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NPS Arrowhead National Park Service
US Department of the Interior
Office of Public Health 1201 Eye Street, NW
Room 1131
Washington, DC 20005

Phone: 202-513-7215
Fax: 202-371-1349
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Office of Public Health - Flea Factsheet
Points Of Contact
(202) 513-7217
Assistant to Director for Science
(202) 513-7097
(505) 248-7806
Assistant to Director for Field Operations
(202) 513-7056
National Capitol Region
Northeast Region
(215) 597-5371
Southeast Region
(404) 507-5730
Mid-West Region
(402) 661-1718
Intermountain Region
(505) 988-6040
Pacific West Region
(510) 817-1375
Alaska Region
(206) 220-4270

What are fleas?
Adult fleas are small, brownish wingless insects averaging about 1/10th of an inch in length. They have piercing-sucking mouth parts used to obtain a blood meal from their host. They are flattened laterally and have powerful jumping legs that enable them to move quickly and jump a foot or more longitudinally and several inches horizontally.

Public Health Importance
Fleas can transmit diseases from animal hosts to man. Flea-borne diseases of concern in the United States include sylvatic and murine plague, murine typhus and tularemia. The flea of greatest domestic concern in the U.S. is the widely distributed cat flea (Ctenocephalides felis). A closely related but less common flea is the dog flea (C. canis). Both fleas feed indiscriminately on cats and dogs. If these preferred host species are unavailable, they will aggressively attack humans. These fleas are hosts for tapeworms of dogs (Dipylidium caninumn) and rodents (Hymenelopis nana and H. diminut). These tapeworms occasionally infect children who place the eggs in their mouth from hands contaminated while the child craws on the floor where flea larvae have been deposited.

Infested pets will scratch and gnaw at these irritating bites. In heavy infestations and in pets sensitive to these bites, bald spots will be created where the pet has pulled out its fur.

Human bites typically result in itchy reddish welts. The intensity and duration of the bite reaction depends largely on individual sensitivity to flea bites. Typically children are more sensitive than adults.

Flea Biology
Fleas have four stages in their development: egg, larva, pupa and adult. Eggs are laid as the female feeds on the host. They fall on the ground, in animal burrows, wooden floors, carpet, pet's bed etc. After 2-4 days, legless larvae hatch from the eggs. They feed on any available organic material such as food crumbs, animal hair and excrement produced by adult fleas. The larval stage of cat and dog fleas lasts from 1-3 weeks, depending on ambient temperature and humidity. (Fleas do best under warm moist conditions.) The larvae spin silk cocoons in which they incorporate soil, if outdoors, or soil and carpet fibers, if indoors. The pupal stage generally lasts 5-7 days, although the adult can remain within the protective pupal case for extended periods of time until a suitable host and/or required environmental conditions occur. The total life cycle takes from 2 weeks to several months depending on environmental conditions.

Flea management
Effective flea management focuses on the pet and where the pet rests and sleeps.

Flea combing:
Combing pets with a finetoothed metal flea comb will help control adult fleas if the infestation is light. However, this method is not effective by itself. It needs to be done in conjunction with chemical treatment of the pet and the pet's sleeping area. The main value of combing is as a screening tool to determine if the pet is infested with fleas. Fleas caught in the comb can be killed by placing them in soapy water or water containing ammonia.

Chemical Treatment (Pediculocides):
Pediculocides are available over the counter from hardware, pharmacy, and grocery stores and from veterinarians as sprays, shampoos, dips and dust formulations. Also available from veterinarians are products given orally. Pediculocides are available with several different active ingredients. Many of these products can be toxic to your pets, especially young animals. Among the least toxic are products made from citrus peels, pyrethrins and permethrin (a synthesis pyrethrin). An advantage of permethrin is its residual effect. Juvenile hormones are a special class of pediculocides. They prevent flea larvae from developing into adults. Although juvenile hormones are effective, complete control of existing infestations takes a period of weeks since this pediculocide doesn't kill adult fleas. To achieve immediate relief, it will be necessary to use the juvenile hormone in conjunction with an adulticide such as a citrus peel derivative, pyrethrin or permethrin. Be certain to read the label directions, precautions and warnings before using these products. An important consideration when selecting a pediculocide formulation is cats don’t like to be bathed. They prefer to groom themselves. They tend to react aggressively when bathed or immersed in a dip. Because they groom themselves, they are more likely than dogs to ingest toxic quantities of pediculocides. Therefore, it is recommended you use one of the low toxicity products that rapidly breaks down into non-toxic constituents. Shampoos have several advantages. Cats are less likely to ingest toxic quantities of pediculocides than compared to sprays, dips or dusts. Some shampoos are medicated. They alleviate itching hence promote healing of the bite wound. They also remove dried blood and skin flakes that provide food for the flea larvae.

Pet collars: Pet collars are not very effective in controlling fleas when there is a heavy flea infestation or with large and/or long-haired pets. In addition, prolonged contact with the pesticide may be irritating or toxic to your pet's skin.

Wash or replace infested pet bedding in soap and hot water. Vacuum carpets and rugs, floor and upholstered furniture, if pets are allowed on it. Concentrate on areas where pets sleep. Vacuuming will remove many of the fleas and organic material that flea larvae feed on. To avoid re-infestation, seal the vacuum bag in a plastic bag when finished vacuuming, then dispose.

Pediculocides: See the discussion above about pediculocides used on pets. Pediculocide sprays or dusts are applied to areas where fleas are most likely to live including animal bedding, cracks in floors, and baseboards, in carpets and rugs and on furniture, if pets are allowed on it. Commonly used active ingredients include, the already mention citrus peel derivatives, pyrethrins, permethrin and juvenile hormones used alone or in conjunction with an adulitcide such as pyrethrin or permethrin. Other useful products are boric acid, silica gel and diatomaceous earth powders. These agents are relatively non-toxic to pets and have a long residual effect. They kill fleas by abrading their exoskeleton resulting in desiccation and death of the flea.

Prevent or minimize pet contact with other animals by keeping them on a leash, rope or restricted within a fenced yard. Also restrict pet access to difficult to treat places such as under decks and buildings.

Habitat Modification: Keep lawn mowed short so that sunlight can penetrate to the ground.

Biological Control: Nematode can be effective in reducing flea populations. These pediculocide formulations are applied to the lawn as a spray. The nematodes destroy the flea larvae by parasitizing them.

Pediculocides: Outdoor treatment is primarily used in severe cases of flea infestation and may not be necessary if fleas are controlled on the pet and in the home or kennel. To treat the outdoors, any of the above-mentioned products can be sprayed or dusted in areas frequented by your pets. Since flea larvae are susceptible to sunlight, concentrate your spraying in shaded areas.

If you have any questions, please contact your nearest Regional Point of Contact, park sanitarian or call WASO Public Health for more information.

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