Cases of tuberculosis reached an all-time low in the United States last year, but the disease continued to affect minorities at much higher rates than whites, health authorities said Thursday.

There were fewer than 10,000 U.S. cases of TB for the first time since records began being compiled in 1953, said the Centers for Disease Control and Prevention.

A U.S. agency has issued a long-awaited report saying it found no proof that decades of military practice bombing on the Puerto Rican island of Vieques sickened residents who blame it for high rates of cancer, asthma and other illnesses.

The report was released this week and follows four previous assessments and several updates by the Agency for Toxic Substances and Disease Registry that reached similar conclusions.

The United Nations launched a campaign Friday to lift a deadly taboo on talking about toilets and to turn the world into an "open defecation-free zone."

The World Water Day initiative aims to cut the 3,000 children under five who die each day from water-borne diseases like cholera, dysentry and diarrhea, and the 2.5 billion people without access to a toilet.

A study of mercury contamination in a southeastern Peruvian jungle area ravaged by illegal gold mining found unsafe levels of the toxic metal in 78 percent of adults in the regional capital and in 60 percent of fish sold at markets.

The study by the Carnegie Institution for Science calls the contamination a "grave and mounting threat to public health."

Freshly dumped hypodermic syringes litter alleys, cemeteries and shaded corners in Myitkyina, the provincial capital of Kachin state, on Myanmar's northern border with China.

Myitkyina is known for having one of the highest concentrations of drug addicts in the world. The Kachin Baptist Convention, an evangelical group with more than 300 churches in the state, says nearly 80 percent of ethnic Kachin youth are addicts. Their drug of choice is heroin.

Experts on infectious diseases Thursday warned people to stay away from bats worldwide after the recent death of an eight-year-old boy bitten in Australia.

The boy last month became the third person in the country to die of Australian bat lyssavirus (ABLV), for which there is no effective treatment.

More than three-quarters of British doctors prescribe a treatment they know probably won't work at least once a week, like low-dose drugs, vitamins, nutritional supplements or an unnecessary exam, according to a new survey.

This use of placebo treatments directly contradicts advice from the British Medical Association, which deems them unethical.

Physical therapy is often as effective as knee surgery when treating patients with tears to the meniscus or arthritis, according to a clinical study published on Tuesday.

In the study, half of 351 participants aged over 45 suffering with meniscus tears or osteoarthritis were randomly selected to undergo knee arthroscopy with the other half getting several weeks of physical therapy.

A government survey of parents says 1 in 50 U.S. schoolchildren has autism, surpassing another federal estimate for the disorder.

Health officials say the new number doesn't mean autism is occurring more often. But it does suggest that doctors are diagnosing autism more frequently, especially in children with milder problems.

The World Health Organization has expressed concern that the Philippines is encouraging smoking by hosting one of the world's largest tobacco trade shows.

The two-day fair called ProTobEx ASIA opened Wednesday in the capital's Pasay city for the second consecutive year. Organizers said they chose the Philippines over other locations in Asia because of its vibrant tobacco industry and the "phenomenal" support of the Pasay city government.