No abstract

Subclinical mastitis (SCM) represents a major proportion of the burden of mastitis. Determining somatic cell count (SCC) and electrical conductivity (EC) of milk are useful approaches to detect SCM. In order to correlate grades of SCM with the load of five major mastitis pathogens, 246 milk samples from a handful of organized and unorganized sectors were screened. SCC (>5 × 10(5)/mL) and EC (>6.5 mS/cm) identified 110 (45 %) and 153 (62 %) samples, respectively, to be from SCM cases. Randomly selected SCM-negative samples as well as 186 samples positive by either SCC or EC were then evaluated for isolation of five major mastitis-associated bacteria. Of the 323 isolates obtained, 95 each were S. aureus and coagulase-negative staphylococci (CoNS), 48 were E. coli and 85 were streptococci. There was no association between the distribution of organisms and (a) the different groups of SCC, or (b) organised farms and unorganised sectors. By contrast, there was a significant difference in the distribution of CoNS, and not other species, between organized farms and unorganized sectors. In summary, bacteria were isolated irrespective of the density of somatic cells or the type of farm setting, and the frequency of isolation of CoNS was higher with organized farms. These results suggest the requirement for fine tuning SCC and EC limits and the higher probability for CoNS to be associated with SCM in organized diary sectors, and have implications for the identification, management and control of mastitis in India.

Reliable diagnostic tests that are able to distinguish infected from vaccinated animals are a critical component of regional control programs for foot-and-mouth disease (FMD) in the affected countries. Non-structural protein (NSP) serology based on the 3ABC protein has been widely used for this purpose, and several kits are commercially available worldwide. This report presents the development of a 3ABC-antigen-based indirect ELISA, employing a peroxidase-conjugated protein G secondary antibody that can detect antibodies from multiple species. Recombinant 3ABC protein was expressed in insect cells and purified using affinity column chromatography. Using this protein, an indirect ELISA was developed and validated for the detection of NSP antibodies in serum samples collected from animals with different status of FMD. Diagnostic sensitivity and specificity were found to be 95.8 (95 % CI: 92.8-97.8) and 97.45 % (95 % CI: 94.8-99.0), respectively. The in-house ELISA compared well with the commercially available prioCHECK FMDV NS-FMD kit, with a high agreement between the tests, as determined by the kappa coefficient, which was 0.87. The in-house ELISA showed higher sensitivity for detecting vaccinated and subsequently infected animals, when compared to the reference test. Both of the tests were able to detect NSP antibodies as early as 7-8 days after experimental infection.