Salmonella can cause diarrhea, fever and stomach pain. Victims typically recover on their own, but the elderly, infants and people with impaired immune systems may require treatment. Untreated, salmonella can cause death in vulnerable victims, the health department said.

Boiling water for 15 seconds will kill the bacteria, but health officials advised residents to use bottled water for brushing teeth, washing dishes, making ice, cooking, drinking and making baby formula. People can use tap water to bathe, as long as they are careful not to ingest it, Salley said.

City officials plan to start flushing and disinfecting the water system in the next few days, a process that could take a week or more. While the flush is under way, no municipal water should be used, even if it is boiled, they said.

The first salmonella victim began showing symptoms around March 8, and state health officials became aware of the outbreak Friday, said Ned Calonge, the health department’s chief medical officer.

Officials tested city water on Monday, and the results showing bacteria in the water system came back Wednesday, Salley said.

Health officials are still investigating how the water was contaminated.

Tainted tap water led to a large salmonella outbreak in a Southern California town in 1965, Salley said. In that case, as in Alamosa, the city was drawing water from a deep well and the water was not chlorinated.

Grocery stores and distributors were working to ship more bottled water to Alamosa. Some companies offered to give away water and hand sanitizers, Calonge said.