Effect of sunlight on the survival of Salmonella on surfaces.

AIMS: To investigate the effect of simulated full-spectrum tropical sunlight on the survival of Salmonella in droplets on surfaces.

MATERIALS AND

RESULTS

The survival on surfaces of three Zambian strains of Salmonella enterica serovars Enteritidis and Heidelberg was compared with that of a strain of S. enterica serovar Enteritidis phage type (PT) 4 with known characteristics which had been isolated from poultry in the UK. Samples were taken from surfaces every hour for 3 h and after 24 h exposure in either dark or 12 h light/12 h dark cycle conditions. Differences were analysed for significance using a one-way analysis of variance (anova). Results show that there were a significantly higher number of cells surviving on surfaces after 24 h in the dark when compared with populations exposed to a 12 h light/12 h dark cycle. Significantly more cells also survived exposure to sunlight under dirty than clean conditions.

CONCLUSIONS

Exposure to sunlight results in a significant decrease in numbers of Salmonella on surfaces.

SIGNIFICANCE AND IMPACT OF THE STUDY: Under field conditions exposure of contaminated surfaces to sunlight could be used in place of chemical methods of control as a cheaper way to reduce Salmonella contamination of surfaces.