H7N9: The Good, The Bad, The Very Bad

[Reasonable Rascal]

The Good, the Bad and the Very Bad
Date: Wed 24 Apr 2013
Sosurce: The Washington Post, World News [edited]
<http://www.washingtonpost.com/blogs/worldviews/wp/2013/04/24/chinas-bird-flu-outbreak-3-good-signs-3-bad-signs-and-3-very-bad-signs/?wpisrc=nl_cuzheads>

China's bird flu outbreak: 3 good signs, 3 bad signs and 3 very bad signs
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Since the new avian flu strain H7N9 began appearing in China earlier this year, it's infected over 100 people, killed 22, spread to five provinces plus Beijing and Shanghai and, as of Wednesday, is confirmed to have spread abroad to Taiwan. How worried should you be about this? How serious is the H7N9 outbreak? The simplest and most honest answer is that we don't know what's going to happen next, either with the virus, which may or may not mutate and become more transmittable, or with Chinese and international health-care authorities responsible for tamping it down. But there are some good signs, some bad signs and some very bad signs. Here are a few.

Three good signs:
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1. China is being unusually transparent so far. Ten years ago, as the deadly viral respiratory illness known as SARS first spread across China, the government did not respond well. It suppressed information about the outbreak, making it that much harder to contain and study the disease, ultimately costing lives. This time, though, Chinese authorities have been sharing information about the disease's spread, and state media appear to be freely reporting on new cases. Chinese officials seem to take the disease seriously and want to combat its rise, even if it means overcoming more secretive instincts. All health care for H7N9 is now free in China, for example, to help encourage
people to report cases.

2. The number of cases has largely flatlined in the last week. After weeks of rising cases, the number seems to have stayed stable at around 110 over the last week. Big caveats here that there might be cases we don't know about, and the count could change at any moment.

3. Shanghai has found some success limiting new cases. A lot of the cases started around Shanghai, but the city was able to reduce the number of new infections after it closed poultry markets, according to Laurie Garrett, a senior fellow at the Council on Foreign Relations covering health-care policy. The Wall Street Journal found the same thing.

Three bad signs:
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1. It's spreading. With cases recently reported in Shandong province and now in Taiwan, the virus seems to be moving outward.

2. No verified human-to-human transmissions, but it's possible. Neither China nor the World Health Organization has documented human-to-human transmission, which would allow the virus to spread far more quickly and widely, but nor have they ruled it out. The Taiwanese case had no known exposure to poultry.

3. Tough to identify birds with the virus. World Health Organization officials say the virus is more difficult to detect in sick poultry than were previous strains because the birds do not show symptoms that are as clearly identifiable. This makes it tougher to keep sick birds off the market.

Three very bad signs:
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1. It's very deadly, with 18 percent mortality so far. For comparison, tuberculosis has a mortality rate of about 4 or 5 percent in China. Still, the avian flu virus that had its first outbreaks in China in 2006, known as H5N1, has a mortality rate of 60 percent and has killed hundreds of people on multiple continents. It's way too early to tell H7N9s mortality rate, given that many infected patients have not yet fully recovered, but it's so far killed about 18 percent of patients.

2. "This is definitely one of the most lethal influenza viruses that we have seen so far." That's according to Keiji Fukuda, the World Health Organization's assistant director general for health, security and the environment, who added, "This is an unusually dangerous virus for humans." Fukuda said the WHO is still struggling to understand the disease, but he certainly seems to be sounding the alarm.

3. More easily transmitted than the 2006 avian flu outbreak. That's alsoaccording to the WHO's Fukuda, who says this new strain is more easily contracted than the H5N1 virus.

(By Max Fisher)

 

[FarmerJohn]

Re the 1918-1919 flu epidemic, the "Spanish Flu":

The global mortality rate from the 1918/1919 pandemic is not known, but an estimated 10% to 20% of those who were infected died. With about a third of the world population infected, this case-fatality ratio means 3% to 6% of the entire global population died

http://en.wikipedia.org/wiki/Spanish_flu#Around_the_globe

So the big question is: How transmisable from human to human? Actual contact required of a cough from 20 feet?

