A restaurant worker at a Nordstrom Cafe in Stonestown Galleria, San Francisco was diagnosed with typhoid fever recently, prompting a warning to customers from San Francisco health officials.

Customers who ate at the restaurant on April 16, 17, 18, 20, or 27 should go see a doctor immediately if they start to experience fever, weakness stomach pains, headache, nausea, vomiting, diarrhea, or loss of appetite.

Nordstrom is offering free testing to customers, which can be arranged by calling (415) 753-1344.

Typhoid fever is caused by the bacteria Salmonella typhi and may be life-threatening . The bacteria is typically spread when infected people prepare food for others, particulary by the fecal-oral route. A person infected with Salmonella typhoid sheds the bacteria in their feces, which gets onto their hands, then into the food they prepare, and eventually to the mouths of whoever eats it.

The disease is more prevalent in parts of the world where handwashing is less common and sewage mixes with the water supply.

The U.S. Centers for Disease Control (CDC) estimates that there were 5,700 cases of typhoid fever in the U.S. in 2012, compared with 21.5 million cases worldwide.

People can avoid typhoid fever by avoiding "risky" food or getting vaccinated, which is recommended for people who are travelling to areas where typhoid fever is common. However, the vaccine is not completely effective.

Symptoms include a high, sustained fever, stomach pains, weakness, headache, or loss of appetite. Some people may develop a rash of flat, rose-colored spots.

The most famous carrier of typhoid fever was a cook remembered as Typhoid Mary, who infected 51 people and was later quarantined by public health authorities in 1907 and 1915. She died in 1938, after 28 years in isolation.