Fleas and Disease

The most serious human disease transmitted by biting fleas is bubonic plague or the "Black Death" of the Middle Ages. In India alone, this bacterial disease resulted in more than 7 million deaths from 1896 to 1911. The oriental rat flea, Xenopsylla cheopis (Rothschild) and X. brasiliensis (Baker), are the most important vectors of plague from rat to rat and from rat to humans. Other species such as the northern rat flea, Nosopsyllus fasciatus (Bosc); cat and dog flea, Ctenocephalides felis (Bouche) and C. canis (Curtis); and the human flea, Pulex irritans L., may also transmit plague (Graatz and Brown, 1983). In Arizona, California, New Mexico and other western states, ground squirrels and chipmunks are a reservoir of sylvatic plague (plague in wild rodents) and rodent fleas play an important role in its transmission. Greatest risk to humans exists at urban/rural interfaces, parks and recreation areas.

Another very important disease transmitted by fleas is murine typhus. Murine typhus is transmitted when feces or crushed bodies of ectoparaites infected with reckettsiae, Rickettsia mooseri, are rubbed into an open sore or wound, not the bite of the flea. Once common in southwestern and Gulf states, it has spread to port cities and routes of commerce where rats are prevalent (Traub et al., 1980). The disease may be transmitted from rat to rat by the tropical rat mite, Ornithonyssus bacoti (Hirst), and the rat louse, Polyplax spinulosa (Burmeister), or from man to man possibly by the human louse, Pediculus humanus L., but it is most commonly transmitted by the rat flea, X. cheopis. There is circumstantial evidence to indicate that the cat flea may also transmit murine typhus in areas where X. ceopis is absent. (Adams et al., 1970).

Fleas are common sources of skin lesions in humans. Some individuals become accustomed to fleas and are not disturbed by them.

Others are extremely irritated by the mere presence of fleas, let alone their painful bites. The bite of a flea varies with the species of the flea and the person bitten. The bite of the human flea is said to be painful and result in severe reactions (Mitzmain, 1910), whereas the bite of the cat flea often goes unnoticed.