Maggie's Farm

Avian Influenza - Bird Flu

Bird Dog has forwarded me posts by Instapundit and Rick Moran, both of whom have been keeping an eye on the Bird Flu happenings in Asia and Russia. Rick's series of pieces on the subject here. Here's my brief medical background on the story - kindergarten virology.

Viruses are hardly living things in the usual sense. They are tiny packages of genetic material, either DNA or RNA, in a protein wrapper. They are inert until they enter their host (which can be an animal, plant or even bacteria), at which time they enter the cells of the host and replicate. Thus they are obligatory parasites, and each virus has a preferred host. The photo is an electron micrograph of a human influenza virus, in which you can clearly see the helical genetic material inside the spiky protein package.

There are thousands of virus varieties, and most do not cause disease. After all, it is not in the interest of a parasite's future to kill or seriously tax its host. For example, the usual Avian Flu virus typically lives in the GI tract of wild birds without causing any trouble.

Animals protect themselves naturally against disease-causing viral invasion by creating antibodies – killer proteins – which attach themselves to the protein “antigens” in the viral wrapper. However, the animal must have time to create such effective antibodies (known as "immunity") before it dies. Immunization comes from either surviving the disease, or is induced via vaccines, which contain virus surface proteins, permitting antibodies to be produced.

The family of influenza viruses, all of whom use vertebrates as hosts, are among the most commonly associated with disease in humans. There are three varieties of flu virus, Types A, B, and C, and all can infect and cause disease in humans. Type A flu viruses can infect many varieties of animals but their natural host seems to be wild birds, hence “bird flu”. Subtypes of Type A flu viruses are named by the proteins (antigens) in their wrappers.  “H5N1” is the one with which we have become concerned.

The problems with viruses and disease are that 1. not being alive, they cannot be killed with antibiotics, and 2. viruses change readily through mutation, altering their infectiousness. They change through “antigenic drift”, which are slow minor changes (of the sort that render a flu vaccine from 2004 ineffective against a new flu “strain” in 2005), and through “antigenic shift,” which are abrupt major changes. Avian flu is prone to both. Thus avian flu has changed to become an infectious disease in their bird hosts, mostly domestic poultry but increasingly in wild birds too. And thus avian flu has already mutated so that it can cross the "species barrier"  - to be able to reproduce in new hosts - so as to be able to infect man and other animals.

To date, H5N1 requires physical contact with infected bird material to cause infection in man. There have been dozens of such deaths in Asia over recent years and, when it occurs, it seems to have a 55% mortality. However, infectious disease experts predict that a mutation will occur to make H5N1 contagious – ie spread from human to human in the air, like the regular influenza we are familiar with. Because there is little natural immunity to this virus among humans, such a mutation will create a "pandemic" – a widespread and dangerous epidemic. Jakarta is currently the focus of concern.

Why aren't more people jumping up and down and screaming "the sky is falling" about H5N1? Well, there is this little thing called "denial" - "New Orleans will never flood"; and there is a sense that the infectious disease folks have cried wolf in the past; plus it's all complicated and far away - and we don't think the break-out has happened, yet. Should we wait for the levees to fail before we get excited, blaming, and planning? This is an historic opportunity for public health organizations to get in front of a major problem, and I suspect that they will. Australia has just issued a warning, and the business world is on top of things - see this week's conference hosted by Deutsche Bank.

What can be done? First, cases, when they occur, need to be quarantined (which would have saved millions of lives worldwide with AIDS). Second, people in an at-risk area need to be immunized. Currently Jakarta has 10,000 vaccine doses, and 12 million people. Let us all hope that the vaccine factories are working overtime. Third, anti-viral drugs need to be warehoused on a massive scale, even though their effectiveness is unclear against H5N1. This disease could go global very quickly, once it starts. We have been forewarned, and we know what to do to try to minimize a danger which man does not have the power to prevent.

(One last thought: Those of us living in the secure and highly comfortable USA have become a bit arrogant when it comes to the power of nature. We would like to imagine that, when bad things happen like hurricanes, crime, earthquakes, plagues, war, ordinary diseases, accidents, bad luck, or plain death itself, someone dropped the ball. No. We are a little transient part of nature, and our proper response is one of awe in the face of nature's power in relation to ours. Nature is bent on killing each one of us, in time, and our species too, eventually - God or no God, government or no government, doctor or no doctor, vegetarian or carnivore, good or evil. We are created to be destroyed, which is a strangeness which goes far beyond my job description and my pay grade into a realm which I view as theological hard-hat territory.)