Specific surveys of the air for Aspergillus fumigatus were carried out in rural and urban situations over a 2-year period. Overall, low concentrations of spores were recorded with a higher incidence during the 'winter' months. Counts in the open air and in a hospital ward showed similar fluctuations, the indoor counts being consistently lower. Plant debris in the form of compost heaps and stacks of hay and straw baled with a high moisture content in which self-heating occurs, produces large numbers of spores which may be liberated into the air causing high but localized counts if disturbed. The widespread distribution of decaying leaves following leaf fall represents a potential source of smaller concentrations of spores but over a much larger area. This availability of decaying plant debris with high water content fullils the growth requirements o^ Aspergillus fumigatus and is the probable explanation of its winter seasonaiity.

Early studies confirmed Bacillus anthracis in emesis and feces of flies under laboratory conditions, but there is little empirical field evidence supporting the roles of flies in anthrax transmission. We collected samples during outbreaks of anthrax affecting livestock and native and exotic wildlife on two ranches in West Texas (2009-2010). Sampling included animal carcasses, maggots, adult flies feeding on or within several meters of carcasses, and leaves from surrounding vegetation. Microbiology and PCR were used to detect B. anthracis in the samples. Viable B. anthracis and/or PCR-positive results were obtained from all represented sample types. Genetic analysis of B. anthracis samples using multilocus variable number tandem repeat analysis (MLVA) confirmed that each ranch represented a distinct genetic lineage. Within each ranch, we detected the same genotype of B. anthracis from carcasses, maggots, and adult flies. The results of this study provide evidence supporting a transmission cycle in which blowflies contaminate vegetation near carcasses that may then infect additional browsing animals during anthrax outbreaks in the shrubland environment of West Texas.

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The contrasting patterns both in the pollen records and land-use changes between the three sites emphasize the need for regional data. The predictive models achieved a high degree of explanation enabling pollen season severity to be forecast with high confidence shortly before the start date.

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