How can I ever speak to my sister again?

My daughter has just been diagnosed with a highly contagious rash called molluscum contagiosum. I have been incredibly diligent, researching online and warning all of my parent friends. I also try to keep it covered with a gauze bandage at all times. Recently, I discovered that both of my sister's children have it and it has become obvious that my daughter has caught it from them. My sister did not tell me about it and failed to warn me at all. Now I am losing my job because my daughter's preschool will not take her while she is contagious (it is a private school that she has been on the waiting list for two years for) and there are no other options in terms of schooling for her in my area. I would have to put her on another two to three year waiting list as child care is very limited here. I need to go back to work because I have very little time left to obtain my permanent certificate which will expire if I don't acquire my necessary credits. If my certificate expires, I will lose my job. So now, because she did not warn me about this infectious disease, I am at risk of losing my job, not to mention that my daughter now has this nasty rash that could eventually cover her entire body if I am not careful. The doctors say that this could last years and there is no guaranteed cure. I am currently not speaking to my sister as I am appalled at how irresponsible she was with this. I am sure that she has neglected to warn anyone of this and has probably spread it all through her children's schools as well. What is the statute of limitations on the silent treatment for sister's that give your child a long term, infectious disease with no precaution? I seriously can not even look at her right now I am so angry.