"Cholera bacterium tests have shown results of poisonous strength," said Nguyen Van Binh from the Ministry of Health at a meeting of the Steering Committee for Influenza Pandemic Prevention on June 9.

"It is noticeable that cholera bacterium usually found in molluscs living in brackish water has also been found living in fresh water."

Health experts have also said the risk of a cholera outbreak has risen as a result of increasing international exchanges, unhygienic food, and untreated canal water.

According to statistics from the ministry, Vietnam has had a total of 69 cholera vibrio positive cases but no fatalities in nine cities and provinces surveyed nationwide since the beginning of 2010. Ben Tre provincial authorities continue to report scattered occurrences of cholera-positive cases.

The National Institute of Hygiene and Epidemiology also reported a dysentery outbreak with a total 140 infected cases in 4 hamlets of Duc Hanh Commune of Cao Bang province since May 19.

Six children in Lung Man Hamlet died from serious disease conditions after developing dysentery and local health officials were unable to reach the children in time. Health authorities later isolated and decontaminated the affected area and treated those infected.

Duc Hanh is a mountainous commune with a majority Mong ethnic population.