A Plethora Of Pathogens, Even During A Pandemic

Photo Credit CDC Influenza Home Care Guide

 

Keypoints

• New study found H1N1pdm virus among a small minority of samples tested during the opening weeks of the 2009 Pandemic in New South Wales

 

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During the opening days, weeks and months of the 2009 H1N1 pandemic, just about anyone who came down with an influenza-like Illness (ILI) was convinced they had contracted  the dreaded `swine flu’. It was, after all, featured on just about every newscast, some governments were handing out antivirals based on symptoms alone, and there were daily dire warnings about its global spread.

 

But during the pandemic, just as we see during every flu season, influenza isn’t the only respiratory virus in circulation.  That terrible `flu’ you think you had last year? 

Well, it may have been something else, entirely.

 

During the fall of 2009, at the height of the H1N1 pandemic in the United States, I highlighted the following CDC graphic in a blog called ILI’s Aren’t Always The Flu, that showed that 70% of the samples taken from symptomatic patients tested negative for influenza.

 

While we tend to think of influenza as the `severe’ respiratory virus, and all of the others as milder, that isn’t always the case.  Again, during the fall of 2009, we saw reports indicating that a large number of `non-influenza’ severe respiratory infections were treated at Philadelphia’s Children’s Hospital.

 

Thu, Nov. 12, 2009

Tests show fall outbreak is rhinovirus, not swine flu

By Don Sapatkin

Inquirer Staff Writer

(EXCERPT)

Tests at Children's Hospital of Philadelphia suggest that large numbers of people who got sick this fall actually fell victim to a sudden, unusually severe - and continuing - outbreak of rhinovirus, better known as a key cause of the common cold.

Experts say it is logistically and financially impossible to test everyone with flulike symptoms. And signs, treatment, and prognoses for a bad cold and a mild flu are virtually identical, so the response hardly differs.

(Continue . . .)

 

And the same is true every flu season. Common respiratory viruses include metapneumovirus, parainfluenzavirus, respiratory syncytial virus (RSV), adenovirus, or most likely, one of the myriad Rhinoviruses (Common cold).

 

Something that Dr. Ian Mackay has addressed well, and often, in the past.  The following chart comes from his recent blogs on the topic; Respiratory viruses: the viruses we detect in the human respiratory tract:

 

All of which serves as prelude to a new study, conducted in New South Wales, that examines 255 respiratory samples taken during the opening months of the 2009 pandemic, to try to examine exactly what viruses were present.  The results, as you have probably already ascertained, were heavily weighted towards `non-influenza’ viruses.

 

Pandemic clinical case definitions are non-specific: multiple respiratory viruses circulating in the early phases of the 2009 influenza pandemic in New South Wales, Australia

Vigneswary Mala Ratnamohan, Janette Taylor, Frank Zeng, Kenneth McPhie, Christopher C Blyth, Sheena Adamson, Jen Kok and Dominic E Dwyer

Virology Journal 2014, 11:113  doi:10.1186/1743-422X-11-113

Published: 18 June 2014

Abstract (provisional)

Background

During the early phases of the 2009 pandemic, subjects with influenza-like illness only had laboratory testing specific for the new A(H1N1)pdm09 virus.

Findings: Between 25th May and 7th June 2009, during the pandemic CONTAIN phase, A(H1N1)pdm09 virus was detected using nucleic acid tests in only 56 of 1466 (3.8%) samples meeting the clinical case definition required for A(H1N1)pdm09 testing. Two hundred and fifty-five randomly selected A(H1N1)pdm09 virus-negative samples were tested for other respiratory viruses using a real-time multiplex PCR assay. Of the 255 samples tested, 113 (44.3%) had other respiratory viruses detected: rhinoviruses 63.7%, seasonal influenza A 17.6%, respiratory syncytial virus 7.9%, human metapneumovirus 5.3%, parainfluenzaviruses 4.4%, influenza B virus 4.4%, and enteroviruses 0.8%. Viral co-infections were present in 4.3% of samples.

Conclusions

In the very early stages of a new pandemic, limiting testing to only the novel virus will miss other clinically important co-circulating respiratory pathogens.

 

The entire study is available as a PDF at this link.    I’ve excerpted the last two paragraphs from the study below:

 

Even  prior  to  the  widespread  transmission  of  A(H1N1)pdm09  virus  in  Australia,  limiting testing to travellers did not improve the specificity of testing. Furthermore, if laboratories use NAT  to  determine  other  causes  of  infection,  testing  capacity  in  an  outbreak  may  soon  be reached. However, when the causative pathogen of an outbreak has been  identified and the outbreak  has  progressed  beyond  containment,  then  the  testing  algorithms  need  revision  to target  only  specific  indications,  such  as  a  location  of  new  or  significant  clusters,  or  for individuals at risk of severe disease.

In  conclusion,  laboratory  testing  specifically  targeting  only  the  new  virus  will  miss  other clinically  important  co-circulating  respiratory  pathogens  in  the  very  early  stages  of  a pandemic. Detecting the presence of other viruses may provide important information on the impact of pre-existing viruses when a new pandemic virus is circulating.

 

 

It should be noted that the 2009 H1N1 pandemic began when the northern hemisphere’s flu season was coming to an end, and the southern hemisphere’s flu season was just getting started.

 

One can’t automatically assume that the same sorts of ratios would have prevailed in regions where other viruses were circulating less frequently. Interestingly, the rate of H1N1pdm positive tests may very well have been dampened in the Southern Hemisphere by the co-circulation of some of these other viruses. 

