The Oriental rat flea is a primary vector of two human bacterial diseases, plague, and murine typhus. Although it is also known as the tropical rat flea, it is found in subtropical and temperate areas, especially in major cities. Studies have found Oriental rat fleas on Norway rats in Los Angeles (2007) and New York City (2015), although they were not infected with the bacteria that cause plague or murine typhus.
The plague was introduced to U.S. port cities from rat-infested ships in the late 1890s. It became established on the Pacific Coast where the last U.S. outbreak of rat-associated plague happened in Los Angeles in 1925. Since then, the plague spread east from urban to wild rodents and current cases tend to occur in the rural West. Norway and roof rats are reservoirs for murine typhus, which tends to occur in coastal urban areas with large rat populations.
Human contact with rodents and their fleas increases the risk of infection with plague and murine typhus in areas where the Oriental rat flea and these diseases are present. People may be bitten and infected if rodents are allowed to forage or nest on a property. Foraging rodents can be offered a rodenticide bait that also contains an insecticide to kill their fleas or they can be trapped and removed from the property. After rodents are removed, any nests on the property can be treated with a residual insecticide to help prevent abandoned fleas from seeking a blood meal from humans.