 

[surfingdemon]

Here's What Happens When You Get Bird Flu

Jennifer Welsh | Apr. 26, 2013, 4:26 PM | 3,623 | 3

REUTERS/Stringer
There are still many things we don't know about the H7N9 bird flu that's been infecting people all over China (and even Taiwan).

Here's what we know happens when you get infected.

First contact
First, you come into contact with an animal infected with the virus. The virus seems to originally come from poultry, but it has adapted to be able to infect mammals and other birds, too.

We aren't sure how many people are coming into contact with the virus — only about 40% remember having contact with poultry. They could be picking it up from other animals.

It may also be transmitted from human to human, but if it can, it doesn't do it well yet.
Incubation

We don't know how long the virus sticks around in the body before showing symptoms. Once you get infected with the virus, you probably won't notice for about a week. The virus seems to have a seven-day incubation time, though that may be different between people.

First symptoms appear
Fever and fatigue : When you do start showing symptoms expect a fever, sweating, and fatigue, but no respiratory or gastrointestinal symptoms, which is what the Taiwanese patient experienced. Other cases, such as patient 8, developed diarrhea as their first symptom.

The Centers For Disease Control (CDC) suggest that symptoms start with a high fever and a cough

Fever worsens
Four days later you will develop a high fever, sweating, and fatigue. You will definitely start feeling sick, and probably visit your doctor.

Pneumonia
After another two days, an X-ray of your chest will shows signs of pneumonia — your lungs are getting inflamed and leaky in an effort to fight off the virus. Your symptoms worsen and it will get progressively more and more difficult to breathe.

Respiratory failure
The pneumonia leads to respiratory failure, which is when your inflamed lungs get so full of fluid that they can no longer perform their main function: exchanging carbon dioxide in your blood for oxygen in the air.

Acidosis
Your blood oxygen levels plummet and the carbon dioxide builds up in your blood, making it acidic.
Intubation

To keep your brain and body from failing, you are put on a respirator, which pumps 100 percent oxygen into your lungs with enough pressure to push it through the liquid that's built up and preventing gas exchange.

You will be sedated while on the respirator.

Septic shock
As your lungs continue to fail and the virus wreaks havoc on your body, you go into septic shock as the virus invades your bloodstream. You will have a fever over 100 Fahrenheit, fast breathing (if you aren't ventilated), a high heart beat, and your white blood cells will be going crazy.
Multiple organ dysfunction

The septic shock will cause multiple organ dysfunction syndrome as your body's inflammatory response in its efforts to beat back the virus injures your organs.

Death
Eventually your body gives in and you die.

The symptoms above are based on our current understanding of the virus, and they are only meant to be a representation of what is currently understood. If you have visited China recently, have been in contact with poultry, and are showing flu-like symptoms, visit your doctor immediately.

http://www.businessinsider.com/what-happens-h7n9-bird-flu-infection-2013-4#ixzz2RcxDHiuy

 

[surfingdemon]

Experts: Past exposures may help explain H7N9 age profile

Robert Roos * News Editor

Apr 26, 2013 (CIDRAP News) – Taking a cue from curious findings noted during the 2009 influenza pandemic, Canadian researchers are suggesting that past exposure to distantly related viruses may help explain why the age curve in H7N9 cases is so skewed to the older side.

Danuta M. Skowronski, MD, of the British Columbia Centre for Disease Control and three colleagues offer the hypothesis that older Chinese men have greater lifetime exposure to H7 avian flu viruses than younger people and therefore may have weakly cross-reactive antibodies that paradoxically promote infection with the novel H7N9 virus. They offer the suggestion in this week's Eurosruveillance.

"At this stage, we should . . . stay open to the possibility that pre-existing cross-reactive antibodies may actually facilitate the viral infection process," they write.

The unusual age and sex distribution of H7N9 cases has puzzled experts. Skowronski and colleagues note that two thirds of the 109 case-patients reported as of Apr 23 were at least 50 years old, and an equal fraction of them were male.

