Saturday, 2 May 2009

SwineDeathPlague In Perspective

(ps. xkcd rocks - go and read it on Mondays, Wednesday and Fridays!)

Thursday, 30 April 2009

Pandemic 'Flu

As readers will doubtless be aware, the World Health Organisation pandemic alert stands at level 5, which is potentially a precursor to a pandemic (level 6), and countries are gearing up to ensure the response to the outbreak if effective, efficient and clearly communicated.

Before talking about what you should do, I think it's worth making the point that at the moment we have very few cases in the UK (5:60,000,000), which is a tiny fraction of the UK population. At the moment, it is highly unlikely that you will have come into contact with someone infected with H1N1 influenza virus (aka swine 'flu, Mexican 'flu).

The Department of Health (DH), Health Protection Agency (HPA) and National Health Service (NHS) have been planning for pandemic 'flu for more than 5 years, and the NHS will take the lead in implementing the plan.

It worth noting that the response to crises of many types has been practised on many occasions. In the UK, the Civil Contingencies Act, which places a duty on many agencies to plan for public emergencies, has been in operation for a number of years, and the response to different situations is well practiced; for those who are interested I will prepare a later post on this topic.

As the pandemic plan is put into operation, stores of oseltamivir (aka Tamiflu) and zanamivir (aka Relenza) will be distributed to appropriate agencies. You will shortly be receiving a leaflet from DH outlining what your response should be, there is additional information at NHS Choices which may be of interest.

If you have flu-like symptoms, and have either returned from Mexico or another affected area or been in contact with someone who has you should ensure other people are not affected by phoning NHS Direct (0845 46 47) and not attending your GP surgery.

To prevent spread, you should practice good hygiene, as I know most people with primary immunodeficiency already do routinely.

In order to effectively prepare for the pandemic, you should:

  • Establish a network of "flu friends" who can help if you come down with the illness.
  • Ensure you have about two weeks worth of food and 'flu remedies.

As a slight aside, I personally recommend not worrying about "branded" drugs; the cheaper "supermarket brand" will do; I'd also not go with combination products (such as LemSip) because they're often not full dose. Consider paracetamol, ibuprofen, pseudoephedrine (Sudafed - sometimes only available branded): you know which drugs you can take. Don't forget to get paracetamol and ibuprofen suspension for children.

Once the pandemic is confirmed, there are rules on the issuance of antivirals.

The NICE (National Institute of Health and Clinical Excellence) guidance for prescribing antivirals when influenza is circulating in the community are:

oseltamivir and zanamivir are recommended to treat at-risk adults who can start treatment within 48 hours of the onset of symptoms; oseltamivir is recommended for at-risk children who can start treatment within 48 hours of the onset of symptoms.

The definition of "at risk" is:

At-risk patients include those aged over 65 years or those who have one or more of the following conditions:
  • chronic respiratory disease (including chronic obstructive pulmonary disease and asthma)
  • significant cardiovascular disease (excluding hypertension)
  • chronic renal disease
  • immunosuppression
  • diabetes mellitus

Prophylactic (preventative) therapy is indicated in at-risk patients when they "have been in close contact with someone suffering from influenza-like illness in the same household or residential setting".

Oseltamivir is available both as a capsule and in a sugar-free tutti-frutti flavour suspension (syrup) for children. Zanamivir is taken as an inhaled powder and is suitable for both adults and children over the age of 5.

If you need to seek help for a person with an immune deficiency who has 'flu-like symptoms, you should mention they are immunodeficient when you contact NHS Direct or your GP.

If you have concerns about attending school or work, the current advice is that staying off school (or work) is not necessary, but if you are concerned about your child you should discuss your concern with the head teacher.

ALL THIS SAID, I remain convinced there is no need to panic. Most people who have had this disease have been poorly, but it doesn't seem to have a very high mortality rate. The biggest risk is transmission, which is controlled by good hygiene; panic will tend to prevent good hygiene.

Good luck and keep your hands clearn!

But is it a hamdemic?

Just thought I would draw your attention to the World Health Organisation's pandemic phase system, which can be found on the WHO's website. We're currently in phase 5 which suggests that we may be facing a pandemic. However, that is not a reason to panic: we still don't understand what that means as we don't yet have an insight into the morbidity (rates of illness) or mortality (rates of death) associated with H1N1 inflenza virus.

Tuesday, 28 April 2009

Storm: Why PIDers may be better off...

A couple of people asked why people with PIDs might be more likely to survive a 'flu pandemic.

Immunocompetent people respond to infection in a numbers of ways simultaneously, one of which is the complement system. However, the complement system can also be activated by the actions of antibodies: this was graphically demonstrated in the TGN1412 tragedy in which the monoclonal (ie: identical) antibody caused the complement system to over-react by causing a "cytokine storm".

The complement system is activated by a cascade of proteins (cytokines, a type of signalling molecule), each of which activates the next protein in the chain. In fact, each parent protein in the chain activates many of their child proteins.

When this cascade isn't regulated (eg. by feedback turning off the parent proteins), it becomes an uncontrolled "storm", resulting in massive, rapid inflammation, oedema (water swelling), vasoconstriction (reduced blood flow) and shock.

The hypothesis is that this type of reaction causes many of the serious complications in healthy, young people. This is the pattern of fatality that was seen in the 1918 Spanish Flu pandemic, in which working-age, healthy men had higher mortality rates than any other group.

However, there may be other explanations as to why that group had higher mortality rates - not least of which is that this is the group perhaps most likely to mix together and most likely to attend work when unwell. So it's far from clear that the hypothesis is proven, and even then it might be just part of the explanation.

The logical extension of the hypothesis is that if you have certain immune problems, this might reduce your susceptibility to this type of reaction, which would confer a survival advantage on those of us with those immune problems. However, it's difficult to say at this point in time whether that is relevant to the current outbreak of swine flu.

In short, we may have an advantage but it's far from clear. If we do, I think we'll all be relieved that, for one, the PID is giving something back.

Not so hot...

Feeling a tad under the weather today - viral pharyngitis - doc gave me a gargle to use to reduce symptoms and opportunistic infections.

First thing the doc asks? "What do you think to this swine flu then? How will it affect you?"

"Well, doc, it's been suggested, although it's far from clear, that my crappy immune system might mean I don't have the same sort of problems that healthier people with normal immune response will get."

"Hmmmm," he says. He also said that he has two child patients with a PID on his books (bear in mind most GPs will see 1 PID patient in their career).

Towards the end of the consultation, after he's peered into my ears and down my throat, confirming what I already told him, I add to my original reply.

"When someone can sneeze in Airdrie and infect me in Sheppey, I'll start worrying about it."

Mind you, imagine what that would mean for the space in between Airdrie and Sheppey! I mean, that's a lot of snot...

Monday, 27 April 2009