On December 5, health officials in Johnson County, Texas reported an unusual outbreak of mumps — 28 cases, mostly in school-age children. Texas has had no more than 20 cases per year since 2011.
“We’re having more than a year’s worth of cases in one community,” said Dr. Elvin Adams of the Texas Department of State Health Services. “It’s really unusual,” he told the Star-Telegram.
Texas is not alone. All across the United Sates, mumps outbreaks are at their highest levels in the last 10 years. As of November 26, the CDC recorded 3,832 mumps cases in 45 states and Washington, D.C. — nearly triple the total in 2015, and the highest count since 2006.
The mumps comeback is especially unusual because most cases are occurring in teenagers and young adults who are fully vaccinated, according to Dr. Manisha Patel of the CDC Division of Viral Diseases.
That odd fact has several possible explanations. One is that mumps is highly-contagious and spreads easily in crowded college dormitories. Another explanation is that the 50 year-old mumps vaccine may be less effective against newer genotypes of the mumps virus. The CDC recommended a 3rd vaccine after outbreaks in 2015 and early 2016.
On average, the mumps vaccine is 78% effective after the first dose, and 88% effective after the second dose, according to the CDC.
In 2010, two former virologists at Merck & Co. filed a whistle-blower lawsuit claiming that the mumps vaccine did not work as well as advertised. Merck says there are no recent studies of its effectiveness. The whistle-blowers also said Merck holds an exclusive license to sell the mumps vaccine — an unfair monopoly that discourages improvement.
Before vaccination programs in the 1960s, around 180,000 cases occurred in the U.S. per year. Most kids in the U.S. get two doses of the MMR vaccine (measles, mumps, and rubella).
Mumps is an incurable viral disease that is transmitted in saliva and mucous. It is highly-contagious and spreads through coughing, sneezing, kissing, talking, or sharing eating utensils. Infections cause painful swelling of the face for 2-3 weeks. Two in five victims do not have symptoms but are still contagious. Rare complications include inflammation of the brain (meningitis), infertility, and deafness.
Source: Wall Street Journal