It’s an interesting puzzle, this bird flu. On one side, while birdwatchers are all disturbed about even the suggestion of wild bird culling as a control measure to prevent spread of bird flu by migratory birds, on the other hand, for the public health professionals, it is just among various available ‘vector-control’ measure…..kinda like control mosquitoes to prevent malaria. Who would listen if for whatever reason, ‘mosquito-rights’ activists want to prevent any such measure!!
Anyways, neither are there any mosquito-rights activists, nor are things as simple as taking a leaf from malaria vector control and applying it in bird flu. Understandably, things are much more complex than that. In two posts to two different groups, I have shared my opinions with both interest groups – birdwatchers and public health professionals…….here is the birds edition, and soon to come the public health edition.
Just a few comments of mine especially in view of several discussions that I have been witness to in course of my study here. I just share below some of my thoughts for the general reader and may be writing on topics way out of the purview of our discussion group in hope that many birdwatchers would be interested in topics related to bird flu – an interesting situation that calls for a lot of inter-disciplinary work and understanding of concepts in biology, epidemiology, public health and veterinary science.
Sudheendra’s mail and Krishna’s and Deepa’s subsequent replies about Avian flu bring up many issues on avian flu that are hardly being considered. Sudheendra rightly points out the serious economic consequences of mass culling being undertaken in response to ‘declared’ cases of the flu in Orissa and Bengal. Many of the people involved here are small poultry owners for whom livelihood is a much more proximate concern than an unheard ‘flu’.
Flu is definitely not something to be taken lightly. As Krishna points out, if the virus does ‘cross-over’ to humans, the chances are only among the animal handlers, and that is exactly where the public health authorities must focus. It is also to be noted that until recently bird-human infection was not yet reported and it was only spreading among birds. But, the worldwide panic is because IF there is such a mutation that enables the flu to spread among people, it could take up the pandemic proportions that the world has seen before.
The thing about flu is that it is clinically….well…so insignificant! Fever, feeling of weakness, body pain, red eyes are symptoms that dont get reported. MOre so in the health system landscape that India has with a zillion private clinics, quacks, traditional healers and disgruntled and frustrated public health system. The reports we are getting now are the ones we could detect.
Flu viruses have the uncanny ability of sweeping across the world bringing about widespread deaths and then, suddenly disappearing. This has happened many times before. The classical example quoted is that of the Swine Flu epidemic in the US which is supposed to have killed over 20 million people over 4 months just in the US! Of course, the pandemic was worldwide, but you
can get numbers only for the US, UK and some other countries which did have such systems. Over 200,000 people are supposed to have died in this pandemic in UK. It took more lives than in the First world war. And then, suddenly Swine Flu vanished into thin air. Poof! I say this to emphasize the point that flu is a very real danger. The reason why it flares up so suddenly is
attributed to mutations.
Influenza is caused by a virus which are comparable to “a bad xerox machine inside a protein cover”, the xerox machine in this case referring to its genetic material. I call it bad because it lacks a particular ‘proof-reading’ mechanism that other living things have and hence there are
no ‘errors’ when for example our own skin cells multiply in a healing wound. If our cells did not have a good way of keeping our genetic material intact during division, then we would all be doomed! But, for the virus this is quite an advantage, and hence through mechanisms called drifts and shifts, the virus keeps changing its protein clothing, which is what enables our immune system to identify them. So, how does the human immune system grapple with a virus that keeps changing its appearance……It cant!…which is why, HIV and many other such viruses pose a great threat for vaccines. We would have to keep making vaccines for every new dominant appearance (strain) of the virus. IN simple language what I spoke about here is recognized as Genetic drifts and Genetic shifts. Drifts are minor changes occuring in the protein coat of the virus that leads to failure of vaccines and sometimes, major catastrophes, such as the Spanish Influenza Pandemic in the spring of 1918 which is supposed to have killed anywhwere between 40-100 million people! Get ready for this one – The Spanish Flu strain was supposed to have been an avian virus that underwent a shift!
Coming back to avian flu, the present strain finds it very difficult to get transmitted from human to human. Still, over 300 worldwide deaths that have been reported today are mostly bird-human transmissions with a few rare ‘within family’ transmissions reported mostly again, within the family of the animal/poultry handlers. The virus strain causing the flu is called H5N1
which is the standard name for naming influenza viruses. H stands for one of the surface proteins on the virus that enables entry into cells, and N stands for an enzyme that enables the new virus particles to break out of the dying cell. Now, 4 sub-types of the avian flu virus are recognized. All
of them are deadly to birds, and can cause disease and death among humans. It is important to remember here that the virus presently is an AVIAN FLU virus and is being incidentally passed on to humans because of the way in which we have organized our poultry system! Wild birds, especially waterfowl are natural carriers of the virus, although, they are not as susceptible to
the disease as are the domestic birds. For eg. Russian vets are supposed to have drawn over 4000 samples of blood in Siberia with around 50 showing antibodies, which indicates active infection or past infection.
It is quite evident that migrant birds can carry these strains. But, it is important to note the following:
1) Birds carry several kinds of flu viruses and they have been doing so for zillions of years.
2) Wild birds themselves pose NO THREAT to any person directly. The only way is for them to pass on their infection to poultry birds, where the flu could spread like wildfire.
What we need to focus on is the situation within our poultry industry, handling of dead birds and a surveillance system that reports bird deaths in poultry houses. Moreover, awareness on this for animal handlers is extremely important. I find it quite ridiculous that may international bodies are calling for culling of wild birds. Such measures are not only scientifically untenable, they are also quite a schoolboy solution, I must say….a bit like trying to kill all mosquitoes to eradicate malaria!
What we must concentrate on is surveillance systems, awareness on animal handling and vaccine research. Prototypes of the vaccines are being reported. If the virus does acquire mutations that enable human-human transmission, it could definitely be catastrophic, else, it could just go away into the thin air like a million other strains of flu that we in the third world could never ever find document, let alone naming them after their surface proteins. India must’ve seen so many other previous outbreaks that were never documented.
Just a final word, Avian Flu is a disease that presents a lot of research opportunities. There could be many PhDs created. It creates good business opportunities, many patents, awards, paper presentations, conferences and well, sales of the vaccine will rake in millions…….it’s not the same
situation for diseases like Malaria, Kala-azar, Tuberculosis etc. which continue to kill millions of people across millennia….these are the neglected diseases that no one ever bothers about. There are no new vaccines being tried, and no new drug being developed for these diseases….there is
simply no ‘market’!!! An irony that avian flu gets so much attention.
Wonder how many of you got this far into my long rant at the end of a busy week here in cold, birdless Antwerp….most of the birds around my house are around where most of you are sitting. Who knows, maybe some of them carried the flu!!! I started the mail saying “…just a few comments”……
Some references for those who are interested:
Johnson, NP; Mueller, J (2002 Spring). “Updating the accounts: global
mortality of the 1918-1920 “Spanish” influenza pandemic.
J. D. Earn, J. Dushoff, S. A. Levin (2002). “Ecology and Evolution of the
Flu”. *Trends in Ecology and Evolution* 17: 334-340.
Bill Bryson (2003) A Short History of Nearly Everything. pp. 386-388