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Have Virus, Will Travel

Posted Aug 24 2008 8:05pm
Is the name of my thesis that is done done DONE.

And here, for your reading pleasure, is the introduction.*

Out of Africa

The end of 2003 became the rainy season that wasn’t, plunging Kenya and other East African countries into drought. Crops were in danger. Drinking water was in danger. Where water used to be everywhere, women were now forced to walk long distances, often twice daily, to get fresh water. So they began to store the water in any kind of container they could find, to save their aching feet from the twice-daily walk to fetch water for drinking, cooking, and cleaning.

What they didn’t know—what they couldn’t have known—was that an invisible danger in those containers would set off a series of events whose effects would be felt thousands of miles away. The pools of water that collected in the nooks and crannies of the seemingly empty containers—as well as the stored water itself—was the perfect breeding ground for Aedes aegypti mosquitoes. These mosquitoes have evolved to live alongside humans, taking advantage of environmental quirks that come with Homo sapiens . They can breed in mere teacups of water, and their eggs can survive long after the water is gone. Aedes aegypti can spend their entire lives in houses and huts, never once venturing outside. Their meal of choice is human blood. “These are cosmopolitan animals,” said entomologist Kathleen Walker of the University of Arizona. “They’ve hooked [their] life styles on people.”

The close relationship between Aedes aegypti and humans was also utilized by viruses. They, too, have adapted and evolved. Diseases like dengue and yellow fever exist in a perpetual cycle between humans and mosquitoes. So, too, does an unusual disease with an even more unusual name: Chikungunya. Known in research circles as “Chik,” the virus has probably been around for centuries, transferred to person to person by Aedes aegypti . Most people in the US had never heard of the disease and it might have remained a tropical curiosity if not for the drought.

With plenty of containers and water for breeding, and ready access to human blood for food, the Aedes aegypti population skyrocketed. And at least one of these mosquitoes was infected with Chikungunya, buzzing from victim to unknowing victim and injecting the virus. In the beginning of 2004, hundreds of rural Kenyans reported headache, fever, and rash, as well as excruciating joint pain. This pain, the characteristic symptom of Chikungunya, is so severe that victims bend over, unable to stand. Indeed, it gives the disease its name: “Chikungunya” translates from Swahili as “that which bends over.” Fingers, wrists, knees and ankles swell, leaving limbs gnarled for weeks. The joint pain finally caught the attention of public health officials, who sent blood samples to advanced laboratories for more testing. Lab tests showed an outbreak of Chikungunya in Kenya.

An outbreak of Chikungunya in Kenya—indeed, anywhere in East Africa—is hardly a noteworthy event. This is the region where the virus likely evolved, so it makes sense that it would show up on its own front porch. Yet the outbreak that began in 2004 in Kenya soon left Africa and began a journey eastward, traveling in a large arc in the countries around the Indian Ocean. The total number of people infected with Chikungunya since 2004 is approaching four million, and cases have been reported in Malaysia, Taiwan, and Australia. And the virus shows no sign of stopping.

The Chikungunya virus was first discovered from a febrile woman in 1957, in modern-day Tanzania. By comparing the genes of the Chikungunya virus to those of closely related viruses, virologists knew that the virus had been circulating in east Africa for several hundred years. Perhaps it went unnoticed because the virus was confused with many of the other diseases circulating in tropical Africa. Indeed, the joint pain characteristic of Chikungunya can easily be mistaken as a symptom of dengue fever, another mosquito-borne disease endemic to Africa. And in impoverished countries such as Kenya, Uganda, and Tanzania, modern diagnostic equipment usually isn’t available to distinguish the different viruses causing the same symptoms.

For most of the virus’ history, Chikungunya would flicker in and out of sight, causing small, localized outbreaks. Once a person has been infected with Chikungunya, they are essentially immune for life. When the virus ran out of people to infect, it moved on to other remote areas of East Africa, leaving as suddenly as it had arrived. Up until 1962, Chikungunya had been known to exist only within Africa. Beginning in the 1960s, however, Chikungunya began to move, both around Africa and around the globe. India and Indonesia recorded outbreaks of Chikungunya in the 1960s and 1970s. Both Aedes aegypti and the closely related Asian tiger mosquito ( Aedes albopictus ) had always lived in those areas. As populations increased, and more of these people moved to urban areas, outbreaks grew larger. The virus could multiply rapidly with large numbers of people in very high concentrations, easily jumping from person to person. And the virus’s carrier, Aedes aegypti , could live just as easily in an apartment complex as in a hut in a dusty village.

Because Chikungunya infections require both mosquitoes and humans, treating both populations is necessary to stop current outbreaks and prevent future ones. Controlling mosquito populations has long been an effective way to combat infectious diseases such as yellow fever, dengue, and malaria, as well as Chikungunya. Given the cost-effective use of chemical insecticides, most countries combating Chikungunya have focused on reducing the number of both Aedes aegypti and Asian tiger mosquitoes.

This is so important because no medications exist to fight the virus once a person has become infected. Chikungunya is a virus, so antibiotics—which only kill bacteria—won’t help. And the development of antiviral medications is still in its infancy. Existing antiviral medications can only treat either the influenza virus or HIV. Treatment remains supportive: plenty of fluids, rest, and anti-inflammatory pain medications, such as Tylenol or Advil, as necessary. A person must then wait for the virus to run its course.

Currently, no vaccine exists to protect a person from becoming infected with Chikungunya. The US Army Medical Research Institute on Infectious Disease (USAMRIID) had been working on a vaccine back in the 1970s, but progress stalled and the project was abandoned. The gravity and scale of the current outbreaks has prompted scientists at USAMRIID to resume work on the project, though an effective vaccine is years in the future. The vaccine is still not ready for animal or human trials. If it passes this stage, then scientists must jump the hurdles of production. Many American pharmaceutical industries are not interested in developing treatments or vaccines for what they see as “Third World” diseases. To them, the Third World is a separate entity, a place far away that is dramatically different than the US. To Chikungunya, a person in Texas is the same as a person in Nairobi.

As the virus began traveling, it appeared in areas where no one was immune, and would strike again. Viruses like Chikungunya “replicate very quickly and spread through the population very fast,” said Ann Powers, director of the Alphavirus Labs at the Centers for Disease Control and Prevention. Because of this, she says, the virus rapidly runs out of people to infect, and the epidemic comes to a halt.

For example, Chikungunya existed in Kenya throughout 2004 and 2005 in cycles, striking and disappearing as groups of people became immune. But Chikungunya had no sooner burned through possible victims in Kenya that it began a slow trek eastward. Traveling east out of Africa, the virus first hit the idyllic Indian Ocean islands of the Comoros, the Seychelles, and Mauritius. The presence of Chikungunya in these French protectorates, popular vacation destinations made French virologists look closely at this disease. More than a full year after the first cases of Chikungunya were diagnosed in Kenya, the international community finally began fighting the disease in earnest. Why the delay? “Of course you have people dying of disease—that’s just what people do in Africa,” said Walker. “Any time you have tropical disease in developed country, it’s easier to get people’s attention.”

*This is copyright by ME, so don't go snatching it. The writing gods will give you bad juju for the rest of your life, and besides- it's not nice. Ask and ye shall receive. Take and I shall smite you.
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