Agriculture Reference
In-Depth Information
Preharvest Contamination of Crops
The majority of pathogens implicated in fruit-associated outbreaks are enteric micro-
organisms that originate from the gut of warm-blooded animals. Hence infectious
agents acquired from the consumption of contaminated fruit are transmitted via the
fecal-oral route. Transmission of pathogens in agricultural settings is distinctive with
respect to time elapsed subsequent to shedding, the nature of implicated vectors, and
distance from source. A schematic representation of potential sources of infectious
microorganisms and their mode of transmission in fruit production systems is provided
in Figure 2.1 .
The risk of contamination with enteric microorganisms introduced to the produc-
tion environment is clearly infl uenced by the nature of the plant. Melons, for example,
are generally grown in intimate contact with the ground where the risk of direct
adsorption of soil microorganisms is high (Materon and others 2007). Evidence of
biofi lm formation by
Salmonella
spp. in melon rinds suggests that some enteric micro-
organisms may be capable of growth in the fi eld (Annous and others 2005). In contrast,
aerial fruit such as apples develop in an environment where direct contact with con-
centrated sources of microorganisms is less common and opportunities for growth are
likely rare.
Contamination via Animal Wastes
Human pathogens can be introduced to fruit production systems through animal
feces from wildlife or livestock or by the application of manures or sewage sludges
Wind
Dust
Insects
Feces from
livestock, wildlife
Harvesting
equipment
Irrigation
water
Human contact
Urban, agricultural
pollution
Postharvest
handling
Animal fertilizers
Figure 2.1.
Potential sources of human pathogens and their transmission in fruit pro-
duction systems.
