Microbiological contamination and quantitative microbial risk assessment of Salmonella in street-vended ready-to-eat papaya under informal tropical vending conditions

Abstract

Ready-to-eat fresh fruits sold in informal urban settings in West Africa are highly susceptible to microbial contamination because of poor hygiene and uncontrolled storage conditions. This study assessed the microbiological quality of street-vended sliced papaya (Carica papaya) in urban Benin and estimated the associated Salmonella infection risk using quantitative microbial risk assessment (QMRA). Hygienic practices were documented among 135 vendors, while consumption data were collected from 437 informants. A total of 135 papaya samples were collected from street vendors in three major cities of Benin, namely Abomey-Calavi, Cotonou, and Porto-Novo. The samples were analyzed for total viable counts, Escherichia coli, fecal coliforms, coagulase-positive staphylococci (CPS), and Salmonella spp. Poor hygiene practices, namely the use of non-potable water, inadequate utensil sanitation, bare-hand handling, and prolonged ambient storage (up to 16 h at ca. 30 °C), were common. High contamination levels were observed: E. coli was detected in 75.6% of samples (3.4 log CFU/g), fecal coliforms reached 6 log CFU/g, and CPS was detected in all samples (5.5 log CFU/g). Salmonella spp. was confirmed in 3% (4/135) of samples. QMRA estimated a median daily probability of Salmonella infection (P50) of 1.33E-03 during the high availability period of papaya, with 90% of simulated outcomes ranging from 5.47E-05 to 2.90E-02 (P5-P95). The P50 estimate corresponded to an annual burden of 244,370 cases per million consumers. Lower risk levels were estimated during the low availability period. A scenario analysis indicated that continuous refrigerated storage during vending could reduce the infection risk by 91.1%. These findings highlight the value of combining field microbiological data with probabilistic risk assessment to guide context-specific food safety interventions in the region.