Focus Earth Episode: The Dawn of New Disease

This week, Focus Earth looks at what the world infectious diseases look like today: H1N1, malaria, and the West Nile virus are just a few of the infectious diseases many epidemiologists say could become more prevalent—and more fatal—thanks to climate change. The Centers for Disease Control is tracking the rapid movement of diseases across borders and around the country, spurred on by the effects of our changing climate. Severe weather like flooding, drought and heat waves can create the perfect breeding grounds for the pests that transmit deadly diseases. Malaria-carrying mosquitoes are reaching populations in warming mountain regions once too cold for them to survive. Lyme disease, the number one insect-borne disease in the U.S., is moving further north than ever before. And unusual climate patterns helped create the perfect conditions for mosquitoes to spread West Nile virus from coast to coast. Now, some are even making the link between our "Swine Flu" pandemic and climate change. Are we headed for a global outbreak of dangerous diseases or, worse yet, the emergence of new, more resistant ones? Bob Woodruff talks with the Assistant Surgeon General and other health specialists to find out.

Next, against a rising tide of voices saying changing climates will increase infectious disease epidemics, one man is sparking controversy with the claim that this may not exactly be the case. Bob Woodruff talks with ecologist Kevin Lafferty of the U.S. Geological Survey, who argues that the effects of climate change will be more complex than has been acknowledged—and that there may even be a reduction in cases of some infectious diseases. It's a point of view, he says, that is overshadowed by the media-friendly fear factor embedded in predictions of worldwide outbreaks. When he published an article earlier this year making this point, it set off a firestorm of debate and rebuttals by scientists around the world. 

Then, Brownsville is the southernmost city in Texas, and it is also the gateway for diseases traveling north. The H1N1 virus reportedly first crossed onto U.S. soil here, after originating just across the border in Mexico. The state-of-the-art Biosafety Level 3 lab at the University of Texas School of Public Health, Brownsville was one of the first labs in the U.S. to track and research the virus. And now, it's part of the nation's first defense against other diseases emerging from south of the border. Dengue Fever, a tropical disease responsible for some 22,000 deaths around the world, is endemic throughout Mexico. And it has slowly started to make its way into the local bloodstream, likely from contact with carriers from across the border. Bob Woodruff talks with a public health expert in Texas and a scientist at Natural Resources Defense Council, which has discovered that the two types of mosquitoes that carry Dengue have been increasing their territory in the U.S. Twenty-eight states, including Texas, are now vulnerable to Dengue, and all it takes is one infected person to start an outbreak of this disease.

Finally, just across the Rio Grande from Brownsville, Texas is Matamoros, Mexico, where the Dengue virus is endemic. Local health officials report that 78 percent of Matamoros residents have been infected at least once. That's why the city has put together a vector surveillance and patrol team to send them on a seek-and-destroy mission for the mosquitoes that carry the disease. They fan out across this poor community, overturning old tires and plastic containers, the perfect hiding places for mosquitoes that breed in the rain-filled hollows. They cruise the community tossing larvacide to kill the pests before they mature, and go door-to-door documenting cases of the disease and educating residents about prevention. Bob joins the mosquito hunt and learns how their efforts are actually helping to bring the Dengue epidemic in Matamoros under control.

Watch Focus Earth: The New Dawn of Disease on Planet Green. Here's a video preview.

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