Credit CDC
# 6613
ILIs . . . or Influenza-like Illnesses . . . are among the most common reasons for doctor’s visits each year. While often attributed to `flu’ - there are actually hundreds of `flu-like’ viruses vying for temporary residence in your upper respiratory tract.
Symptoms generally include fever, cough, and body aches - but may also commonly include rhinitis, sneezing, headache, fatigue, sore throat, nausea & vomiting, and diarrhea.
Most of these symptoms are not caused by the invading virus - but are part of the body’s immune response to infection - so theses illnesses often tend to look alike.
Influenza A & B, which can produce serous illness, are only responsible for a fraction of these cases. By some estimates, 90% of ILIs reported each year are due to non-influenza viruses.
In October of 2009, during the height of the fall wave of the H1N1 pandemic, I posted the following graphic on my blog.
Of the more than 10,000 samples submitted for testing during the 1st week of October 2009, more than 72% – almost 3/4ths – came back negative for influenza.
According to the CDC, each year adults (on average) experience 1 to 3 bouts with an ILI, while children may see 3 to 6 flu-like illnesses (cite MMWR)
For the layperson, respiratory infections are pretty much divided up into three broad categories; colds, Flu, or pneumonia.
But the reality is, there are myriad causes of influenza-like illnesses, with contributions from viral strains that include:
metapneumovirus
parainfluenzavirus
coronaviruses
respiratory syncytial virus (RSV)
adenoviruses
enteroviruses
Rhinoviruses (Common cold)
The Rhinovirus group alone consists of more than 100 varieties, and so by the time you add in all of the others you are talking about hundreds of different causes of ILI.
And more are being identified every year.
Less commonly - bacterial pneumonias (e.g. Legionella spp., Chlamydia pneumoniae, Mycoplasma pneumoniae & Streptococcus pneumoniae) – and illnesses like West Nile Virus, Dengue, and Q fever can produce ILI symptoms.
Most viral infections are mild, self-limiting, and are almost never identified since testing (beyond, perhaps, a rapid influenza test) is rarely warranted.
Which is why doctors generally refer to ILIs, or Influenza-like Illnesses (or sometimes ARI Acute Respiratory Infection), when making a clinical diagnosis.
Your first line of defense against this yearly onslaught of respiratory viruses is the seasonal flu shot, which most years provides decent levels of protection against three flu strains. This year’s shot is formulated against:
- A/California/7/2009 (H1N1)pdm09-like virus
- A/Victoria/361/2011 (H3N2)-like virus
- B/Wisconsin/1/2010-like virus
Two of these strains are new in this year’s vaccine A/Victoria/H3N2 & B/Wisconsin) and community levels of immunity against these strains are likely low, making getting the shot this year doubly important.
Flu Vaccines have an excellent safety record, and are now recommended for nearly everyone over the age of 6 months.
To protect against viruses not in the seasonal flu vaccine, your next line of defense is practicing good flu hygiene. Frequent hand washing, covering coughs and sneezes, and staying home if you are sick are key, even if you got the flu shot this year.
Of course, even if you are vigilant, you or someone in your family may get tagged by a respiratory virus this winter.
With that prospect in mind, the CDC has prepared an excellent 24-page PDF guide for the home-care of influenza, which you can download.
And finally, a few years back I was hit by a very nasty virus that laid me up, delirious and unable to move, for 24 hours. I described the experience HERE, and since I live alone, it inspired me to take steps in case it ever happens again.
First, and perhaps most important, I’ve moved my cell phone charger to my beside table. My phone now goes with me when I retire at night, that way I can call for help if ever the need arises.
A sensible precaution for anyone of my years.
Second, I made a simple under-the-bed flu kit.
In a small plastic box, I keep:
A couple of pouch Sports drinks (rehydration)
A bottle of acetaminophen
A bottle of expectorant pills
Imodium pills
A thermometer
Throat lozenges
Surgical masks for me to wear in case I have to call for help or have visitors.
Putting together this little flu kit may seem like too small of of a prep to bother with - but believe me - I wish I’d thought of it before I needed it.
