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Title: Occurrence of enteric pathogens on fresh produce grown on irrigated soils

Author
item ABAKPA, G. - AHMADU BELLO UNIVERSITY
item UMOH, V. - AHMADU BELLO UNIVERSITY
item AMEH, J. - AHMADU BELLO UNIVERSITY
item YAKUBU, S. - AHMADU BELLO UNIVERSITY
item KWAGA, J. - AHMADU BELLO UNIVERSITY
item Ibekwe, Abasiofiok - Mark

Submitted to: British Microbiology Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2014
Publication Date: 12/8/2014
Citation: Abakpa, G.O., Umoh, V.J., Ameh, J.B., Yakubu, S.E., Kwaga, J.K., Ibekwe, A.M. 2014. Occurrence of enteric pathogens on fresh produce grown on irrigated soils. British Microbiology Research Journal. 6(1):13-23.

Interpretive Summary: Developing countries are disproportionally affected by lack of access to clean water; hence the re-use of wastewater for crop irrigation offers a very promising alternative. Wastewater reuse in developing countries is thought to be responsible for approximately 4 billion cases of diarrhea that cause about 2.2 million deaths a year according to the World Health Organization. The World Health Organization also estimated that in Nigeria, about 200,000 deaths per annum is associated with food borne pathogens. In this study, fresh produce irrigated with wastewater on manure treated soils were assessed for the prevalence of Escherichia coli O157, Salmonella Spp and Vibrio cholerae in Kano state, Nigeria. Fresh produce grown in the manure treated soils were carrots, cabbage, cucumber, lettuce, tomatoes, spinach, green peas and spring onions. Our results showed that Salmonella spp and Escherichia coli O157 were the most detected pathogens, and these were mainly from fresh produce. The use of untreated irrigation water in vegetable production in Nigeria may represent a significant route of transmission of diarrheal pathogens to humans and hence represents a public health risk. This information will be of interest to produce growers, government and non-government organizations, as well as livestock producers in both developed and developing countries.

Technical Abstract: Aims: To assess the potential health risks of fresh produce grown on irrigated soils treated with manure in Kano State, a large produce region in Nigeria. Methodology: Fresh produce irrigated with wastewater on manure treated soils were assessed for the prevalence, serotype distribution and toxigenicity of Escherichia coli O157, Salmonella spp and Vibrio cholerae in a large produce region in Nigeria. A total of 230 samples obtained from five designated produce locations were examined using selective isolation method with prior enrichment. Fresh produce comprised carrots, cabbage, cucumber, lettuce, tomatoes, spinach, green peas and spring onions. Suspect isolates were identified and characterized by conventional biochemical methods and Microbact 24E (Oxoid, UK) kit. Confirmed isolates were serotyped and E. coli O157 and Vibrio cholerae O1 were assayed for their toxigenic potentials using the Reverse Passive Latex Agglutination kit. The enterotoxigenicity of Salmonella spp was determined by detection of stn gene using polymerase chain reaction (PCR) techniques. Results: Results obtained showed that overall, Salmonella spp and Escherichia coli O157 had the highest prevalence of 17.0% and 10.9%, respectively. Both were most commonly detected from fresh produce. The serotypes of Salmonella detected include Salmonella typhi (51.3%), Salmonella paratyhpi (20.5%) and Salmonella typhimurium (28.2%); strains of Vibrio cholerae O1 detected include Vibrio cholerae O1 of the Ogawa, Inaba and the Hikojima serotypes. Conclusion: The use of untreated irrigation water in vegetable production represents a significant route of transmission of diarrheal pathogen to humans and hence represents a public health risk. We recommend proper and adequate wastewater treatment before use.