Health Highlights: Oct. 5, 2007

ByABC News
March 24, 2008, 1:32 AM

Mar. 23 -- Here are some of the latest health and medical news developments,compiled by editors of HealthDay:

Former U.S. Track Hero Admits Steroid Use

Former American track star Marion Jones pleaded guilty Friday to lying to U.S. federal agents about her use of performance-enhancing steroids, The New York Times reported.

Jones pleaded guilty to one count of making false statements to federal agents about her use of performance-enhancing drugs. She was also to plead guilty to one count of making false statements to federal agents in connection with a separate check fraud case. She appeared Friday afternoon at the U.S. District Court in White Plains.

Jones, 31, won three gold and two bronze medals at the 2000 Olympics in Sydney, Australia. She's been under a cloud of suspicion for years, but had repeatedly denied using banned substances, the Times reported.

An admission to using performance-enhancing drugs would likely result in Jones being stripped of her five Olympic medals.

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Vaccine Caused Nigeria Polio Outbreak

A vaccine meant to protect poor Nigerian children from polio ended up triggering an outbreak in the African country, according to health officials.

At least 69 children are paralyzed and experts say a weakened form of live polio virus used in an oral vaccine appears to be the cause, the Associated Press reported.

Children in developed countries typically receive a polio vaccine with an inactivated strain of virus. But that vaccine is given by injection, is more expensive, and requires more training to deliver. For that reason, the cheaper oral vaccine -- containing a weakened live virus -- is used in many developing countries, the AP said.

Vaccinated children can excrete the virus, which can then end up in the water supply in countries with poor sanitation, experts say. Once ingested by non-immunized children, the weakened polio strain can, in rare cases, mutate into something more dangerous, health officials say.

Such vaccine-linked outbreaks have occurred before in countries such as China, Haiti and the Philippines, the AP noted.

Officials at the U.S. Centers for Disease Control and Prevention and the World Health Organization (WHO) announced the cause of the Nigeria outbreak last week, although they said they have known about it for a year.

WHO's top polio official, Dr. David Heymann, said his organization felt the outbreak was a problem for scientists and not something that would impact on global immunization practices, so WHO did not immediately publicize the incident.