A Planet of Viruses - Carl Zimmer [27]
West Nile virus has fit so successfully into the ecology of the United States that it’s probably going to be impossible to eradicate. Unfortunately, doctors have no vaccine to prevent West Nile virus and no drugs to treat an infection. If you get sick, you can only hope that you are among the majority who suffer a fever and then recover. And in the future, West Nile virus may become even more entrenched in its new home. Jonathan Soverow of Beth Israel Deaconess Medical Center and his colleagues examined sixteen thousand cases of West Nile virus that occurred between 2001 and 2005, noting the weather at the time of each outbreak. They found that epidemics tended to occur when there was heavy rainfall, high humidity, and warm temperatures. Warm, rainy, muggy weather makes mosquitoes reproduce faster and makes their breeding season longer. It also speeds up the growth of the viruses inside the mosquitoes.
Unfortunately, we can expect more of that sort of weather in the future. Carbon dioxide and other heat-trapping gases are raising the average temperature in the United States, and climate scientists project that the temperature will continue to rise much higher in decades to come. Now that West Nile virus has made a new home here, we’re making that home more comfortable.
Predicting the Next Plague
Severe Acute Respiratory Syndrome and Ebola
A hunter emerges from a tropical forest, a shotgun in one hand, the carcass of a monkey in the other. He walks into a village in the southeast corner of Cameroon. It’s a scene that replays itself every day in villages, not just in Africa, but around the world. Hunters kill wild animals and bring them home to feed their families or to sell for cash. But on this day, the scene ends with a twist. The hunter hands over the monkey to his wife to butcher. As she cuts up the monkey, she stops to hold a dismembered leg over a piece of paper marked with five circles. Drops of blood fill one circle after another. The hunter’s wife then slips the sheet of paper in a Ziploc bag and hands it to a team of scientists who have paid her a visit. The scientist, who belongs to an organization called the Global Viral Forecasting Initiative, will analyze the blood-soaked paper for viruses infecting the monkey.
The Global Viral Forecasting Initiative is trying to change the way we fight viruses. Someday, somewhere, a virus we don’t know about is going to emerge as a major new threat to human health. We’ve seen it happen many times before, and so we know it will happen again. GVFI scientists think we’ll do a better job fighting that new virus if we can learn something about it in advance. To eliminate the advantage of surprise, GVFI scientists are looking for these viruses before they jump into humans. The best place to look for them is in animals, such as the monkeys that Cameroonian hunters kill for food.
The threat of new viruses has inspired a string of cheesy Hollywood movies over the years. In The Andromeda Strain, which came out in 1971, a satellite falls to Earth with an extraterrestrial virus that threatens to wipe out humanity. In the 1995 movie Outbreak, a monkey imported from Africa spreads a deadly virus through a California town, which the Army wants to bomb to prevent it from spreading across the country. And in 28 Days Later, released in 2002, a virus sweeps through London, turning its victims into homicidal maniacs.
The reality of new viruses is nothing like these fantasies. In its own way, it’s far more frightening. Over the course of human history, many viruses have made the evolutionary leap from animal hosts to our own species. And just over the past century, dozens of viruses have made this transition, giving rise to new diseases. Scientists have found that these new viruses