Flea bites are miserable to some persons, while other people are not much disturbed by them. The development of sensitivity to flea bites requires an initial sensitization by the insect. Thus, a latent period occurs between the time of first exposure and the time when subsequent flea bites elicit skin reactions (Benjamini, Feingold, and Kartman, 1960).
In people who have been bitten by fleas, reactions vary from small red spots (where the mouthparts of the flea have penetrated the skin) surrounded by a slight swelling and reddish discoloration to a very severe generalized rash.
Relief from the irritation of a bite may be obtained by treatment with carbolated vaseline, menthol, camphor, calamine lotion, or other soothing medication.
Although most fleas have a preferred host, many of them are known to take a blood meal from a wide variety of animals and will bite man readily in the absence of their normal host animal. The cat flea (Ctenocephalides felis) and the dog flea (Ctenocephalides canis), two of the most common species, may be very annoying to man. The adult fleas feed and mate on these pets. The female fleas lay their eggs among the hairs of these animals and the eggs drop off onto the mat or rug where the pets sleep or rest, onto carpets or overstuffed furniture, cellar floors, and similar places.
Larval development usually requires at least two to three weeks and the newly emerged fleas simply hop onto cats or dogs as they walk about. However, if people leave their homes and take their pets VII - 1 with them, or "board" their cats and dogs at an animal hospital for two to four weeks or longer, enormous numbers of adult fleas may come through to maturity in a vacant house or apartment. These fleas have had no opportunity for a blood meal. When such people return to their homes, they are greeted by hundreds or thousands of hungry fleas and may suffer excruciating pain.
In the summer, cat and dog fleas will breed outdoors in vacant lots, under houses, in barns, and similar situations, particularly if there are stray dogs or cats about.
The human flea (Pulex irritans) occasionally becomes abundant on farms, particularly in abandoned pig pens.
Many people are bitten by tiny, dark, wingless insects popularly known as "sand fleas." In the North "sand fleas" usually are cat or dog fleas associated with stray cats or dogs in vacant lots.
In the West "sand fleas" may be human fleas associated with ground squirrels or prairie dogs.
In the South "sand fleas" sometimes are sticktight fleas, but more commonly are cat or dog fleas. Along the beaches, tiny crustaceans belonging to the Order Amphipoda occurring abundantly in sea weed are often called "sand fleas", "sand hoppers", and "beach fleas."
The oriental rat flea (Xenopsylla cheopis) and the northern rat flea (Nosopsyllus fasciatus) normally spend most of their adult life on Norway and roof rats. However, when these rodents are killed, these fleas leave their rodent hosts and bite man readily.
The western hen flea (Ceratophyllus niger) and the European hen flea (Ceratophy1lus gallinae) occasionally become extremely abundant in chicken houses, occupied or vacant, and attack man in large numbers.
On occasion other fleas, such as the squirrel flea (Orchopeas howardii) leaving the nests of their rodent host in attics or hollow trees, may bite man and cause great discomfort.
Most people are familiar with the irritations and allergic reactions due to flea bites and welcome the assistance of public health workers in controlling these insects. Identification of the species of flea involved, its habits and preferred hosts will assist people in locating the source of the infestation and preventing these attacks.