Purpose: To estimate the probability of transmission of S. enterica, C. sakazakii, L. monocytogenes, and E. coli O157:H7 to housefly eggs and F1 generation adults after parental flies consumed a contaminated meal.
Methods: Adult flies were given liquid food containing low, medium, and high concentrations of each bacterium. Using a PCR detection method followed by isolation of the pathogen on specific media, the presence of pathogens was assessed on surface-disinfected eggs laid by parental flies and on body surfaces and alimentary canals of newly emerged F1 adults.
Results: The probability of transmission of pathogens to housefly eggs was higher when parental flies ingested food containing medium bacterial loads. Cronobacter sakazakii was 16, 6, and 3 times more likely to be transmitted to housefly eggs than S. enterica, E. coli O157:H7, and L. monocytogenes, respectively. Only S. enterica and C. sakazakii were transmitted to F1 adults and their presence was 2.4 times more likely on their body surfaces than in their alimentary canals. The highest probabilities of finding S. enterica (60%) and C. sakazakii (28%) were observed after parental houseflies ingested food containing medium and high concentrations of each pathogen, respectively.
Significance: Foodborne bacteria ingested by adult houseflies are transmitted to the housefly’s progeny, giving another insight into the transmission capabilities of flies. To better protect public health, it is important to highlight the need for effective implementation of preventative pest management plans in food facilities to minimize the hazard posed by the presence of flies.