Queensland influenza sees a shift in age...

Image adapted from Geoscience Australia,

The Australian Government.[3]

The media Down Under have been doing their thing this influenza season...

• Vaccine delay to cause horror flu season, say experts
• Qld sniffles through highest flu count
• CHART: Australia could be in for its worst flu season on record
• Flu cases tracking at record levels

...lots of inflammatory (pun intended) headlines to make us all fear just about everything and everyone. Blah.

Nonetheless, it is flu season down here - and hopefully you gave vaccination a try this year, or you got your annual shot. Top marks if so! If you can safely and pretty painlessly dodge a preventable disease, save yourself some misery, avoid making your kids sick - who will require time off to be looked after, not make Aunty Robyn crook as a dog and not put Grandad's ailing ticker under extra stress...why wouldn't you? 

VDU Figure 1. Figure 2 from the State of
Queensland (Queensland Health) report
found here.[1]Click on image to enlarge

Thanks to the excellent and publicly available wealth of data presented by the epidemiologists of the State of Queensland (Queensland Health), I talked about influenza in Queensland and the distribution of types (i.e. Flu A or B) and subtypes (e.g. H3N2 or H1N1) last year.[2]

In 2014, influenza A viruses were the big bad, but in 2015, as we can see in VDU Figure 1 (orange), influenza B viruses are ruling the mean streets.

VDU Figure 2. Appendix 1 from the State of
Queensland (Queensland Health) report
found here.[1]Click on image to enlarge

From the look of VDU Figure 2, the influenza season remains in full swing (hint-get that vaccination if you haven't already). 

VDU Figure 2 also shows that things are not tracking all that unusually for a Queensland influenza season when you compare this year to curves from the past 5 years. So I'd suggest taking those media headlines with a box of tissues!

However, something stood out to me when looking at the latest report so I went back and cut-and-pasted the age and sex graphs from the past few consecutive weeks to make VDU Figure 3. Sure enough, there was a particular spike in the 5-9 and 10-19 year old age bands (yellow arrows in graph boxed in red). Even allowing for changed y-axis scale in the first 4 graphs (dates are listed in each graph's legend) these 2 bands seem to have risen just in the past reporting week. 

Still, the overall pattern of rising case numbers, a dip in the 20-29 year old age band, then a rise before a consistent drop off is retained. Is this the result of school kids returning from school holidays on the 23rd of July, sharing their viruses, incubating an infection and becoming ill? If so - will we see a rise in parent - age age bands in the report after next's? Let's watch and see!

VDU Figure 3. Figure 4s from previous weeks of State of Queensland (Queensland Health) report found here.[4]
Images excised from PDFs and pasted together using 
Adobe Photoshop CC 2015.0.0
Click on image to enlarge

References....

1. https://www.health.qld.gov.au/ph/documents/cdb/influenza-qld-150802.pdf
2. http://virologydownunder.blogspot.com.au/2014/03/influenza-viruses-in-queensland.html
3. http://www-a.ga.gov.au/web_temp/1531782/61756.pdf
4. https://www.health.qld.gov.au/ph/cdb/sru_influenza.asp
5. http://education.qld.gov.au/public_media/calendar/holidays.html

Influenza in Queensland, Australia: 1-Jan (Week 1) to 8-June (Week 23)

Map of Queensland's Hospital and Health service 

areas. Adapted from

http://www.health.qld.gov.au/maps/hhs_facilities.pdf.

Click on image to enlarge.

Waaaay back on 18-March we looked at how influenza notifications in Queensland (population ~5mill) were above the 5-year-to-date (YTD) average. 

"Woopty Doo" some, perhaps very few, of you said. "That number means nothing until you look back at it later". 

So, let's look back at it now that it's later. 

It was Autumn then and now its Winter which is Flu season and also the season when we get some more public info on a handful of other  respiratory viruses circulating here in Queensland thanks to the collatory (I don't care if a dictionary doesn't recognize it) genius of the crew at the State of Queensland, Queensland Health (SoQ|QH).

