The breadth of the outbreak of mumps in Northwest Arkansas appears to be linked in part to that area's community of Marshall Islanders, the director of the state Department of Health said Monday.
Meanwhile, the region's high rate of unvaccinated schoolchildren compared with the rest of the state doesn't appear to be a factor in the unusual size of the outbreak, said Nate Smith, director of the state Department of Health.
Despite making up a small fraction of the region's total population, Marshall Islanders account for about 60 percent of the 2,220 people who had been infected as of Friday in the outbreak that started in August, according to figures Smith presented to the state House and Senate's committees on public health, welfare and labor during a joint meeting on Monday.
By contrast, only 82 of the 1,324 school-age children who have been infected with the mumps had less than the recommended two doses of the measles, mumps and rubella vaccine.
The 2,220 cases that have been reported in Arkansas account for more than half of the 4,258 cases that have been reported nationwide so far this year, Smith said.
According to the U.S. Centers for Disease Control and Prevention website, Arkansas' outbreak is the largest since 2009 and 2010, when an outbreak in New York City affected about 3,000 people, most of them students of high school age.
Smith said few unvaccinated children have been infected because they account for a small percentage of the student population and are removed from school once an infection at the school has been reported.
The unvaccinated account for a greater share of adult infections, however. Of the 660 adults who have been infected and whose immunization status is known, 444 had received less than the recommended doses of vaccine, Smith said.
The mumps vaccine is thought to be effective for 88 percent of people who receive two doses, according to the CDC.
Why so many Marshallese have been infected is unknown, he said. A high percentage of Marshallese children have been vaccinated, he said, but the rate could be lower among adults.
He noted that the Marshallese also tend to live in close quarters, "oftentimes with multiple families in the same household."
"It's a little bit more like a college dorm in terms of intensity of exposure," Smith said. He added the Marshallese tend to be "community-oriented," gathering in church and other settings where infections can spread.
Public health officials are also investigating whether the mumps vaccine is less effective for certain groups of people, such as the Marshallese, than others, he said.
Spread through saliva and often transmitted when infected people cough or sneeze, mumps can cause swollen salivary glands, body aches and other mostly mild or moderate symptoms. But it can lead to rare complications such as deafness or brain inflammation, particularly among adults.
Since a mumps vaccine first became available in the late 1960s, cases of the disease in the United States have fallen drastically, from more than 186,000 a year, according the CDC.
Smith has said Arkansas' outbreak appears to have been started by an out-of-state resident who caught the disease in Iowa, then traveled to Arkansas and passed it on to another adult before the virus spread to children.
An estimated 8,000 to 12,000 Marshallese live in Northwest Arkansas, which is the largest population of Marshallese in the continental United States.
A 1986 compact allows citizens of the islands unrestricted travel in the United States.
An outbreak of mumps on the Marshall Islands 10 to 15 years ago was snuffed out after about 20,000 people there were vaccinated, Smith said.
"They were able to get their mumps outbreak under control there," Smith said. "I'm very confident we can do the same here."
He said the Health Department had vaccinated 6,596 people as of Friday, including 2,288 in schools and 2,488 at worksites.
The efforts appear to be paying off, he said. During the last three days of last week, only 12 cases were reported, "which is quite a bit less than we have had, really, for months," Smith told lawmakers.
While unvaccinated children don't appear to have been a big factor in spreading the virus, their removal from schools has sparked complaints from parents and lawmakers.
At a meeting in September, some members of the public health committees complained that previously unvaccinated children can return to school immediately after receiving a vaccine, even though the vaccine doesn't become fully effective until two weeks after it's administered.
Smith has said the department follows CDC guidelines, which call for unvaccinated children to be excluded from schools where an outbreak has occurred until 26 days after the last instance of a person developing the swollen salivary glands often caused by the disease.
Students who develop symptoms are excluded until the disease is not considered contagious -- five days after they develop the swollen glands.
About 75 unvaccinated children are barred from school because of a mumps case, Health Department spokesman Meg Mirivel said Monday.
Arkansas Code 6-18-702 requires students to meet immunization requirements established by the state Board of Health unless they receive an exemption from the Health Department.
This school year, 6,262 students have received such exemptions, including 4,340 based on philosophical grounds, 1,775 on religious grounds and 147 for medical reasons.
Earlier this month, state Rep. Karilyn Brown, R-Sherwood, filed a bill that would eliminate exemptions based on religious or philosophical grounds.
But Brown said Monday she doesn't think the bill would have the support to become law and doesn't plan to seek to advance it during next year's legislative session.
"It needs a lot of discussion. and I thought perhaps we would be able to have that discussion," Brown said. "I'm hoping that we still can."
A Section on 12/20/2016
Print Headline: Mumps hitting state's Marshallese hard