# 5134
ILIs . . . or Influenza-like Illnesses are among the most common maladies reported to doctors each year, and while often attributed to `flu’, the causes extend far beyond influenza.
The symptoms generally include fever, cough, and body aches - but may also commonly include rhinitis, sneezing, headache, fatigue, sore throat, nausea & vomiting, and diarrhea.
Many of these symptoms are not caused by the invading pathogen, but are actually part of the body’s immune response. So they naturally occur with many different types of infections.
Influenza A & B, which get most of the headlines, are only responsible for a fraction of the cases of ILI each year.
Some estimates put that share as low as 10%.
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, influenzas, and pneumonias.
But in reality, the causes of influenza-like illnesses are far more diverse with contributions from various strains of:
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.
Most of these 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.
Added to these are a number of less common causes of ILIs, such as bacterial pneumonias (e.g. Legionella spp., Chlamydia pneumoniae, Mycoplasma pneumoniae, and Streptococcus pneumoniae) - and more rarely from such diverse pathogens as meningitis, West Nile Virus, Lyme disease, Dengue, and Q fever (and dozens more).
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.
Influenza A & B get most of our attention because they, along with RSV and some of the more common bacterial pneumonias, can cause serious complications requiring hospitalization.
Which isn’t to say you can’t be hit hard by any of the other viral illnesses. You can.
Even a severe rhinovirus (common cold) can land you in the hospital. But most of the time, people recover without incident from these myriad non-influenza viral strains.
Which explains why a lot of people think influenza is `no big deal’, because the mild illness they had last year that they thought was flu, was probably something else.
And since the Influenza vaccine offers no protection against non-influenza viruses, many people mistakenly believe the vaccine failed to protect them against the flu.
Late last year, in a blog entitled When The `Flu’ Isn’t The Flu, I wrote about the discovery at the Children’s Hospital of Philadelphia of an unusually virulent (and possibly new) rhinovirus – essentially a common cold – that began hitting some children hard earlier that fall.
We turn to Reuter’s ace Health and Science Editor Maggie Fox for the details, in her article from last fall
Not just swine flu - new cold virus may lurk, too
Tue Nov 17, 2009 3:24pm EST
By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - Runny nose, fever, cough, even pneumonia -- the symptoms sound like swine flu but children hospitalized at one U.S. hospital in fact had a rhinovirus, better known as a common cold virus, doctors said on Tuesday.
The spectrum of viral causes of ILIs is no doubt greater than we realize, with new strains coming and going all of the time.
Most are mild, and are clinically indistinguishable from all of the others.
Occasionally however, as with SARS in 2002-2003 and Swine Flu in 2009, we end up with something far more serious.
So we tend to pay attention when we see reports like the one last year from the Children’s Hospital of Philadelphia. Most turn out to be nothing serious, but they can be an early sign of the emergence of a novel pathogen.
Yesterday the Egyptian media carried a similar report – that has since been denied by the Egyptian Ministry of Health – regarding more than 200 children being treated for an as-yet unidentified, severe, and long-lasting ILI.
FluTrackers has a lengthy thread following these conflicting media reports, and ProMed Mail published a summary last evening.
For now this is simply an undiagnosed (likely) viral illness. And there is nothing particularly unusual or alarming about that.
As the ProMed editors point out, this may be nothing more than an particularly virulent strain of rhinovirus. Which would be consistent with what we saw last year in Philadelphia.
The testing facilities in Egypt (including NAMRU) are excellent, so I’m confident that if there is anything unusual about this `outbreak’ (and given the conflicting statements, I use that word with some trepidation), we will certainly hear about it.
In the meantime, the newshounds on the flu forums will no doubt be monitoring the Egyptian media for more information on these cases. Because, while it only happens rarely, reports like these can be our first clue that something out of the ordinary is unfolding.
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