When a flea infestation is troublesome in domestic residences, most flea bites occur around the ankles and lower legs. Great variations in the degree of irritation exist between individuals. The irritation, which can persist for days, is due to the injection of saliva, which acts as an anticoagulant. Typically, a tiny cluster of bites may occur, and these usually develop into a small red spot, surrounded by a redish halo but seldom with any swelling. In Australia it is the frequency of bites, which may occur indoors or outdoors, that can annoy and irritate to the extent where control measures are sought.
The role of leas in disease transmission and human welfare has been profoundly important, because any flea bite allows the possibility of infection at the wound site, and because a number of disease, some devastating, are transmitted by fleas.
Historically, bubonic plague (the ‘Black Death’ that occurred during the Middle Ages) has clamimed untold millions of human lives. The disease is caused by a bacterium called Yersinia pestis, normally carried by rats. The bacterium is transmitted from one rat to another by fleas, when an infected flea regurgitates while feeding on an uninfected new host. The principle vector of plague is the oriental rat flea (Xenopsylla cheopis) but many other flea species are thought to be capable of carrying the dreadful disease. Instances of plague still occur, but Australia has fortunately avoided its attentions for many years.
Important pest species
- Cat Flea (Ctenocephalides felis) This is perhaps the most common pest flea in many regions. In addition to cats. It known to attack dogs.
- Dog Flea (Ctenocephalides canis) This is very similar in appearance to the cat flea but seems to be less commonly encountered. It also attacks a wide range of mammals.
- Human flea (Pulex irritans) This is becoming much less associated with humans since the advent of the vacuum cleaner and other aids to better housekeeping. It also attacks dogs, pigs, rat, and mice. It is often encountered in piggeries.
- Oriental rat flea (Xenopsylla cheopis) Favoured host is the rat. This is the principal vector of bubonic plague and murine typhus.