Cryptococcus neoformans, an encapsulated yeast, is a common soil fungus found throughout the world. Areas contaminated by pigeon droppings are particularly likely to contain this organism. It is often the predominant organism in desiccated alkaline environments with high nitrogen and high salt contents. It cannot compete successfully when soil mixing and irrigation foster the growth of other fungi and amoeba. C neoformans can remain viable after 2 or more years in moist or desiccated pigeon excreta. Antigenic variations in the polysaccharide capsule are used to define 4 serotypes, of which A and D most commonly cause human infections (Benham 1950). Two varieties are distinguished: C neoformans var neoformans (serotypes A and D) and C neoformansvar gattii (serotypes B and D). C neoformans need not infect a vertebrate to complete its life cycle. In the animal model of disease, strain differences with respect to total capsule volume and rate of accumulation are correlated with neurovirulence (Pool et al 2013).