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Wednesday, August 05, 2009

In Cambodia, Proximity to Wildlife Sparks Influenza Fears

Fred De Sam Lazaro reports how Cambodians' proximity to wildlife is sparking new concerns about the spread of avian flu.

FRED DE SAM LAZARO: On the street outside Phnom Penh's most prominent Buddhist temple, the merit bird business is brisk. It's an age-old ritual in many parts of Southeast Asia based on the belief that freeing a caged bird brings merit to one's soul.

But in recent years, these wild birds have come to symbolize something very different to public health workers: potential carriers of H5N1, the avian flu virus.

PRISCILLA JOYNER, Wildlife Conservation Society: Sellers are very interested in whether or not these birds do have avian influenza. And so they're interested in knowing about the health of the wildlife and how this impacts their health, as well.

FRED DE SAM LAZARO: And their livelihood, too.

PRISCILLA JOYNER: And their livelihood, too, yes.

FRED DE SAM LAZARO: Priscilla Joyner is with the Wildlife Conservation Society. Its staff regularly tests samples of wild birds across East Asia for any signs of flu.

PRISCILLA JOYNER: A big concern here in this area is the very close proximity of people living with domestic animals and interacting with wildlife. And this can either be in the home or this can be in the market or in merit bird training. And this close proximity can be enough pressure to allow a pathogen to jump from one species to the next and then lead to a disease that otherwise may not have occurred.

FRED DE SAM LAZARO: Although so far merit birds have been free of avian flu, Joyner says Cambodia is in many ways an ideal Petri dish for its spread. People are always around wild birds and domestic animals and poultry in the markets and in backyards of this mostly rural country still recovering from decades of war.

H5N1 is common but harmless in ducks. It is lethal in chickens. And it's deadly when it does make the cross-species leap to humans. Two-thirds of the 400 people who've contracted bird flu have died.

Cambodia has seen just eight human cases since 2005. Almost all had very close contact with infected chickens. So far, the virus has not spread from human to human.

Still, Dr. Sirendes Vong of the Pasteur Institute says bird flu remains a concern, especially if it infects someone who already has another form of flu, including swine flu that spread widely in recent months.

Deadly Combination
DR. SIRENDES VONG, Pasteur Institute, Cambodia: Once humans are infected, if they're infected with seasonal flu, that's a possibility for H5N1 to mix with the seasonal flu and to come up with a new virus that would have the potential to be a pandemic one.

FRED DE SAM LAZARO: To spread like seasonal flu.

DR. SIRENDES VONG: Exactly. How deadly? I don't know. But there's a potential to get a virus that is as deadly as H5N1 and as transmissible as...

FRED DE SAM LAZARO: The bird flu?

DR. SIRENDES VONG: ... as seasonal flu or the current swine flu virus.

FRED DE SAM LAZARO: He says Cambodia doesn't have the resources to check on every case, but with agencies like Pasteur, it is monitoring selected sites across the country for any signs of flu in chickens and responding to major outbreaks.

DR. SIRENDES VONG: If there is something, there's a team from the Ministry of Agriculture, from the veterinary services, that would go to the field and investigate the phenomenon. And the difficulties, again, is to come at the early stage so that you would be able also to test at the early stage of the outbreak.

FRED DE SAM LAZARO: And they are hoping the message gets out on how to lower the risk of an outbreak, separating chickens from ducks, for example, keeping kids away from ponds where ducks swim, and improved hygiene around the backyard. It's a message that's gotten through to small farmers like Khieu Nyim.

KHIEU NYIM, farmer (through translator): I heard the news from the TV and radio. I heard that swine flu makes the pigs sick first and also infects human beings. First, I heard that it spread in Mexico, and then it also spread in America.

I take precautions for myself. I clean the pigs and make sure I wear a mask when I enter the cage.

Risk of Inter-Species Diseases
FRED DE SAM LAZARO: No one's sure whether most farmers are adopting such practices or whether most farmers can afford protective gear. And even though there's fear of the bird flu and swine flu viruses mixing, no one's sure when or if such a super-bug might emerge.

Dr. Michael O'Leary heads the World Health Organization office in Cambodia.

DR. MICHAEL O'LEARY, World Health Organization: I think it's largely a theoretical concern at this point, because we have, you know, many kinds of viruses around us all the time. And so while we have to say that it's possible that these two or other viruses may mix and result in a new virus, that's essentially always the case. We can have such a scenario any time.

FRED DE SAM LAZARO: He says the risk of diseases that jump from one species to another has risen in recent decades with dozens of examples, from Ebola to Lyme disease.

DR. MICHAEL O'LEARY: The destruction of forests or the urbanization of people, that's created new opportunities, I think, for new kinds of interaction between humans and animals. Another is the ease with which people move around the world now.

There have been so many emerging diseases in the last few decades. We've seen dozens of new diseases, HIV being only one, most of which did result from a spread of an organism from the animal world to the human world.

FRED DE SAM LAZARO: O'Leary says it will be important to strike a balance, watching for early signs of outbreaks while avoiding socially disruptive measures, like shutting down the merit bird trade or shutting down markets.

