ISOLATION OF CRYPTOCOCCUS-NEOFORMANS FROM PIGEON (COLUMBA-LIVIA) DROPPINGS IN MEXICO-CITY

To determine the ecological and epidemiological significance of pigeon excrement in cryptococcosis in Mexico City, 251 samples of pigeon dro ppings were studied. These were collected from houses, public building s, churches, parks and pigeon nests. Each sample was suspended 1:10 in isotonic saline solution and then cultured in Staib medium. Identific ation of Cryptococcus neoformans was performed based on the developmen t of brown-coloured colonies and the presence of encapsulated yeasts. Of 251 samples, 52 (20.7%) were positive for Cr. neoformans. The highe st frequency was observed in droppings from public buildings (31.2%), followed by churches (22.0%) and houses (13.3%). No significant differ ences in isolation frequency were observed between fresh or dried excr ement. All isolates obtained were Cr. neoformans var. neoformans. As i n other studies on Cr. neoformans from pigeons, performed in other cou ntries, these frequency data are considered 'normal'. The results, how ever, accentuate the potential risk of cryptococcosis acquisition, esp ecially now that cryptococcosis frequency is increasing in Mexico, mai nly in AIDS patients.