So what's happening with flu Down Under? For all the detailed detail, I recommend you check out the Open Access document, Statewide Weekly Influenza Surveillance Report that spans up to Week-23 (that's the week ending 8-June; we're in Week 25 now)

Turns out its still 2x (well,  1.987x but who;/s counting?) above the 5-year-to-date mean. No, this is not a "I told you so" - just that it's interesting to see that on this occasion at least, autumn trends predicted a winter event. Still, its only early winter. We've also had a very warm and dry autumn (see the Bureau of Meteorology for more on Autumn) for those who like to link weather and influenza activity.

I like to look at virus interactions as driving their own seasons. How is that possible I eerily hear you ask (I'm not listening to the "Oh what a load of..." comments by  the way, so sit back down and put up your hand)? Well, they don't do anything themselves of course, but my theory goes like this...

When there are enough of us in the community infected by one virus (say respiratory syncytial virus [RSV]) and our immune-thing-a-me-whats-it is all fired up and producing an inflammatory response to rid us off said pestilence, that responsey thing offers a kind of "Shield's Up" effect. 

For a short while we feel like rubbish but we also don't let other viruses get in as easily because we're in an "antiviral state". Enough of us in that state and we get a kind of short-term herd immunity (a fairy died) - where the number of people fully susceptible to another virus (say, an influenza virus) is too small for it to get a good toehold in us and the population. This pattern among seasonal respiratory viruses is most often observed, in my experience, for viruses with an RNA genome like RSV, rhinoviruses and influenza viruses. 

Thankfully for my hypothesis, the data from SoQ|QH show a nice example of this pattern of viruses interacting with viruses within us, projected to the level of the community. 

A snippet from the State of Queensland, Queensland 

Health Statewide Weekly Influenza Surveillance 

Report  for 1-January-2014 to 8-June-2014.
Edited by Ian M Mackay, VDU.

Click to enlarge. 

Let's have a look at the adjacent figure I've mixed around from reference [1]. Hopefully I haven't broken any copyright laws in hacking pasting as I have.

Part A shows the notifications for influenza viruses in Queensland. Peaks and troughs, As and Bs. Cool

Part B shows some of the respiratory viruses, including RSV which has been having a bonza season this past autumn by the looks of things.

Can you see the pattern?

Part C is a cobbled together composite I made in Photoshop/Illustrator by laying B over A and making B partly transparent. It's a bit rough and has had the axis labels and legend trimmed off for clarity, but it makes the point. What it shows (to me anyway) is that when RSV numbers go up, influenza virus notifications head downwards. 

Is this due to RSV influencing influenza or influenza exerting its muscle on RSV? Can't tell from this sort of analysis. 

The fact that RSV can rise in the presence of influenza virus may speak to its dominance. But take a step back. Remember we're taking about people not cells in a dish. It may be that 2 distinct populations are at play initially; perhaps younger children with RSV versus older children and adults with influenza. Once infected people reach a critical mass, that virus may win out and "push put" the other.What's happening in a single household - kids bringing home one virus, parents another perhaps? That would be intriguing to know with these concepts in mind using molecular methods and longitudinal regular sampling of whole families, regardless of symptoms.

Statistically, when I've looked at this with other data, that negative association, more obvious and frequent between influenza virus and rhinoviruses, does reach significance. You can read one of my group's hospital-based studies in [4] and a collaborative community study in [5]. Rhinovirus seasons usually bracket influenza season. So I offer a different view of how seasonal viruses are seasonal. With the sources of variability I discuss above as well as genetics and differences in everyone's past virus exposures and immune-thing-a-me-whats-it status to each virus, some cross-protective, some not, some having got really sick last year, some not...its not hard to see how those virus seasons can shift around from year to year as well.

Yet another reason to test for viruses, and to include more than just 1 or 2 viruses in that testing; the more you test, the more you can observe and learn.