 

A topic that Ian Mackay explored earlier this week in  Influenza in Queensland, Australia: 1-Jan (Week 1) to 8-June (Week 23); the idea that the body’s immune response to one viral infection may temporarily protect you against infection from another. 

 

And an idea similar to one we looked at back in 2010 in  Eurosurveillance: The Temporary Immunity Hypothesis  (and again, in 2012 in EID Journal: Revisiting The `Canadian Problem’.

Montgomery County Flu Updates – Dec 19th

 

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We’ve a brief statement from the Montgomery County Public Health Department this evening on their ongoing investigation into a number severe `flu-like’ illnesses that now confirms that 2 of the 8 suspect cases have tested positive for the H1N1 virus.  Additional testing is underway.

 

We also have a news story, and some Tweets from the KHOU-TV Managing Editor, that provide additional details not included in the official release.  After which I’ll be back to try to put this into some kind of perspective. 

 

First stop, the MCPH update from their Facebook page.

Contact: Jennifer Nichols-Contella FOR IMMEDIATE RELEASE

Cell: (936) 444-9724 12/19/13
Email: jnichols@mchd-tx.org

UPDATE - INFLUENZA LIKE ILLNESS ARISES IN MONTGOMERY COUNTY

As of Thursday afternoon, one additional case of H1N1 has been confirmed in Montgomery County. This patient is currently in an area hospital receiving treatment. Labs are being repeated on all remaining cases by the CDC. There are currently two confirmed H1N1 cases in Montgomery County.

The Montgomery County Public Health District is coordinating with regional and state resources to manage the case investigations. Health officials continue to encourage the public to be vaccinated for the flu, especially those who are at high risk.

Montgomery County Public Health District is monitoring the situation closely and will provide more information as it arises.
###

 

Meanwhile KHOU-TV is reporting that doctors now suspect that all eight of the Conroe Medical Center cases are infected with the (new in 2009) H1N1 virus, and that additional severe cases have been reported from two other counties in the region.

H1N1 kills 6 people, leaves 14 critically ill in Greater Houston area

By Jeremy Desel / KHOU 11 News and KHOU.com staff

Posted on December 19, 2013 Updated today at 5:28 PM

HOUSTON – Health officials say there have been six confirmed deaths from H1N1 in the Houston area recently, KHOU 11 News confirmed Thursday afternoon. That includes the four deaths at Conroe Regional Medical Center.

At least 14 people have become critically ill in Harris, Montgomery and Jefferson counties, including the four patients at Conroe Regional Medical Center.

This is the same strain of H1N1 that caused a pandemic in 2009. Doctors have been seeing hundreds of new cases recently in Texas and nationwide. In fact, H1N1 is one of the viruses included in this year’s flu shot.

Health officials from all over the region spent Thursday afternoon in a conference call comparing notes about all the cases. They suspect that all of the cases at the Conroe Regional Medical Center are H1N1, or what used to be called the “swine flu.”

(Continue . . .)

 

In the past couple of hours, Bill Bishop, Managing Editor fro KHOU-TV News has tweeted the following updates from his account.

 

 

 

While the 2009 H1N1 virus is no longer a `pandemic’ virus, it – like all seasonal influenza viruses – still has the ability to cause considerable morbidity and mortality.  Last year, we had a fairly serious flu season, but it was dominated by the H3N2 virus – one that traditionally impacts those over the age of 65 the hardest. 

 

And as one would expect, the elderly were particularly hard hit last winter.

 

This year, early reports (see MMWR Update: Influenza Activity — United States, September 29–December 7, 2013) indicate that H1N1 – not H3N2 virus – is the dominant strain in the United States right now.   One of that strain’s characteristics is that it hits younger patients particularly hard.  Here is what the CDC had to say about the impact of the virus during the pandemic.

 

2009 H1N1 Pandemic Hits the Young Especially Hard

This study estimated that 80% of 2009 H1N1 deaths were in people younger than 65 years of age which differs from typical seasonal influenza epidemics during which 80-90% of deaths are estimated to occur in people 65 years of age and older. To illustrate the impact of the shift in the age distribution of influenza deaths to younger age groups during the pandemic, researchers calculated the number of years of life lost due to 2009 H1N1-associated deaths. They estimated that 3 times as many years of life were lost during the first year of 2009 H1N1 virus circulation than would have occurred for the same number of deaths during a typical influenza season.

 

While it may be distressing, it wouldn’t be surprising to see the H1N1 virus causing the same lopsided impact today.  The virus remains antigenically very similar to what emerged in 2009, and for many people who may have not bothered to get a flu shot this year, their immunity levels may be waning.

 

Nor would it be unusual to see a resurgence of a pandemic strain several years after the pandemic has ended.  In fact, that has been the pattern in year’s past.   The chart below shows that type of activity in the six years following the H2N2 pandemic of 1957.  Notice how the mortality rates dropped in 1958-59, and 1960-1962, only to jump again in 1963.

 

H2N2  Pandemic Waves - NEJM 2009

 

All of this is a not-so-gentle reminder that seasonal flu can still pack a wallop, and that individual immunities wane over time, making it a good move to update that flu shot every year. It is certainly not too late to get the shot, as we have several months of flu ahead.

I’m sure we’ll revisit this story as more details become available.

Dealing With `The Fog Of Flu’

 

Photo Credit CDC

 

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Although influenza is a hot topic right now (avian, human seasonal, even `mystery’), not every influenza-like-illness (ILI) out there is caused by an influenza virus. In fact, of the more than 6,200 specimens tested by U.S., WHO and NREVSS collaborating labs last week, only about 13% were positive for influenza. 

