EPIDEMIOLOGICAL AND MICROBIOLOGICAL STUDIES ON CALF DIARRHOEA AND PNEUMONIA IN DEBRE ZEIT, HOLETA AND MUKE TURI DAIRY FARMS, ETHIOPIA
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2008-06
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Abstract
A six-month prospective study was conducted in Holeta, Debre Zeit and Muke Turi dairy farms between November, 2007 and April, 2008 with the major objective of determining both the cumulative incidences of neonatal calf diarrhoea (NCD) and pneumonia. In addition, determination of calf mortality rates, identification of agents of NCD, pneumonia and potential risk factors as well as determinations of the antibiotic sensitivity patterns of the bacterial pathogens.
Cluster sampling was used. A total of 429 calves, from seven intensive dairy farms were followed up. The farms were described using a pre-tested questionnaire and personal observations. Study calves in each farm were visited weekly and appropriate test samples collected from diarrhoeic and pneumonic cases.
Antigenic ELISA test was utilized to identify four major enteropathogens (rotavirus, coronavirus, Cryptosporidium parvum and E. coli K 99). Standard isolation techniques were used to identify Salmonella and other strains of E. coli from diarrhoiec cases (n=112) and Pasteurella species, Mannheimia species and Haemophilus somnus from pneumonic cases (n=28). In addition, the antimicrobial susceptibility pattern of the bacterial isolates was performed.
The cumulative incidences (CI) of NCD in Holeta, Muke Turi and Debre Zeit dairy farms were 0.41, 0.63 and 0.37, respectively. While for pneumonia, they were 0.12, 0.09 and 0.07, respectively. Higher CI of NCD was recorded from Farm 1 with 0.65 followed by Farm 3 with 0.63. The least CI was observed in Farm 2 of 0.11. Highest calf pneumonia was observed in Farm 6 followed by Farm 1. No calf pneumonia was observed in Farm 5.
Associations of the potential risk factors for NCD and pneumonia revealed significant results with young ages. Significant positive hazard rates of both diseases were recorded in young age-groups. Other risk factors (sex of calves, breed, etc) were not significantly associated with these diseases.
The ELISA results showed that, C. parvum was prevalent in the majority of calves with diarrhoea followed by rotavirus, coronavirus and E. coli K 99. The bacterial isolates were 91.96 % of E.
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coli other than the strain K 99 and 24.11 % of Salmonella species. Nasal swab samples taken for isolation of Pasteurella and Mannheimia species revealed 42.85 % positive reactors for Pasteurella and Mannheimia species. No Haemophilus somnus was isolated.
Antimicrobial sensitivity test was performed for all the bacterial isolates. Norfloxacillin and gentamycin were highly sensitive and clindamycin the least sensitive. The susceptibility to other antimicrobial agents varied by different bacterial isolates, but resistance to all antimicrobials used were observed in most of the isolates.
In conclusion, NCD is a serious problem among dairy calves followed by pneumonia. Both of them were influenced by the age of calves. These diseases have complex etiopathogenesis. Therefore, further epidemiological and microbiological studies of NCD and pneumonia with aims of designing and implementing appropriate prevention and control strategies are strongly recommended. In addition, the higher rate of antimicrobial resistance necessitates the strategic use of the drugs.
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Calf diarrhoea, Calf pneumonia, rotavirus, coronavirus, Cryptosporidium parvum