Europe and North and South America are the places with the least rise in such cases.
The finding comes as an international research team prepares the first map of emerging-disease hot spots.
Medically, the term 'emerging diseases' is defined as newly identified pathogens, or old ones moving to new regions. It takes within its sweep the HIV/AIDS, SARS, and African Ebola virus.
Marc Levy of the Center for International Earth Science Information Network (CIESIN), an affiliate of Columbia University's Earth Institute, has revealed that disease emergences have roughly quadrupled over the past 50 years.
The researcher, who is a co-author on the study report, also says that about 60 per cent of the diseases travelled from animals to humans, such as zoonoses. The majority of such diseases came from wild creatures, he adds.
"We are crowding wildlife into ever-smaller areas, and human population is increasing. The meeting of these two things is a recipe for something crossing over," Nature magazine quoted Levy as writing in the report.
The study suggests that the main sources of diseases are mammals, and that some pathogens may be picked up by hunting or accidental contact.
Kate E. Jones, an evolutionary biologist at the Zoological Society of London and first author of the study, said the work urgently highlights the need to prevent further intrusion into areas of high biodiversity.
"It turns out that conservation may be an important means of preventing new diseases," she said.
According to the researchers, about 20 per cent of known emergences are multi-drug-resistant strains of previously known pathogens like tuberculosis. They say that richer countries' increasing reliance on modern antibiotics has helped breed such dangerous strains.
Biologist Peter Daszak of the Consortium for Conservation Medicine at the Wildlife Trust, another Earth Institute affiliate, feels that some strains—including lethal variants of the common bacteria E. coli—now spread widely with great speed because products like raw vegetables are processed in huge, centralized facilities.
"Disease can be a cost of development," he said.
The group's analyses showed also that more diseases emerged in the 1980s than any other decade—likely due to the HIV/AIDS pandemic, which led to other new diseases in immune-compromised victims. In the 1990s, as per their report, insect-transmitted diseases saw a peak, possibly in reaction to rapid climate changes that started taking hold then.
Stressing that the study has immediate uses, Daszak said: "The world's public-health resources are misallocated. Most are focused on richer countries that can afford surveillance, but most of the hotspots are in developing countries. If you look at the high-impact diseases of the future, we're missing the point."
He even suggested that countries share more technology and resources in hotspots to reduce risk.