Fewer than three dozen nations are capable of the early detection and quick response needed to contain rapidly spreading bird flu and other viruses that could threaten humans, a health official said on Tuesday.

Combating the spread of the H5N1 avian influenza, which has killed 103 people worldwide since it reemerged in 2003, has become critical to governments across the globe because experts fear it could become a pandemic that could kill millions and cause catastrophic economic damage.

“Developed countries are in position to practice satisfactory early detection and rapid response. Worldwide, only 20 to 30 countries are able to do that currently,” said Dr. Bernard Vallat, director-general of the World Organization for Animal Health. “All the others, 140 or more, need help.”

Rich countries need to help poorer ones with detection programs and compensation for farmers to prevent the global spread of “zoonoses,” diseases that can spread from animals to humans, Vallat said at the International Conference of Emerging Infectious Diseases in Atlanta.

At a January conference in Beijing, governments and organizations pledged $1.9 billion for a global “rapid containment” program for bird flu.

The World Health Organization said on Tuesday that bird flu killed five young people in Azerbaijan, taking the global death toll to 103 since it reemerged in late 2003. The virus has spread with alarming speed in recent weeks, pushing into Europe and Africa.

The United States said this week it expects to see its first cases of bird flu this year.

Scientists say the virus is mutating and could evolve into a form that would pass easily from human to human, potentially causing a pandemic that could kill millions because people would have no immunity.

The issue of ways to contain it has been a primary topic of debate between hundreds of health experts from some 80 nations gathered in Atlanta this week for the infectious disease conference.

Vallat named European Union nations, the United States, Canada, New Zealand and Australia as having the ability to respond quickly to an outbreak of bird flu or another threatening virus.

Experts say outbreaks can be contained by early detection and a quick response. U.S. wildlife officials, for example, are monitoring Pacific bird migration routes for signs of bird flu with the hope of tracking infected birds and giving advance warning to U.S. poultry producers.

But in many poor countries, it is nearly impossible to know what diseases are circulating because of poor surveillance programs.

“There are parts of Africa without any surveillance,” Vallat said. “Diseases can circulate for weeks in some parts of Africa without being known by the authorities in the capital.”

One of the keys to early detection is a plan to compensate farmers if governments decide to destroy infected flocks. Outbreaks of H5N1 have forced the destruction of more than 200 million birds.

But in poor countries, farmers may be reluctant to report mysterious deaths in their flocks because they are uncertain whether they will be paid for the lost birds.

“You can’t go to poor areas and take away the people’s livelihoods and the food supply and not have them compensated. It’s just not right,” said Dr. Keiji Fukuda of the World Health Organization.

European nations such as France, Germany and the Netherlands have compensation plans, as do Vietnam, Thailand and other Asian countries. But many nations have not addressed the issue.

Vallat said the World Bank and other international financing organizations were working to develop “sustainable” compensation programs. For example, the World Bank made a loan to Vietnam on the condition that it establishes a sustainable compensation plan for farmers.