GWEN IFILL: For more on how viruses are transmitted from animals to humans and for Fred's reporter's notebook on Cambodia, visit our global health Web site at

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Thailand and Cambodia resume ministerial talks

BANGKOK — Foreign ministers from Cambodia and Thailand resumed joint policy talks for the first time in three years Wednesday after months of fractious relations over a border temple dispute.

Cambodian foreign minister Hor Namhong and his Thai counterpart Kasit Piromya met at a Bangkok hotel to discuss the spat and deeper economic ties.

Violent clashes near the ancient 11th century Preah Vihear have left seven soldiers dead since July 2008 when the temple was granted UN World Heritage status.

High level delegations have met at various times over the past year in an attempt to heal rifts, but Wednesday's meeting is the first time since 2006 that ministers have convened their joint policy commission.

The body had previously met once a year to oversee relations between the two countries.

Cambodia and Thailand have been at loggerheads over the Khmer ruins for decades. Although the World Court ruled in 1962 that the temple belonged to Cambodia, its most accessible entrance is in northeastern Thailand.

Tensions have also arisen over disputed waters where both countries have granted oil and gas exploration rights to private companies.

After Wednesday's meeting both foreign ministers said the talks signified progress in relations.

"We agree to speed up the border talks so that the existing problems will be solved," Hor Namhong told a press conference.

"We also agreed to cooperate over human trafficking, as Cambodia faces this problem," he said.

The pair said they would resume a Joint Technical Committee on the maritime dispute and vowed the disagreement would not be an obstacle.

"Our problems will not trouble our relations. Whatever our troubles are, we will solve them," Kasit said following the two-hour meeting.

Senior officials met a day earlier in Bangkok, where they kicked off the talks covering cooperation on the economy, trade, education and the border issue.

The ministers also agreed to advance plans for visa exemption scheme when they celebrate the 60th anniversary of diplomatic relations next year.

They also signed an agreement that will allow some prisoners, after serving minimum periods of imprisonment, to be transferred in order to serve their remaining sentences in their own countries.

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Mosquitoes deliver malaria 'vaccine' through bites

AP Medical Writer

In a daring experiment in Europe, scientists used mosquitoes as flying needles to deliver a "vaccine" of live malaria parasites through their bites. The results were astounding: Everyone in the vaccine group acquired immunity to malaria; everyone in a non-vaccinated comparison group did not, and developed malaria when exposed to the parasites later.

The study was only a small proof-of-principle test, and its approach is not practical on a large scale. However, it shows that scientists may finally be on the right track to developing an effective vaccine against one of mankind's top killers. A vaccine that uses modified live parasites just entered human testing.

"Malaria vaccines are moving from the laboratory into the real world," Dr. Carlos Campbell wrote in an editorial accompanying the study in Thursday's New England Journal of Medicine. He works for PATH, the Program for Appropriate Technology in Health, a Seattle-based global health foundation.

The new study "reminds us that the whole malaria parasite is the most potent immunizing" agent, even though it is harder to develop a vaccine this way and other leading candidates take a different approach, he wrote.

Malaria kills nearly a million people each year, mostly children under 5 and especially in Africa. Infected mosquitoes inject immature malaria parasites into the skin when they bite; these travel to the liver where they mature and multiply. From there, they enter the bloodstream and attack red blood cells - the phase that makes people sick.

People can develop immunity to malaria if exposed to it many times. The drug chloroquine can kill parasites in the final bloodstream phase, when they are most dangerous.

Scientists tried to take advantage of these two factors, by using chloroquine to protect people while gradually exposing them to malaria parasites and letting immunity develop.

They assigned 10 volunteers to a "vaccine" group and five others to a comparison group. All were given chloroquine for three months, and exposed once a month to about a dozen mosquitoes - malaria-infected ones in the vaccine group and non-infected mosquitoes in the comparison group.

That was to allow the "vaccine" effect to develop. Next came a test to see if it was working.

All 15 stopped taking chloroquine. Two months later, all were bitten by malaria-infected mosquitoes. None of the 10 in the vaccine group developed parasites in their bloodstreams; all five in the comparison group did.

The study was done in a lab at Radboud University in Nijmegen, the Netherlands, and was funded by two foundations and a French government grant.

"This is not a vaccine" as in a commercial product, but a way to show how whole parasites can be used like a vaccine to protect against disease, said one of the Dutch researchers, Dr. Robert Sauerwein.

"It's more of an in-depth study of the immune factors that might be able to generate a very protective type of response," said Dr. John Treanor, a vaccine specialist at the University of Rochester Medical Center in Rochester, N.Y., who had no role in the study.

The concept already is in commercial development. A company in Rockville, Md. - Sanaria Inc. - is testing a vaccine using whole parasites that have been irradiated to weaken them, hopefully keeping them in an immature stage in the liver to generate immunity but not cause illness.

Two other reports in the New England Journal show that resistance is growing to artemisinin, the main drug used against malaria in the many areas where chloroquine is no longer effective. Studies in Thailand and Cambodia found the malaria parasite is less susceptible to artemisinin, underscoring the urgent need to develop a vaccine.
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