Hello. This is Paul Auwaerter with Medscape Infectious Diseases, speaking from Johns Hopkins University School of Medicine, Division of Infectious Diseases.
Seasonality is something that many of us in infectious diseases think is important when considering certain infections. For example, Rocky Mountain spotted fever might only be thought of during warmer months in northern states when ticks are active.
What about wintertime? Influenza, respiratory syncytial virus, and even the common cold and pneumococcal disease are all things that many physicians think of. But can you think of additional infections that might have a wintertime seasonality?
I came up with a list that is, no doubt, incomplete. But see how many you can think of there. Some are historical, and some are of modern interest. But I start off with the historical ones. For example, measles virus often seemed to have a predilection during wintertime, especially for bacterial superinfections. Of course, with immunization, that is thankfully a rare event today.
Likewise, diphtheria, which can cause severe pharyngitis and fatal disease owing to myocarditis, historically occurred more commonly during the wintertime months, and it's still only occasionally seen in underimmunized populations.
The third is also becoming less relevant during wintertime. Rotavirus infection had its greatest impact on infantile and pediatric diarrhea, but less so with an effective vaccine.
What about some more modern ones? For number 4, I have leptospirosis. This is only endemic in Hawaii. Many of you might think about going to Hawaii for your winter vacations and don't think of it as wintertime. But it's part of the United States, and the highest rates of leptospirosis in Hawaii are from October to February, generally in the wetter winter months.
The next one I'd call attention to is the endemic fungus Coccidioides immitis infection, which occurs mostly in the Sonoran Desert in the southwest United States and California. Many states report their highest rates of infection during wintertime months, when there is less rain, dust, and perhaps more tourists visiting those regions.
Number 6 is lymphocytic choriomeningitis virus (LCMV), which is not one that many people think of for wintertime infections and is typically a cause of aseptic meningitis. It is mostly carried by the common house mouse. Of course, the mouse, especially in North America, likes to go indoors after late fall and early winter. So there is often a peak incidence during that time frame of this quite underreported infection.
Finally, we have norovirus. The historical name for norovirus is "winter vomiting disease." It was first described in 1929 by a pediatrician who reported more than 30 years of episodic bouts of nausea, vomiting, and diarrhea afflicting children in his St. Louis practice. A recent study by Hall and colleagues in 2012 found that more than one half of deaths seemed to occur between December and February, rightfully earning the disease the now older term "winter vomiting disease." It is clearly something that we tend to see more of during this time of year.
It is unclear whether meningococcal disease is due to seasonality or merely the fact that many students, for example, start aggregating in colleges and dormitories and so on. It typically has a January peak, although perhaps less so with the advent of effective meningococcal immunizations. But this is not universally the case.
These are some thoughts about wintertime illnesses that you might see, albeit on a rare basis. I hope you had some fun, and best wishes for a new year.
Medscape Infectious Diseases © 2014 WebMD, LLC
Cite this: Wintertime Infections, Beyond the Usual Suspects - Medscape - Jan 13, 2014.