Relation of the pigeon to cryptococcosis: Natural carrier state, heat resistance and survival of Cryptococcus neoformans

Littman, M. L.; Borok, Rele

doi:10.1007/bf02050749

Cited by 72 publications

(39 citation statements)

References 28 publications

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“…However, pigeons do not acquire cryptococcosis, most likely because C. neoformans cannot grow at the pigeon's normal body temperature of 42°C. Nevertheless, the yeasts can survive passage through the pigeon intestinal tract (19), and yeast cells of C. neoformans were found to survive for 2 years in moist or dry pigeon excreta that was protected from the sun (12). In soil, C. neoformans may compete with certain microorganisms and can be inhibited by others, such as amoeba, which can devour the yeast (7).…”

Section: Discussionmentioning

confidence: 99%

Comparative Analysis of Environmental and Clinical Populations ofCryptococcus neoformans

et al. 2005

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Cryptococcus neoformans is a major, global cause of meningoencephalitis in immunocompromised patients. Despite advances in the molecular epidemiology of C. neoformans, its population structure and mode of reproduction are not well understood. In the environment, it is associated with avian guano or vegetation. We collected nearly 800 environmental isolates from three locations in the United States (viz., North Carolina, California, and Texas) and compared them with one another and with clinical isolates from North Carolina. As expected, they consisted of the most prevalent serotypes, serotypes A and D, as well as serotype AD hybrids. The majority of environmental isolates were obtained from pigeon excreta. All environmental and clinical isolates of serotype A or D had the MAT␣ mating-type allele. However, the AD hybrids included MATa alleles typical of serotypes A and D. Using an amplified fragment length polymorphism fingerprinting technique with two primer pairs, we identified 12 genotypes among the isolates of serotype A. Six of these genotypes were present in both the clinical and the environmental populations. However, one of the most prevalent environmental genotypes was absent from the clinical samples, and two other genotypes were isolated only from patients. The combined molecular data suggest that this environmental population of C. neoformans is predominantly clonal, although there was evidence for recent or past recombination.

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Section: Discussionmentioning

confidence: 99%

Comparative Analysis of Environmental and Clinical Populations ofCryptococcus neoformans

et al. 2005

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“…The temperature influences the proliferation and survival of this yeast-like fungus 16 . Very high summer temperature in Rio de Janeiro could inhibit C. neoformans growth or even could cause cell inactivation, perhaps explaining low rates of isolation during this season.…”

Section: Discussionmentioning

confidence: 99%

“…The towers have sheltered pigeons as well as large deposits of the bird excreta, facilitating this microorganism spreading by airborne propagules and, very likely, migratory patterns of insects (beetles). It needs to be reminded that according to BULMER (1990) 4 , the problem is that C. neoformans remains viable on dry excreta for two years 16 . Old buildings and churches of historical interest have been abundant in Rio de Janeiro and the significance of these spaces as ecological niches for C. neoformans must be seriously considered by public health authorities.…”

Section: Discussionmentioning

confidence: 99%

“…In many situations, reports of cryptococcosis have been associated to pigeon droppings as the source of infection; however, an epidemiological analysis showed that patients with pigeons contact had a high exposure risk 16 . The major problem is that C. neoformans remains viable on dry pigeon droppings, for many years, being a reservoir of inhaled infecting particle, persisting with small capsule which are compatible with alveolar deposition.…”

Section: Introductionmentioning

confidence: 99%

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Cryptococcus neoformans strains isolated from church towers in Rio de Janeiro City, RJ, Brazil

Baroni

Paula

Silva

et al. 2006

Rev. Inst. Med. trop. S. Paulo

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SUMMARYCryptococcosis has been a significant cause of morbidity and mortality in patients with Aids. Many reservoirs of the agent Cryptococcus neoformans have been reported, but the ecology of this yeast must be elucidated in order to establish surveillance programs and to prevent infections. The objective of this study was to evaluate the presence of C. neoformans in Rio de Janeiro City, RJ, Brazil. Ten churches were selected for sampling and detection of the yeast collecting pigeon dropping, air samples from church towers and neighboring areas during one year. The data demonstrated that C. neoformans has been present in every church selected and was present in 37.8% of 219 pigeon dropping samples. As well as, the yeast was isolated from soil, insects, eggs, pigeon nests and feathers. Fifteen air samples (4.9%) were positive. The growth on C.G.B. medium showed that all strains belonged to C. neoformans var. neoformans, with 98.8% of the strains belonging to serotype A.

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“…This finding may help to more clearly define the role of birds and bird excreta, particularly pigeons, in the transmission of C. neoformans. The growth of these organisms on pigeon guano provides a potential mechanism for explaining how pigeons might play a role in harboring C. neoformans, either internally or on external parts of their anatomy that come into contact with guano, such as their feathers or feet (1,8,15,30,36,39,48,54,67,80). Pigmentation is observed when Cryptococcus is grown on pigeon guano and increases as the concentration of guano in the medium increases.…”

Section: Vol 6 2007 C Neoformans Mates On Pigeon Guano 955mentioning

confidence: 99%

Cryptococcus neoformans Mates on Pigeon Guano: Implications for the Realized Ecological Niche and Globalization

Nielsen¹,

Obaldia²,

2007

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The ecological niche that a species can occupy is determined by its resource requirements and the physical conditions necessary for survival. The niche to which an organism is most highly adapted is the realized niche, whereas the complete range of habitats that an organism can occupy represents the fundamental niche. The growth and development of Cryptococcus neoformans and Cryptococcus gattii on pigeon guano were examined to determine whether these two species occupy the same or different ecological niches. C. neoformans is a cosmopolitan pathogenic yeast that infects predominantly immunocompromised individuals, exists in two varieties (grubii [serotype A] and neoformans [serotype D]), and is commonly isolated from pigeon guano worldwide. By contrast, C. gattii often infects immunocompetent individuals and is associated with geographically restricted environments, most notably, eucalyptus trees. Pigeon guano supported the growth of both species, and a brown pigment related to melanin, a key virulence factor, was produced. C. neoformans exhibited prolific mating on pigeon guano, whereas C. gattii did not. The observations that C. neoformans completes the life cycle on pigeon guano but that C. gattii does not indicates that pigeon guano could represent the realized ecological niche for C. neoformans. Because C. gattii grows on pigeon guano but cannot sexually reproduce, pigeon guano represents a fundamental but not a realized niche for C. gattii. Based on these studies, we hypothesize that an ancestral Cryptococcus strain gained the ability to sexually reproduce in pigeon guano and then swept the globe.

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Relation of the pigeon to cryptococcosis: Natural carrier state, heat resistance and survival of Cryptococcus neoformans

Cited by 72 publications

References 28 publications

Comparative Analysis of Environmental and Clinical Populations ofCryptococcus neoformans

Comparative Analysis of Environmental and Clinical Populations ofCryptococcus neoformans

Cryptococcus neoformans strains isolated from church towers in Rio de Janeiro City, RJ, Brazil

Cryptococcus neoformans Mates on Pigeon Guano: Implications for the Realized Ecological Niche and Globalization

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