This article is transferred from: People’s Daily Online – Popular Science China
Why is the meal-sharing system a healthy eating habit? Why beware of mosquito breeding in the living environment? Why can you use hugs to convey encouragement to AIDS patients? Because gastrointestinal transmission and vector-borne transmission are the means of transmission of infectious diseases; blood, body fluids and mother-to-child transmission are the means of transmission of HIV, but physical contact during hugging is not.
These are actually related to scientific infectious disease prevention. Respiratory transmission, gastrointestinal transmission, contact transmission, insect vector transmission, blood or body fluid transmission and mother-to-child transmission are the six ways of infectious disease transmission.
1. Respiratory transmission
After the pathogen is excreted from the source of infection, it exists in the droplets or aerosols in the air, and the human body causes infection after inhalation. For example: measles, tuberculosis, chickenpox, influenza, severe acute respiratory syndrome, and novel coronavirus pneumonia, etc.
2. Digestive tract transmission
After the pathogen is excreted, it contaminates food, water sources or tableware, etc. People cause infection through the mouth when eating and drinking, and infants and young children can pass the infection. Contaminated milk source or feeding bottle, pacifier and infection. Example: Bacillary dysentery, typhoid, cholera, rotavirus infection, etc.
3. Contact transmission
After the pathogen is excreted from the source of infection, it contaminates soil, articles, etc., and people get infected when they come into direct or indirect contact with pollutants. Examples: leptospirosis, schistosomiasis, hookworm, etc. Some diseases may also cause infection when they are in close contact in daily life, such as influenza, diphtheria, etc. Dirty sexual contact can spread AIDS, viral hepatitis B, viral hepatitis C, syphilis, gonorrhea, etc.
4. Insect-borne transmission
Mainly for blood-sucking arthropods (such as mosquitoes, lice, rat fleas, sandflies, hard ticks, chiggers, etc.) transmit pathogens to others. Examples: malaria, Lyme disease, epidemic typhus, etc.
5. Blood and body fluid transmission
Pathogens can be transmitted to others through blood transfusion, application of blood products, organ transplantation, etc. Example: AIDS, viral hepatitis B, viral hepatitis C, etc.
6. Mother-to-child transmission
For some infectious diseases, the pathogens can infect the fetus through the placenta, or through the birth canal during natural childbirth. Example: AIDS, Hepatitis B, etc. Another part can cause upward sexual transmission, that is, pathogens reach the chorion or placenta from the vagina of pregnant women to cause intrauterine infection of the fetus, such as herpes simplex virus, cytomegalovirus, etc.
The spread and prevalence of infectious diseases are influenced by natural and social factors. The survival and reproduction of all pathogens can be affected and controlled by natural factors such as geography, meteorology and ecological conditions. Some viruses are not resistant to high temperature, and the mucosal defense capacity of the human respiratory tract is reduced in winter and spring. Therefore, respiratory infectious diseases such as measles and chickenpox are more likely to occur in winter and spring.
Schistosomiasis must depend on snails to survive, and snails can only live in water areas with mild climate, abundant rainfall and overgrown weeds. Therefore, in my country, schistosomiasis is mostly prevalent in the areas south of the Yangtze River.
Japanese encephalitis is only transmitted by mosquitoes, and mosquitoes require specific temperature and humidity for reproduction, so in my country, Japanese encephalitis basically occurs in summer and autumn.
Guide experts: Zhang Jieli, Deputy Chief Nurse and Zhang Xin, Deputy Chief Physician, Fifth Medical Center, PLA General Hospital