Cryptosporidium contamination of lettuce and associated risk factors at some production, markets and street food vendor sites in urban and Peri Urban Kumasi
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Date
2008-08-19
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Abstract
Wastewater has been used for several decades in agriculture in both the industrialized and developing countries including Ghana due to the scarcity of clean water for irrigation. However, its use may pose danger to farmers as well as consumers because it contains pathogens including Cryptosporidium. This study investigated the Cryptosporidium contamination of lettuce and associated risk factors at production, markets and street food vendor sites in urban and peri urban Kumasi.
A total of 596 lettuce and 192 water samples were collected between October 2006 and February 2007 for the dry season and between April and July 2007 for the wet season. The samples were washed and centrifuged using the KVL protocol to isolate the oocysts. Slides were prepared from the isolated samples and allowed to air-dry. The slides were examined under the light microscope using the oil immersion lens after staining using the Ziehl-Neelsen's technique. Structured questionnaires, focus group discussions and observation check lists were used to assess the risk factors at all stages of sampling and the statistical package for Social Scientists (SPSS) version 13.0 was used for testing the various statistical relationships between and within variables.
Cryptosporidium oocysts recovered from the irrigation water and farm lettuce had a mean of between 0.25-0.88/L and 0.15-0.40/10g wet weight respectively whiles refreshing water (water used to keep the vegetables fresh) and market lettuce had a mean of between 0-0.10/L and 0-0.08/10g wet weight respectively. However, no oocyst was counted on the chopped lettuce leaves sold to consumers at the street food vendor sites. The number of Cryptosporidium oocysts decreased by 100% from the farm to the street foocl vendor level. Considering the fact that the farms studied depended mainly on wastewater from hand dug wells for irrigation, education should be intensified on the need to use sanitizers to wash vegetables before consumption.
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A thesis presented to the Department pf Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, in partial fulfilment of the requirements for the award of the degree of Master of Science ((Environmental Science), 2008