Which pest is widely known to transmit endemic typhus?

The correct choice is the flea, as this pest is primarily associated with the transmission of endemic typhus, which is caused by the Rickettsia typhi bacteria. Endemic typhus is often linked to areas with poor sanitation and high rodent populations because fleas commonly inhabit the nests of rats and other rodents. When these fleas bite humans, they can transmit the bacteria, leading to endemic typhus infections.

Though other pests like ticks and bed bugs may transmit other diseases, they are not typically associated with the spread of endemic typhus. Ants are generally not carriers of diseases in the same way fleas are. Fleas, particularly the Oriental rat flea, are recognized as significant vectors for the bacteria responsible for this illness, establishing their importance in public health regarding endemic typhus.