This Thursday, Jan. 29, 2015 file photo shows boxes of the measles, mumps and rubella virus vaccine (MMR) and measles, mumps, rubella and varicella vaccine inside a freezer at a doctor's office in Northridge, Calif. (AP Photo/Damian Dovarganes)

By Tom Charlier of The Commercial Appeal

In the wake of a rapid threefold increase in confirmed measles cases, Shelby County health officials Monday stepped up their efforts to control the emerging outbreak, while at least one hospital began screening patients for the highly contagious viral infection.

The Health Department has confirmed six cases of measles across the county, up from two as of Friday. The cases involve a "widely diverse" group of patients in terms of age, gender and place of residence, said Dr. Helen Morrow, the department's health officer.

With the newest cases, the county apparently has more confirmed measles cases than the entire rest of the nation. The federal Centers for Disease Control and Prevention listed four cases nationwide as of April 1 and "is not aware" of any others in addition to the newly reported ones in Shelby County, CDC press officer Kristen Nordlund said in an email.

Measles, largely preventable through a vaccine administered to most children by the time they enter school, begins with a fever, runny nose and coughing, followed by a rash that spreads from the head down the body. It usually causes only a minor illness, but 1 in 4 cases leads to hospitalization and 1 out of every 1,000 patients dies.

Measles had been considered eradicated in the U.S. by the year 2000, but the refusal of some people to get vaccinated, or have their children vaccinated, has led to occasional outbreaks since then.

Prior to the current outbreak, there were only nine cases of measles in all of Tennessee during the past decade, Morrow said.

Citing privacy laws, the Health Department declined to provide details on the six local cases, such as whether they were vaccinated or had traveled to countries where measles is widespread. Morrow said only that they included people of varying ages living in "just about every quadrant" of the county, and that all were expected to recover.

Some of the cases appear linked through "sites of contact," she said, but health officials have not identified the source of the outbreak.

Although more than 90 percent of the county's school-age children have been vaccinated, Morrow said she "wouldn't be a bit surprised" if additional measles cases are detected.

As part of their efforts to control the spread of the disease, Health Department officials are retracing the movements of each of the patients.

"We're having to look at where those people were during their infectious period, and who they were around," Morrow said. "Those people are being reached out to to inform them of their exposure ..."

People who have been exposed will be offered immune globulin, which contains antibodies that protect against disease.

The department also is urging residents who haven't gotten vaccinated to do so. Officials have launched a hotline — 901-222-9299 — and a website, www.schdresponse.com, dealing with the measles outbreak.

Meantime, at Le Bonheur Children's Hospital, incoming patients are screened for measles, with plans in place to isolate those who show symptoms, said Dr. Jon McCullers, pediatrician in chief.

McCullers, who also chairs the pediatrics department at the University of Tennessee Health Science Center, said he doesn't expect the outbreak to become rampant. The large percentage of vaccinated residents locally provides some "herd protection," he said.

"A handful of cases is typical for small outbreaks. You wouldn't expect it to really get out of control or anything."