SURVEY OF THE PRESENCE OF CRYPTOCOCCUS NEOFORMANS AND OTHER PATHOGENIC YEAST IN RACING PIGEONS HOUSES OF NORTHERN ITALY

INTRODUCTION: Messenger pigeons are domesticated races of Columba livia, bred for they homing ability and used in the past to carry messages; nowadays these animals are basically used for sport purpose. Pigeon racing is the sport of releasing trained racing pigeons that then return to their home over a carefully measured distance. In this paper the presence of C. neformans or other potentially pathogenic yeasts and their relationship with breeding management was investigated in racing pigeon houses from Modena, Bologna and Udine provinces (Northern Italy). MATERIALS AND METHODS: Seventy-three samples of dry pigeon droppings collected from 21 racing pigeon house were analyzed. Mycological analyses were conducted according to Galuppi et al (2002-6° congresso Nazionale FIMUA Modena, 12-14 settembre 2002). Briefly, two grams of each specimen were suspended in 10 ml of sterile saline solution with antibiotics (50000 U penicillin, 50000 U streptomycin/100ml of saline) and stored at 5°C overnight. One hundred microliters of the suspension was then spread, in duplicate, on plates containing Niger Seed Agar (Shields & Ajello, 1996, Science, 151: 208-209). The plates were incubated at 25°C and 37°C, respectively, for 10 days and daily observed. The yeasts isolated were identified with Api 20C AUX (Biomerieux Italia S.p.a, Firenze, Italy) and Dalmau plates on Yeast Morphology Agar DIFCO (Becton Dickinson Italia S.p.a, Milano, Italy). RESULTS: Yeasts were isolated from 35 samples incubated at 25°C and from 22 incubated at 37°C. Cryptococcus neoformans was isolated in at least one samples from 11 pigeon houses (52.4%), Candida guilliermondii in 10 (47.6%), C. albicans in 5 (23.8%), C. famata in 6 (28.5%) and Rhodothorula sp. in 2 (9.5%). The frequency of isolation of C. neoformans was lower in farms in which disinfection treatment has been done (46.2%) than in the ones where only mechanical removal were performed (62.5%), but the differences was not statistically significant. No differences were also observed in relation to different disinfection methods (sodium hypoclorite, steramine or flame). Vice versa, the daily mechanical removal of feces was significantly related (p<0.05) with a lower frequency of isolation of C. neoformans, compared to the farms where the removal was performed every 7-15 days (14% vs 71%). No differences were observed related to treatment or frequencies of mechanical cleaning and the isolation of C. guilliermondii and C. albicans; instead C. famata was isolated in the 46% of the farms without daily mechanical removal and not found in the other ones (fisher exact<0.05). CONCLUSIONS: It is well known as the pigeon’s guano is a source of infectious elements of C. neoformans and is involved in their transmission from the environment to the humans (Nielsen et al, 2007, Eukariotic cell., 6: 949-959). In the past it has been shown a high seroprevalence of antibodies against C. neoformans in pigeon fanciers (Walter et al., 1996, J Bacteriol., 92: 82-87), although studies in this regard are very scarce. In this work it is highlighted as mechanical cleaning decreases the environmental presence of this yeast, whereas the use of different disinfections methods don’t seems decrease their presence. The daily cleaning and the use of a disposable filtering face mask could decrease the infection risk in the pigeon fanciers.