Sero-epidemiological survey of egg-transmitted bacterial diseases in broiler breeder flocks in Korea

The purpose of this study was to investigate the immune status or infection rates for primary egg-transmitted bacterial diseases such as pullorum disease-fowl typhoid (PD-FT), Mycoplasma gallisepticum (MG) infection, and Mycoplasma synoviae (MS) infection among 70 broiler breeder flocks throughout Korea between July 2011 and August 2011. The sero-prevalence of flocks and individual chickens for PD-FT was 50.0% and 9.7%, respectively. The prevalence of PD-FT sero-positivity increased over time from rearing to advanced age period. The sero-positive rate of flocks and individual chickens for Salmonella Gallinarum 9R (SG 9R) was 95.7% and 83.6%, respectively. Only two flocks in the brooding period and one flock in the laying period out of all flocks tested were sero-negative for SG 9R. When evaluating MG infection rates, 63 flocks were sero-positive. This excluded two flocks in the brooding period, one flock in the rearing period, and four flocks in the laying period. The sero-prevalence of individual chickens was as high as 66.1% and 67.8% in the rearing and laying periods, respectively. Additionally, birds that were an advanced age period had a high sero-prevalence rate of 86.6%. The rates of sero-positivity for MS infection among flocks and individual chickens were 88.6% and 64.2%, respectively. Data from the present investigation confirmed that the sero-prevalence of PD-FT, MG infection, and MS infection among broiler breeder flocks in Korea is very high. Consequently, we recommend that a national intervention strategy should be established in the near future to eradicate these diseases from broiler breeder flocks.