Influenza and the weather

By: Dr. Jeff Masters , 1:14 PM GMT on May 04, 2009

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It is well known that influenza hits hardest in winter--November to March in the Northern Hemisphere, and May to September in the Southern Hemisphere. In fact, the name influenza comes from the Italian word influenza, meaning "influence"--referring to the "influence of the season" (winter) in causing the illness. In the tropics, where there is little change in seasons, influenza occurs year-round (though increased incidence has been noted in rainy seasons--Viboud et al., 2006). Do the cold temperatures and lower humidities of winter cause increased transmission of the flu virus? If so, why is the current H1N1 swine flu outbreak doing so well, now that it is May, traditionally the end of flu season in the Northern Hemisphere? Or could it be that indoor crowding, lack of sunlight lowering vitamin D levels, and a more depressed immune system in winter are largely responsible, as some researchers have suggested?

Flu infections increase under cold or dry conditions
To test these hypotheses, researchers at the Mount Sinai School of Medicine in New York did a study in 2007 that looked at flu transmission among guinea pigs, which are highly susceptible to human influenza and easily transmit the virus to other guinea pigs (Lowen et al., 2007). The animals were placed in adjacent cages, so that infections could occur by airborne transmission, but not by direct contact (guinea pig lovers will be happy to know that the influenza virus-infected guinea pigs did not display detectable symptoms of disease--weight loss, fever, sneezing, and coughing--during the experiments). By carefully controlling temperature and humidity, the scientists were able to study the effects of each. They found that the animals shed much more of the virus--and over a longer period of time--at cold temperatures, which led to increased infection rates. The animals' immune system showed no signs of stress from the cold weather, arguing against the idea that cold conditions lead to increased infections by lowering the immune system. Lower humidities were also found to increase flu transmission rate, though the variation of infection rate with humidity was more complicated. The scientists built a model (Figure 1) to fit the data, and proposed that lower humidity increased infection rates through two mechanisms:

1) The stability of influenza virons in the suspended aerosol particles infected creatures cough out is dependent upon the humidity. Viruses are most stable at low RH (20%-40%), least stable at intermediate RH (50%), and stable again at high RH (60%-80%) (Schaffer et al., 1976). Thus, the virus has better staying power at the low moisture levels typical of winter.

2) At high RH (80%), exhaled respiratory droplets grow quite large as water vapor condenses around them, and these drops quickly settle to the ground under the force of gravity. Thus, even though the virus is stable at high humidities, it settles out of the atmosphere quickly, and cannot contribute to influenza virus spread.


Figure 1. A model of influenza transmission rates at 68°F (20°C) (dashed line) and 41°F (5°C) (solid line), as a function of relative humidity. Transmission efficiency is highest at low relative humidity, when influenza virions in an aerosol are relatively stable, and exhaled respiratory droplets stay small and don't settle out under the force of gravity. Transmission is diminished at intermediate humidity when virus particles are relatively unstable, but improves in parallel with influenza virus stability at higher humidities. At high humidity, evaporation from exhaled particles is limited, respiratory droplets settle out of the air, and transmission is blocked. At cold temperatures (solid line), transmission is more efficient than at warm temperatures (dashed line), but is reduced to a rate of 50% at higher humidities. Image credit: Lowen, A.C., S. Mubareka, J. Steel, and P. Palese, 2007, "Influenza Virus Transmission Is Dependent on Relative Humidity and Temperature", PLos Pathogons, October 2007.

The researchers found no guinea pig infections at 86°F (30°C), which implies that in tropical climates, people may transmit the virus by direct contact rather than by coughing and sneezing. A second study Lowen et al., 2009) confirmed this idea--at least among guinea pigs. The authors concluded, "To our knowledge, we demonstrate for the first time that cold temperatures and low relative humidity are favorable to the spread of influenza virus. Although other factors likely contribute to the periodicity of influenza epidemics, it is clear that air temperature and RH could play an important role. Influenza virus transmission indoors could potentially be curtailed by simply maintaining room air at warm temperatures (>20 °C) and either intermediate (50%) or high (80%) RHs".

