Why do contagious respiratory diseases attack patients in spring?

The contagious respiratory diseases are such contagious diseases that during the course of the disease, pathogens invade susceptible persons via the airway, and then go on to spread by the secretions of the airway to invade other susceptible persons.

The pathogens that can cause common respiratory diseases and some contagious respiratory diseases are mainly one of two kinds: one is viral and the other is bacterial. These pathogens usually parasitize in the nasopharynx of patients. When a patient speaks or sneezes, the pathogens are transferred to the air with spittle. If a healthy person inhales the germs or viruses in the air, he/she might catch disease.

The infection of an acute contagious respiratory disease caused by virus (eg. the epidemic influenza) is very strong. Acute onset patients suffer from fever, pharyngalgia, pantalgia, conjunctival congestion, watering eyes and a dry cough, and complications such as pneumonia can occur.

Contagious respiratory diseases often attack during Spring Festival. Why is this?

During Spring Festival, people have more physical contact with each other - more than during other seasons. Respiratory contagious diseases spread through air-borne droplets. In winter and spring, the air temperature is fairly low; people live and work in rooms where they have close contact with each other, they go shopping, visit friends and go out on tours more often. All these situations increase the transmission chances of contagious respiratory diseases.

Additionally, the resistance of the airway mucosa becomes lower. Airway mucosa is a layer of tissue covering the airway. Cold air and dry air is inhaled into the airway to stimulate the mucosa, thus the blood vessels in the mucosa contract, then ischemia and nutritional disturbance occur in the local tissues. In addition, ventilation in rooms is weaker and the fumes inhaled by humans (including passive smoke) can also stimulate airway mucosa, so the ciliary motion of mucosa become weaker and its purifying and defense functions decrease. Therefore, the pathogens have a greater chance to invade the airway, thereby causing patients to catch the diseases.