josh michaud, paula avila and gisele carano are still with me. how does sexual transmission change the conversation? >> it's lard to know right now how common that sexual transmission occurs, we know that it does occur. there has been a documented case in dallas. there was documented cases before at a. we know it happens but what we don't know is how often. the answer to the question which you just posed really depends on how often it does occur, and there needs to be much more research to ferret out that answer. >> isn't it up to a doctor who is giving primary care to a woman patient or an ob-gyn during the time there is a public health challenge to raise the possibility to women? >> absolutely. in fact the cdc came out with some guidelines both for general public and for doctors to talk to their patients about this problem of sexual transmission of zika. and for example, men who may have traveled in areas with zika infection or may have had a positive zika test, the cdc is actually recommending now that they use condoms, or obtain from sex, in