Enjoy the holidays but be careful of food-related illnesses

To celebrate the Spring Festival, visiting relatives and friends and getting together is inevitable. At this time, everyone must prevent diseases from eating and eat, and pay special attention to Listeria and Brucella.

The easiest place for Listeria to hide is the refrigerator at home. Poultry, eggs, meat, milk and their products, aquatic products, fruits and vegetables are all hotbeds for Listeria to attach to, and it is also called the "refrigerator killer". The freezer of the refrigerator is not a safe for food ingredients. Refrigerating or freezing food cannot completely inhibit the growth of bacteria. The reason is that there is a type of "psychrophilic bacteria" among bacteria that prefer low-temperature environments. The lower the temperature, the happier they live. 0℃-20℃ is their suitable growth temperature. In a low-temperature environment, these psychrophilic bacteria will never "hibernate" as everyone imagines. If the food we store in the refrigerator happens to be contaminated by this type of bacteria, it will provide them with nutrients for their growth and reproduction. Listeria belongs to this type of "psychrophilic bacteria".

When preparing for the Chinese New Year, the above-listed foods must be the main ones. If people eat food that is contaminated with Listeria but is not fully cooked or heated, they are likely to be infected.

The most common manifestation of Listeria infection in healthy people is mild gastrointestinal symptoms, such as diarrhea or nausea and vomiting, which usually disappear on their own after 2 days; there may also be cold-like symptoms, such as fever, dizziness, etc. Pregnant women, the elderly, people with diabetes or weakened immunity may even develop meningoencephalitis, which manifests as severe headache, high fever, vomiting, stiff neck, and even impaired consciousness; infants and young children who have any of the above symptoms or eat less than usual, have shortness of breath, and are listless should seek medical attention in time. If not treated in time, the mortality rate can be as high as 30%.

How to prevent Listeria infection? Wash your hands before and after preparing food, and wash raw fruits and vegetables thoroughly; store raw and cooked food separately, and use separate tools and equipment for preparing raw and cooked food; store cooked food at room temperature for no more than 2 hours, and refrigerate it in time; cook cooked food thoroughly, especially meat, poultry, milk, aquatic products, etc.; heat refrigerated cooked food thoroughly, as Listeria is not heat-resistant and can be killed in 5 minutes at 60℃-70℃; pregnant women, people with low immunity, the elderly and other high-risk groups should try to avoid eating refrigerated cooked food and dairy products, and avoid eating raw aquatic products, etc.

Another type of brucellosis is a zoonosis caused by infection with Brucella, which is a Class B infectious disease legally established by the state, referred to as brucellosis. Sick livestock, especially sheep, cattle, cats and dogs, are the main sources of infection. People come into contact with the meat, secretions, excrement, milk and fur of sick animals, which can cause disease through the digestive tract, respiratory tract, skin wounds or mucous membranes. This bacterium parasitizes in cells and is more likely to spread throughout the body through lymphatic and blood circulation, forming single or multiple lesions. During the Spring Festival, every household will prepare a rich supply of meat and dairy products as New Year's goods, so the chance of Brucella infection will also increase compared to usual days.

Brucella infection is quite special. It is an intracellular bacterial infection. After entering the human body, it is engulfed by white blood cells and multiplies inside the white blood cells, causing bloodstream infection along with the white blood cells. Therefore, there are no obvious lesions in early imaging examinations, which can easily lead to misdiagnosis and missed diagnosis.

Brucellosis is also known as the "lazy man's disease". It generally has an incubation period of about 2 weeks, and the main symptoms are fever, sweating, fatigue, weakness, and joint pain. Once exposed to Brucella, you should seek medical attention immediately. Early diagnosis and early treatment can cure most people. Fortunately, although brucellosis is a zoonotic infectious disease, there is currently no evidence of human-to-human transmission.

How to prevent brucellosis? Buy meat, milk and their products from merchants with formal sales qualifications; avoid drinking and eating raw food, boil water before drinking, and cook meat before eating; separate raw and cooked chopping boards to prevent cooked food from being contaminated by bacteria on raw meat; avoid contact with sick animals, cats, dogs and their secretions and excrement, etc.

If you have similar symptoms to brucellosis, you must go to a regular hospital for medical treatment in time. Do not take antipyretics at home on your own to avoid delaying the disease.

(The authors Zhang Chaofan, Hou Xiufeng and Zhang Cen are members of the "Xiaosheng Miji" popular science team of the Department of Infectious Diseases of Peking Union Medical College Hospital)