 

And this among samples highly suspected of being influenza.

 

The truth is, it is very difficult to differentiate between influenza infections, RSV (respiratory syncytial virus), respiratory adenoviruses, parainfluenza viruses, rhinoviruses, coronaviruses, metapneumovirus, (and others) without using sophisticated lab tests. 

 

While commonly viewed as `lesser’ respiratory viruses, the rogue’s gallery of non-influenza viruses above are all perfectly capable of causing severe illness, and even death.  Particularly in the very young, very old, or those with comorbid medical conditions.

 

In a clinical setting - most influenza-like-illnesses go unidentified. Viral respiratory infections are generally self-limiting illnesses, treatment is pretty much the same regardless of etiology, and so there is little point in trying to identify the cause of every illness.

 

When doctors do test for influenza, they generally use an RIDT (Rapid Influenza Detection Tests), but as we’ve seen reported often over the years (see MMWR: Evaluating RIDTs) these tests often suffer from a lack of sensitivity (and to a lesser extent) specificity.  Less often, samples will be sent for more detailed PCR testing.

 

Researchers – with better tools available today – are indentifying `new’ viruses all of the time. A few well distributed viruses that until recently, were unknown, include:

 

• The human metapneumovirus (HMPV) was identified in Dutch children with bronchiolitis about a dozen years ago.  Since then, it has been found to be ubiquitous around the world, and responsible for a significant percentage of childhood respiratory infections . . . yet until 2001, no one knew it existed.
• Human Bocavirus-infection (HBoV) wasn’t identified until 2005, when it was detected in 48 (9.1%) of 527 children with gastroenteritis in Spain (cite).  It has since been found around the globe using PCR testing.

 

And the list grows longer every year.

 

Adding to our misery, it is not all that  uncommon to be infected by more than one virus (or a viral/bacterial combination) at the same time. In 2008 a study (see Frequent detection of viral coinfection in children hospitalized with acute respiratory tract infection using a real-time polymerase chain reaction) looked at clinical samples taken from 254 children treated in Germany over a 10 month period, finding:

 

Respiratory syncytial virus (RSV) was the most frequently detected pathogen in 112 samples (44.1%), followed by human bocavirus (hBoV) in 49 (19.3%), and rhinovirus in 17 samples (6.7%).

 

Viral coinfection was detected in 41 (16.1%) samples with RSV and hBoV being the most dominating combination (27 cases, 10.6%). Viral coinfection was found in 10 cases (17%) of children with bronchitis (n = 58) and in 7 cases (23%) of bronchiolitis (n = 30). In patients with pneumonia (n = 51), 17 cases (33%) were positive for 2 or more viral pathogens.

 

This plethora of pathogens helps to explain – in part - why so many people who get the flu shot every year complain they still caught `the flu’.  

 

Often, they’ve caught one of these ubiquitous `flu-like illnesses’ that are not covered by the shot.

 

And it also helps to explain why, in Montgomery, Texas, public health officials have not yet been able to determine the cause of a handful of unusually severe respiratory infections (see Montgomery County, Tx Influenza-Like Illness Investigation Update – Dec 18th.  There are literally dozens of possibilities to be explored and ruled out.

 

Dr. Ian Mackay weighs in this morning on the discovery process in:

 

Texan flu step: flu-like illness outbreak in Montgomnery County [UPDATED]

 

In places like Hong Kong, China, Indonesia, Saudi Arabia, and Egypt, the elimination process becomes even more difficult.  There they not only have the above complement of seasonal flu and non-flu viruses, they have multiple strains of novel influenza (H5N1, H7N9, H9N2) to contend with, and in the Middle East, an emerging coronavirus as well (MERS-CoV).

 

All of which can present with more or less the same symptoms . .. at least at the start of the infection.

 

Testing is both imperfect and time consuming, and getting accurate results depends on more than just the laboratory diagnostics employed.  Patient samples have to be taken at the right time (when the patient is shedding virus), from the right place (with respiratory viruses, deeper into the respiratory system is usually better), and packaged and transported properly to give the best chance of detection.

 

All of which means that we are often left to deal with the `fog of flu’.   Incomplete, or sometimes erroneous reports, from around the world. 

 

After nearly 9 years of doing this blog, I can only recommend patience and a healthy dose of skepticism when we see news reports of something `unusual’ or perhaps, even `alarming’  somewhere in the world.  Early media reports are often misleading, and are designed more to drive web traffic or sell newspapers than they are to inform the public.

 

None of which is to suggest that we shouldn’t watch these reports with interest.  We should, since one of these days, one of them could certainly herald the arrival of a serious threat.

 

But, as I wrote last year in  Novel Viruses & Chekhov’s Gun, most of these threats will  turn out to be less dangerous than they first appear.

 

As for that rare virus that genuinely poses a serious public health threat?

 

Well, that’s why we urge people to follow good flu hygiene year-round, stay informed, and have a good pandemic (and all threat’s disaster) preparedness plan in place (see Pandemic Preparedness: Taking Our Cue From The Experts.)

 

Because - regardless of what may come down the pike tomorrow - the advantage always goes to those who prepared today.

Montgomery County, Tx Influenza-Like Illness Investigation Update – Dec 18th

 

 

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Over the past 36 hours we’ve been following a report out of Montgomery County, Texas where an unidentified flu-like illness had hospitalized 8 local residents in recent weeks, killing 4 of them. This afternoon the Montgomery County Public Health Department announced on their Facebook page they would hold a press conference before 5pm local time to update the public on what their investigations have shown.