World Health Organization officials pointed out this week that this pattern contrasts with the general Chinese population, which includes a large share of young and middle-aged adults and a preponderance of women in the older age brackets. Others have noted that the H7N9 age distribution is very different from that of H5N1 case-patients in China, most of whom have been young.

Some have suggested that older Chinese men may have more exposure to poultry or birds than other groups, but no answers have emerged so far.

The phenomenon of cross-reacting antibodies that facilitate infection is best known in dengue infections, according to Skowronski and colleagues. The dengue virus comes in four types, and a person who has a second dengue infection involving a different type from the first one can suffer a severe illness.

The phenomenon is called antibody-dependent enhancement (ADE), the Canadian experts write. "ADE is thought to occur when low levels of weakly heterotypic, cross-reactive but not cross-protective, antibodies generated by past exposure to virus antigen, eg, through prior infection or immunisation, form bridging complexes to facilitate uptake and replication of related but non-identical variants," they state.

Flu experts have long been interested in the possibility of ADE in influenza, and some Canadian findings during the 2009 H1N1 pandemic may offer indirect evidence of it, the article goes on to say.

Early in that event, the Canadian researchers found that people who had previously received a seasonal flu vaccine that contained a virus distantly related to the pandemic strain had about a doubling of risk for medically attended pandemic H1N1 illness.

In a follow-up experiment, the researchers found that vaccinated ferrets had higher lung virus titers and more severe illness after exposure to the pandemic H1N1 virus than ferrets with no previous exposure to flu or flu vaccine, according to the article.

The authors say there's little information to suggest whether older Chinese men have had greater lifetime exposure to H7 avian flu viruses than other groups. Few serologic surveys to assess H7 antibodies in the Chinese population are available in English, and the ones available lacked statistical power to compare different groups by age and sex.

The researchers conclude by suggesting that serologic surveys to compare cross-reacting antibodies and neutralizing effects by age-group could be important for assessing protection and risk.

See also:

Apr 25 Eurosurveillance article by Skowronski and colleagues

Apr 22 CIDRAP News story "WHO ponders preponderance of older men with H7N9"

Apr 19 CIDRAP News story "Why does H7N9 age profile tilt older?"

http://www.cidrap.umn.edu/cidrap/content/influenza/h7n9/news/apr2613age.html

 

[Intestinal Fortitude]

Still only guesses and speculation.

 

[surfingdemon]

At what stage is the spread of the H7N9 virus considered an epidemic?

Question submitted by Patrick Carlson, from United States, April 29, 2013

Answered by: Laurie Garrett, Senior Fellow for Global Health

The H7N9 virus, a new strain of the bird flu in China, has so far claimed twenty-two victims and officials are watching its spread closely. Most worrying, at least one case has turned up in Taiwan, and three of the victim's healthcare workers have developed flu symptoms, suggesting both that this epidemic has crossed country borders and that it can pass from person to person. Even more distressing, the healthcare workers wore full protective gear.

There are three stages to infectious disease spread, and the boundaries between them are a bit fuzzy. The first, outbreak, starts with the initial case(s) in people or animals, typically as a virus mutates or exploits a new ecological opportunity to infect a broader range of species. An example of this is the H5N1 avian flu, which periodically breaks beyond birds to infect (and often kill) humans.

The term epidemic is applied if that virus (or bacterium) manages to spread from person-to-person for two "generations." If John passes his virus to Jill, that is one generation of transmission; if Jill then passes infection to Mary, that's a second generation. Public health officials usually grow especially alarmed if a third generation of spread occurs, as that indicates genuine contagion is unfolding. Examples of this would be the 2003 initial Chinese SARS epidemic, and this month's bird flu in China.

Finally, a pandemic is an epidemic that spreads from one continent to another, threatening the entire world. The so-called swine flu, caused by H1N1 influenza in 2009 would be an example of this. The World Health Organization tried to create a standard pandemic alert system, but the biology of outbreaks and microbes defies simple algorithms.

One can only hope that the new H7N9 virus is not a new pandemic being born, but we will have to wait and see.

http://www.cfr.org/public-health-threats/stage-spread-h7n9-virus-considered-epidemic/p30581