In October of 2007, Julie Volberding, chief of the Centers for Disease Control and Prevention (CDC), was supposed to testify before a Senate panel on the health consequences of global warming. At the last minute (literally the day before), White House political hacks prevented her from telling the story she intended to tell. This is not unusual: This administration has waged an undeclared war on Science, especially when the facts are inconvenient. So, in the interest of telling the unvarnished truth, here are a couple of examples of the effect of globalization and global warming on health.

 

The case of Bluetongue Disease

From the British New Scientist magazine:

Bluetongue is an animal virus, spread by tiny flies called midges—also called biting gnats or no-see-ums. Scientists have been predicting for ages that insect-borne diseases would move north as global warming takes hold. They have predicted since at least 2002 that bluetongue could invade northern Europe and Britain. Those predictions have now come true.

Bluetongue infects ruminants—cattle, sheep, goats, deer, and the like—throughout Africa, southern Asia, and parts of Latin America. It does not infect humans. In most places that have it, livestock has evolved resistance to the virus, though it still takes a toll.

Sheep get much sicker with bluetongue than cattle; they develop fever, difficulty with breathing and swallowing, and swollen feet and faces. Sheep’s tongues can turn blue if the swelling restricts circulation to the mouth, but despite the disease’s name, this rarely happens. In non-resistant sheep, up to 80% of those infected can die.

How did it get to Europe? First, the midge species that normally carries bluetongue in Africa and the Middle East has moved north into Europe, taking the virus with it. In 1998, just the southern tips of Spain, Italy and Portugal, and a few Greek islands had bluetongue. Now the midge has carried five of the 24 known strains of the virus through much of Spain, Italy and Portugal, southern France and Greece, and across the Balkans.

Scientists warned that the disease might continue spreading past the most northerly point reached by the invading southern midge because some midge species in northern Europe can also carry the virus.

But the virus had a second route into Europe. Bluetongue suddenly appeared in the Netherlands in August 2006, and rapidly spread to Belgium, Germany, France, and Luxembourg, carried by local midges. The strain was completely different from the viruses in southern Europe—instead, matching viruses from South Africa.

The outbreak was 6° of latitude farther north than bluetongue had ever been seen before, and there were hundreds of miles of uninfected territory between it and the affected southern regions. No one knows how it arrived. Midges like to breed in damp manure, and one notion is that manure with infected flies accompanied a horse shipped in by air.

Then, the virus did something really new: It survived the winter and broke out again in August 2007. It invaded eastern England, as scientists had predicted, probably in midges blown across the Channel from Belgium. So far, more than 1.8 million sheep have died across Europe. Unusually, the northern outbreak is also killing cattle.

 

What about us, humans?

Have you ever heard of Chikungunya disease? Me neither.

The mosquito-borne disease has caused massive outbreaks for at least half a century, but they all happened in developing countries in Asia and Africa. And although the virus causes severe rashes and joint pains, it never seemed to be fatal; many even called it “benign”. Few researchers took an interest.

No longer. Things have changed in large part, researchers say, because chikungunya has finally struck a rich country. In 2005 and 2006, the virus caused a massive outbreak on La Réunion, an island twice the size of New York City—700 kilometers east of Madagascar and a French département.

Almost 40% of the population of 785,000 fell ill.

The big surprise of the outbreak at La Réunion was that the infamous Asian tiger mosquito, which is spreading fast across Europe and the United States, proved an excellent vector. This summer, Italy had a small Chikungunya outbreak, the first ever in Europe. There’s no reason why the same couldn’t happen elsewhere in Europe or in the United States.

Chikungunya—or “chik,” as some scientists call it—belongs to the alphaviruses, a group that includes the Ross River virus in Australia and the viruses that cause eastern and western equine encephalitis, two serious diseases occurring in the United States. First isolated from a patient in Tanzania in 1953, the chik virus has surfaced occasionally since in countries across Africa, South Asia, and Southeast Asia. It causes high fevers, rash—sometimes with massive blisters—and excruciatingly painful swelling of the joints in fingers, wrists, and ankles.

The outbreak that hit La Réunion appears to have started in Kenya in 2004. It wasn’t reported at the time, but in a paper published in 2007, researchers noted that the epidemic started in the coastal towns of Lamu and Mombasa, Kenya. Later, the virus appears to have gone on an island-hopping tour of the Indian Ocean, landing in Madagascar, the Comoro Islands, Mayotte—a much smaller French territory west of Madagascar—Mauritius, and the Seychelles (see map). It reached India, where it hadn’t been seen for 32 years, in December 2005, infecting an estimated 1.4 million people so far.

A more alarming finding is that the Asian tiger mosquito (Aedes albopictus) proved to be an efficient vector. Previously, a species called Ae. aegypti, which feeds on humans almost exclusively, was always the virus’s main vector. Ae. albopictus, the predominant species on La Réunion, was considered a poor one, in part because it bites a wide variety of species. But recent studies have suggested why Ae. albopictus suddenly became a much better vehicle.

Between the first, small outbreak in early 2005 and the big one that started in December, the virus underwent a point-mutation change that altered a single amino acid in its envelope protein. Papers published last month by Anna-Bella Failloux of the Pasteur Institute in Paris and her colleagues, and a team led by Stephen Higgs of the University of Texas Medical Branch in Galveston, have shown that the change makes it much easier for the virus to reproduce in the mosquito’s midgut. This leads to 100-fold higher virus concentrations in its salivary glands, which in turn increases the virus’s chances of being transmitted during the next bite. Those findings strongly suggest that the mutation helped the virus adapt to the mosquito and “enhanced the epidemic”.

That’s worrisome because Ae. albopictus, originally from eastern Asia, has been spreading across the globe during the past 2 decades. The outbreak this summer in Italy—where Ae. albopictus is rampant—got started when a chikungunya patient from India traveled to a small village in the province of Ravenna. Such “imported” cases happen all the time: Mainland France had almost 800 in 2005 and 2006, and the United States 38. It’s a matter of time before a patient kicks off a new outbreak in an unexpected place, Higgs says.

 

What can be done?

The usual remedies, such as drugs, vaccines, and chemical sprays to control the insect vectors, are notoriously difficult. Antiviral drugs are few and far between, and take many years to develop. Vaccines are likewise hard to develop. Both modalities are prone to development of resistance by the ever-mutating virus. And insecticides are notorious for their adverse effects on health, the environment, and the eventual development of resistance by the insect vector.

The inescapable fact though, is that we will have to confront the new reality. And no amount of muzzling scientists by ideological politicians who refuse to acknowledge reality will change it. There is precious little we can do about globalization. But global warming? All we need is political will and signs of intelligent life in Washington.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.