 

At 6pm EST the following update was posted on the MCPH’s Facebook page, indicating that one case has been identified as being H1N1 influenza, while the cause (or causes) of the other illnesses have yet to be determined.  The investigation is ongoing.

 

12/18/2013
UPDATE: INFLUENZA LIKE ILLNESS ARISES IN MONTGOMERY COUNTY

As of Wednesday afternoon, there has been one confirmed case of H1N1 virus. Of the eight reported cases, four patients have deceased. Of the remaining four cases in an area hospital, one case has tested positive for the H1N1 virus. Two of the patients tested negative for all flu viruses. Montgomery County Public Health District is awaiting test results for the remaining patient. The 2013 Influenza vaccine does protect against the H1N1 virus. At this time no known deaths received the vaccine.

Based on CDC data, the H1N1 virus is nationally on the rise. It can reasonably be expected that the occurrence of more H1N1 cases will be reported. Public Health Officials will continue to monitor the situation diligently and will provide more information as it is received.

The Montgomery County Public Health District is grateful for Conroe Regional Hospital’s astute physicians who recognized the unusual nature of the illness and began the appropriate testing to reach a diagnosis.

Montgomery County Public Health District has been in discussion with the Texas Department of State Health Services along with the CDC to coordinate investigation efforts. Despite ongoing investigations, it cannot be emphasized enough that common infection control practices should be followed to prevent the spread of infection. As with common flu strains, some people are more likely to develop flu complications than others. Please reference the CDC’s website, http://www.cdc.gov/flu/about/disease/high_risk.htm, which further explains the high risk population, including children under the age of 5, adults over the age of 65, and people with certain medical conditions.

 

It is also recommended that you receive your flu shot. Montgomery County Public Health Clinic is offering the vaccination by appointment, while supplies last. Call (936) 523-5020 to set up an appointment. For any other questions or concerns, please contact the Public Health hotline at (936) 523-5050. The line will be staffed Monday thru Friday from 8AM-5PM, it is for non-media inquiries only.

 

As I wrote this morning, now is the time of the year when we should all be cognizant of, and diligent in, practicing good flu hygiene.  The CDC recommends:

• Wash your hands often with soap and water or an alcohol-based hand rub.
• Avoid touching your eyes, nose, or mouth. Germs spread this way.
• Try to avoid close contact with sick people.
• Practice good health habits. Get plenty of sleep and exercise, manage your stress, drink plenty of fluids, and eat healthy food.
• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• If you are sick with flu-like illness, stay home for at least 24 hours after your fever is gone without the use of fever-reducing medicine.

And, with holiday travel and gatherings, and the bulk of the flu season still ahead  . . it isn’t too late to get that flu shot.

 

I’ll update this story again, once more news becomes available.

 

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The Many Flavors Of ILI

 

 
Photo Credit CDC

 

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Although flu reports figure prominently in this winter’s news headlines, not every influenza-like-illness (ILI) out there is caused by an influenza virus. In fact, of the more than 12,300 specimens tested by U.S., WHO and NREVSS collaborating labs last week, less than 30% were positive for influenza.

 

 

The rest of the respiratory miseries out there are caused by a variety of viral villains (some unidentified, and some flu-negatives may really be positive), that include RSV (respiratory syncytial virus), respiratory Adenoviruses, parainfluenza viruses, rhinoviruses, coronaviruses, and metapneumovirus (to name a few).

The latest Ontario Respiratory Virus Bulletin, 2012-2013 (Week 2: January 6, 2012 – January 12, 2013) provides a fascinating graph that shows both the variety and seasonal fluctuation of respiratory viruses in institutional outbreaks over the past year.

 

While influenza A is the dominant player this winter, you’ll notice that last season was truly a mixed bag, with comparatively little flu.  The summer months were dominated by Rhino/enterovirus detections.

 

The DARK BLUE part of  the chart represent unidentified organisms.

 

The truth is - in a clinical setting - most influenza-like-illnesses go unidentified. Viral respiratory infections are generally self-limiting illnesses, treatment is pretty much the same regardless of etiology, and so there is little point in trying to identify the cause of every illness.

 

Scientists – with better tools available today – are indentifying `new’ viruses all of the time. A few well distributed viruses that until recently, were unknown, include:

 

• The human metapneumovirus (HMPV) was identified in Dutch children with bronchiolitis about a dozen years ago.  Since then, it has been found to be ubiquitous around the world, and responsible for a significant percentage of childhood respiratory infections . . . yet until 2001, no one knew it existed.
• Human Bocavirus-infection (HBoV) wasn’t identified until 2005, when it was detected in 48 (9.1%) of 527 children with gastroenteritis in Spain (cite).  It has since been found around the globe using PCR testing.

 

And the list grows longer every year.

 

Adding to our misery, it is fairly common to be infected by more than one virus at the same time.

 

In 2008 a study (see Frequent detection of viral coinfection in children hospitalized with acute respiratory tract infection using a real-time polymerase chain reaction) looked at clinical samples taken from 254 children treated in Germany over a 10 month period, finding:

 

Respiratory syncytial virus (RSV) was the most frequently detected pathogen in 112 samples (44.1%), followed by human bocavirus (hBoV) in 49 (19.3%), and rhinovirus in 17 samples (6.7%).

 

Viral coinfection was detected in 41 (16.1%) samples with RSV and hBoV being the most dominating combination (27 cases, 10.6%). Viral coinfection was found in 10 cases (17%) of children with bronchitis (n = 58) and in 7 cases (23%) of bronchiolitis (n = 30). In patients with pneumonia (n = 51), 17 cases (33%) were positive for 2 or more viral pathogens.