Climate change and influenza
The results of this study imply that global warming may significantly reduce influenza world-wide, since a warmer climate will also be more humid. Typically, there are between three and five million cases of severe flu and up to 500,000 deaths worldwide each year. In the United States alone, an average of 41,400 deaths and 1.68 million hospitalizations are attributed to influenza each year. A warmer world should reduce these numbers, if the current research is correct. However, these gains must be balanced against the possibility that malaria will become more widespread in a warmer world, since malaria kills about one million people per year.


Figure 2. Combined flu and pneumonia deaths in the United Kingdom during the great 1918 flu pandemic showed that the flu had three distinct peaks: one in June - July (a relatively mild form of the disease), followed by an extremely deadly outbreak in October, then another during the winter of 1918 - 1919. The 1918 flu pandemic infected 1/3 of the world's population, killing 50 - 100 million people. Strangely, the October peak occurred almost world-wide, with Bombay, India and Boston, Massachusetts peaking the same week. Image credit: Jordan, E., "Epidemic influenza: a survey", Chicago: American Medical Association, 1927.

Flu pandemics show little seasonality
The current Mexican H1N1 swine flu outbreak is seemingly unusual, since it is hitting at the end of the traditional flu season, in April - May. However, when a new flu strain develops that humans have no immunity to, the new strain is less constrained by seasonality. According to Dr. Jeffery Taubenberger, the virologist who helped isolate the genetic code of the virus responsible for the great 1918 flu pandemic, "Historical records since the 16th century suggest that new influenza pandemics may appear at any time of year, not necessarily in the familiar annual winter patterns of inter-pandemic years, presumably because newly shifted influenza viruses behave differently when they find a universal or highly susceptible human population." Indeed, the 1918 flu pandemic reached its peak in September - October (Figure 2), and the most recent flu pandemic, the 1968 Hong Kong flu, began in July. It wouldn't surprise me if the current flu outbreak dies down in the Northern Hemisphere over the summer months, as the combined effects of high temperatures, higher humidities, less indoor crowding, and increased sunlight interfere with its spread. However, we need to be ready for the virus to reappear in the Fall--potentially in a mutated, more virulent form--such as occurred during the 1918 flu pandemic.

References
Lowen, A.C., S. Mubareka, J. Steel, and P. Palese, 2007, "Influenza Virus Transmission Is Dependent on Relative Humidity and Temperature", PLos Pathogons, October 2007.

Lowen, A.C., S. Mubareka, J. Steel, and P. Palese, 2009, "High Temperature (30°C) Blocks Aerosol but Not Contact Transmission of Influenza Virus", Journal of Virology, June 2008, p. 5650-5652, Vol. 82, No. 11 0022-538X/08/$08.00+0 doi:10.1128/JVI.00325-08

Schaffer, F.L., M.E. Soergel, and D.C. Straube, 1976, "Survival of airborne influenza virus: effects of propagating host, relative humidity, and composition of spray fluids", Arch Virol 51: 263-273.

Viboud, C, W.J. Alonso, and L. Simonsen, 2006, "Influenza in tropical regions", PLoS Med 3: e89 doi:10.1371/journal.pmed.0030089.

Vitamin D and influenza links:
http://www.medicalnewstoday.com/articles/51913.ph p
http://www.sciencedaily.com/releases/2008/08/0808 11195629.htm
http://www.vitamindcouncil.org/science/research/v itamin-d-and-influenza.shtml

Jeff Masters

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You mean this?
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Quoting Tropicsweatherpr:
Is this the first Tropical Wave of 2009 or there is no data to confirm that?

img


I think its too far south.
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Forgot to say where it is,at the right of pic at Westcentral Africa.
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Weather456,is that big area of convection in West Africa the possible first Tropical Wave of 2009 or there is no data to confirm that?

img
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190. Skyepony (Mod)
After reading about the lack of Vit D causing your body to attack itself in the face of the flu in the 1st place, treating it with nicotine seems more treating the symptom, than correcting the cause.
Member Since: August 10, 2005 Posts: 223 Comments: 39361
As for the Gulf, Xie's data indicate the likelihood of three to five named storms forming, of which one to three will become hurricanes. The researchers expect two to four named storms to make landfall along the Gulf, and there is a 70 percent chance that at least one of those storms will be of hurricane status.

