Canary in a coal mine: disease prevention

Mosquitoes like this one, captured in a photo by the CDC, can transmit diseases

The term canary in a coal mine comes from the early days of the mining industry. A canary was often brought in a small cage down into the mine to accompany the miners as an early warning system. One of the dangers of deep mines is that poisonous gas can be released from subterranean pockets and can seep into the mine. The concentration of gas can build up slowly over time until it reaches a fatal concentration. A canary would be killed by levels much lower than would a human being so miners would keep an eye on the canary. As long as the caged bird was alive, the air wasn't likely to kill the miners.

Today, of course, there are all sorts of air quality monitoring devices that can detect a wide ranges of gases and oxygen levels within the mine. Birds, however,still function as an early warning system, but on a much broader scale.

Birds can give us early warnings about a number of potentially hazardous conditions in our local areas and across the globe. For example, the virus that causes Eastern Equine Encephalitis (EEE) affects not only horses, as the name implies, but also humans and birds. It can be fatal in all three. Eastern Equine Encephalitis is transferred from animal to animal by the bite of mosquitoes. Since migratory birds covered large distances in their travels, they are often responsible for carrying the disease from one region to another. Once the bird is bitten by local mosquitoes, other, more stationary animals including human beings can become infected.

Many states have dead bird reporting procedures by which citizens who find a dead bird on their property can call the designated state or local agency to have the bird picked up and tested. In New Hampshire, residents are advised to call their local Health Department or Animal Control Officer. If dead birds are found to be infected with EEE or with the also dangerous West Nile Virus (WNV) then the state will issue an alert to the affected areas. When an alert is in effect, residents are advised to take extra precautions against mosquito bites. In this way, the early warning provided by birds saves lives.

• View a slide show of swine flu quarantine procedures at an infected turkey farm in South America

The bird flu, also caqlled the avian flu, is another disease that can be detected in an area by unusual numbers of dead birds. Although to date, the bird flu does not easily transfer from birds to humans, a mutation could change that in a hurry. Another possibility is that the highly contagious swine flu could combine with the more lethal bird flu and produce a hybrid strain that carries the worst properties of both along with the ability to easily jump from humans to birds.

For a  complete list of precautions recommended by the state of New Hampshire and more information about both West Nile Virus and Eastern Equine Encephalitis visit the website of the NH Department of Health and Human Services.