 

This plethora of pathogens helps to explain – in part -why so many people who get the flu shot every year complain they still caught `the flu’.   Often, they’ve caught one of these ubiquitous `flu-like illnesses’.

 

So today, a closer look at three common non-influenza respiratory viruses, and one rare one. 

 

RSV (Respiratory Syncytial Virus)

One of the most common infections of young children, it has been estimated that by the age of two, nearly all children in the United States have endured at least one bout with this virus. 

 

For those wondering, `syncytial’ is pronounced (sin-SISH-uhl).

 

While for most people this virus produces a mild illness, often indistinguishable from a `cold’, it is also considered by the CDC to be the the primary cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children under 1 year of age in the United States (cite).

 

The CDC estimates between 75,000 and 125,000 children are hospitalized each year with RSV, and while normally thought of as a childhood illness, adults with weakened immune systems and those over 65 are also at increased risk of severe disease.

 

The CDC maintains an extensive RSV information page.

 

 

Respiratory Adenoviruses

 

With more than 50 varieties identified, respiratory adenoviruses are one of the most common causes of respiratory illness in the world.

 

The CDC’s Adenovirus Information page describes the virus this way:

 

Adenoviruses most commonly cause respiratory illness. The symptoms can range from the common cold to pneumonia, croup, and bronchitis. Depending on the type, adenoviruses can cause other illnesses such as gastroenteritis, conjunctivitis, cystitis, and less commonly, neurological disease.

 

Infants and people with weakened immune systems are at high risk for severe complications of adenovirus infection. Also, adenoviruses commonly cause acute respiratory illness in military recruits.

 

Interestingly, a person can have – and shed – adenovirus for weeks or even months without showing symptoms. 

 

While no vaccine is currently available for the public, the military is using a recently approved (March, 2011) oral vaccine against types 4 and 7 on new recruits to help prevent outbreaks.

 

Over the years we’ve seen some high-profile outbreaks of adenovirus infections that have, at least until they were identified, sounded alarm bells, including  China: Hebei Outbreak Identified As Adenovirus 55.

 

On rare occasions, outbreaks of emerging strains of adenovirus that have caused more serious illness, including one serotype (Ad14) that has been associated with a number of deaths during the past decade (see 2007 MMWR Acute Respiratory Disease Associated with Adenovirus Serotype 14 --- Four States, 2006—2007).

 

 

Parainfluenza Viruses

Human parainfluenza viruses (HPIVs) belong to the Paramyxoviridae family, of which there are 4 types (1-4) and two subtypes  (4a & 4b). Each type has its own set of clinical and epidemiological features.

 

From the CDC’s HPIV page:

Symptoms and Illnesses

The incubation period, the time from exposure to HPIV to onset of symptoms, is generally 2 to 7 days.

• HPIV-1 and HPIV-2 are most often associated with croup (laryngotracheobronchitis). HPIV-1 often causes croup in children, whereas HPIV-2 is less frequently detected. Both types can cause upper and lower respiratory tract illnesses. People with upper respiratory tract illness may have cold-like symptoms.
• HPIV-3 is more often associated with bronchiolitis, bronchitis, and pneumonia.
• HPIV-4 is not recognized as often, but may cause mild to severe respiratory tract illnesses.

Reinfection

People can get multiple HPIV infections in their lifetime. These reinfections usually cause mild upper respiratory tract illness with cold-like symptoms. However, reinfections can cause serious lower respiratory tract illness, such as pneumonia, bronchitis, and bronchiolitis in some people. Older adults and people with compromised immune systems, in particular, have a higher risk for severe infections.

Most children 5 years of age and older have antibodies against HPIV-3 and approximately 75% have antibodies against HPIV-1 and HPIV-2.

 

 

Our last stop is with Human Enterovirus 68 (HEV68), which made headlines in 2011, but of which we’ve heard little of since. In MMWR: Clusters Of HEV68 Respiratory Infections 2008-2010 we looked at reports of six clusters of this rare, emerging enterovirus over the previous couple of years.

 

Enteroviruses encompass a large family of small RNA viruses that include the three Polioviruses, along with myriad non-polio serotypes of Human Rhinovirus, Coxsackievirus, echovirus, and human, porcine, and simian enteroviruses.

 

First detected in California in 1962, but rarely seen since that time, the CDC was notified of six clusters of HEV68 from Asia, Europe, and the United States between 2008-2010.  These clusters included severe illness, and three fatalities.

 

Occurrence of human enterovirus 68, by month, duration, and geographic location --- Asia, Europe, and United States, 2008—2010 –MMWR

 

The summary provided for this MMWR release reads:

 

What is already known on this topic?

Human enterovirus 68 (HEV68) is a unique enterovirus that shares epidemiologic and biologic features with human rhinoviruses.

What is added by this report?

Although isolated cases of HEV68 have been reported since the virus was described in 1962, clusters of cases have been recognized only recently. The clusters described in this report occurred late in the typical enterovirus season and included severe cases, three of which were fatal.

What are the implications for public health practice?

Clinicians should be aware of HEV68 as one of many possible causes of viral respiratory disease. Some diagnostic tests might not detect HEV68 or might misidentify it as a human rhinovirus.

 

The number of `known’ respiratory viruses increases practically every year, due to advances in microbiology and sequence-independent amplification of viral genomes.

 

There is, no doubt, much more to discover about the myriad of non-influenza respiratory viruses in circulation around the world.

 

Most of these viruses will prove clinically indistinguishable from the respiratory viruses we already know. 

