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Mayo Clinic Microbe Watch Flu Update – Jan. 9

November 11, 2019


It’s very important that healthcare providers
and patients understand how serious influenza can be, and that influenza is very different
than an illness like the common cold. Influenza is a very contagious respiratory illness caused
by viruses, and it causes more than 30,000 deaths each year in the United States. I’ll
often hear an individual who’s suffering from a runny nose and sore throat say they
have the flu, or in other cases, a patient with a gastrointestinal illness like vomiting
and diarrhea may say they have the stomach flu. This really isn’t accurate, and statements
like those can create a lot of misconception about what influenza really is.
In contrast to the common cold, in which patients may develop a cough, sore throat, runny nose,
and feel generally unwell, influenza can be much more severe. Most patients with influenza
have a rapid onset of symptoms, which means they go from feeling fine to feeling very
sick in a short period of time. Patients with influenza often times have a fever, a dry,
non-productive cough, a sore throat, and very severe body aches and a headache. Vomiting
and diarrhea are actually uncommon symptoms of influenza, but can be seen in some individuals,
especially young children. Importantly, influenza can make some patients more susceptible to
other serious infections, like bacterial pneumonia. So this really is something to be aware of
and concerned about. Yes, there definitely is such a thing as Flu
season, which basically means that we see influenza at certain times of the year, usually
between the months of November and February each year. This is because the viruses that
cause influenza don’t persist well, and therefore don’t cause disease, during the
spring and summer months, when it’s warm outside and the sun’s UV rays are strongest.
The big question is always, when will influenza “hit”, and this is always very challenging
to predict. This year, the influenza season seems to be following a fairly typical pattern,
with activity starting to pick up over the last few weeks. The Centers for Disease Control has analyzed
some of the strains from this influenza season, and it appears that the predominant virus
that is circulating in the population is the influenza A H1N1 virus that caused the pandemic
in 2009. This is important, because this strain was one of the components of the influenza
vaccine for this year, so hopefully, the vaccine will offer a good level of protection against
the predominant, circulating strain. We also know that influenza doesn’t strike
at the same time in all regions of the United States, and right now, it appears that the
southern part of the country is experiencing the highest levels of influenza activity.
Now this doesn’t mean that the other regions of the country are in the clear, as it is
very common to see influenza spike in certain regions, taper off there, and then show up
in other parts of the country. Although influenza activity in the state of
Minnesota has lagged behind other regions of the country, especially the south, we are
seeing a similar upward trend over the last few weeks in the state. As of last Friday,
the Minnesota Department of Health is categorizing influenza activity in the state as “Widespread”,
so I think we’re approaching peak influenza season.
The good news is that the trends in Minnesota are closely mirroring what is being seen nationally,
with the predominant influenza type being the 2009 H1N1 pandemic strain. Again, this
means that the primary virus circulating in the population was included in this year’s
influenza vaccine. Another important piece of information for
healthcare providers is that the majority of strains that have been tested have been
found to be susceptible to antiviral medications used to treat influenza. This means that for
those cases where antiviral treatment is indicated, the medication should be effective against
the strains that are circulating this influenza season. However, it’s really important for
me to emphasize that influenza viruses can mutate and acquire resistance to antivirals
quickly. So we are recommending that antivirals for influenza be limited to hospitalized patients,
or those individuals with risk-factors for severe disease, including the very young and
the very old or patients with an immune deficiency. One of the most important steps that we can
take to help prevent and fight influenza is to communicate what’s happening, in regards
to influenza activity, to our healthcare providers and patients. The CDC and state departments
of health provide excellent resources, such as the CDC’s FLU VIEW, to help track influenza
activity. But the data from these sources are typically 1-week old when they are published.
To help supplement the CDC and state lab’s data, Mayo Clinic has developed an on-line
tool called Mayo Clinic Microbe Watch. This resource provides real-time data on influenza
activity at Mayo Clinic in Rochester, MN, with the data being pulled directly from reports
generated by our testing laboratory. The tool also provides data for other common infections,
including pertussis, group A strep, and RSV. By providing up-to-date, real-time data, we
can keep our healthcare providers armed with the latest information to help them diagnose
and treat their patients. Mayo Clinic has also formed an influenza steering
committee, composed of infectious disease experts, pharmacists and laboratorians. This
group meets year-round to 1) plan for the upcoming season, 2) generate diagnostic and
treatment algorithms, and 3) develop communication plans so that our providers are getting the
most up-to-date and reliable information. Well, the first thing I’d emphasize is that
it’s not too late to get vaccinated against influenza. Vaccination is the best way to
help prevent from getting sick. Second, it’s important to be diligent about washing your
hands, especially before you touch your eyes, nose or mouth, or after you cough. And finally,
if you get sick with influenza, it’s really important that you stay home until at least
24 hours after your fever has resolved without the use of fever-reducing medication. Staying
home from school or work not only helps you get better faster, but it also helps prevent
the spread of influenza in your community.

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