Friday, 27 September 2013

Cryptococcus gattii and the spread of infection

Cryptococcus gattii is a type of fungus that was previously only found in warmer climates throughout the tropics. However, since 1999 outbreaks of highly virulent strains of the fungus have been reported in the cooler climes of Canada and Northwestern USA, causing serious illness in otherwise healthy people and domestic and wild animals and proving fatal in some cases.

C. gattii is found in the soil and in association with certain trees such as eucalyptus, pine or fir trees. It is transmitted to humans and other animals by inhaling spores of the fungus that are carried in the air. After infecting the lungs, cells of the fungus can travel through the bloodstream to infect other areas of the body, including the brain. The most common symptoms are shortness of breath, coughing, fatigue, fever, and headache.

To try to understand how likely it is that the disease will spread further, a team of researchers in the US and UK interbred different strains of the fungus to test how easily the characteristics of these more dangerous strains can be transferred to other less harmful strains.

The results show that genes conferring traits that make the fungus more dangerous are easily passed to the offspring when the two parent strains are closely related. When the strains are distantly related to each other, the genes are much less likely to spread.

To read more about this research, see the following paper:

Kerstin Voelz, Hansong Ma, Sujal Phadke, Edmond J. Byrnes, Pinkuan Zhu, Olaf Mueller, Rhys A. Farrer, Daniel A. Henk, Yonathan Lewit, Yen-Ping Hsueh, Matthew C. Fisher, Alexander Idnurm, Joseph Heitman, Robin C. May. Transmission of Hypervirulence Traits via Sexual Reproduction within and between Lineages of the Human Fungal Pathogen Cryptococcus gattii. PLoS Genetics, 2013; 9 (9): e1003771 DOI: 10.1371/journal.pgen.1003771

Posted by Tim Sandle

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