By Gary Evans, Medical Writer

A large outbreak of mumps last year in Texas included nine healthcare workers, many of whom were apparently infected in the community.

The outbreak was very disruptive as healthcare workers with no proof of immunity had to be furloughed, and one occupational case was acquired by a phlebotomist.

“This was a nurse who was born before 1957, but had no documented immunity,” said Thi Dang, MPH, CHES, CIC, a state health investigator who worked to educate workers and prevent mumps spread in healthcare facilities. “She collected specimens from suspected cases and did not consistently wear a mask.”

The 2016-2017 mumps outbreak in Texas was the largest in 20 years, Dang recently reported in Minneapolis at the annual conference of the Association for Professionals in Infection Control and Epidemiology (APIC).

“We had nine mumps cases who worked in healthcare, including in acute care, a community clinic, EMS/fire, a skilled nursing facility, and a state-supported living center,” Dang said. “The point is that even if you don’t have cases in your hospital, they could be coming in from the community because your staff live in the community.”

From 2011 to 2015, annual mumps cases in the state ranged 13 to 68 people. Dang usually only sees nine mumps cases annually in the large rural public health district she covers.

“From October 2016 to May 2017 in Texas we had 490 cases with 12 outbreaks,” she said. “In our region, we had 387 cases with seven outbreaks.”

In her health district, the situation became like “outbreaks within outbreaks.” For example, the phlebotomist who acquired mumps in a hospital exposed 34 patients before the diagnosis was made, she said.

“We monitored those 34 patients, and two of them went into long-term care so we monitored them there as well,” she said.

A childhood disease now largely eliminated through vaccination, mumps can result in outbreaks in susceptible populations much as is seen with measles. With both viruses, clinicians who rarely see a case may miss the diagnosis, compounding subsequent follow-up of exposures. Mumps is a paramyxovirus that usually causes parotitis, the classic swelling in the salivary glands. It also can present with a low-grade fever, malaise, and headache.

“It spreads through mucous or droplets from an infected person, usually through a cough or a sneeze,” Dang said. “The incubation period for mumps is anywhere between 12 and 25 days. However, we typically see signs around 16 to 18 days following an exposure.”

Within the wide variety of healthcare facilities in her health district, Dang said many staff knew little about mumps, and proof of immunity often was lacking. During the outbreak, mumps education signs and procedure masks were placed at entrances and in waiting areas.

“The staff at these facilities were educated on the signs and symptoms of mumps and how to properly mask patients,” she said. “We made sure they were separating people with potential mumps from the rest of the population in a waiting area or in the actual hospital.”

Anyone in the community diagnosed with mumps was excluded from work or school until five days after onset of parotitis. “It was really difficult to get immunization history for these patients, for children as well as adults,” Dang said.

The mumps message was somewhat complicated by flu season, which calls for respiratory etiquette to prevent spread in waiting areas and within facilities.

“It was difficult to get people focused on looking for parotitis and to still emphasize and follow respiratory etiquette,” she said. “They had to tie in the [saliva] swabbing with the rest of the regular respiratory precautions that people were looking for. That was actually a big learning curve.”

Much like community members, healthcare workers with active mumps were excluded from work until five days after onset of parotitis.

“Ever facility I talked to, I asked them to check for documented immunity [of staff],” she said. “Documentation was two doses of MMR [measles, mumps, and rubella vaccine], physician documentation of disease, or positive titers. Birth before 1957 was not accepted as evidence of immunity.”

Healthcare workers with documented immunity — even if they did not wear a mask and were exposed to a mumps case — were not recommended for exclusion from work, she said.

“Those who did not have documented immunity and had unprotected exposures were excluded from work from the 12th day after the first exposure to mumps through the 25th day after the last exposure,” Dang said.

Complicating the response, Texas state law allows individual long-term care facilities to decide whether staff must be immunized for mumps. “None of the facilities I worked with had any immunization requirements,” she said. “They only did the minimum, which was to offer hepatitis B and influenza [vaccines]. That was very difficult for me, coming from acute care.”

The number of healthcare workers excluded from duty due to lack of documented immunity included five in skilled nursing facilities, three in acute care facilities, and one in a community rehabilitation center.

In January 2018, the CDC recommended giving a third dose of the MMR vaccine in outbreaks — an action that was not implemented until after the outbreak. Thus, even for those with the standard two-dose history of immunization would receive a third dose if they are considered by local health authorities at increased risk of acquiring mumps during an outbreak.