I don't like this part... Thanks for providing this information Keeper.
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ya its something that must be prepare for
its happen before it will happen again just a matter of time

Member Since: July 15, 2006 Posts: 178 Comments: 55984
Quoting hurricane23:
Again if the pattern some mentioned yesterday does develop than the "Newfoundland wheel" will certainly endanger the east coast and Florida with whatever storms that do form. The NAO is such a tough thing to predict but i do think we have a better chance for a negative NAO in late Summer/early Fall then past years.

Adrian


Oh boy. LOL.. Thanks Adrian
Member Since: August 12, 2007 Posts: 2 Comments: 2838
Its been so long since our last storm up here in the northeast a long island express storm would be dangerous, too much complacency up here.
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2009 Hurricane Season Should Contain No Surprises, Researchers Say
April 9th, 2009 (PhysOrg.com) -- Researchers at North Carolina State University believe that 2009 will bring a near-normal hurricane season, with storm activity in the Atlantic basin and the Gulf of Mexico slightly above the averages of past 50 years, but staying in line with those from the past 20 years.

According to Dr. Lian Xie, professor of marine, earth and atmospheric sciences, and collaborators Dr. Montserrat Fuentes, professor of statistics, and graduate student Danny Modlin, 2009 should see 11 to 14 named storms forming in the Atlantic basin, which includes the entire Atlantic Ocean, the Gulf of Mexico and the Caribbean Sea.

Of those named storms, six to eight may grow strong enough to become hurricanes, and there is a 45 percent chance that one of those storms will make landfall along the coast of the southeastern United States as a hurricane.

As for the Gulf, Xie's data indicate the likelihood of three to five named storms forming, of which one to three will become hurricanes. The researchers expect two to four named storms to make landfall along the Gulf, and there is a 70 percent chance that at least one of those storms will be of hurricane status.

"The data show that the number of storms this year will not vary significantly from those of the past 20 years; in fact, 2009's numbers are slightly lower than last year's prediction of 13 to 15 named storms," Xie says.

Xie's methodology evaluates data from the last 100 years on Atlantic Ocean hurricane positions and intensity, as well as other variables including weather patterns and sea surface temperatures, in order to predict how many storms will form and where they will make landfall.
The Atlantic hurricane season runs from June 1 through Nov. 30.

Provided by North Carolina State University
Member Since: July 15, 2006 Posts: 178 Comments: 55984
Quoting Ossqss:


There is your cure in post 179.

They have been talking of the over reation of the immune system in some actually solidifying the lungs with excessive amounts of white cells. They said it was liver like afterwards. That does not sound good. Similar to what the SARS virus did to some.

Who woulda thunk it, smokin can cure the flu ?


Avoid the flu but get lung cancer??? I think I'll just take my chances with the flu! :)
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Quoting CaneWarning:


Well that's not good. I've been taking my vitamins and drinking lots of O.J. I also keep hand sanitizer with me so hopefully I'll be ok.


There is your cure in post 179.

They have been talking of the over reation of the immune system in some actually solidifying the lungs with excessive amounts of white cells. They said it was liver like afterwards. That does not sound good. Similar to what the SARS virus did to some.

Who woulda thunk it, smokin can cure the flu ?
Member Since: June 12, 2005 Posts: 6 Comments: 8188
Quoting hurricane23:
Again if the pattern some mentioned yesterday does develop than the "Newfoundland wheel" will certainly endanger the east coast and Florida with whatever storms that do form. The NAO is such a tough thing to predict but i do think we have a better chance for a negative NAO in late Summer/early Fall then past years.

