Confirmed measles cases in California have more than doubled in the last week, according to the state health department.
Almost all of the new cases were from the greater Sacramento region.
"The measles situation this year, so far, is looking like a very bad year," Sutter Medical Center Infectious Disease Director Dr. Brett Lawrence said. "I mean, we already have over 350 cases so far this year. On average, we have less than 200, if not even less than 50 cases for a whole year in the past decade.
Lawrence says the potential severity of measles means people should take it seriously. When asked if parents should intentionally expose children to buildup immunity as is sometimes done with chicken pox he said there's a chance it could be fatal.
"It potentially can be more severe than chicken pox," he said. "One to two out of every thousand people infected with measles will die."
In California, there are 17 confirmed cases, 10 of which are within a two-hour drive of Sacramento. Three cases are in Placer County and seven more related cases across Butte, Calaveras, Shasta and Tehama counties.
Another possible case was reported later Thursday in Stanislaus County.
Some local health departments will not say whether the infected have been vaccinated or not but at least three cases have been linked to unvaccinated people or people without documented vaccinations.
"The only people who should not get vaccinated for measles are those with severe immune problems that can’t have a live virus vaccine," Lawrence said.
While basic hygiene is still advised, doctors warning that measles is highly infectious and can live in the air for two hours after an infected person has been there.
The standard for full immunization changed to two doses back in 1989.
Measles in Placer County
A drop-in question and answer session with Placer County's health officer Thursday was the latest way the Auburn Racquet and Fitness Club was trying to put its 5,200 clients at ease after a mother and her two kids brought measles into the gym.
The exposure happened on March 18, after the unvaccinated family had visited a sick relative in the hospital in Butte County. They didn't know then that their relative had measles. They also didn't know they were sick with the disease when they subsequently visited the club.
The first timeframe for possible exposure to club members was from 7 to 9 p.m. on that Monday. However, on Thursday, that was expanded 90 minutes to 5:30 through 9 p.m. after county investigation proved the infected family was actually at the club longer than they first thought.
"In a crisis, the first information you get you try to get the best information out," said Placer County Health Officer Dr. Rob Oldham. "But often that changes and that's just part of what we do here. We try to get as accurate information out as we can but as soon as we get new information we verify it and have a process for updating that and getting new information out."
Before expanding the possible exposure window, Placer County public health officials had already completed a contact investigation and interviewed 100 people. They expect that number to increase by 50 given the 90 additional minutes other members might have been in the club with the infected family.
Investigators say that aside from the gym, the only other place they've determined the infected family visited before diagnosis was a non-public location.