Modern Transportation, Not Global Warming, Is Allowing the Spread of Mosquito-Related Disease

Published February 1, 2008

A World Health Organization (WHO) official claims the current chikungunya virus outbreak in northern Italy is the result of climate change. This widely reported absurdity undermined rational debate at a time when world leaders were negotiating climate policy in New York and Washington.

World leaders discussing far-reaching policies at the UN’s High Level Event and at President George W. Bush’s Meeting of Major Economies on Climate Change and Energy Security were bombarded with this kind of distortion.

The reality is that such outbreaks have nothing to do with global warming, but are the inevitable result of global transportation.

Diseases Rampant Recently

Not far from Graceland, Elvis Presley’s home, is a quiet cemetery dating back to the American Civil War. In the middle is a large mound like a megalithic tomb, and underneath are the bones of more than 6,000 people who died in the terrible Yellow Fever epidemic in 1878. More than 20,000 people were infected in Memphis alone, and more than 120,000 throughout the United States, as far north as Ohio.

The virus and the mosquito that transmitted it were first brought over from Africa in the seventeenth century. The mosquitoes bred in shipboard barrels of water, and the virus circulated among the slaves. Many died.

The mosquito is now present from South Carolina to Buenos Aires, and it remained a scourge in many cities until the advent of DDT. It still lurks in the rainforests of South America.

New Breeds Arriving

Twenty-five years ago, working on another mosquito-borne virus in another Memphis cemetery, I was astonished to find another mosquito from distant shores. The species had never, ever, been found on the American side of the Pacific Ocean.

Two years later I was sent to Houston, Texas, where the biting was so bad that people were abandoning their barbecues. I found the city littered with discarded tires that contained rainwater infested with Aedes albopictus, now dubbed the Asian Tiger mosquito.

I chanced upon several people gathering these tires for a company that shipped them–with the mosquitoes–to Mexico and Guatemala. Next surprise: The company supplemented the scavenged tires by importing thousands more from Japan.

Finally, I was amazed to find there was (and still is) a large international commerce in used tires. Millions are shipped to and from nearly all countries of the world.

Surviving Cold Weather

The Tiger is now well-settled from New York to Buenos Aires, in 12 European countries, and in at least three African countries. It arrived in Italy in the 1990s in tires from Atlanta, Georgia and is ubiquitous from the Alps to Naples, creating misery from early spring to late autumn.

In our studies in America we confirmed the Tiger originated in Japan and was splendidly adapted to cold winters. At present its northern limit is Holland, but I suspect it will soon move at least as far north as Denmark. It will doubtless adapt to the southern, warmer parts of Europe by natural selection.

Virus Follows Mosquitoes

Just as with Yellow Fever, a virus has followed the Tiger. Its exotic name–chikungunya–means “bent double” in Swahili. The disease is endemic in Africa, and massive pandemics of it occasionally sweep through Asia. Creating unpleasant flu-like symptoms, chikungunya causes painful arthritis that can last for months or even years, and it is incurable.

Three years ago, something new happened. Chikungunya hit Mauritius, Reunion, and the Seychelles, not because of any mysterious climate change but because an infected person boarded an airplane, landed in those islands, and transferred the virus to the local Tigers. It had never occurred there before, so the virus swept through the population like wildfire.

The globalization of mosquitoes and mosquito-borne diseases is nothing new, and we can expect further such surprises in the future. There is also nothing new about mosquito-borne disease in Europe. Until DDT, malaria was endemic and common in many regions as far north as Russia, with 13 million cases a year in the 1920s. At Archangel, on the edge of the Arctic Circle, 10,000 people died of malaria in one year.

In Italy the highest incidence was in the Po valley, in exactly the same area now hit by chikungunya. Dengue, another so-called tropical virus, infected a million people in Greece in the 1920s.

Global Warming Falsely Blamed

Despite all this, a WHO official has claimed warming allowed this cold-weather mosquito to settle in Italy. Whether this is ignorance or deliberate misinformation, it diverts attention from the real cause: The increasing globalization of disease is a result of modern transportation.

The public will surely soon get fed up with the constant hype about global warming. Sadly, when they realize the alarmists were crying wolf, confidence in science and scientists will suffer. The only solution is to stick to the science and nothing but the science.

Professor Paul Reiter ([email protected]) is director of the Insects and Infectious Diseases Unit of the Institut Pasteur, Paris. He worked for the U.S. Centers for Disease Control for more than 20 years. This article was first published in the Korean Times and is reprinted with permission.