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By the end of this week, all blood banks in the continental United States must begin testing donated blood for contamination with the Zika virus. Many banks are doing so already, and the early results indicate that the country has dodged a bullet — for now. Screenings in a dozen states suggest that Zika infection remains exceedingly rare. Among the approximately 800,000 blood donations tested in the past six months or so, about 40 were initially positive for the virus. (Saint Louis, 11/14)

Holiday travelers headed to Mexico this winter were warned Monday to protect themselves against Zika-carrying mosquitoes. Any travel to Mexico is now considered to be risky for Zika virus infections, especially for pregnant women, according to the California Department of Public Health, which specifically cited popular tourist destinations such as Cancun, Acapulco, Cabo San Lucas, Puerto Vallarta, Ixtapa and Mazatlan. (Buck, 11/14)