The prevalence and factors influencing occurrence of Bovine Fasciolosis in the Kafue and Zambezi river basins

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Phiri, Malata Andrew
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In Zambia, very little is known on the prevalence and impact of fasciolosis especially in cattle of the poor traditional farmers most of whom live along the Kafue and Zambezi flood plains. The main aim of this study, consisting of four components, was to determine the prevalence and factors influencing the occurrence of bovine fasciolosis in the Kafue and Zambezi rivers basins. In the prevalence study carried out from March to December 2002, 841 cattle from selected abattoirs in Central, Southern and Western provinces were inspected and 677 faecal samples collected and analysed for fluke eggs. 53.3% of cattle were positive at meat inspection while 48.7% on coprological examination. Cumulative prevalence of 59.4% (n=677) was recorded using both methods. Significant differences in the prevalence were found among the slaughterhouses (p<0.001), age groups (p<0.050) and origin (p<0.001) of the examined cattle. These results indicate that Fasciola gigantica infection is an important condition in cattle and that a high number of livers are condemned or trimmed because of this infection. Seasonal pattern of bovine fasciolosis was determined by liver inspection and coprological examination of 288 cattle at slaughter from March 2002 to February 2003. The post rainy season had the highest prevalence rate at liver inspection and coprological examination (41.3% and 45.0%, respectively) while the lowest were in the cold and dry season (24.8% on both methods). The distribution of fluke eggs was significantly different (p<0.001) among seasons with the rainy season having higher egg counts (median=146) than both the cold and dry season and the hot and dry season (median=118). Based on the results of faecal egg examination and slaughterhouse studies, it was found that even though F. gigantica is present throughout the year in cattle in Zambia, it is highest in the post-rainy season. A total of 70 condemned and 32 non-condemned livers were collected at random and dissected to assess liver fluke burden. Significantly higher (t=19.33, p<0.001) flukes were found in condemned livers (mean=1.70, SD=0.59) than in non-condemned livers (mean =0.07, SD =0.25). Liver flukes were found in 9.4 % (n=32) of the non-condemned livers. Fluke egg counts from animals with condemned livers were significantly higher (x^=84.24, p<0.001) than in animals with non-condemned livers. However, there was no correlation (r=0.003, p=0.978) found between egg counts and the number of flukes. Between August and October 2003, freshwater snails representing six species were collected from the Kafue river basin. Out of the 984 snails collected and shed for infection, 135 were positive with larval trematodes representing 13.7% prevalence. Most trematode infections were recorded from Lymnaea natalensis (42.8 %) which harboured four of the five morphologically different cercariae found. Gymnocephalous (family Fasciolidae) and Longifurcate-pharyngeate distome (LPD) (families Strigeidae and Diplostomatidae) were the commonest cercariae types recorded while brevifurcate-apharyngeate distome (BAD) (family Schistomatidae) was the least common. Critical determinants of this infection were found to be distance of settlements and/or cattle kraals as well as the number of animals in nearby homesteads and presence of Lymnaea snails. This study strongly shows that fasciolosis caused by F. gigantica is a major constraint of cattle production in the Zambezi and Kafue river basins throughout the year and favourable factors are available to introduce and maintain the infection.
Fasciola and Fascioliasis -- Zambia , Animals--diseases -- Kafue and Zambezi river basins