Is It Time to Panic Yet?
by Sheila Buff

What are your chances of getting West Nile virus? Bird flu? Some other emerging disease that hasn't made it onto the evening news yet? Is it time to panic, or can you wait a little longer?

So far, your odds of catching either of the diseases above are extremely low--and likely to stay that way. Take West Nile virus, for example. This import from eastern Africa first turned up in the United States in 1999. West Nile virus is carried by mosquitoes. Someone bitten by a infected mosquito can develop a severe or even fatal case of encephalitis (inflammation of the spinal cord and brain). No question about it, West Nile virus is a serious disease. From 1999 to 2001, 149 confirmed cases of illness and 18 deaths linked to the West Nile virus were reported to the federal Centers for Disease Control (CDC). From January 2005 to the end of October 2005, 2,435 confirmed cases, including 73 deaths, were reported.

The increase comes from the wider distribution of infected mosquitoes. The early cases were reported from just a few states; by 2005, infected mosquitoes had been reported in all states except Hawaii, Alaska, and Oregon. The increase in cases is worrisome, but it's important to put the number into perspective--it's still very small. By contrast, 9,300 people are treated in emergency rooms every year for fireworks-related injuries. Realistically speaking, your chances of getting West Nile virus are low. They're even lower if you follow the commonsense precautions to avoid mosquito bites recommended by the CDC:

—Use insect repellent, preferably one containing DEET.

—When weather permits, wear long sleeves, long pants, and socks outdoors. Spray insect repellent directly onto your clothes.

—Be aware of peak mosquito activity--the hours from dusk to dawn. Take extra care to use repellent and protective clothing in the evening and early morning, and consider avoiding outdoor activities during these times.

—Drain standing water. Limit the number of places around your home for mosquitoes to breed by getting rid of or emptying containers that hold standing water, such as old tires, buckets, swimming pool covers, pet dishes, and clogged rain gutters.

—Keep mosquitoes out of the house by installing or repairing screens on windows and doors.

Bird Flu

Right now your risk of getting bird flu is considerably lower than even your risk of getting West Nile virus. Avian influenza, or bird flu, is an infection that occurs naturally in wild birds and generally causes them little harm. For some domestic birds such as chickens, however, bird flu can cause illness and death. Starting in late 2003, bird flu became widespread among domestic poultry in a number of Asian countries, including China, Thailand, and Vietnam, and is now appearing in other parts of the world as well.

Bird flu viruses do not usually infect humans. Fewer than 100 human cases of this strain of the disease, known as H5N1, have been reported--all in Asia. In almost all cases, contact with infected poultry or contaminated surfaces was the cause; person-to-person transmission of the illness is thought to have occurred in only a few cases.

Nevertheless, the bird flu virus is currently widespread among domestic poultry in some parts of the world--and domestic poultry are usually in close contact with people. This factor increases the likelihood that the virus could mutate into a much more contagious form that could spread easily among humans. The Hong Kong flu pandemic (global outbreak of a new flu strain) of 1968-69, for instance, was caused by a virus that contained a combination of human and avian influenza genes. The virus that caused the great 1918-19 Spanish flu pandemic was probably of avian origin.

Most scientists believe that it is only a matter of time before the next flu pandemic. The impact could be substantial, with millions of Americans getting sick and several hundred thousand dying. Even so, it's not yet time to panic. International agencies, including the CDC, are actively tracking the current outbreak of bird flu and so far, human cases are very, very rare. The stepped-up surveillance now in place means that if a more dangerous form of the virus does develop, it will be noticed quickly and preventive steps can be taken, starting by isolating sick individuals. The best approach to preventing a pandemic is the same as for earlier flu viruses: a vaccine. Researchers are doing safety testing on vaccines now, in the hope they won't be needed.