# 4789
I’ve returned from my 5-day vacation, and given a couple of days of rest, I should be recovered from the experience.
Luckily, the tropics remain quiet, the pandemic continues to wind down (see Crofsblog Branswell: WHO could declare end of H1N1 pandemic this week), and in the dead of summer H5N1 is producing little more than tiny blips of background noise.
While the news may be quiet, we continue to see a flood of research articles in the wake of the 2009 pandemic, giving us much to look at during these dog days of summer.
One such article, published ahead of print in the CDC’s EID Journal, is called Rhinovirus Outbreaks in Long-term Care Facilities, Ontario, Canada.
Thankfully, the research is more interesting than the title might suggest.
But then, it would almost have to be . . .
For the layperson, respiratory infections are pretty much divided up into three broad categories; colds, influenzas, and pneumonias.
But in reality, the spectrum of common respiratory viruses is far more diverse and includes such pathogens as metapneumovirus, parainfluenzavirus, respiratory syncytial virus (RSV), any of the myriad Rhinoviruses (Common cold), and a number of varieties of adenovirus.
Last October, 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.
Although testing may miss some cases (samples degrade, viral shedding at the time of sampling may have been low, etc), it is pretty obvious that a lot of flu-like illnesses are caused by something other than influenza.
And frankly, except for a few peak weeks every flu season, the percentage of samples testing positive for influenza A is usually less than 10%.
Which is why doctors generally refer to ILIs, or Influenza-like Illnesses (or sometimes ARI Acute Respiratory Infection), when making a clinical diagnosis.
Testing to find out exactly what kind of virus a patient may have is time consuming, expensive, and not usually justified. By the time test results come back, most patients will have recovered.
But for research purposes, testing can reveal a great deal of information.
And one of the things we are learning is that some of the `lesser’ respiratory viruses – even the ubiquitous Rhinovirus – can produce serious (and sometimes even fatal) illness.
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 this 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.
Which sets the table for today’s research piece, which looks at the incidence of Rhinovirus among patients in long-term care facilities in Canada during the last half of 2009.
Some excerpts from the the study, then some discussion.
Rhinovirus Outbreaks in Long-term Care Facilities, Ontario, Canada
DOI: 10.3201/eid1609.100476
Longtin J, Marchand-Austin A, Winter A-L, Patel S, Eshaghi A, Jamieson F, et al. Rhinovirus outbreaks in long-term care facilities, Ontario, Canada. Emerg
Infect Dis. 2010 Sep; [Epub ahead of print]
Respiratory tract illnesses are a major cause of illness and death among elderly persons, especially those in long-term care facilities. Although the most commonly identified viruses have been influenza virus and respiratory syncytial virus (RSV) (1), human rhinovirus (HRV) is being increasingly associated with severe respiratory disease and outbreaks in these facilities (2–6).
Clinical diagnosis of HRV by immunofluorescence and virus culture has been difficult because these methods are unreliable (7,8). Moreover, because multiple serotypes of HRV exist, retrospective serologic testing cannot be used to evaluate the prevalence of HRV disease (5). As a result, the number of outbreaks caused by HRV in long-term care facilities, and the associated illness and death, may be substantially underestimated.
We therefore used 2009 surveillance data to estimate prevalence of HRV disease in long-term care facilities.
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In conclusion, using data from a routine surveillance network, we found high prevalence of HRV during a period that encompassed the first and second waves of pandemic (H1N1) 2009. These findings are in accordance with the increasing knowledge that HRV outbreaks cause severe and fatal disease.
I’ve only excerpted some of the highlights. While only 4 pages long, the entire article is well worth reviewing.
Given the elderly demographics in most long-term care facilities, it isn’t terribly surprising that the impact of pandemic H1N1 was as low as is depicted here. Those born before about 1957 have shown varying levels of immunity to the virus.
But the big news here is the high prevalence of HRV (Human Rhinovirus) which comprised nearly 60% of the samples, and that these viruses were implicated in a number of deaths.
This research did not test for human bocavirus or influenza C virus, which the authors state could be involved in the outbreaks that had no identified cause.
Additionally, we’ve seen other research that has identified mixed infection - by more than one virus – in more than 10% of cases (see ILI’s Aren’t Always The Flu).
All of which points out the complexity that this panoply of human respiratory pathogens represent.
Rhinoviruses are not necessarily the burdensome, but relatively benign viruses, that most of us think of.
Particularly among vulnerable populations, like children, the elderly, and the medically frail.
Granted, pandemics never are a `good’ thing. But they often spur advances in scientific research, and sometimes that leads us down surprising paths.
While it is influenza that usually makes the headlines, developing a better understanding of the impact of non-influenza ILI’s may eventually lead to better testing and treatments, which could end up saving lives down the road.
