival in the environment enable the yeasts to escape many of the defences of the human immune system. Because human-to-human transmission does not occur, the genetic traits of any clinical isolate must have been selected in the environment. Cryptococcal disease initially was restricted to sub-Saharan Africa but now has spread to other parts of the world. It is not clear how this has occurred given that there is no human-to-human transmission. |
