May 1, 2004
Timothy M. Beardsley, Editor-in-Chief
West Nile virus began its season early this year, with infected dead birds recorded in April in California. Indications are that the pathogen will hit the state hard in coming months, moving north as it infects mosquitoes and birds in farming country. This year, its fifth in North America, could well see it complete its march across the lower 48 by penetrating Oregon and Washington. It is not hard to imagine the agent hitching a ride from the West Coast to Hawaii with a mosquito lurking in some dark corner on a ship. The likely effects on the endangered endemic birds of Hawaii are not pleasant to contemplate.
Press attention understandably focuses mainly on human illness and death associated with West Nile virus—over 250 people in the United States died last year from its effects, and more suffer from its long-term neurological consequences. But as Peter P. Marra and his colleagues detail in the article that begins on p. 393, the toll on wildlife is far larger. The promiscuous virus could well push already threatened bird species over the edge to extinction, both in Hawaii and elsewhere.
Unfortunately, the options for dealing with the menace are few. A vaccine that is available to protect horses has demonstrated some efficacy in other animals in tests, but broadcasting vaccines to wildlife is usually impractical. Molecular biology offers little help, for similar reasons. Vigorous mosquito control in conjunction with improved animal surveillance is the main hope for limiting West Nile’s effects in the foreseeable future. Yet many states’ budgets are inadequate to conduct proper surveillance; some have simply stopped recording dead birds. Border controls that could prevent the importation of infected animals and mosquitoes are likewise lax.
Failure to adequately fund surveillance is surely shortsighted. West Nile is unlikely to be a unique or even a particularly special case. All biological intuition points to the probability of a troublesome procession of unwelcome invasive pathogens that will exploit the expansion of global trade and travel in coming decades. The economic consequences for agriculture alone could be massive. Efficient wildlife monitoring systems, expanded research on transmission, and stepped-up emergency preparedness efforts instituted now will repay their costs manyfold during plagues still to come.
There is much to learn about the details of West Nile’s spread: which species of birds are the most important reservoirs, which animals are most vulnerable, and which landscapes are most usefully targeted by mosquito abatement efforts. Other diseases might threaten more human deaths, but this one is here and now. Ecological prudence—any kind of prudence—demands an attack more vigorous than we have seen so far.