A health alert about duck eggs has been issued in the Irish Republic following its largest outbreak of salmonella poisoning in recent years.

Around 30 people have been infected so far and half of them have been hospitalised. With the outbreak continuing, the Food Safety Authority of Ireland (FSAI) has warned that these cases may be “only the tip of the iceberg as many more will have gone unreported”.

It linked the outbreak to duck eggs from small backyard flocks and private farms rather than commercial operations.

The confirmed cases, which have been reported from across the Republic, are of the Salmonella typhimurium DT8 strain, and victims have ranged from babies to pensioners. The FSAI stressed that hen eggs are not affected and said that a quality assurance scheme for duck eggs was being developed by Bord Bia to protect consumers and provide a safe supply source.

In a message to consumers, retailers and caterers, FSAI chief executive Alan Reilly warned that they should treat duck eggs as they would raw chicken, preventing contamination with ready-to-eat food and ensuring they were cooked thoroughly. Strict hygiene was important when handling them. “Even when duck eggs look clean, they may still have salmonellae on the outside of the shell,” he said.