The San Francisco Department of Public Health (SFDPH) has issued a notice that an active measles patient spent three days in the city in early April, riding both Muni and Caltrain and visiting several local businesses in Hayes Valley.

The patient, an adult Santa Clara County resident, was not hospitalized (they're currently recovering at home), and the agency says that the overall risk to the public is "very low." But anyone who was exposed to the patient in their travels around the city from April 1-3 could potentially develop measles if they haven't been vaccinated against the disease.

While measles was officially declared eliminated from the United States in 2000, occasional cases do pop up in people who visit from or have traveled to other countries, sometimes causing serious illness or death.

Prior to the 1963 introduction of the measles vaccine, an estimated 400 to 500 Americans died of measles each year. Another 48,000 were hospitalized, and 1,000 suffered encephalitis (swelling of the brain) from measles, according to the CDC.

Symptoms, which can emerge from 7 to 21 days after exposure, include fever, cough, runny nose, and red eyes, followed by a red rash that starts on the head or face. Unvaccinated children and adults born after 1957 are at higher risk, as are people with weakened immune systems due to age, illness or disability.

A vintage measles awareness poster from 1939. | Photo: City of Minneapolis Archive/Flickr

SFDPH has provided a full list of the infected patient's travels throughout San Francisco (below), allowing locals to determine if they may have been exposed to the patient on April 1-3.

Most notably, the patient rode Caltrain and the 47-Van Ness Muni bus during rush hour, and patronized several Hayes Valley businesses, including Hayes Valley Bakeworks, Johnny Doughnuts and Double Decker. They also spent three workdays at the Federal Building (450 Golden Gate Ave.)

The patient visited the Hayes Valley Bakeworks location in the CPUC building on three subsequent mornings. | Photo: Connie T./Yelp

Anyone who believes their symptoms could be associated with measles is advised to contact their doctor immediately, and to notify their medical facility in advance of the appointment so that they can ensure that others are not potentially exposed to the disease.

The city is also encouraging anyone who hasn't received the MMR (measles, mumps, rubella) vaccine, which is typically administered to young children, to get one. It's covered by health insurance and Medi-Cal at doctor's offices, while those without insurance can get the vaccine for a low cost (or no cost) through the Department of Public Health.

Here's the full list of the places the patient visited while infected, with estimated times for each visit:

Monday, April 1

6:56 - 8:13 a.m.: Caltrain train 319 northbound. First car of train (car 116).

8:45 - 9:15 a.m.: Caltrain train 232 southbound. Last car of train (car 116).

8:15 - 9:45 a.m.: 47-Van Ness Muni bus

8 - 10 a.m.: Hayes Valley Bakeworks (525 Golden Gate Ave.)

8:30 a.m. - 7 p.m.: Federal Building (450 Golden Gate Ave.)

Tuesday, April 2

8:30 a.m. - 7 p.m.: Federal Building (450 Golden Gate Ave.)

8 - 9:30 a.m.: Johnny Doughnuts (392 Fulton St.)

8 - 10 a.m.: Hayes Valley Bakeworks (525 Golden Gate Ave.)

6:30 - 8 p.m.: Double Decker (465 Grove St.)

Wednesday, April 3

8 - 10 a.m.: Hayes Valley Bakeworks (525 Golden Gate Ave.)

8:30 a.m. - 3:30 p.m.: Federal Building (450 Golden Gate Ave.)

3 - 4:30 pm: Caltrain station (700 4th St.)

3:34 - 5:10 p.m.: Caltrain train 258 southbound. Second car from the back (car 3861).

5:32-6:15 p.m.: Caltrain train 279 northbound. Second car from the front (car 3861).