The experts (and I do mean experts) at Effect Measure have posted an excellent discussion of why "swine flu parties" are a really bad idea.

I'd like to thank them for doing so.  Not only does this post get out an important public health message that will help people make better decisions about how to keep themselves (and their families) safe... but it also saves me some work!

Hong Kong Quarantines: No proof they were effective

Once again, our friends at the Wall Street Journal are a bit confused by the H1N1 outbreak, and public health principles in general.  

In a story on the Hong Kong quarantines today entitled Flu Lockdown Spurs Quarantine Debate, Peter Stein gets it wrong when it comes to the evidence for/against the effectiveness of the quarantine measures, saying:

"No new cases of the A/H1N1 virus, also known as human swine flu, have emerged in Hong Kong since officials ordered nearly 300 people quarantined at the Metropark Hotel Friday, apparently vindicating the policy."

He is right in noting that no new cases of the virus occurred... but he neglects to mention the fact that this means none occurred in the people who were quarantined, either.  

That means is that none of these people who were locked away from their lives for days on end could have transmitted the virus to anyone.

The lack of new cases that Mr. Stein puts forth as evidence of the quarantine's apparent effectiveness is exactly the same thing that would have happened had there been no quarantine at all.

Update: Suspected H1N1 case in Indonesia tests negative

Did I say it's the place to turn for the latest news, or what?

The Bird Flu Information Center is now reporting that the patient with the suspected case of H1N1 in Indonesia has tested negative for the virus.

Suspected H1N1 in Indonesia

Apropos of my last post:

The Jakarta Post is reporting the first suspected case of H1N1 in Indonesia.  

The patient was identified by thermal scanning in the airport at Surabaya after arriving from Hong Kong, and is being treated in an isolation unit at a nearby hospital.  H1N1 infection has not yet been confirmed.

Indonesia is epicenter of the H5N1 epidemic in humans.  Not only is it the country with the most H5N1 infections to date, it is also home to the deadliest version of the virus.  The most recent official numbers* from Indonesia are 115 dead out of 141 cases, for a case fatality rate of 81.6%.  

*As you can see here, the WHO hasn't received official reports of any cases at all this year, despite the fact that we know the disease continues to occur in Indonesia, so any recent changes that might be occurring in the spread or virulence of the virus would not be reflected in these numbers.

If you're interested in (necessarily) unofficial reports of suspected cases and the latest news on H5N1 avian influenza in Indonesia, check out Bird Flu Information Center. 

H1N1 + H5N1 = ?

Until the surprise outbreak of what the CDC is now calling "novel influenza A (H1N1)" a couple of weeks ago, if you had asked which strain of flu virus was most likely to cause the next pandemic, most experts (and even news-consuming lay people) would have told you the same thing: H5N1

The H5N1 flu virus is either a panzootic in birds (a panzootic is just like a pandemic, but for animals), and has shown the ability to infect a number of other species in a more limited way, including the friendly neighborhood tom cat... and yes, the occasional human.

And we've been quite lucky that it's only been the occasional human, because of the 421 confirmed cases we've seen over the years, 257 have been fatal.  That's a case fatality rate (CFR) of just over 61%.  It's a mean and nasty bug.

So, at this moment when much of the world is learning about recombinant flu viruses for the first time, it's not surprising that a lot of people (or at least a lot of the people who post comments in blogs and bulletin boards) are wondering whether the H1N1 virus and the H5N1 virus could combine to create a virus far more lethal than H1N1 and far more capable of human-to-human transmission than the H5N1 virus.

The bad news is that, yes, it's possible.

The good news is that it's not terribly probable, because -while the H5N1 virus is capable of infecting humans and a broad range of animals- for the most part it continues to be a disease of birds.  It typically doesn't reproduce very well in pigs at all, and humans seem to be a dead-end host for the virus so far.

The Novel Influenza A/H1N1 virus, of course, is mostly a disease of humans (though it is apparently willing to move back in with the pigs too).

In an interview with Science Insider, virologist Yi Guan of SARS fame shared his thoughts on the possibility:

Discussing the our inability to predict whether the H1N1 virus will become more virulent....

Q: It depends on further mutations?

Y.G.: It depends on mutations and whether the virus further reassorts with other viruses—like H5N1. That could be a super nightmare for the whole world.

Q: You’re talking about the Armageddon virus?

Y.G.: The chance is very, very low that these two viruses will mix together, but we cannot rule out the possibility. Now, H5N1 is in more than 60 countries. It’s a panzootic, present everywhere except North America.

