36.3.1  Mode of transmission of louse-borne typhus

There is one difference in how the Rickettsia bacteria that cause typhus, and the Borrelia bacteria that cause RF, are transmitted by body lice to new human hosts. The Rickettsia bacteria acquired during a blood meal from an infected person multiply in the gut of the louse and pass out of its body in the louse’s faeces, which are deposited on the person’s skin. These bacteria can survive for several days in the faeces. The louse bites are itchy and when the person scratches them, the louse faeces are rubbed into breaks in the skin. This is how the typhus bacteria are transmitted to healthy people when an infected louse gets into their clothes or bedding. They quickly enter the new host’s body cells and begin to multiply.