 

But outliers like SARS CoV in 2003,  HEV68 in 2008-10, or recent infections in the Middle East with the novel coronavirus EMC/2012 – all capable of producing significant levels of serious illness - show that novel viruses can emerge with little warning.

Which makes the surveillance and identification of these respiratory viruses more than just an academic exercise.

Dozens Of Ways To Spell `I-L-I’

 

Credit CDC

 

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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.

Study: Antimicrobial Prescribing Practices During The 2009 Pandemic

Photo Credit – CDC

 

# 6479

 

One of the most common dilemmas that doctors face is whether or not to prescribe an antibiotic for a patient presenting with an FRI (Febrile Respiratory Illness) often defined as a fever > 38C accompanied by a cough, sore throat, or runny nose.

 

While these illnesses are often caused by a simple viral infection, there is always the possibility that the patient may have (or may subsequently develop) a bacterial infection.

 

Since there is little in a patients physical appearance that can help distinguish between a viral and a bacterial respiratory infection, many doctors will decide to err on the side of caution and prescribe an antibiotic, “just in case”.

 

The problem is that the over-prescribing of antibiotics is viewed as one of the main forces driving the continual growth of antibiotic resistance.  

 

Guidelines (created by the CDC in cooperation with other medical organizations) have been developed to assist the doctor in the prescribing of antibiotics for upper respiratory infections (Adult Treatment Guidelines, Pediatric Treatment Guidelines).

 

The CDC has also prepared patient education information on when antibiotics are appropriate (see the CDC’s GET SMART ABOUT ANTIBIOTICS website).

 

 

But in the end, it often comes down to the primary care provider’s gut feeling whether or not to prescribe an antibiotic. According to a study that appeared yesterday in the Annals of Internal Medicine, Epidemiological Context – not just patient appearance - can be one of the factors that influences this decision.

 

The study is called:

 

The Influence of Context on Antimicrobial Prescribing for Febrile Respiratory Illness: A Cohort Study

Courtney Hebert, MD; Jennifer Beaumont, MS; Gene Schwartz, MD; and Ari Robicsek, MD

 

The authors undertook a 5.5 year retrospective cohort study on the prescribing of antibiotics to patients seen by a network of Midwest primary care providers during influenza seasons between 2006 and 2011.

 

Their results, compiled from 28,301 patient encounters with signs of an FRI – seen by 69 physicians across 26 practices - is illuminating.

 

• They found that during the pandemic flu season (April to June 2009 - Sept 2009 to March 2010) antibiotic prescribing dropped significantly over that seen during non-pandemic flu seasons (39.2% versus 47.5%)
• Furthermore, they found the odds that a doctor would prescribe an antibiotic decreased as the number of FRI cases that they had seen in the previous week increased.

 

In other words, the more viral illness that a doctor perceives to be circulating in their community, the less likely that doctor is to prescribe an antibiotic.

 

Perhaps more surprising was the range of antibiotic script writing by doctors across this limited geographic region.

 

Overall, antibiotics were prescribed in just under half (45.2%) of all FRI cases, but among individual clinicians that number ranged from a low of 17.9% to a high of 83.7%.

 

While there may be other factors not readily apparent from these numbers, there does appear to be a surprising diversity of opinion among clinicians over the appropriateness of prescribing of antibiotics for FRIs.

 

Although limited in both size and scope, this study suggests that finding ways to keep doctors better informed on what illnesses are currently circulating in their community might help moderate the unnecessary prescribing of antibiotics.

 

You’ll also find an accompanying editorial in the same issue of Annals Of Internal Medicine, that stresses it is important to not only determine which external factors affect clinician’s decisions, “but how and why”.

 

The Context of Antibiotic Overuse

Sara Ackerman, PhD, MPH; and Ralph Gonzales, MD, MSPH

 

 

For more on the importance of proper antibiotic usage, you may wish to revisit these earlier blogs.

 

Chan: World Faces A `Post-Antibiotic Era’

Get Smart About Antibiotics Week

IDSA: Educational Guidelines Lower Antibiotic Use

 

 

And for a far more complete (and eye-opening) discussion of antimicrobial resistance issues, I can think of no better primer than Maryn McKenna’s book SUPERBUG: The Fatal Menace of MRSA.

 

And Maryn’s SUPERBUG Blog, part of Wired Science Blogs, continues to provide the best day-to-day coverage of these issues.

MMWR: Clusters Of HEV68 Respiratory Infections 2008-2010

 

 

 

# 5871

 

 

There is probably no more nebulous disease description than that of `ILI’ or an influenza-like-illness.  It ranks up there with `malaise’ and `fatigue’ among the most common of human complaints, and is just about as specific.

Nearly all viral (and a fair number of bacterial, parasitic, and fungal) infections present – at least in their prodromal stage – with flu-like symptoms.

The public tends to categorize mild respiratory infections as `colds’ and more severe illnesses as `the flu’, but doctors know there is a whole galaxy of pathogens out there that can mimic influenza.

 

Which is why doctors usually refer to `picking up a virus’, or having an ILI (Influenza-like Illness or sometimes ARI Acute Respiratory Infection), when rendering a diagnosis. 

 

Elaborate testing isn’t usually done because of the costs involved, and because knowing the etiology doesn’t really affect treatment. Bed rest, fever reducers, and plenty of fluids is the usual regimen.

 

Consequently, there are probably still a number of as-yet unidentified respiratory viruses running around out there.

 

All of which serves as prelude to a report in today’s MMWR on the detection of  HEV68 – or Human Enterovirus 68 – that has produced a number of clusters of respiratory illness around the world over the past couple of years.

