TMC PULSE

t m c » p u l s e | j u n e 2 0 1 7 19 The Loop family at Disneyland. T he spots started on the back of his neck. Ariel Loop's 4-month-old son, Mobius, was battling his first illness. His fever was 102 when Loop noticed the telltale rash— flat red spots that started on his head and gradually spread throughout his body. "I thought I was crazy. There's no way," Loop said, laugh- ing incredulously. Even two years later, the experience is sur- real. Loop, a nurse, knew some of the signs of the measles, but they didn't spend much time studying it in nursing school, she said. Who expects to see cases of an eliminated disease, let alone in their own child? The Loops had taken their son to Disneyland a couple of weeks earlier, in mid-January 2015. Living in Pasadena, California, Disneyland was a regular destination. Ariel and Christopher Loop were married there. It's where they announced they were expecting Mobius, and it was only a matter of time until they visited the park as a family. As the spots spread and the fever wouldn't break, real- ity sank in: Mobius had caught the measles at Disneyland. Knowing how contagious the disease is, the couple called ahead to warn the emergency department of their local hospi- tal. They were ushered through a back door and whisked into a negative pressure room where their infant was treated by doctors and nurses in protective gear—medical experts who had never seen measles in person. The hospital did bloodwork, warned them of complica- tions and sent them home under quarantine. Four days later, the test came back positive for measles. One of the most contagious diseases Distill the threat of measles down to its quantitative essence and you're left with a number between 12 and 18. That's its R 0 , or basic reproduction number. On average, one person with the measles will infect 12 to 18 others. Each one of those people infects a dozen or more, and each one of them infects another dozen. That's how an epidemic begins. One cough or sneeze sends the measles virus airborne. There, it can linger, able to infect for up to two hours. The R 0 of influenza? Two to three. The R 0 of SARS, the respiratory illness that in 2003 infected more than 8,000 people worldwide? Two to five. Measles is one of the most contagious of all infectious diseases, but the development of a vaccine in the 1960s led to dramatically decreased rates of infection. It was officially We've got about 50,000 kids whose parents have opted them out of getting vaccinated for non-medical reasons, and this has accelerated precipitously. — PETER HOTEZ, M.D. Dean of the National School of Tropical Medicine at Baylor College of Medicine and president of the Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development declared eliminated in the United States in 2000. In the years since, however, misinformation about the safety of vaccines has caused immunization rates to reach dangerous lows in a number of places throughout the country, including some areas in Texas. A recent outbreak among unvaccinated people in Minnesota has public health experts wondering— could Texas be next? "We've got about 50,000 kids whose parents have opted them out of getting vaccinated for non-medical reasons, and this has accelerated precipitously," said Peter Hotez, M.D., Ph.D., dean of the National School of Tropical Medicine at Baylor College of Medicine and president of the Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development. Non-medical reasons to forgo vaccinations—known as conscientious exemptions—are often based on religious or philosophical beliefs. The key to preventing measles from spreading is "more than 95 percent immunity through a two-dose vaccina- tion regimen," the World Health Organization says. In the 2015-16 school year, 97.6 percent of Texas kindergarteners had received both doses of the measles, mumps and rubella vaccine (MMR), according to the Texas Department of State Health Services. While this is above the recommended rate, the number of exemptions still poses a threat, because unvac- cinated children are not spread evenly throughout the state. "They tend to be concentrated more in the Travis County, Austin area and around Denton, Texas," Hotez said. "I think that's where we're going to start seeing measles outbreaks." When more people are immune to a disease through vaccination, it's more difficult for the disease to spread. High vaccination rates protect those who can't be vaccinated for health reasons, a concept called herd immunity. Low vaccina- tion rates threaten herd immunity and put vulnerable com- munities—children too young to be vaccinated, individuals with compromised immune systems, people who are severely allergic to certain vaccines—at risk. (continued)

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