June 13, 2007

Not Just A River In Egypt

By: AFF Editors

With another summer upon us, the media is again abuzz with news about the West Nile virus. News agencies across the nation are offering tips and advice on how to avoid contracting the disease. Advice ranges from the pragmatic (drain water on your property) to the impracticable (limit time outside at dawn and dusk, when mosquitoes are most active). Innumerable experts have been consulted and their consensus is clear: be afraid, very afraid.

The mosquito, an insect smaller than the width of a human finger, has our nation on its knees.

The truth is that most people will never come in contact with the West Nile virus. Chances of contracting the virus vary according to location, but they are invariably small across the board. In fact, according to the National Safety Council you’re more likely to die from summer’s heat than you are from its mosquitoes.

If you get bit by a mosquito infected with the West Nile virus, there’s a 20 percent chance that you’ll develop West Nile fever. Even if you bit by a mosquito infected with the West Nile virus (not likely) and you develop West Nile fever (even less likely), there’s just a one in 150 – .67 percent – chance of developing a severe illness!

(In fact, Iowa state epidemiologist Dr. Patricia Quinlisk has hinted that the only person diagnosed with the West Nile virus so far this year was probably infected last year. Like most people who contract the West Nile virus, the Iowa woman presumably didn’t notice.)

Reducing the already-small risk of contracting the West Nile virus has proven costly. Last year, the federal government spent $43 million on human vaccine development alone. State governments pile on the money, paying up to $1.4 million for insecticidal intervention according to one Harvard study.

The study also analyzed the potential costs to humans of eastern encephalitis, a mosquito-borne viral disease similar to the West Nile virus. The researchers found that the average cost of a short-lived infection was $21,000. Those with a pathological condition could face up to $3 million in lifetime economic costs. Because public intervention is cheaper the private costs of a single case of residual West Nile fever, the researchers suggest that intervention is worth it.

While it is true that personal costs associated with a West Nile infection are exceedingly large, the probability of facing them is exceedingly small. Among more than 280 million Americans, less than five thousand were diagnosed with the West Nile virus last year. Yet although personally you’re unlikely to benefit from West Nile virus intervention, it is almost certain that you’re paying for it – on the federal, state and local level.

“Are there more important problems? Sure,” asks William Reisen of the UC Davis Center for Vectorborne Diseases. “Does that mean we should not try to control WNV? I think we should address all the public health problems, not just one or the other.”

Unfortunately, a limited budget means doing finite good in society. Each lifesaving technique has a different cost-effectiveness: it costs just $39 per life saved to install defibrillators in emergency vehicles for resuscitation after cardiac arrest, but it costs $18 million per life saved to strengthen buildings in earthquake-prone areas. While it’s easy to say which costs are worth it, it can be hard to say which are not.

Is WNV intervention worth it? Perhaps, the answer pivots on information that we don’t have. To know if we’re making any progress we need to know how many mosquitoes are infected in the general population. At $20 a pool, taking samples is cost prohibitive. So instead, we test what we can and hope that the millions of tax dollars spent on public intervention is doing something.

It’s normal for people to want to reduce a small risk to zero, especially when the risk is of brain and spinal swelling. Nevertheless, our tax dollars are limited and to put them toward this project is, well, wasteful. The risk of death from the West Nile virus amounts to a fraction of one percent. Letting that bug you – and spending millions to reduce the risk – is just plain silly.

Taylor W. Buley is a graduate from the University of Pennsylvania and is author of “The Fresh Politics Reader.”

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