Health risks associated with urban farming: Cryptosporidium and non-sorbitol fermenting Escherichia coli as indicator organisms in Dar Es Salaam, Tanzania

A DISSERTATION SUBMITTED IN PARTIAL FULTILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN PUBLIC HEALTH AND FOOD SAFETY OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.

Cryptosporidium and enterohaemorrhagic (EHEC) Escherichia coli O157:H7 are two important pathogens in humans among other common representative zoonotic pathogens carried by animals especially cattle and are discharged through their faeces into the environment. With the increasing practice of urban farming, the risk of transmission of these pathogens to humans is increased. The study aimed at determining the public health risks associated with integrated urban farming using Non-Sorbitol Fermenting (NSF) E. coli and Cryptosporidium as indicator organisms in Dar es Salaam, Tanzania. A questionnaire survey was used to collect data on knowledge and practices associated with urban farming. Livestock manure, leafy vegetables and fish samples were collected to isolate and identify NSF E. coli and detect Cryptosporidium oocysts. Confirmed isolates on biochemical tests were subjected to antimicrobial resistance testing and genetic similarities of the isolates were determined using Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR). A total of 156 samples including 63 cattle faeces, 26 poultry faeces, 53 vegetables and 16 fish samples were tested for presence of Cryptosporidium and NSF E. coli. Out of 156 samples, 36 (23.1%) yielded NSF E. coli and 16 (10.3%) had Cryptosporidium oocysts. Five samples (3.2%) had both Cryptosporidium oocysts and NSF E. coli including four from vegetables and one from fish. Out of the 48 isolates of NSF E. coli tested for antimicrobial resistance to six antimicrobial agents, 25 (52.1%) were resistant to at least one antimicrobial agent and of these, 12 (48.0%) showed Multidrug Resistance. ERIC-PCR profiles of the 47 isolates from different sources showed genetic similarities (74.5% - 100%) with nine major clusters identified (I - IX) determined at 90% threshold level of similarity. These results showed potential health risks that would emanate from urban integrated farming and hence the need to monitor and improve husbandry practices used in urban farming.