Airborne infection

Japanese: 空気感染 - くうきかんせん

This is one of the modes of infection in which airborne pathogens are carried by wind (air currents), attach directly to the skin or are inhaled, and then attach directly to the mucous membranes of the nose, throat, trachea, lungs, etc., causing the disease. There are two types of airborne pathogens, depending on the route or mode they take to become airborne:

[Noriaki Yanagishita]

Droplet nucleus infection

When a patient or carrier coughs, sneezes, talks, laughs, etc., the pathogens on the respiratory tract or mucous membranes of the mouth are dispersed along with tiny particles of saliva and phlegm. Because these particles are very fine, they remain suspended in the air for a while and become a source of infection. At the same time, relatively large particles are dispersed and sprayed directly onto the skin or mucous membranes of people nearby, causing infection. This is called droplet infection and is treated separately as a type of contact infection.

[Noriaki Yanagishita]

Dust infection

Even if droplets or secretions containing pathogens fall onto or adhere to clothing, bedding, or the floor and dry, highly resistant pathogens may still survive and become airborne with dust, becoming a source of infection. This type of airborne infection is called dust infection, but in terms of practical importance, droplet nucleus infection is greater.

[Noriaki Yanagishita]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

空気中に浮遊する病原体が風（気流）によって運ばれ、皮膚にそのまま付着したり呼吸により吸い込まれ、鼻、のど、気管、肺などの粘膜に直接付着して発病の原因となる、伝染病の感染様式の一つ。病原体が空気中に浮遊するまでの経路あるいは様式により、次の2種類に分けられる。

［柳下徳雄］

飛沫核感染

患者または保菌者の咳(せき)、くしゃみ、会話、大笑いなどの際、呼吸器や口の粘膜にあった病原体が唾液(だえき)や痰(たん)の細かい粒とともに飛散するもので、この粒が非常に細かいため、しばらく空気中に浮遊して感染源となる。このとき同時に飛散する比較的大きな粒は、周囲の人の皮膚や粘膜に直接吹き付けられて感染の原因となる。これは飛沫(ひまつ)感染といい、接触感染の一つとして別に扱われる。

［柳下徳雄］