Typhus is an acute infectious disease caused by microorganisms called rickettsia. It is transmitted to human body through arthropods such as lice, fleas and ticks. Once infected, the mortality rate is high. Its epidemic season is the same as lice, mostly in winter and spring. People are easily infected with this disease under the condition of excessive fatigue and decreased body resistance, so in the era of war and famine, the epidemic of this disease can often be seen. During World War I, the epidemic of typhus once changed the course of the war between Russia and the Balkans. Therefore, some people once dubbed typhus "war typhoid".