Q: If the nightmare comes true?

Y.G.: If that happens, I will retire immediately and lock myself in the P3 lab. H5N1 kills half the people it infects. Even if you inject yourself with a vaccine, it may be too late. Maybe in just a couple hours it takes your life.

Sounds pretty scary, and it could be... but you'll recall that he said the chance of it happening is very, very low.  

This is a good illustration of the difference between a hazard (something that can cause harm) and a risk (the likelihood of that harm actually occurring).  

An H5N1/H1N1 recombinant virus represents a serious hazard, but the risk of it actually happening is thankfully rather low.

That doesn't mean we can afford to take our eyes off the ball, however.  The H5N1 virus is no less of a threat today than it was before the H1N1 outbreak began, and we ignore it at our peril.  President Obama says that the President of the United States needs to be able to walk and chew gum at the same time, and he's right.  Here's to hoping the global public health preparedness community can do the same.

Some statistics from today's CDC H1N1 Swine Flu Briefing

The following information comes from today's press conference with Dr. Besser, Acting Director of the CDC.

Stats for the United States:

• 279 confirmed cases in 36 states
• > 99% of probable cases so far have tested positive
• > 700 probable cases in 44 states
• Median age of confirmed cases: 16 years old 
• Age range for confirmed cases: 3 months to 81yrs
• 62% of confirmed cases are in patients < 18 years old
  
• The most recent confirmed case occurred on May 1st
• 35 known hospitalizations 
• 1 known death

Because probable cases are so likely to be confirmed when they are tested, they provide us with a more clear and timely picture of where we stand in the way of actual infections right now than the number of confirmed cases.  

No matter what the situation, the "confirmed" number will always lag behind reality, but right now it's lagging even further behind because of the significant backlog of samples to be tested.  This is inevitable when a novel pathogen emerges and a new test has to be invented to deal with it; the CDC's public health laboratory scientists have exceeded any rational expectations in the speed and the quality of their response.  

Dr. Besser said that the CDC intends to start reporting probable cases on its website the near future.

He also said that the number of probable cases is likely an underestimation of the real number, as well, because the CDC's definition of a probable case requires that a person have flu-like symptoms and test positive for Influenza A, but negative for the H1 & H3 subtypes --and we know this testing is not happening for every person with influenza-like illness (ILI).

The CDC is now rolling out H1N1 Swine Flu test kits to the states, so state public health laboratories will be able to test for the virus.  Over time, this will help to reduce the backlog for confirming cases, but states will still not be able to test all possible or even probable cases.  

That's okay, though, because the point isn't to ensure that we confirm all cases of the disease, it's to ensure that we know where, when, and in whom the virus is spreading.  --That's the data we need to make sure we're taking the right steps in the right places to protect the public. 

Egypt's ham-fisted, pigheaded ploy leads to riots

In Egypt today, Coptic Christian shantytown residents rioted over government attempts to slaughter all pigs in the country.  The government's action was ostensibly undertaken as an attempt to prevent the introduction of the H1N1 swine flu virus into the country.  However, as the story linked above (from the Telegraph) says: 

"The Egyptian authorities have admitted since ordering the slaughter last week that it was mainly a pretext for carrying out a reorganisation of the country's pig farms, which are used to supply the country's Coptic Christians, ten per cent of the population." 

The goal, apparently, is to ensure that pigs in the country are no longer raised in small, "unhygienic" holdings, for instance by trash collectors who feed their hogs with the trash they collect.

A story by Reuters opines that:

"...culling swine, largely viewed as unclean in Muslim Egypt, could help quell any public panic in the most populous Arab country."

So far, the only known case of this H1N1 Swine Flu strain actually being found in pigs occurred in Alberta Canada when a farmworker who had recently visited Mexico passed the virus on to his porcine charges.  That's right, human-to-swine spread, not swine-to-human.  (The pigs are all expected to recover, by the way.)  

There have been no cases of the disease identified in Egyptian swine (or any other beyond that one farm in Alberta).  There is certainly no epidemiological justification for slaughtering an entire nation of uninfected pigs.  

Both the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) have issued statements condemning the action, but Egypt is clearly not as interested in the science of the situation as they are in the propaganda value of being seen to do something (especially if that something only hurts a powerless minority group).

So far, the only Swine Flu-associated casualties in Egypt aren't cases of the disease, but 13 to 15+ civilians and police who have been injured in the rioting.  Let's hope it gets no worse.