By Yang Nan
As summer transitions into autumn, microorganisms that cause gastrointestinal infections - such as Vibrio cholerae, Shigella, norovirus, and Entamoeba histolytica - become increasingly active. These microorganisms can enter the digestive tract through contaminated water, spoiled food, or contact with public surfaces like handrails and buttons, leading to intestinal infections that seriously affect personal health and public safety. This article outlines common gastrointestinal tract infections and effective preventive measures.
I. Common Gastrointestinal Infections
Common illnesses of this kind include cholera, bacillary dysentery, norovirus infection, and amoebic dysentery. Understanding their pathogens and symptoms helps identify risks early and contain outbreaks at the source.
(I) Cholera is an acute intestinal infection caused by Vibrio cholerae. It is classified as one of the two Category A infectious diseases under the Law of the People’s Republic of China on the Prevention and Control of Infectious Diseases and as one of the three quarantinable diseases under the Frontier Health and Quarantine Law of the People's Republic of China. It has a rapid onset and spreads quickly, with an incubation period ranging from a few hours to five days (typically 2 to 3 days). Typical symptoms include severe, painless watery diarrhea, up to more than ten times a day in serious cases, leading to profound dehydration. This can cause restlessness, lethargy, sunken eyes, and may be fatal without prompt treatment.
(II) Bacillary dysentery, as a Category B notifiable disease under the Law of the People’s Republic of China on the Prevention and Control of Infectious Diseases, has an incubation period of several hours to seven days. It often begins abruptly with chills and high fever (over 39°C), accompanied by headache, fatigue, and loss of appetite, abdominal pain, and diarrhea. Stools are initially watery but typically become mucoid, bloody, or pus-filled within one to two days. Other signs include hyperactive bowel sounds and tenderness in the lower left abdomen. Severe cases may involve convulsions, headache, and generalized muscle pain, dehydration, and electrolyte imbalance.
(III) Norovirus infection, which causes diarrhea, is a leading cause of non-bacterial diarrhea outbreaks. Norovirus has a low infective dose, is shed for prolonged periods, and is highly resistant in the environment, making it prone to outbreaks in relatively enclosed settings.The incubation period is 12 to 72 hours (usually 24 to 48 hours). Common symptoms include nausea, vomiting, fever, abdominal pain, and diarrhea, while headache, chills, and muscle aches may also occur. Children primarily experience vomiting, whereas adults predominantly have diarrhea, with stools typically being loose or watery. This self-limiting illness currently has no specific antiviral treatment.
(IV) Amoebic dysentery is a gastrointestinal tract infection, primarily characterized by dysenteric symptoms, which is caused by the protozoan Entamoeba histolytica invading the colonic wall. It is classified as a Category B notifiable disease under theLaw of the People’s Republic of China on the Prevention and Control of Infectious Diseases.It is prone to recurrence and chronicity, and may lead to abscesses in organs such as the liver or lungs, as well as other intestinal and extra-intestinal complications. Its mortality rate is among the highest for parasitic diseases after malaria. The incubation period is generally 1 to 2 weeks but can extend to months or even a year. Typical symptoms include intermittent fever, nausea, vomiting, decreased stamina, weight loss, debility, abdominal cramping and pain, and increased frequency of bowel movements, with daily diarrhea episodes reaching 3 to 10 or more. Stools may contain mucus and pus, be bloody, resemble 'raspberry jam', or be accompanied by bloody discharge.Children may also experience rectal bleeding without diarrhea, as well as chronic diarrhea.
II. Modes of Transmission
Gastrointestinal infections spread mainly via the fecal-oral route through:
(I) Waterborne transmission - the most efficient pathway. Large outbreaks can occur when feces or vomit from infected individuals enter water sources (such as rivers, wells, or tap water systems) and this contaminated water is then consumed or contacted without being thoroughly disinfected.
(II) Foodborne transmission.Food is at risk of pathogen contamination during production, processing, transportation, storage, and sale. Contaminants may originate from storage containers, dining utensils, or hand contact, among other sources.
(III) Contact transmission.This occurs when an individual touches contaminated objectssuch as utensils, toys, or doorknobs, and then contacts their mouth or nose without washing hands.
(IV) Vector transmission. Insects such as flies and cockroaches can indirectly transmit pathogens by contacting contaminated substances and then polluting food sources.
III. Personal Prevention Measures
(I) Practice sound dietary and hand hygiene.Maintain hand hygiene. It is essential to wash your hands before taking food, during food preparation, before eating, and after using the toilet. It is recommended to wash thoroughly using the seven-step technique (palm to palm, back of the hands, fingers interlaced, back of fingers, base of thumbs, fingertips, wrists) for at least 20 seconds each time. Use separate knives and cutting boards for raw and cooked foods to avoid cross-contamination.Rinse fruits and vegetables under running water or peel before eating.Meanwhile, avoid picking wild fruits. Avoid raw or cold foods. Ensure food, especially shellfish and other seafood, is thoroughly cooked. Do not purchase imported frozen seafood of unknown origin. Do not drink untreated water; ensure drinking water is boiled for safety. When purchasing bottled water, select products that meet hygiene standards.
(II) Maintain environmental cleanliness and disinfection. Keep indoor spaces well-ventilated at a comfortable temperature. Surfaces and objects contaminated with patient vomit or feces should be disinfected with chlorine-based agents. When cleaning vomit-soiled items, wear plastic gloves and a mask to avoid direct contact with contaminants.
(III) Implement vector control measures. Avoid environments where rodents, flies, cockroaches, and other disease vectors breed.
(IV) Strengthen immunity through healthy lifestyle habits. Maintain a balanced diet with adequate nutrient intake. Engage in appropriate physical exercise, such as about 150 minutes of moderate aerobic activity per week. Ensure sufficient sleep, aiming for 7 to 8 hours per night.
IV. Customs Advisory
Upon entry into China, travelers experiencing symptoms such as fever, rash, diarrhea, abdominal or muscle pain, fatigue, or subcutaneous bleeding should proactively declare to Customs officials and provide recent travel history. Cooperate with body temperature monitoring, epidemiological investigations, and medical screenings to enable prompt diagnosis and treatment. After entering the country, travelers should continue to monitor their health. If any of the above symptoms occur, seek medical attention immediately or consult a local International Travel Health Care Center. Be sure to provide detailed travel and contact history to facilitate timely treatment.
