The Department of Health in Australia issued a recall for prepackaged salad greens produced by the Victorian-based Tripod Farmers company earlier this month after an unusually large number of cases of salmonella, a bacteria that causes food poisoning, were reported in the state.
This sounds like a mere piece of news that took place 5,800km away that has nothing to do with Thai consumers -- but earlier last week Thailand's Food and Drug Administration (FDA) also recalled similar products found to be available in Thai supermarkets. This came after the Ministry of Public Health was warned by Infosan Secretariat under the World Health Organization (WHO)'s Department of Food Safety and Zoonoses of possible health hazards from the said salad leaves.
According to the FDA's report, the contaminated produce was imported into Thailand twice, altogether 9kg. Unfortunately, all were distributed. In the meantime, the FDA said it has tested random samples of imported fresh produce to check if they are contaminated and urged consumers to contact its call centre at 1556 should suspicious cases be found.
Medical adviser from the Department of Health in Australia said that the outbreak could have been caused by the fertiliser used to grow the vegetable. This is in line with information from certified dietitian Somsri Tachavarakul who explained that a lot of salmonella cases are contaminated from water, fertiliser or soil used during the farming process.
"This is why salmonella is found less in vegetables that are grown hydroponically or without soil," said Somsri.
Salmonella is a type of bacteria that is a major cause of foodborne illnesses throughout the world. The bacteria can be transmitted to humans through the consumption of food as well as through animals such as rats, poultry and bugs. But most of the salmonella-infected cases, added Somsri, have fresh fruit and vegetables to blame.
Salmonella can grow well at room temperature or around 37C. There are a large number of salmonella strains, some of which are even heat tolerant.
"Besides fruit and vegetables, salmonella outbreaks can also be associated with meat. But fruit and vegetables can be more easily contaminated because they are more fragile and more likely to leak liquid. And liquid is easily infected with the bacteria," the nutritionist explained.
Salmonella-infected cases in humans are usually mild. Symptoms can develop six to 48 hours later, or in some cases up to five days later, after the consumption of contaminated food, according to Somsri.
And symptoms might vary according to the strain of the bacteria and the amount of food consumed. They include mild symptoms like nausea, headache and fatigue to more serious effects such as vomiting, diarrhoea, dehydration, fever and shivering.
"In very serious cases, salmonella is also likely to lead to severe intestinal ulcers and blood infections but, fortunately, this is quite rare. But the good news is most cases of salmonella infections self heal," she added.
Cooking techniques at high temperature are able to kill the bacteria, meaning people who eat cooked food are less likely to fall victim to salmonella-causing complaints. According to Somsri, the killing temperature of salmonella is over 60 degree's Celsius.
"Ingredients that are cooked under the temperature of 60 degree's Celsius for four to five minutes can be free from salmonella. And in case you put ingredients into a boil, one to two minutes is just enough," she said.
The dietitian added that the growth of salmonella can temporarily be brought to a halt by the temperature of under 4 degree's Celsius.
"This means the bacteria will no longer grow in the refrigerator. But if you take the ingredient out of the fridge and leave it at room temperature without cooking or heating it right away, then the bacteria will resume proliferating," she said.
For the cases of fresh fruit and vegetables which are often found to be infected with salmonella, it is paramount to prepare them under good hygienic standards. This means anybody who touches the ingredient must wash their hands thoroughly and keep clean during the entire cooking process.
Washing fruit and vegetable in water and vinegar, Somsri recommended, is one of the effective and cheap ways to get rid of salmonella -- just mix 2ml of vinegar with 1 litre of water and then allow fresh produce to sit in it for 15 minutes.
"Some certain types of fruit and vegetable washing liquid that contain chlorine are able to kill salmonella," she added. "But they must be used exactly as instructed because too much chlorine can be harmful to health."
Before consumption, it is also crucial to wash fresh produce under flowing water.
"If you use the same tub of water to wash your fruit and vegetable over and over, germs, bacteria and dirt will then remain in that tub and this is indeed a source of contamination."
Last but not least, personal hygiene for people working with food is crucial. Coughing and sneezing over food or having long nails which can collect bits of bacteria are among practices that should be avoided for food safety reasons.
"Or else, you'd better eat cooked food," concluded Somsri.
