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HEALTH BRIEFS 2005-1: Malaria Vaccine; Avian Flu Clues from Canine Virus; Appetite-Suppressing Hormone Discovery


Health Briefs is a new weekly feature on VOA that will bring attention to breaking health and medical news in the United States and around the world.

New Malaria Vaccine Yields Promising Results

Scientists and health policy experts gathered in Cameroon recently to discuss ways to fight malaria, the leading cause of death among African children. The Pan Africa Malaria Conference 2005 released findings that suggest there is progress in efforts to create a vaccine for the mosquito-borne disease.

A study in 2004 -- in collaboration with the Mozambique Health Ministry -- indicated that the trial vaccine RTS, S-AS02 cut severe malaria episodes in half. Eighteen months later its effectiveness had dropped as feared, but not significantly.

Vaccine inventor John Cohen told conference goers that if the findings hold up, the vaccine could save hundreds of thousands of lives. Three million people die of malaria each year. Ninety percent of the cases are in sub-Saharan Africa.

RTS, S-AS02 is one of several malaria vaccines now in development. Dr. Cohen says the American pharmaceutical company Glaxo-Smith-Kline is working on a new formulation of the vaccine, which the company hopes to field test within a year. The product could be on the market by 2010.

Canine Virus Provides Clues to How Avian Flu Might Spread in Humans

A new study in the Annual Review of Microbiology examines the origin of new pandemic viruses by comparing severe outbreaks of influenza in humans and canine parvovirus in dogs.

Cornell University scientist and co-author Colin Parrish says an emerging canine virus must undergo several simultaneous mutations to promote an epidemic. He says several genetic mutations are also required for the growth and spread of the bird influenza virus among humans. "There's a special circumstance which has to happen to make that bird virus transfer into humans with the right mutations… or alternatively," he says, "it has to jump into humans with just the right mutations just as it replicates in that first human, and then gain the ability to spread from human to human."

The H5N1 avian influenza has led to the slaughter of 140 million birds in several Asian countries. Half of the 120 people who have contracted the disease from poultry have died. The virus has apparently not yet undergone sufficient mutations in humans to initiate a pandemic. But as Mr. Parrish observed in dogs, the time to take action is when the virus is least active. "There may be an early stage in the emergence of avian flu where the virus isn't fully human adapted, where it doesn't spread rapidly from human to human, but it can spread in some degree," he says. "So there may be a time when we can more easily control the virus because it is not as transmissible."

Mr. Parris says that there seems to be a period of a year or so between the point when viruses emerge and when they become better adapted to their hosts.

Scientists Discover Appetite-Surpressing Hormone

Scientists from Stanford University have discovered a new stomach hormone that can reduce appetite. They report in the journal Science that when the hormone known as obestatin was injected into laboratory mice, the rodents cut their food intake in half and lost 20% of their body weight over 8 days.

But according to University of Cincinnati psychiatry professor Matthias Tschop,who reviewed the study, the hormone is not a quick fix for reducing fat mass and body weight. "We have to understand better all the factors involved in body weight regulation," he says. "It will probably not be as easy as just using obestatin, administering it to obese patients and expect them to be cured, because the effects so far only have been tested in mice." And, Mr. Tschop says, those laboratory tests left some unanswered questions. "If you inject a new substance, you never know if that could cause a visceral illness or nausea in the animal because rats and mice don't have the ability to vomit and therefore they could just feel nauseated and therefore eat less."

Interestingly, the Stanford scientists found that the appetite-suppressing obestatin shares a gene with the appetite-boosting ghrelin. Mr. Tschop says it will take years of research to understand how these two dueling hormones work to control weight.

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