 

Enteroviruses encompass a large family of small RNA viruses that include the three Polioviruses, along with myriad non-polio serotypes of Human Rhinovirus, Coxsackievirus, echovirus, and human, porcine, and simian enteroviruses. 

 

The few excerpts from today’s MMWR report (follow the link to read it in its entirety):

 

Clusters of Acute Respiratory Illness Associated with Human Enterovirus 68 --- Asia, Europe, and United States, 2008--2010

Weekly

September 30, 2011 / 60(38);1301-1304

In the past 2 years, CDC has learned of several clusters of respiratory illness associated with human enterovirus 68 (HEV68), including severe disease. HEV68 is a unique enterovirus that shares epidemiologic and biologic features with human rhinoviruses (HRV) (1).

 

First isolated in California in 1962 from four children with bronchiolitis and pneumonia (2), HEV68 has been reported rarely since that time and the full spectrum of illness that it can cause is unknown. The six clusters of respiratory illness associated with HEV68 described in this report occurred in Asia, Europe, and the United States during 2008--2010.

 

HEV68 infection was associated with respiratory illness ranging from relatively mild illness that did not require hospitalization to severe illness requiring intensive care and mechanical ventilation. Three cases, two in the Philippines and one in Japan, were fatal. In these six clusters, HEV68 disproportionately occurred among children.

 

CDC learned of clusters of HEV68 from public health agencies requesting consultation or diagnostic assistance and from reports presented at scientific conferences. In each cluster, HEV68 was diagnosed by reverse transcription--polymerase chain reaction (RT-PCR) testing targeting the 5'-nontranslated region, followed by partial sequencing of the structural protein genes, VP4-VP2, VP1, or both, to give definitive, enterovirus type-specific information.

 

This report highlights HEV68 as an increasingly recognized cause of respiratory illness. Clinicians should be aware of HEV68 as one of many causes of viral respiratory disease and should report clusters of unexplained respiratory illness to the appropriate public health agency.

(Continue . . . )

 

Occurrence of human enterovirus 68, by month, duration, and geographic location --- Asia, Europe, and United States, 2008—2010

 

In recent years, with advances in microbiology and sequence-independent amplification of viral genomes, the ability of scientists to identify new viruses has improved greatly and so they are adding new names to the `suspect list’.

 

About a decade ago the human metapneumovirus (HMPV) was identified in Dutch children with bronchiolitis.  Since then, it has been found to be ubiquitous around the world, and responsible for a significant percentage of childhood respiratory infections . . . yet until 2001, no one knew it existed.

 

Human Bocavirus-infection (HBoV) wasn’t identified until 2005, when it was detected in 48 (9.1%) of 527 children with gastroenteritis in Spain (cite).  

 

And the list grows longer every year.

 

While discovered 40 years ago, according to this MMWR report, testing for HEV68 remains problematic. So we probably don’t have a good handle on how common it really is. 

 

The summary provided for this release reads:

 

What is already known on this topic?

Human enterovirus 68 (HEV68) is a unique enterovirus that shares epidemiologic and biologic features with human rhinoviruses.

 

What is added by this report?

Although isolated cases of HEV68 have been reported since the virus was described in 1962, clusters of cases have been recognized only recently. The clusters described in this report occurred late in the typical enterovirus season and included severe cases, three of which were fatal.

 

What are the implications for public health practice?

Clinicians should be aware of HEV68 as one of many possible causes of viral respiratory disease. Some diagnostic tests might not detect HEV68 or might misidentify it as a human rhinovirus.

 

For more on the expanding universe of non-influenza respiratory viruses, you might wish to revisit these earlier blogs:

 

BMC Study: A Crowded Viral Field

ILI’s Aren’t Always The Flu

The Korean `Mystery’ Pneumonia

 

 

 

 

A formerly unknown virus - SARS-CoV (coronavirus) particles (arrows) – PHIL

# 5548

 

 

While it may be of relatively little comfort, there are almost certainly a significant number of – as yet – unidentified respiratory viruses that routinely circulate among humans. 

 

Most of the time there is little about their clinical signs and symptoms to suggest anything unusual about the infection. The patient quickly recovers, and the illness is assumed to be due to one of the `usual suspects’;  a seasonal influenza, RSV, or one of the myriad rhinoviruses that plague mankind.

 

In recent years, however, with advances in microbiology and sequence-independent amplification of viral genomes, the ability of scientists to identify new viruses has improved greatly and so we are adding new names to the `suspect list’.  

 

About a decade ago the human metapneumovirus (HMPV) was identified in Dutch children with bronchiolitis.  Since then, it has been found to be ubiquitous around the world, and responsible for a significant percentage of the world’s respiratory infections . . . yet until 2001, no one knew it existed.

 

In 2003, a coronavirus called SARS-CoV emerged in China, and infected roughly 8,000 people (killing about 800) before it burned itself out. While coronaviruses were first characterized in the 1960s, and were known to cause many relatively mild upper respiratory infections (common colds) every year, a deadly strain had never been identified before.

 

Human Bocavirus-infection (HBoV) wasn’t identified until 2005, when it was detected in 48 (9.1%) of 527 children with gastroenteritis in Spain (cite).  

 

The list grows longer every year. 

 

But only a small number of virus samples are given this sort of scientific scrutiny, and so it is safe to assume there are still unknown viruses out there, waiting to be discovered.

 

Of course,  unknown (or unidentified) doesn’t necessarily mean `new’.

 

Most of the time, these viruses have been around for a long time, and classifying them has very little impact on the public’s health.

 

On very rare occasions, as in the case of SARS, we get a new player; a virus that we’ve never seen before (that we know of).  

