Researchers in New Orleans who double as clinicians spent the days after the hurricane tending to patients and sick evacuees. Fortunately, the flood-borne epidemics doctors feared never came to pass.

Officials have not yet detected signs of West Nile virus, which was a primary concern after the hurricane. Three people have died after infections with Vibrio vulnificus, a bacterium common in warm seawaters, and there have been small outbreaks of Norovirus among evacuees in Houston shelters.

The US Centers for Disease Control and Prevention has sent teams to the region, but the broad scattering of evacuees makes illnesses difficult to document. The agency also recommended that evacuees living in shelters be brought up to date on their vaccinations. It is unclear whether existing stockpiles hold enough of several crucial vaccines, such as those that prevent tetanus and flu, to treat everyone in need. ES