This is a systemic infection caused by the yeast Cryptococcus neoformans. The commonest manifestation is a subacute or chronic form of meningitis resulting from the inhalation of the organism. Pulmonary infection can also occur. The disease affects both healthy and immunosuppressed individuals and occurs world-wide. C. neoformans can be isolated in large numbers from pigeon droppings in the environment, although such birds do not appear to harbour the yeast.