Surveys of vegetables in the southern and northern growing regions of mainland Tanzania and Zanzibar during 1997 and 1998 indicated the presence of three wilt pathogens of tomato. Clavibacter michiganensis subsp. michiganensis (cause of bacterial canker) was isolated from wilting plants in the southern highlands and Lushoto District (Tanga Region, north) on selective King's medium B with polymyxin B (1). The identity of the isolates was confirmed by cultural, morphological, and biochemical characteristics and a plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA) kit (Pathoset 113-08, Adgen, Auchincruive, U.K.). Pathogenicity was confirmed by host inoculation. In addition, the bacterium was detected directly by the same methods in several sources of seed, including commercial farmers' saved seed and seed extracted from infected plants. Of 61 tomato seed lots tested, 18 samples were positive. Ralstonia solanacearum (cause of bacterial wilt) was isolated from tomato and potato by semiselective media and detected directly in stem and tuber tissues, respectively, by polymerase chain reaction and ELISA (4) in all vegetable-growing areas surveyed. In 1998, R. solanacearum was detected for the first time in Zanzibar on tomato and eggplant. Pathogenicity was confirmed by inoculation on and reisolation from tomato seedlings of cv. Money Maker. Only biovar 3 (2) occurred in tomato. Biovar 3 also was found in midaltitude potato. Biovar 2 has been found only in potato plants grown above 1,500 m. Pseudomonas corrugata (cause of pith necrosis) was isolated from tomato on semiselective media at only one location. From wilted tomato plants in the southern highlands, 38% of samples tested positive for C. michiganensis subsp. michiganensis and ≈ 10% for R. solanacearum. Of samples collected from the northern highlands, 43% tested positive for R. solanacearum. Wilt incidence of ≈35% was observed in tomato fields where the bacterial wilt pathogen was isolated in the northern highlands compared with gt;90% incidence and almost total crop loss in tomato fields of the southern highlands infected with bacterial canker. Although all three pathogens caused systemic wilt of plants, bacterial canker occasionally caused downward turning of lower leaves, unilateral wilting, and marginal necrosis of leaflets as well as fruit spotting. In general, wilts caused by C. michiganensis subsp. michiganensis, R. solanacearum, and P. corrugata were not readily differentiated in Tanzania prior to this research. Plants with pith browning had often been assumed to be infected by P. corrugata, until R. solanacearum was isolated (3) frequently from such plants. References: (1) Anonymous. OEPP/EPPO Bull. 22:219, 1992. (2) A. C. Hayward. J. Appl. Bacteriol. 27:265, 1964. (3) J. B. Jones et al., eds. 1991. Compendium of Tomato Diseases. The American Phytopathological Society, St. Paul, MN. (4) S. Seal and J. G. Elphinstone. Pages 35–57 in: Bacterial Wilt. The Disease and Its Causative Agent, Pseudomonas solanacearum. A. C. Hayward and G. L. Hartman, eds. CAB International, Wallingford, U.K. 1994.
In order to improve diagnostic services and plant quarantine capabilities in Tanzania, the techniques of semi-selective media, the BACTID system, metabolic profiling (Biolog), indirect enzyme-linked immunosorbent assays (ELISA) and polymerase chain reaction (PCR) were assessed for suitability with the existing facilities for the diagnosis and detection of plantpathogenic bacteria of vegetables. Field-collected samples as well as farmers' own and commercial germplasm were used in studies involving Ralstonia solanacearum, Clavibacter michiganensis subsp. michiganensis and Xunthomonas campestris pv. vesicatoria in Solanaceae and X . c. pv. cumpestris in Brussicaceae. Each of the techniques was used successfully with one or more of the target pathogens; each had advantages depending on the speed, sensitivity and specificity required, as well as the costs of carrying out the diagnosis. However, constraints emerged relating to the use and disposal of materials such as plastic Petri dishes and toxic substances. The more familiar underlying constraints of high cost and poor availability of consumables and erratic water and electricity supply continued to present problems. These problems will be discussed in relation to the development of an integrated and sustainable approach to the provision of routine diagnostic services.
Risky practices among food handlers are a major contributing factor to food contamination with resultant morbidities and mortalities among food consumers. This study aimed at investigating awareness on marine fish associated diseases and risk practices among marine fish value chain actors in Zanzibar (fishermen, vendors and consumers) and witness if they could contribute on marine food contamination. This was a cross-sectional research study conducted to asses awareness on marine fish associated diseases and risk practices between February and March 2019. The study utilized structured questionnaire that were administered to 256 respondents. Stratified random sampling was used to select 8 out of 207 fish landing sites from five Zanzibar regions followed by random selection of twenty-four villages, three from each fish landing sites. Pilot study yielded Cronbach’s alpha value of > 0.755 for validity and reliability on questions of awareness and practices. Risk practices assessed were- handwashing after toilet, consumption of spoiled fish, health checkup as well as information sharing practice. Scores of respondents’ answers were summed up and cut off mean was calculated. The results were then used to calculate chi-square and p-values. Odds ratio was also calculated to asses likelihood of association between variables. Data was processed by SPSS version 6.0. Statistical significance was determined at a probability of p≤0.05. Majority (92%) of the population under study had access to mobile phones. 64.1% were aware and 35.8%) males were 1.6 times more aware than females (p<0.05). 30-39 age group and Secondary school group were 3 times more aware than 20-29 group and Primary school group respectively. 74% of the population find it worth sharing information with others (p<0.001). Only 50%) of fishermen had regular health checkup compared with 72% of fish vendors and 85% of fish restaurant workers. Majority (64.7%) of fishermen admitted washing hands overboard without soap or any washing facility and differed significantly with other ways of relieving themselves after toilet (p<0.01). Restaurants are 10 times and 2.4 times more likely to AVOID sell of spoiled fish than fishermen and vendors respectively. Greed for money was pointed as reason for selling spoiled fish by 40% of respondents. 28% of fish consumers regularly consume spoiled fish. Malpractices investigated in this study may all contribute to health risks. High awareness and knowledge on marine fish associated diseases in Zanzibar community were not interpreted into appropriate food handling behavior. Factors that could contribute to the risky practice could include negligence, optimistic bias and illusion of control. Results of this study entail that it is critical for any food safety training conducted in Zanzibar to incorporate behavior based training that will improve food handling practices throughout the food value chain.
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