 

For the past couple of days there have been media reports out of South Korea that suggest they may be seeing an unusually severe and potentially unknown respiratory virus – and efforts are underway to identify it.

 

Yesterday, Sharon Sanders of FluTrackers  picked on up early reports of a number of pregnant women in a Seoul Hospital with a `mystery’ respiratory virus.  Since then several more articles (some machine translated) have been posted to this ongoing thread.

 

These media reports are confusing, incomplete, at times contradictory, and just a little hyperbolic.

 

Whether there is really anything unusual going on here, is way too soon to tell.   The cause of viral pneumonia often goes unidentified.

 

That said, the following report comes from the Korea Times.

 

05-10-2011 18:36

Woman dies from unidentified viral pneumonia

By Kim Rahn

A woman died from pneumonia caused by an unidentified virus, according to the health authorities.

Fears are rampant as seven others, mostly pregnant women, are hospitalized with the same illness.

 

The Korea Centers for Disease Control and Prevention said Tuesday that a 36-year-old woman, who had been in the intensive care unit at a Seoul general hospital, died in the morning from a cerebral hemorrhage related to her condition. The unidentified woman was one of seven hospitalized for an unknown viral pneumonia.

(Continue . . .)

 

Unusually, the woman who died apparently developed rapidly progressing Idiopathic pulmonary fibrosis – a scaring and stiffening of lung tissue without a known cause that normally takes months or years to manifest.

 

Sifting through the other reports, it appears that these 9 patients:

 

• had no previous contact with each other
• have been transferred from various clinics around the country
• have occurred over an period of a month or more
• and victim’s families and contacts have not developed similar symptoms.

 

Whatever this might be (and it may be something perfectly ordinary, presenting in an unusual way), it doesn’t appear to be terribly contagious.   

 

But this is interesting.  

 

And so we’ll keep an eye on it and see if anything of note follows these reports.  

Hundreds Of Ways To Spell “I-L-I”

 

 

 

# 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.

 

(Continue. . . )

 

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.

CDC FluView & Non-Flu ILI’s

 

 

 

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Influenza continues to circulate at low levels across the United States, with fewer than 7% of ILI (Influenza-like illness) samples submitted for analysis testing positive for the flu.

 

First some highlights from this week’s FluView report, and then some discussion about the other 93% of flu-like illnesses that weren’t influenza.

 

 

2010-2011 Influenza Season Week 44 ending November 6, 2010

All data are preliminary and may change as more reports are received.

Synopsis:

During week 44 (October 31-November 6, 2010), influenza activity remained low in the United States.

• Of 2,704 specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division, 185 (6.8%) were positive for influenza.
• Two human infections with novel influenza A viruses were reported.
• The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
• One influenza-associated pediatric death was reported and was associated with an influenza A virus for which the subtype was undetermined.
• The proportion of outpatient visits for influenza-like illness (ILI), 1.3%, was below the national baseline, 2.5%. All 10 regions reported ILI below region-specific baseline levels; one state experienced low ILI activity, 49 states experienced minimal ILI activity.
• Geographic spread of influenza in three states was reported as local; the District of Columbia, Puerto Rico, and 34 states reported sporadic activity; Guam and 13 states reported no influenza activity, and the U.S. Virgin Islands did not report.

 

As you can see, last year’s novel H1N1 virus was identified in only a small fraction (8%) of the positive influenza tests returned last week, while Influenza B and H3N2 appeared far more frequently.   

 

P&I (Pneumonia & Influenza) related deaths were once again below the epidemic threshold, although they did climb a bit in the latest reporting week.

 

 

 

 

The `big’ story of the week was, of course, the release of information regarding two novel influenza A(H3N2) swine-origin flu virus infections.

 

Novel Influenza A Virus:

Two cases of human infection with a novel influenza A virus were reported: one case by the Wisconsin Department of Health Services and one case by the Pennsylvania Department of Health. Both patients were infected with a swine origin influenza A (H3N2) virus similar to the three other swine origin influenza A (H3N2) viruses previously identified in 2009 and 2010. The Wisconsin case reported contact with pigs in the week preceding symptom onset on September 8, 2010 and required hospitalization. No contact with pigs has been identified in the Pennsylvania case in the week before symptom onset on October 24, 2010; however the case lives in an area close to pig farms. Both patients have fully recovered from their illness. The cases are not related and the viruses from these two cases have some genetic differences, indicating that they did not come from the same source.

 

Although both investigations are ongoing, there is no evidence of human-to-human transmission with this virus in either case. Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission. Surveillance for human infections with novel influenza A viruses continues year round.

 

For additional information on these cases and swine influenza, see

http://www.cdc.gov/media/subtopic/heard.htm#h3n2.

 

 

 

For most people, respiratory infections are pretty much divided up into three broad categories; colds, the flu, and most seriously, pneumonia.

 

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 year, 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.

 

One of the reasons that many people dismiss influenza as a serious threat is because often, when they’ve thought they had the flu, they had something else entirely.

 

And this can also lead people who got the flu vaccine, and later got `the flu’, to erroneously conclude the vaccine didn’t protect them.  

 

 

Of course, even non-influenza viral infections can cause significant morbidity and mortality – particularly among the very young, the very old, and those with comorbid conditions.

 

While it is estimated that, in a normal year, between 7% and 10% of Americans catch the `flu’, far more of us will endure some other kind of respiratory misery during cold and flu season.

 

So staying home when you have a flu-like illness, washing or sanitizing your hands often during the day, and covering your coughs and sneezes are all important steps you can take to protect yourself, and others, from respiratory infections this winter.

No matter what the cause.