Clinical communication — Kliniese mededeling Cryptococcus neoformans granuloma in the lung and spinal cord of a free-ranging cheetah (Acinonyx jubatus). A clinical report and literature review

INTRODUCTION Cryptococcus neoformans is a saprophytic yeast that is normally found in the environment associated with organic material such a pigeon droppings and leaf litter. However, C. neoformans is a potential pathogen of both humans and animals. The infectious particle, the basidiospore, is adapted for air dispersal and has properties that allow it to adhere to and penetrate the respiratory epithelium of the infected host. Primary infection occurs most commonly via the respiratory route, the infection then spreads through either direct extension or by the haematogenous route to the central nervous system (CNS), eye, skin, bone, lymph nodes and multiple other organs. Cryptococcus neoformans does display some degree of neurotropism. In humans cryptococcal infections occur most commonly in immunocompromised individuals. It has been suggested that the outcome of a cryptococcal infection may depend on the immune status of the host, the subspecies of the Cryptococcus and the virulence factors such as capsular thickness. All of the cheetah cryptococcal infections reported in South Africa to date have been FeLV and FIV negative. In domestic cats there may be a genetic susceptibility to Cryptococcus infection and it has been postulated that the cheetah may also have a similar genetic predisposition owing to their lack of genetic diversity. Other factors, such as chronic stress in captive cheetah may also be a component in this increased susceptibility. C. neoformans var. gattii is found most commonly in tropical areas such as Australasia, South America and Africa. C. neoformans var. neoformans occurs worldwide but is the predominant subspecies causing infection in North America. As with domestic felids, adult male cheetahs appear to have the highest incidence of Cryptococcus infection. This report describes a cheetah displaying CNS symptoms due to C. neoformans var. gattii and is the first reported case of C. neoformans in a wild born, free-ranging cheetah. All previous reported cases have been in captive cheetah.