Food Safety Focus (208th Issue, November 2023) – Article 2

Reminding Travellers: Lessons from a Campylobacter Outbreak

Reported by Dr. Ken CHONG, Scientific Officer,
Risk Assessment Section, Centre for Food Safety

In October, media reported a massive food poisoning outbreak in Japan caused by Campylobacter species affecting around 900 people. The incriminated food was nagashi sŌmen, which involves noodles flowing down a bamboo chute and being caught by diners with chopsticks as they float by.  The pathogen was detected in the spring water sending the noodles down the chute. Travellers can savour local cuisine when visiting overseas countries, but they should exercise caution regarding any threats to their food safety.  Let us learn more about campylobacters in food and travel-related food safety tips in this article.

Campylobacters

Campylobacters are commonly found in the intestinal tracts of animals and some humans. The most commonly reported Campylobacter species in human disease is Campylobacter jejuni followed by Campylobacter coli.  These disease-causing Campylobacter species can only grow above 30°C but can tolerate higher growth temperature and 42°C is their optimum growth temperature. That said, campylobacters have been found to have better survival rates in food stored under refrigeration compared to food stored at room temperature.  On the other hand, most Campylobacter species prefer a micro-aerobic atmosphere, i.e. reduced oxygen atmosphere. Oxygen comprises approximately 21% of the atmosphere, while these bacteria grow optimally at oxygen concentrations ranging from 3% to 5%. According to  literature, consuming as few as 500 Campylobacter cells can cause illness.

Disease Caused by Campylobacters

Gastrointestinal illness caused by campylobacters can affect individuals of different age groups. Among them, children below the age of five and young adults aged 15 to 29 are more commonly detected with gastroenteritis.  Incubation period is usually 2 to 5 days. The most common symptoms include watery diarrhoea or bloody diarrhoea, abdominal pain, fever, headache, nausea and/or vomiting.  The symptoms generally last for 2 to 10 days.  Infected people usually recover on their own while some need antibiotic treatment. A life-threatening infection may occur in people with weakened immunity. In rare cases, infection can be followed by long-term illnesses like reactive arthritis and Guillain-Barré syndrome (GBS). GBS is the attack of nerves by the body’s immune system; people with GBS can experience muscle weakness or even paralysis for weeks. 

Campylobacters in Foods

Campylobacters are widely distributed in most warm-blooded animals such as poultry, cattle, pigs, sheep and dogs. C. jejuni has a very varied reservoir but is predominantly associated with poultry. C. coli is predominantly found in pigs.  Inadequately cooked meats (especially poultry) is one of the sources of campylobacters. 

Other sources include unpasteurised milk and its products, contaminated raw fruits and vegetables, contaminated water or cross-contaminated ready-to-eat foods.  Animal faeces can contaminate lakes and streams; the consumption of contaminated water is responsible for a number of outbreaks globally.  Fruits and vegetables can be contaminated through contact with soil or water containing faeces from animals.

Figure: Transmission of campylobacters via food and water

Smart Food Choice during Travel

The outbreak mentioned earlier was traced back to contaminated spring water as the source of campylobacters.  Consumers should remain vigilant on food choice while travelling and take the following precautionary measures to prevent food- or water-borne illnesses:

• Wash hands thoroughly before handling and consuming food.
• Choose safe beverages and food, e.g. boiled water, bottled drinks, packaged beverages; refrain from consuming raw or undercooked meat, poultry, seafood, and eggs.
• Do not consume untreated water.
• Ice should be avoided in drinks if in doubt about its source or hygienic conditions.
• Buy food from hygienic and reliable premises; do not buy food from street vendors or other food outlets with poor environmental sanitation or seen with improper food handling.
• Avoid cooked food or ready-to-eat food that has been kept at room temperature for several hours.
• Avoid food at buffets, markets, restaurants and street vendors if they are not kept hot (above 60ºC) or refrigerated (at or below 4ºC).
• Peel fruits and vegetables if they are to be eaten raw. Avoid those with damaged skin.