Effect of irrigation water and processing on the microbial quality of lettuces produced and sold on markets in Dakar (Senegal)

Urban Farm DB summary

Lettuces grown at two urban agricultural sites (Pikine and Patte d'Oie) near Dakar, Senegal, and sold in local markets were tested for microbial contamination linked to irrigation water. Salmonella spp. positivity was 6% at Pikine and 7% at Patte d'Oie farm sites, with lettuces irrigated by shallow 'Ceanes' groundwater most contaminated at both sites (8%), compared to wastewater irrigation (4% at Pikine) and well water (5% at Patte d'Oie); at market, Salmonella was isolated at every marketplace surveyed, with higher rates around Patte d'Oie (9% at Grand Yoff, 11% at Dalifort) than around Pikine (4% at Zinc, 2% at Sham) or the control site Rufisque (2%), and lettuces washed with Ceanes water before sale were more contaminated than those rinsed with tap water. Reusing wastewater for irrigation is presented as an alternative to animal manure, with the microbial contamination risk significantly reducible by washing vegetables with tap water before sale.