Food-borne diseases appear to be on the rise in both rich and poor countries, officials with the World Health Organization said on Thursday.

More research is needed to determine how much sickness and death stems from contaminated food, such as the tainted Chinese milk that caused kidney problems in more than 50,000 children and killed four, and the U.S. salmonella outbreak that made more than 1,400 people ill, WHO director of food safety Jorgen Schlundt said.

An estimated 30 per cent of new infectious diseases originate in bacteria, viruses, parasites, chemicals and toxins introduced along food production chains, he told an experts' meeting.

"There are some indications that the food-borne disease burden is increasing. But there is not very good data, it is difficult to say exactly what is happening," Schlundt said.

About 2.2 million children die each year from diarrheal illnesses, including cholera caused by dirty water, food, and poor sanitation, according to the United Nations agency.

Food products needed to be monitored at every stage of their handling, Schlundt said.

"If you want to deal with food safety you have to go from the 'farm to the fork.' The notion that you can deal with it at the end of the food chain is clearly wrong," he said.

In many countries, regulatory authorities fail to work together, he said.

"In China there are 16 different authorities involved in some way in dealing with the melamine crisis," he said.

All countries vulnerable

Julie Ingelfinger, a Harvard Medical School professor and pediatric nephrologist, said many people had overlooked the seriousness of complications caused by contaminated food.

For instance, E. coli poisoning can cause hemolytic-uremic syndrome, a cause of kidney failure in children, she said.

"Research into the long-term effects of food-borne disease is increasingly important because it is unquantified and goes on for decades," she said.

David Heymann, WHO assistant director-general for health, security and the environment, told the meeting that rich and poor countries were both vulnerable to food-borne diseases.

"Food-borne diseases occur on every continent and in every country really. We never know where these events will happen," he said.

The recent salmonella outbreak in the United States — its worst in a decade — was an example of the changing picture of food-borne diseases, according to the WHO.

Although salmonella is often linked to poultry, eggs and dairy products, recent outbreaks have been tied to fresh produce, it said. Tomatoes were suspected in the U.S. outbreak before the salmonella was traced to peppers from Mexico.

Nancy Donley, president of the U.S. non-profit group S.T.O.P. (Safe Tables Our Priority), said food safety needed to be taken more seriously as a public health concern.

"It's crucial to keep food-borne disease prevention as a top priority in the world," said Donley, whose six-year-old son Alex died in 1993 from E. coli-contaminated meat. "Behind every statistic is a face, a name, a life."

With files from Reuters