The key change in the virus was the ability for transmission of the virus from dog to dog. (ahdc.vet.cornell.edu)
The goal is to ensure they follow guidelines to prevent transmission of the virus. (latimes.com)
So long as several easily achievable conditions are fulfilled, the risk of transmission of the virus through mother's milk can be reduced to almost zero (0 - 1 %). (ukbreastfeeding.org)