Prevalence, risk factors and bacterial causes of bovine mastitis in southern Ethiopia

Abstract

Mastitis is one of the most economically important diseases in dairy farms worldwide. It is particularly important in Ethiopia where no routine prevention and control practices are in place. This cross-sectional study was carried out between October 2017 and June 2018 to estimate the prevalence of mastitis, identify the associated risk factors and isolate bacterial causes in dairy farms located in southern Ethiopia using standard microbiological methods and questionnaire survey. A total of 686 lactating cows which were found in 122 selected dairy farms were investigated by physical examination and California mastitis test. The overall cow-level prevalence of mastitis was 54.2% (95% CI: 50.5 – 57.9%). Based on the study site, the prevalence was 55.7% in Hawassa, 54.3% in Arsi Negele, 52.6% each in Wondo Genet and Wolayta Soddo towns with no significant (p > 0.05) difference among the sites. The majority of mastitis cases were subclinical (48.1%) while the clinical mastitis was only 6.1%. Of the 122 herds tested, 109 (89.3%; 95% CI: 82.1 – 93.9%) had at least a cow positive for mastitis. The study showed that high parity number (OR = 1.6; p = 0.015), flat (OR = 4.5; p <0.001) and round (OR = 2; p <0.001) teat end shape, history of mastitis in preceding lactation (OR = 3.3; p <0.001), and slightly (OR = 3.5; p < 0.001), moderately (OR = 4.9; p < 0.001), and very dirty (OR = 9.2; p < 0.001) udder and legs were the major risk factors which are significantly associated with higher prevalence of mastitis. Based on the available media and reagents, the major bacteria isolated from subclinical mastitic milk samples were Staphylococcus spp. (57.3%), Streptococcus spp. (18.6%), E. coli (17.3%) and Bacillus spp. (7.5%) in order of their abundance. The present study revealed a high prevalence of mastitis, particularly the subclinical one, and the associated risk factors. Enhancing the awareness of dairy farmers, regular screening of cows for subclinical mastitis, proper treatment of the clinical cases, improving the hygienic condition of the cows, and culling of chronically infected cows are critically important to prevent and control bovine mastitis.
 Keywords: Mastitis, Prevalence, Risk factors, Southern Ethiopia

Bovine Mastitis: Prevalence, Risk Factors, and Bacterial Pathogens Isolated in Lactating Cows in Gamo Zone, Southern Ethiopia

“…Overall, the quarter-level prevalence of 7.94% recorded in this study was in agreement with a report of 8.03% 17 in West Harerghe, but lower than the 29.4%, 1 45.68%, 5 54.75%, 11 21.48%, 20 29.04%, 21 and 39.4% 36 found in other studies. Compared to other quarters, the right rear showed the highest proportion of infection (9.9%), followed by the left rear (9.7%).…”

“…The current study revealed an overall prevalence of 17.1% in 422 lactating cows in and around Arba Minch, comparable with the 16.1% prevalence reported in Tullo, 19 19% in Addis Ababa, 25 23% in West Harerghe, 17 but higher than the 6% 35 in Debrezeit, 5.1% 3 in and around Wolaita Sodo, and 9.9% 30 in Ambo, central Ethiopia. On the other hand, the current result was much lower than the recent findings of Amin et al, 5 Tesfaye and Abera, 36 and Abebe et al, 1 who reported 49.2% in and around Haramaya, 60.65% in Jimma, and 54.2% in southern Ethiopia, respectively. Variations between this and other reports of prevalence might be due to the complex nature of mastitis and its occurrence through the interactions of several factors, such as management and husbandry practices, environmental conditions, animal-level factors, and causative agents.…”

“…The most predominant mastitis causing bacterial pathogens isolated in this study was S. aureus (42.6%), followed by Streptococcus spp. (26.2%), which is in line with Abebe et al 1 and Kumbe et al 20 The predominance of these two bacterial species could be through constant colonization of teats, as they are commensals to the skin. They can then get ready entry to the teat canal while milking or suckling and can be transmitted from quarter to quarter and cow to cow during milking.…”

“…(26.2%) were the second–most predominant bacterial species isolated during this study. This is in line with Abebe et al 1 and Kumbe et al, 20 who reported 18.6% and 21.29%, respectively, though higher than the 7.18% of Mekibib et al 22 and 9.1% of Tesfaye and Abera, 36 where Streptococcus spp. were the third–predominant bacterial species.…”

“…The prevalence of subclinical mastitis (15.2%) was higher than that of clinical mastitis (1.9%) in the current study, which is in the line with several earlier reports from various parts of Ethiopia. 1 , 2 , 5 , 36 , 39 , 40 As reported by Seegers et al, 31 the subclinical form is 15–40 times as prevalent as the clinical form, is of long duration and of high economic consequence, and usually precedes the clinical form. As a result of the defense mechanism of the udder, which tends to reduce the severity of the disease, the subclinical form of mastitis has also been suggested to be higher than that of clinical mastitis.…”