Apr 26, 2009

Swine Flu

Posted in Science at 8:44 am by David Bradley -- 346 Comments; add your comment

UPDATE: World Health Organisation took us to Phase 6 on June 11, which only means that they see the distribution of the virus across the globe as being at levels associated with a flu pandemic, the first such declaration since 1968. The virus itself has not become any worse nor have the chances of any individual dying from the disease increased.

Swine flu is still with us although the media hype has died down. There have been numerous cases and many deaths, but nothing on the scale of the millions predicted early on. Could this first wave strain now be evolving into a more virulent form that will affect the northern hemisphere more severely after the summer is over?

I’ve previously discussed the many latent diseases in hosts as rodents, birds, and cattle. Many of these are ready and willing to make the species leap to humans given the opportunity. For the last ten years or so bird flu and Asia have been the focus of much research and concern. However, the wave of swine flu (H1N1) infections that began in March-April 2009 in Mexico highlight the fact that a potentially lethal strain of virus can emerge from other species and not necessarily in Asia.

Currently, not all the deaths attributed to swine flu have been definitively associated with type A H1N1 influenza, the actual mortality rate could be as low as 1% or as high as 6.5% depending on how you count.

Should we be worried?

No. We should be cautious, but not worried. While some observers are suggesting serious caution others are advising that there is no reason for real concern yet. We are not quite at the danger levels of even the worldwide SARS epidemic and certainly not close to the Spanish flu pandemic that ravaged the world in 1918-9.

Is the WHO scaremongering too?

The World Health Organization (WHO) has declared the Mexican/US swine flu outbreak as a “public health emergency of international concern”. It moved us to a Phase IV alert and then a Phase V alert and told us that the disease could no longer be contained. However, as things are panning out it would seem that this latest emergent virus is not even as bad as the common seasonal flu that kills tens of thousands of people every year. But, there a new strain could evolve in the coming weeks and months.

What is swine flu?

Swine flu is a type A influenza virus. It’s a subtype of H1N1 and is something of a misnomer.

Why is this new H1N1 virus called swine flu?

In the original testing many of the viral genes were shown to be similar to influenza viruses that normally occur in pigs in North America. But further studies have shown that this new virus is very different. It also has two genes from flu viruses present in European and Asian pigs as well as genes from bird flu and human flu strains. It is referred to as a “quadruple reassortant” virus.

What is unusual about the present strain?

The new strain is a hybrid of swine, human and avian flu viruses and the US Centers for Disease Control and Prevention (CDC) says it might spread from human to human but the level of virulence is not yet clear. UPDATE: There have been numerous deaths, but so far the vast majority of people infected have shown only mild symptoms and after treatment have recovered.

What are the symptoms?

Symptoms are similar to regular human flu: fever and chills, a cough, sore throat, aching limbs, headaches, and general malaise. However, there are reports of swine flu also causing diarrhoea and vomiting. Pneumonia and respiratory failure can occur leading to death as also happens in regular human flu.

Are there warning signs in children?

Children having trouble breathing, being averse to drinking, lethargy not waking up or not interacting, being so irritable that the child does not want to beheld, flu-like symptoms improve but then return with fever and worse cough, fever with a rash.

Are there any drugs to treat swine flu?

Oseltamivir (Tamiflu) and zanamivir (Relenza) are the possible pharmaceutical frontline defences against the virus and are proving effective in treating patients diagnosed early enough. There is as yet no vaccine, although researchers are working hard to develop one. It takes several months to create a flu vaccine and any such vaccine will be effective against only the specific strain for which it was created. By the time we have a vaccine the virus may have either died out or evolved into a different strain resistant to the vaccine.

Has the disease spread to the USA?

Cases in California, Texas, and Kansas, have been confirmed and tests are being carried out on students at a school in New York. Cases have been seen in New Zealand, Spain, Scotland, and elsewhere; those infected have been recovering well.

How can we prevent the spread of swine flu?

People at risk should cover their mouth when they cough. They should regularly wash their hands with an alcohol-based cleaner and and avoid close contact with the sick. Patients with the disease should stay at home. There is no need to avoid eating pork.

Will there be a global flu epidemic?

“We do not know whether this swine flu virus or some other influenza virus will lead to the next pandemic,” says, Richard Besser, acting director of the CDC, “However, scientists around the world continue to monitor the virus and take its threat seriously.” UPDATE: the WHO raised its alert level from Phase IV to V, with recent infection rates in Japan, the WHO has been hinting that they will need to upgrade to pandemic Phase VI.

Will there be a second wave?

One of two outcomes are being forecast, first that this rather poorly virulent strain will continue spreading slowly but ultimately die out, thanks to a combination of low virulence and monitoring and isolation of outbreaks, or secondly it will mutate into something much more virulent and bring with it a fast-spreading and more lethal wave of influenza. Thankfully, in the Northern hemisphere, we are heading into summer and influenza viruses do not spread as efficiently in the summer as they do in the winter.

What’s next?

It is impossible to predict what virus will emerge from which host, there are countless different types of pathogen lying dormant in the countless different mammals across the globe. No one predicted SARS, AIDS, Ebola, West Nile virus, or swine flu. This time, health agencies have responded well and although the WHO is saying it is now impossible to “contain” swine flu, it seems that the first wave is not revealing itself to be quite as lethal as was at first feared. However, that does not detract from the possibility of a second wave of H1N1 emerging.

Is this a wake-up call?

At the very least this swine flu outbreak should wake us all up to either getting the dust off our (bird flu) pandemic plans (as the response is the same) or getting started with putting them together. This includes both businesses and individuals. If the outbreak dies out quickly and this turns out not to be the next global pandemic then we can be sure another strain will try to be at some point in the future. Pandemic preparedness for businesses should now be at the forefront of every business manager’s mind.

What is cyberchondria?

Cyberchondria is an anxiety disorder related to hyperchondria and brought on by reading too many tweets with the #swineflu tag, listening to conspiracy theorists, and viewing online news stories about diseases that scare the sheesh kebab out of you. But, just because you’re paranoid does not mean the disease isn’t out to get you.