Adrian

ya this could be the year of the overdue long island express been waitin on that one for a while
Member Since: July 15, 2006 Posts: 178 Comments: 55984
176. IKE

Hello IKE. Particularly nasty cell over Gulf Breeze right.
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180. Skyepony (Mod)
Oss~ I noticed that this morning. Looked like a competing blob had developed..I had not expected it to bomb because of that. Then the 1st storm ate the blob for brunch & wow...lesson learned.
Member Since: August 10, 2005 Posts: 223 Comments: 39361
Is the flu so bad in Mexico City because of their chronic air pollution? Perhaps yes - we'll have to wait for the scientists to make their final determination. Until then, it's well known that chronic air pollution is bad on our lungs and our immunity in general. I've personally experienced decreased lung function and increased rates of illness and severity of illness when living in chronically polluted areas.

HOWEVER, this is very interesting information that I hope gets more study and, if true, more press. Could slapping some nicotine patch on a kid's arm help their bodies to *not* over-respond to the flu? Of course nicotine is a very powerful and addictive drug, but what an interesting finding!
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178. IKE
Quoting RTLSNK:
Hey Ike, long time no see.


I'm around....usually in lurk-mode until the first Atlantic invest(aka invest 90L), pops up.
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Hey Ike, long time no see.
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176. IKE
Quoting RTLSNK:
Heavy rain for the panhandle today:



True...it's raining here now in the panhandle and 67 degrees.
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Heavy rain for the panhandle today:

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Again if the pattern some mentioned yesterday does develop than the "Newfoundland wheel" will certainly endanger the east coast and Florida with whatever storms that do form. The NAO is such a tough thing to predict but i do think we have a better chance for a negative NAO in late Summer/early Fall then past years.

Adrian
Member Since: Posts: Comments:
Skyepony, in that loop,in the beginning, that thing looked like it wanted to form 2 storms, kinda like a crossfire hurricane. I played it back slow and you could see two spots apart from each other swirling separately. Ofcourse I could be experiencing continuous pixel contagion from the 3 monitors staring at me.
Member Since: June 12, 2005 Posts: 6 Comments: 8188
172. Skyepony (Mod)
I've been getting into those Vit D & flu links that Masters left at the bottom of the entry. Good stuff there. Would explain the outbreaks across the world on same lat, in same week back when we didn't move so near freely. Being in that prime young healthy age range that tends to have their body attacked & drownt by itself over these types of strains, sounds like Vit D maybe the new posies...
Member Since: August 10, 2005 Posts: 223 Comments: 39361
Quoting Ossqss:


Their best guess to date is an 8 day incubation period. Ouch


Well that's not good. I've been taking my vitamins and drinking lots of O.J. I also keep hand sanitizer with me so hopefully I'll be ok.
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Quoting SomeRandomTexan:


no offense but the best way to keep from have confrontations is sticking to the subject matter. Hopefully we can all agree. There are a couple of poitical blogs out there that we can have our political discussions on.

Thanks for keeping it real guys :)



your right,my political views are my own...
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Quoting presslord:
Aaahhh....chew!!!!!!!!!!!!!!

...sniffle....sniffle...

...cough...



still sick press???,lol...
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164. Can you please explain this map? I have no clue what I'm supposed to be looking at here.
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167. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #17
TYPHOON KUJIRA (CAT 3)
06:00 AM JST May 5 2009
================================

Subject: Category Three Cyclone In Sea East Of The Philippines

At 18:00 PM UTC, Typhoon Kujira (945 hPa) located at 17.1N 131.0E has 10 minute sustained winds of 80 knots with gusts of 115 knots. The typhoon is reported as moving east at 13 knots.

Dvorak Intensity: T6.0

Storm Force Winds
=================
50 NM from the center

Gale Force Winds
===============
180 NM from the center

Forecast and Intensity
=======================
24 HRS: 19.9N 135.7E - 80 knots (CAT 3/Typhoon)
48 HRS: 24.7N 140.8E - 70 knots (CAT 3/Typhoon)
72 HRS: 32.8N 145.9E - 55 knots (CAT 2/Severe Tropical Storm)

---
conservative JMA.. not again =/
Member Since: May 24, 2006 Posts: 52 Comments: 46907
Quoting presslord:
...just allergies...
Quoting presslord:
...just allergies...
Toss the dock lines, snug the sheets and head due east. Blue water salt spray has the cure.
Member Since: September 11, 2008 Posts: 9 Comments: 10165
Quoting CaneWarning:


Someone sneezed on me today when I was in the elevator. I'm not too happy about it.