By the way, interferon-the major player in causing these virus:virus interactions, got its name because it could block a secondary viral infection much like those that I've described above, but on a population level.

Now, try and get some funding to do any research on that. I hate you if you do by the way (yes, I failed miserably).

References...

1. Statewide Weekly Influenza Surveillance Report, 1-January to 8-June 2014.
   http://www.health.qld.gov.au/ph/documents/cdb/influenza-qld-140101-140608.pdf
2. Queensland in autumn 2014: A warm autumn; coastal rainfall but dry inland of the Great Dividing Range
   http://www.bom.gov.au/climate/current/season/qld/summary.shtml
3. Do rhinoviruses reduce the probability of viral co-detection during acute respiratory tract infections.
   http://www.ncbi.nlm.nih.gov/pubmed/19376742
4. Community-wide, contemporaneous circulation of a broad spectrum of human rhinoviruses in healthy Australian preschool-aged children during a 12-month period.
   http://www.ncbi.nlm.nih.gov/pubmed/22829638

Texan flu step: flu-like illness outbreak in Montgomery County [UPDATE #2]

Click image to enlarge.
County of Montgomery highlighted in red.
From Wikipedia

While 1,920 influenza-like illnesses (briefly that's measurable fever plus one or more particular symptom usually; includes sore throat, fatigue, body aches and complications including pneumonia) have occurred in this county since the start of the local influenza season, 8 severe infections (all with pneumonia) in adults (41-years to 65-years old) have been admitted to 1 (?) facility. These 8 cases are not all testing positive for the "common" influenza virus types. Initial testing may have been by rapid "bedside" influenza test which are known for their lack of sensitivity. PCR testing would be preferred, if that wasn't used.


According to the US Centers for Disease Control and Prevention website, seasonal influenza's populations at greatest risk of severe disease usually include the very young (under 5-years) and older adults (>65-years), pregnant women and indigenous populations, and those with a range of pre-existing medical conditions.

4/8 cases died and none of the fatal cases were vaccinated against influenza (?survivors were vaccinated). Kidney issues have also been reported according to a video report at the Houston Chronicle.

1/4 surviving case has tested positive for influenza A(H1N1)pdm09 virus, which is circulating locally as the annual flu season is well engaged in the region. 2 other survivors have tested NEG for all influenza viruses and have been sent on to the CDC. Test results are outstanding on the other survivor.

Click on image to enlarge.
2013-14 Influenza season data from FluView, CDC at
http://gis.cdc.gov/grasp/fluview/main.html.
Of those 221 antigenically subtyped by the CDC,
184 are H1N1 2009.

Management steps include staying away from ill people, hand-washing using soap and water/alcohol-based hand rubs, covering coughs and sneezes, staying at home when ill, cleaning linens, eating utensils and dishes used by ill people, and wiping down frequently touched surfaces if likely to be a landing spot for virus from an ill co-habitant/co-worker/school or daycare child.

It would be interesting to know what testing has been employed for influenza and what other respiratory viruses and bacteria have been tested for and excluded because, despite some enthusiastic but highly misleading and inflammatory guesswork, there are not yet enough data to identify an infectious aetiology for this pneumonia cluster. I'm sure in a busy environment like this, work is progressing on many levels to resolve the mystery. Since at least 2 of the 8 patients have tested negative for influenza viruses, it is premature to extrapolate from the 1 positive case that H1N1 is the cause of all cases; it may be but those results are not yet in.

References...

• CIDRAP story. http://www.cidrap.umn.edu/news-perspective/2013/12/texas-health-officials-probe-severe-flu-illness-cluster
• Montgomery County Public Health on Facebook page. https://www.facebook.com/mctxpublichealth
• FluTrackers page. http://www.flutrackers.com/forum/showthread.php?t=214964
• Fox Houston. http://www.myfoxhouston.com/story/24257668/the-return-of-h1n1