This is SCIENCE IN THE NEWS in VOA Special English. I'm Dpug Johnson.
And I'm Faith Lapidus. This week -- warnings about a form of tuberculosis that resists almost all treatment ...
New rules about sales of emergency birth control in the United States ...
And some good news if you are looking for dinosaurs.
Health experts are concerned about a newly identified threat from tuberculosis. They call it extreme drug-resistant tuberculosis. In one recent outbreak, fifty-three people became infected in KwaZulu-Natal province in South Africa. All but one of them died after attempts at treatment failed.
A South African news report last week said six gold miners in Free State province were also found to have extreme drug-resistant TB.
Tuberculosis is a bacterial infection that is spread through the air and usually attacks the lungs. The disease kills almost two million people each year. The World Health Organization says one-third of the world's population is infected with TB. Most people who are infected never develop active tuberculosis, so they never get sick from it.
But people with HIV and other conditions that weaken the body's defenses are more likely to develop tuberculosis. Forty-four of the fifty-three patients in KwaZulu-Natal had been tested for the virus that causes AIDS. The tests showed that all forty-four had HIV.
Extreme drug-resistant tuberculosis is the name for TB strains that resist not only the two main drugs used to fight the disease. They also resist three or more of the six kinds of drugs that are used when the first line of treatment fails.
World health officials say it has been found in all parts of the world but is most common in the former Soviet republics and in Asia. These recent findings are based on information from two thousand through two thousand four.
Latvia has one of the highest rates of drug-resistant TB in the world. There, nineteen percent of the cases of drug-resistant tuberculosis met the definition of the newly identified threat. In the United States four percent of cases were identified as extreme drug-resistant TB.
The World Health Organization says the drug resistance results mainly from poor care of TB patients. This includes incorrect treatment plans and the use of poor quality drugs. It also includes the failure of patients to complete the months of treatment required to cure tuberculosis.
The W.H.O. says drug resistant TB appears to be increasing in Africa. The rates are still low compared to Eastern Europe and Asia. But the high rates of HIV in Africa mean that drug-resistant TB could sharply increase the number of deaths.
The South African Medical Research Council says the recent cases in KwaZulu-Natal demonstrate the risks for people with HIV. The patients died an average of twenty-five days after drug-resistant TB was first suspected. These included patients who had been taking antiretroviral drugs to control their HIV infections.
Experts warn that the spread of extreme drug-resistant TB could harm efforts to treat HIV and AIDS.
Earlier this month, W.H.O. officials joined TB experts and representatives from eleven African countries at a two-day meeting in Johannesburg. They agreed on a seven-point plan of action to control extreme drug-resistant tuberculosis. They said the first step needed is to urgently do studies in high-risk countries to identify the extent of the threat. They also said more laboratories are needed to carry out testing.
People with TB have to take a combination of several drugs daily for at least six months. Many stop as soon as they feel better. Yet that can lead to an infection that resists treatment.
In nineteen ninety the World Health Organization developed the DOTS program, or Directly Observed Treatment, Short-course. Health workers watch tuberculosis patients take their pills every day.
Earlier this year, an international partnership of organizations announced a plan to expand the program. The ten-year plan also aims to finance research into new TB drugs. The Global Alliance for TB Drug Development says its long-term goal is a treatment that could work in as few as ten doses. The four most common TB drugs currently used are more than forty years old.
You are listening to SCIENCE IN THE NEWS in VOA Special English.
Federal officials in the United States have eased restrictions on sales of the emergency birth-control drug called Plan B. The Food and Drug Administration will now permit women to buy it without a doctor's order if they are at least eighteen years old. Those age seventeen and younger will still need to get a prescription.
The newly approved sales are expected to begin by the end of the year. But Plan B will not be as widely sold as other medicines that are sold without a prescription. And buyers will have to present proof of age.
Men may also buy Plan B for their sexual partners.
Plan B is taken by mouth. It is often called the "morning-after" pill. It contains a manufactured form of the hormone progestin. Progestin is widely used in birth control pills. But Plan B contains more of it.
The drug comes as two pills. The second pill is taken twelve hours after the first. Plan B works by preventing a woman from producing an egg or by preventing the egg from being fertilized. In addition, it may prevent a fertilized egg from becoming implanted in the uterus.
Barr Pharmaceuticals of New Jersey makes Plan B. The company says the product is almost ninety percent effective if taken within seventy-two hours of a single act of unprotected sex.
Barr says Plan B reduces the risk of pregnancy but will not end an existing pregnancy.
The recent action by the Food and Drug Administration followed almost three years of consideration and debate. A year ago, a former F.D.A. director said the agency did not have the power to make such a decision.
Supporters of the action say Plan B will reduce the number of women who get abortions. But others say Plan B is a form of abortion because it uses scientific methods to prevent the beginning of life.
Critics also say it will be difficult to make sure buyers meet the age requirements -- or that an older person is not buying Plan B for a younger one.
A new report suggests that scientists will find many new kinds of dinosaurs during the next century. Scientists identify all creatures, including dinosaurs, by groups or genera. The report says that at least seventy percent of dinosaur genera have yet to be found. It also estimates that seventy five percent of the currently unknown dinosaur genera will be discovered in the next sixty to one hundred years.
Researchers Steve Wang and Peter Dodson wrote the report. Mister Wang is a mathematician at Swarthmore College in Pennsylvania. Mister Dodson is a scientist with the University of Pennsylvania in Philadelphia. The Proceedings of the National Academy of Sciences published their findings.
The report says the two researchers believe there could be up to one thousand eight hundred fifty different kinds of dinosaurs. It says the fossilized remains of five hundred twenty-seven of these ancient creatures have been found.
Mister Dodson produced a similar estimate in nineteen ninety. Comparison with the recent study shows a big increase in discoveries of dinosaur fossils.
The report noted that for more than one hundred years, science recognized fewer than three hundred kinds of dinosaurs. Their remains were found mainly in the United States, Britain and Canada. In the past twenty years, the number of places with fossils has increased by one hundred percent. Many fossils have been found in China and South America.
The researchers say they made the report because little work has been done to estimate the number of dinosaur genera.
Mister Wang says a child born today could expect a satisfying life's work in the study of dinosaurs. But he also says that almost half of dinosaur genera that lived might have died without leaving a fossil as evidence of their existence.
SCIENCE IN THE NEWS was written by George Grow, Jerilyn Watson and Jill Moss. Brianna Blake was our producer. I'm Faith Lapidus.
And I'm Doug Johnson. You can download transcripts and MP3 files and search through archives of our programs at WWW.51VOA.COM. Join us again next week for more news about science in Special English on the Voice of America.