An experimental challenge compared dose and strain effects in nursery pigs.
Dose comparison in nursery pigs
A study published in BMC Veterinary Research on 14 October 2026 developed an experimental challenge for Streptococcus equi subsp. zooepidemicus in nursery pigs. In its first phase, all pigs given a high dose of strain TN, 10^8 CFU per millilitre, died. Half of those given 10^5 CFU per millilitre died. These figures describe the challenged groups in the experiment, not mortality rates in commercial herds.
Three strains gave different results
The second phase compared strains TN-74097, ATCC 35246 and AZ-45470. Deaths occurred mainly in the TN and ATCC groups; none occurred in the AZ group. The researchers also developed a quantitative PCR test that distinguishes the highly pathogenic ST194 type from other strains of this bacterium. The paper reports an experimental infection model and strain comparison, with no farm-level treatment trial.