America - Andrew Stephen flinches from West Nile fever

West Nile fever has now spread from Africa to my own back garden in Washington, DC, and has killed m

A few days ago, I went out into my back garden, in the mighty heat and humidity here, and saw a crow on a paving stone, clearly unable to fly. Close up, it looked peculiarly beautiful: there was a perfection about its shiny black feathers, but nothing could disguise that it was near death. The most it could do was rhythmically bobble its head and writhe its body. Having read that morning's Washington Post, I knew just what to do: urgently, I should ring the DC animal disease control division. "We'll be there within 45 minutes," they said.

And indeed, they were. They arrived in a big van with a flashing beacon, which parked in a non-parking space immediately outside the house. A smart lady dressed in a police-type uniform came in with a box. "This is the third today," she told me. "We had five yesterday." Carrying the box away, she said: "Yes, this is definitely West Nile fever." Hence the drama of the phone call for what would otherwise have been a common-or-garden dying crow, the speed of despatch and the flashing beacon: in our very own back garden, the symptom of a rare and dangerous other-worldly disease had chosen to alight. The bird, I discovered last Monday, finally died in the van.

I would rather expect affected parts of the country to be in a panic as a result of all this, because West Nile fever has actually killed more Americans in the past three years than the entire anthrax scare. Eighteen have died of it since it was first discovered in the US in 1999, and 149 have become seriously ill. It has also killed countless wild birds and devastated the aviary sections of zoos in Atlanta, Philadelphia and New York. In the past year it has become apparent the disease has spread to DC, where the local zoo reports that two flamingo chicks, a duck and dozens of other birds have died of the virus.

What is striking about this disease is that it is an example of what is becoming known as "travel medicine". Where illness and diseases are concerned, the world is now truly globalised: it is quite possible for a patient to be sitting in a doctor's waiting room in, say, New York, with a disease unknown in the west and contracted somewhere in the developing world only 16 hours or so earlier. The most frightening example is that of the ebola virus, which can be picked up in the Congo or Uganda, for instance, before the traveller heads west. One study estimates that there are 320 infectious diseases and pathogens prevalent in the developing world but not in the west: doctors in hectically cosmopolitan cities such as New York now take special courses in travel medicine so that they can diagnose afflictions previously unknown at home.

West Nile fever, spread by the Culex mosquito, usually starts in humans with fevers and headaches, often accompanied by a skin rash and swollen lymph glands. If it worsens, as it is apt to do in old people or those with weakened immune systems, the symptoms graduate to stiffness of the neck, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis and - ultimately - death. It was first discovered in Uganda in 1937 and is now common in Africa, India, Pakistan and the Middle East (Israel, with its sophisticated medical system, had 430 cases and 18 fatalities last year), but, except for an epidemic in Romania in 1996, it is largely unknown in Europe. As it was in the US until 1999.

The Culex mosquito likes to breed in storm sewers and a simple bite can kill a human or animal: so the normal course, particularly in New York, is to kill the mosquitoes by spraying trees and areas where there are bodies of water. There is no known vaccination or cure; the patient merely has to wait to get better.

Fortunately, the disease is not communicable from one human to another. It's those mosquitoes (that always bite me before I'm aware of their existence and which, as I have said here before, make a beeline for me) that mainly transmit the disease through birds and vice versa. Five hundred million people a year suffer from mosquito-borne illnesses, according to the World Health Organisation. But up to now, they have rarely caused more than irritating itches in the US. Now DC officials are warning people to stay indoors at dawn, dusk and early evening, when mosquitoes are most prevalent; I'm told I live in a "hot zone", where infected mosquitoes are everywhere.

DC officials say that only a small minority of mosquitoes are infected but admit they have no real way of knowing this. The most dead crows, in fact, have been found in my neck of the woods - meaning that the deadly mosquitoes which killed them are ready to swoop down on me, too. Last Tuesday, the animal disease control division told me that my crow's body had been placed in the deep freeze, awaiting an autopsy to prove that it was suffering from America's latest menace from abroad. But even President Bush cannot blame this one on Saddam Hussein.