With spring in high gear and summer just down the road, doctors thought we'd left another year's influenza season in our collective rearview mirror. All of that changed late last week when the national Centers for Disease Control and Prevention began reporting that people in the U.S. had tested positive for a novel strain of the influenza virus. So far the CDC has confirmed 40 cases in individuals ranging from children to middle-aged adults.
The CDC was quick in getting the public up to speed. Its basic message is sound. Keep an eye on this story and know the facts, which include:
- The infection originated in pigs and is known as the swine influenza A, H1N1 strain.
- While outbreaks of swine influenza are nothing new (there was a memorable one in 1976), this strain is novel in its genetic makeup, with RNA from four different sources: avian flu, human flu and swine strains from North America and Eurasia.
- Thus far, Mexico has been hit the hardest, with 1,400 to 1,600 suspected cases and somewhere between 80 to 100 suspected deaths (although only about 20 of those fatalities have a laboratory-confirmed diagnosis of swine flu).
- The CDC was reporting seven cases in Texas and California late last week, but now the number has jumped to 40, including 28 in New York City. Cases were also reported in Kansas, Ohio and Canada.
Although it's nice to have those facts on the table, nothing tests a healthcare system more intensely than an infectious outbreak. Viruses are mercurial little pathogens. They spread and mutate with great speed. That's especially true of the influenza virus. Each year it mutates and lures us into a game of "stump the doctor," as we race to create a vaccine for the most likely strain. Most years, including this one, the strains don't change significantly. Doctors call these minor mutations antigenic drift, which means we get a useful vaccine. In very rare cases, as in 1918, there's a major mutation (a more significant antigenic shift). Then all bets are off. At its worst, as in 1918, an antigenic shift can lead to a pandemic.
This outbreak has taken everybody by surprise and, in its initial description, appears to be a significant antigenic shift. There are other quirks as well. First, this swine flu showed up in the middle of spring; flu season is usually between about November and February. Second, we've observed some nontraditional infections. For example, most cases of influenza affect the elderly and the very young (which is why we try so hard to vaccinate those groups first). However, in this case, those affected in the U.S. are older kids and middle-aged adults. Another mystery with this virus is why it's been so severe in Mexico yet so mild here.
In fact, the whole story about what's happened south of our border is still murky -- the numbers of how many have been infected and killed are still fluid. Among the possible explanations for the differences between the U.S. and Mexico are that another virus has co-infected people, making them sicker; that the lack of access to healthcare for many Mexican citizens has led to a more severely affected population; and that it may even be an accounting error, where the Mexican government has counted only the very ill and not tracked the less severe cases. Regardless, we appear to have a lot of work to do before we have any real answers.
Despite the level of uncertainly, the CDC and World Health Organization appear to have a coordinated plan of action. Both old and new media have so far done a good job in communicating with professionals and ordinary folks in need of advice.
As for doctors, we're expecting a lot of calls this week from patients with questions and concerns. Phrases like "outbreak" and "epidemic" are as medically loaded as they get. And while nobody can predict what's going to happen, there are always some basic steps you can take.
First and foremost, while you should take this news seriously, please don't panic. So far, symptoms of swine influenza are similar to other strains of influenza: fever, chills, aches, cough and congestion. The only thing that's being reported as out of the ordinary is some vomiting and diarrhea as well.
So, as you did last January, wash your hands and cover your mouth with the crook of your elbow if you cough or sneeze. If you get sick, yes, call your doctor, but treat yourself with rest, fever reducers (not aspirin for children) and plenty of fluids. We always have to worry about the very young and old, but again, we haven't seen swine flu in these groups yet. We also have to worry about our patients who have some chronic medical problems like cancer, which can compromise their immune system. However, this, too, is nothing new.
You may have more cause for concern if you recently traveled to Mexico and then got ill, but the CDC is keeping doctors up-to-date on how to test patients. Also, while swine flu can be treated with the antiviral drugs zanamivir and oseltamivir, demanding them or stocking up on them is going to cost you (and our fragmented healthcare system) lots of money for very little benefit at this point. The government already has ample stockpiles of antiviral drugs that can help beat this bug should the outbreak get worse.
While it's true that the Homeland Security Secretary Janet Napolitano declared a "State of Emergency" over the outbreak, she stressed that it isn't anything more than a procedural move to free up resources for those who may need them. So with thoughtful preparedness and surveillance by health agencies, local awareness among citizens and doctors, and more than just a little luck, we can all hope this will pass fairly quickly.