Essay: My parents didn't tell me they skipped my vaccines. Then I got measles.

In May 2016, I'd been feeling sick for a few days. My doctor diagnosed strep and sent me home with antibiotics. But this wasn't like any strep I'd ever had before. My sore throat and fever kept getting worse, and I developed a rash on one of my arms. Then, one morning, I collapsed onto the floor of my apartment. The emergency room doctors took blood and ruled out strep. Maybe it was scarlet fever? Then someone thought to ask: Were you vaccinated against measles? In my haze, I realized that I wasn't sure. I texted my mother the question. She responded with a thumbs-down emoji. When, concerned, she asked why I wanted to know, I informed her that I was in the hospital.

Measles was like the worst flu I'd ever had, combined with the worst hangover I'd ever had. It flattened me. Mentally, I was disoriented. I'd gone to a teaching hospital, Northwestern Memorial in Chicago, so medical students would come to my bedside and ask if they could take photos of my rash, which at this point had spread in pronounced, red blotches. None of them had ever seen this disease in person before. The United States had declared measles eliminated in 2000.

Once my temperature fell and blood oxygen levels rose, the hospital released me with strict instructions to stay home. But before I'd become ill, I'd gone to a tech conference in Las Vegas, with tens of thousands of attendees. I had no idea how many people I'd met, shaken hands with or brushed up against. Measles is so contagious that if one infected person is in a room, 90 percent of the unvaccinated people around him will also become infected. The live virus can linger in the air for two hours after a cough or sneeze.

Officials from the Illinois Department of Health got in touch. They established that I'd caught the measles at a graduation ceremony I'd attended before the conference, at Northern Illinois University, where someone visiting from another country had brought the disease. They then interviewed me about my whereabouts, and followed up with loved ones, acquaintances and anyone else I'd been in contact with to check if they were immunized. Fortunately, I hadn't passed the disease onto anyone else.

It took me months to feel even close to normal: My heart rate was unusually elevated and I was fatigued. During that slow recovery, I had a long talk with my parents to try to understand my medical history. It turned out that I had never been vaccinated against any infection - not measles, not polio, not tetanus - in my thirty trips around the sun. It's hard to draw out the specifics of their beliefs, or drill down to the root cause of their immunization denial. They don't believe that some vast conspiracy is imposing vaccines on us; they're just predisposed to be suspicious of "unnatural" medical intervention, and they stand behind their decision. I love them, and I try not to judge them too harshly: Medical information is much more widely accessible now than it was in the 1980s, when they were raising us and the measles vaccine became widely available. Still, people with that attitude have put their children's lives at risk.

I felt a little dumb for not realizing sooner. My parents held all kinds of alternative beliefs. When someone in our family got sick, they turned to home remedies. They home-schooled my seven siblings and me, and after that, I took college classes remotely. I never passed through any of the usual institutional checkpoints, where some authority would ask for health records, so the subject never came up. I was just lucky that I hadn't gotten sick (or stepped on a nail) before this. As soon as I could manage it, I called my doctor, and we drew up a six-week schedule to catch me up on my immunizations.

In the first few months of 2019, the United States has had its highest number of measles cases in the past five years: 673 reported in 22 states. That total may rise, especially because the number of people claiming vaccine exemptions for nonmedical reasons has increased over the past decade. Vaccine skeptics brush off measles as a once common "childhood illness," making it sound like a manageable nuisance - a rite of passage, even. But they forget that it can lead to serious complications, including pneumonia and meningitis, and that it can be fatal.

I contracted the disease as an adult in good health, and it landed me in the hospital. To this day, I still feel its effects. Years after people seem to recover, measles can suppress the immune system, effectively creating an "immune amnesia" that leaves them more vulnerable to other infections. When someone close to me gets the sniffles, I end up coughing for weeks. Worry about panencephalitis - in which virus lingering in the brain triggers a deadly immune response - also weighs on me.

I've tried to make vaccines an ongoing topic of conversation with my siblings, discussing the science and current medical consensus, in the hopes that they'd become more comfortable with the idea. A few are vaccinated, but it may take time for the gravity of the danger to fully sink in, and for everyone to take action. They don't seem opposed to it, but the risk of infection doesn't feel urgent. Everyone is healthy, so everything is fine - until it's not.

• As told to Washington Post editor Sophia Nguyen. Josh Nerius is a software product manager from Chicago.