Their best guess to date is an 8 day incubation period. Ouch
Member Since: June 12, 2005 Posts: 6 Comments: 8188
164. JRRP
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163. Skyepony (Mod)
Ya'll stare into the pinhole eye. It should calm you..


Kujira has bombed well enough..
Member Since: August 10, 2005 Posts: 223 Comments: 39361
...just allergies...
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Quoting Ossqss:
So on a lighter note, How about that Pandemic ah?
At least Publix has sterile wipes beside cart pickup. That's good.
The weather's warm, airborne quality weakened. That's good.
Press is sneezing. That's bad.
Member Since: September 11, 2008 Posts: 9 Comments: 10165
...nah....haven't been on an elevator today....
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Quoting presslord:
Aaahhh....chew!!!!!!!!!!!!!!

...sniffle....sniffle...

...cough...


Was it you???
Member Since: Posts: Comments:
Aaahhh....chew!!!!!!!!!!!!!!

...sniffle....sniffle...

...cough...
Member Since: Posts: Comments:
Quoting Ossqss:
So on a lighter note, How about that Pandemic ah?


Someone sneezed on me today when I was in the elevator. I'm not too happy about it.
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Please guys... before you all get banned...STOP... I enjoy everyone's input and don't want to see you all get kicked!
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So on a lighter note, How about that Pandemic ah?
Member Since: June 12, 2005 Posts: 6 Comments: 8188
Just trying to help. :)
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Here you go stillwaiting. Think you can get rent assistance and food stamps too. Knock yourself out. You're already covered.

Link
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Quoting stillwaiting:
shep:what field do you work in and how many degrees do you have?????
Keep talking.
I'm in the construction business and have only a simple Bachelor of Science Degree with a Major in Architecture from UF.
And how many degrees did it take for you to be a 31 year old waiter with a wise guy attitude?
Member Since: September 11, 2008 Posts: 9 Comments: 10165
Quoting stillwaiting:


Notice I stated MOST people in FL,not ALL...my friend to the north!!...I just feel like I get attacked every time I defend obama,or state my opinion about bush,I get attacked (shep)so I'll do neither on this blog anymore,I've lost focus that this blog is about weather and its non-productive to argue about peoples personal political views!!!!


no offense but the best way to keep from have confrontations is sticking to the subject matter. Hopefully we can all agree. There are a couple of poitical blogs out there that we can have our political discussions on.

Thanks for keeping it real guys :)
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OK at the risk of ban, I offer this brief interlude.

Member Since: June 12, 2005 Posts: 6 Comments: 8188
and there's a really nice 15-20mph breeze coming right off the water!!!
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I'm on my 3rd story balcony outside looking at the beach right now(waters blueish-green,w/white sand),I'm doing great right now, and god willing my day will be great..(if you don't believe I live on the beach,ask SM next time she's on)
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Quoting stillwaiting:
and can you see the GOM from your apt.???,because I can!!!! I don't even have to put shoes on to walk to the beach ambitiously!!!!,how far inland do you live???,20,30,40 miles????,lol....and how many boars do you have roaming your property my friend???
Keep ranting. The world is listening.
Don't have an apt. Built my own house "ambitiously". I'm centraly located. I can tow any one of my boats anywhere I choose.
Just make sure you bring polished silverware and glasses to the table.
Member Since: September 11, 2008 Posts: 9 Comments: 10165
I don't know if people get banned during the off-season but I think there are a few who are begging for it to happen.
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Quoting Ossqss:


It is still registered with the search engines, just might be down or if located near SF CA affected by the fiber cut .


Notice I stated MOST people in FL,not ALL...my friend to the north!!...I just feel like I get attacked every time I defend obama,or state my opinion about bush,I get attacked (shep)so I'll do neither on this blog anymore,I've lost focus that this blog is about weather and its non-productive to argue about peoples personal political views!!!!
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I hope the day gets better for you Stillwaiting and I do mean that sincerely.
Member Since: June 12, 2005 Posts: 6 Comments: 8188

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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