WASHINGTON — Faced with what they describe as a perfect storm of converging threats from infectious disease epidemics, U.S. officials are launching a global effort Thursday with more than two dozen countries and international organizations to prevent deadly outbreaks from spreading.

The goal is to prevent, detect and respond to infectious disease threats where they start. That’s more effective and less costly than treating sick people after diseases spread. The new initiative will aim to bolster security at infectious disease laboratories, strengthen immunization programs and set up emergency response centers that can react to outbreaks within 120 minutes.

Despite advances in medicine and technology, Americans are at higher risk than ever from new infectious diseases, drug-resistant infections and potential bioterrorism organisms, said Thomas Frieden, director of the Centers for Disease Control and Prevention, which is spearheading the initiative.

On Thursday, even though the federal government was closed because of a major snowstorm, Health and Human Services Secretary Kathleen Sebelius welcomed officials to the meeting at department headquarters. “Microbes and diseases are moving faster and farther than ever,” she said. “A threat anywhere is indeed a threat everywhere.”

“Not only is there the potential for loss of life and serious economic consequences, but ultimately, there is also instability from a security perspective,” said Laura Holgate, senior NSC director for weapons of mass destruction terrorism and threat reduction.

Diseases that once weren’t found in the United States now are widespread, including mosquito-borne West Nile virus-related illnesses. There has also been a resurgence of other diseases, such as drug-resistant tuberculosis.

In Washington and other metropolitan areas – which typically have large immigrant populations and professionals who travel overseas frequently –there are regular reports of the infectious lung disease.

In recent weeks, another mosquito-borne virus common in Africa and Asia has spread quickly through the eastern Caribbean, appearing for the first time in the Western Hemisphere. Chikungunya fever, which is similar to dengue, first appeared in December on the French side of St. Martin and has now spread to seven other countries, including Martinique, Guadeloupe and the British Virgin Islands.

International health regulations require nations to report outbreaks quickly to the World Health Organization, but most countries have not complied.

“We hope this will be the shot in the arm, energizing the global health security agenda,” said Andrew Weber, assistant secretary of defense for nuclear, chemical and biological defense programs.

The WHO, the Food and Agriculture Organization and the World Organization for Animal Health are also participating in the effort.

This year, the CDC and the Defense Department are committing $40 million to work with 10 countries, including Uganda and Vietnam. The CDC recently completed pilots in those countries to improve diagnostic testing and transportation of potentially infectious samples.

Uganda has battled the deadly Ebola virus, cholera and multidrug-resistant TB. Vietnam has experienced outbreaks of severe acute respiratory syndrome, and the H5N1 bird flu strain. The SARS pandemic of 2003, which began in China, killed nearly 800 people in more than 30 countries and cost $30 billion after just a few months.