Salmonella bacteria, which can cause potentially fatal food poisoning, were detected in more than 26 percent of egg-producing farms surveyed by the Japan Poultry Association (JPA).
Although the figure is on par with the 20-30 percent estimated average in the European Union, questions remain about the infection rate in Japan.
Not only was the JPA's salmonella survey the first conducted on a nationwide scale, it also covered less than 6 percent of the layer farms in the country.
In response to the results of the survey for fiscal 2004, the farm ministry plans to conduct a larger-scale survey over five years from next fiscal year. It has requested 87 million yen for the budget in the initial year.
The survey will cover poultry farms, wholesalers and retailers, sources said.
Salmonella bacteria attach themselves to the digestive organs of domestic fowl and cattle. Salmonella is generally passed onto humans through the eggs or meat of the infected animals, and can cause diarrhea or high fevers that can kill those who are physically weak.
The results of JPA's survey were compiled into an unofficial report in March last year, but the JPA did not publicize the results.
"We did not want to give consumers the misunderstanding that many eggs are contaminated," an official said.
The Asahi Shimbun recently obtained a copy of the unofficial report.
The report said there are about 3,600 layer farms in Japan. The JPA chose 10 percent of them for the survey, among which 204 cooperated.
The farmers each submitted droppings of 50 hens, as well as samples of dust from ventilation openings and the fans of their henhouses.
Salmonella was detected in the droppings from 15 farms and in the dust samples of 48 farms. Nine farms had the bacteria in both the droppings and the dust, the report said.
In total, salmonella was found in 54 of the 204 farms, or 26.5 percent. Twenty-seven of the infected farms were large-scale ones that keep more than 100,000 hens.
The United States and some European countries conduct nationwide salmonella surveys on a regular basis.
However, Japan has not done so.
According to experts, hens infected with salmonella pass the bacteria on to less than 10 percent of their eggs.
Experts say the salmonella bacteria do not increase if the infected eggs are kept at 10 degrees or lower, meaning the possibility of people suffering from food poisoning after eating the eggs is low.
In addition, the bacteria are destroyed if the eggs are heated at 65 degrees or higher.
However, Haruo Watanabe, a vice director of the National institute of Infectious Diseases, said: "The results of the survey back up the situation that about three out of 10,000 eggs are infected with the bacteria in Japan.
"Consumers should recognize that it is difficult to completely remove salmonella, which exists in the natural environment, from poultry farms."
