New York City ? New infectious diseases have been appearing more often, says a study that suggests “hot spots” where the next new germs are most likely to appear.

“We need to be out there in the hot spot regions looking for the next HIV,” said study co-author Peter Daszak.

Daszak, the executive director of the Consortium for Conservation Medicine at Wildlife Trust, and other researchers present their analysis in today’s issue of the journal Nature.

To designate the hot spots, researchers found 335 appearances of new disease between 1940 and 2004, and then analyzed social and environmental factors that appeared to promote them. Most disease events involved germs new to humans, but researchers also counted illnesses from established germs that had become drug-resistant, moved into a new region or had become much more common.

The researchers said the highest risk areas are in parts of east Asia, Central America and South America, the Indian subcontinent, Africa, western Europe and some population centers of North America. That’s because the historical analysis had found the risk of such diseases goes up with factors like high population density and diversity of wildlife, the researchers said.