How can fleas spread murine typhus?

Murine typhus, also known as endemic typhus, is a rickettsial disease caused by the bacterium Rickettsia typhi. Contrary to the common assumption that diseases are always transmitted directly through a bite, murine typhus is primarily transmitted to humans through the medium of infected flea feces.12

The cycle of infection typically involves domestic rodents, such as the Norway rat or the house mouse, which serve as the principal reservoirs for the bacteria. The Oriental rat flea (Xenopsylla cheopis) acts as the principal carrier, acquiring the bacteria by feeding on infected rodents. Once the flea is infected, the bacteria can be present in its feces. Humans become infected when these contaminated feces enter the body, often through skin abrasions or by being rubbed into a bite wound.234

It is important to recognize that while fleas are the primary vectors for this disease, the risk to humans is largely determined by the level of contact with domestic rodents. Maintaining good hygiene and controlling rodent populations are essential ethical and practical steps in preventing the spread of this illness.24