Molecular and Seroepidemiology of Mycobacterium avium subsp Paratuberulosis in Dairy Animals
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Date
2012
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
The present study has taken up the molecular and seroprevalence of bovine
paratuberculosis in dairy animals, the impact of managemental risk factors on the occurrence of
Mycobacterium avium subsp. paratuberculosis (MAP) and diagnosis of the disease. The work was
carried out with varying environmental factors located in and around Namakkal districts of Tamil
Nadu between 2009 - 2012. The investigation was done on 500 animals comprising 378 white cattle
and 122 buffaloes. Management practices like low sanitation of periparturient cows udder
contaminated with manure, dirty calving area, history of Johne’s Disease (JD) in the herd, had an
influence on the prevalence of disease.
A total of 500 sera, milk and faecal samples were collected and subjected to MAP antibody
and antigen detection. The seroprevalence of MAP antibody was detected 57 (15.07 per cent) and
15 (12.29 per cent) in cows and buffaloes with an overall seroprevalence of 14.4 per cent of JD in
dairy animals based on the diagnostic test ELISA. Breedwise seroprevalence 32 (14.74per cent), 20
(18.69 per cent), 3 (12 per cent), 2 (6.89 per cent) in Jersey cross breed, Holstein Friesian cross
breed, Red Dane cross breed, Non-descript white cattle and 7 (8.86 per cent), 8 (18.60 per cent) in
Nondescript and Murrah graded buffaloes respectively. There was no statistical significant difference
(P>0.05) within species and breeds. Higher seroprevalence was observed in bovines between 4.5 -
6.5 years of age and above 6.5 years of age when compared to less than 4.5 years of age. The
seroprevalence of MAP was higher in pleuriparous animals (16.98 per cent) when compared to
primiparous animals (7.4 per cent). There was significant difference at (P>0.05) between
pleuriparous and primiparous animals. The stage of lactation does not have impact on MAP
seroprevalence (11.31 per cent, 17.79 per cent and 15.51 per cent) in early, middle and late lactation
of dairy animals respectively. Out of 500 faecal and milk samples screened by PCR and Ziehl-Neelsen
staining technique in which 82 (16.40 per cent), 59 (11.80 per cent) and 20 (4 per cent) animals were
found to be positive for MAP. The per cent positivity by faecal, milk PCR and Ziehl-Neelsen staining
technique in cows were 16.93 and 14.75, 12.43 and in buffaloes 9.83, 4.23 and 3.27 respectively. The
chi-square analysis revealed a highly significant difference (P<0.01). The value of kappa statistic of
faecal PCR in agreement with that of mlk PCR, ELISA and Z-N staining were 0.6136, 0.5705 and
0.3504 in bovines. The PCR amplified products of IS900 gene of MAP were sequenced by dideoxy
chain termination method and by blast analysis the field isolates were found to be having hundred
per cent homology to strain K-10 of MAP. Soil pH was not identified as a significant risk factor, but
contamination of udders of periparturient cows with manure (OR = 21.2, P = 0.00), lack of
cleanliness in the calving area (OR = 3.8, P = 0.06) and history of having suspected cases of Johne's
disease in the animals (OR = 24, P = 0.03) were significantly associated with the infection status of
dairy animals in Namakkal.