December 11, 2009
Patient Zero: The Hundred-Day Cough
I’m fortunate that my patients and their families often recommend me to their friends. So Andy’s best friend David was in the office the following week. He had asthma, so his cough was just the latest in a series of exacerbations. I increased his asthma medication, and he improved. For a while. Then he went back to coughing. So he was back in the office, this time with what sounded like pneumonia. He got antibiotics, and more asthma medication, and he improved. For a while. The cough he had was peculiar, and seemed to come in fits, just like Andy’s cough. Sometimes, one of these coughing fits would stop right after he threw up. For one visit, he and his mom brought along Sean, a friend from school. Sean waited politely in my little waiting area. After the first month of symptoms, two courses of antibiotics, tons of cough and asthma medicine which seemed less and less effective, I got lab tests. He wasn’t thrilled about having to get a blood test. On the way out of the office, he introduced me to Sean. Sean was coughing, too.
Though finding infective bacteria wasn’t likely after the antibiotics he received, I knew what I was looking for and ordered measurement of the antibodies in his blood against pertussis. In the 19th century, it was sometimes called the Hundred Day Cough. The kind that show a long-term memory in the immune system, IgG, would show a healthy response to his series of infant immunizations. Another kind that I requested, IgM, would be evidence of an ongoing or very recent infection that his body was trying to fight off. His pertussis IgM was very high.
After calling his parents to tell them that I had a diagnosis, my next call was to the office of Public Health. Within 12 hours, they were mobilizing in one of the local middle schools. David has an older brother in high school. He was coughing, too. Within 24 hours, they were at the high school, too.
Andy’s mom told me that she felt bad about him starting this growing number of cases. It wasn’t anybody’s fault, I told her. She knew about epidemics, and she called Andy Patient Zero. Patient Zero is the very first case in an epidemic that can be identified. All the other cases can be traced back to this one.
By Halloween, a couple of months had passed from the time that Andy first came to my office. He wasn’t coughing any more; David’s older brother wasn’t coughing any more; even David wasn’t coughing any more. I was at their house for a party on Halloween. (I dressed up as a pediatrician who stayed late at the office. ) Andy’s friend Sean was there, coughing.
I was introduced to Sean’s parents, who, in a friendly way, tried to explain that their decision not to have Sean vaccinated was just a personal choice, like being vegetarian or buying fair trade coffee. Sean wasn’t my patient, and I left the conversation.
I pulled Andy’s mother aside and told her that he wasn’t Patient Zero. Sean was.
Given that unvaccinated children are 23 times more likely to get pertussis, it’s pretty likely that in my neighborhood, the kid that gets it first is probably unvaccinated. David, who has asthma, really struggled with it and needed a lot of medication that he probably otherwise would have been able to avoid. Sean too, I suspect, was suffering. He had been coughing for about 2 months or more by Halloween. In vaccinated kids, the mean duration of the worst cough is 29-39 days. In the unvaccinated, 52-61 days. That’s an average, so some will be longer and some shorter. The incubation period for pertussis is 4-21 days. Sean was the first to have the disease, and is probably spreading it even now, with every frequent cough.
Sean, I assume, and the 3 of my patients who got pertussis from him, will all be OK. But when they come home from school, who gets it from them? What about the grandparent with lung disease? What if there’s a sibling getting chemotherapy?
Andy’s mother is pregnant. When the newborn is home in a couple of months, will Sean come over to hang out with Andy and David? How will she make decisions like this? When I told her that it was nobody’s fault, I didn’t know what I know now.