ATLANTA (USA TODAY) -- Microbial killers such as drug-resistant malaria, tuberculosis, HIV and syphilis continue to ravage the world. Health experts say they know how to prevent and treat these diseases, but first they need to overcome a different kind of public health enemy: complacency.

Public attention in the past two years has focused on new diseases, such as SARS, and new threats, such as bioterrorism, but scientists here at the International Conference on Emerging Infectious Diseases say the lack of attention to older diseases is allowing them to flourish.

"HIV complacency" is partly responsible for rising rates of HIV in the southern USA and syphilis among men who have sex with men in large U.S. cities, researchers reported Tuesday.

In parts of the USA and other industrialized countries, "there is a perception that HIV is no longer a major threat," said Ronald Valdiserri of the Centers for Disease Control and Prevention, and "many countries report a resurgence of unsafe behaviors" and outbreaks of sexually transmitted diseases since the introduction of anti-HIV drugs.

Malaria, which kills nearly 2 million people a year, most of them children in Africa, has grown resistant to the most common drug used to treat it, chloroquine. Other drugs, more expensive and not as readily available, are effective, and efforts are underway to mobilize resources, said the CDC's Peter Bloland. "But it's a slow process and it means some people will be without these drugs for a long time," he said. In the meantime, he urged other strategies, such as the use of insecticide-treated bed nets, found to reduce deaths among children by almost 25%.

Tuberculosis can be stopped if it is correctly diagnosed and treated. Yet each year, 9 million people are newly infected and 2 million die, said Thomas Frieden, commissioner of the New York City Department of Health and Mental Hygiene.

Treatment with a six-month course of medications taken under the observation of medical workers is effective, he said, but control measures can't be sustained without political will and the funding to back it.

In New York City, immigrants account for 70% of cases. "Unless we are able to support global TB control, we will not eliminate TB in the United States," he said. "We are all connected by the air we breathe."

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