Introduction
There are over 2,000 described species of fleas. The most common domestic flea is the cat flea, Ctenocephalides felis felis. The adult cat flea, unlike many other fleas, remains on the host. Adults require a fresh blood meal in order to reproduce.
The dog flea, Ctenocephalides canis, appears similar to the cat flea, but is rarely found in the United States. Cat fleas are commonly found on both cats and dogs in North America, while dog fleas are found in Europe. The two species are distinguished by a slight morphological difference which is detectable only under high magnification.
Distribution
Although it exists worldwide, the cat flea is most commonly found in the United States, in and around homes with pets.
Description
Eggs: Cat flea eggs are laid at the rate of up to one egg per hour. They are oval, smooth, and about 0.5 mm in size. Due to their dry, smooth surface, the eggs easily fall out of the animal's hair. Though otherwise visible, the white eggs are nearly impossible to see against surfaces such as carpet, bedding, and lawn. It is here where the eggs will remain until the larvae emerge.
Larvae: Within two days of oviposition, wormlike larvae hatch from the eggs. They range from 1.5 to 5 mm in length. This stage lasts five to 15 days. Larvae lack eyes, legs, are covered with few hairs, and possess dark guts, visible through their thin translucent exoskeleton. Larvae feed on almost any organic debris in the floor covering, but their main dietary component is dried adult cat flea fecal matter. Adult flea feces, also known as "flea dirt", consist of relatively undigested blood which dries and falls from the pet to serve as food for the newly hatched larvae. The larvae prefer to develop in areas protected from rainfall, irrigation, and sunlight, where the relative humidity is at least 75 percent and the temperature is 70 to 90ºF.
larva
Pupae: Before becoming adults, the larvae spin silk cocoons in which they will develop. Because of the sticky outer surface of the cocoons, dirt and debris are attracted to them and provide camouflage. The pupae remain in the cocoons until they have fully developed into adult fleas.
pupae
Adults: Adults are stimulated to emerge by vibration or an increase in carbon dioxide. They are about one to three mm in size, reddish-brown to black in color, wingless, and are laterally compressed. They possess powerful hind legs which allow for running and jumping through hair, fur, and feathers. Adult cat fleas require fresh blood to produce eggs. This is the only stage in the cat flea life cycle when the fleas live on the pet. Adults live four to 25 days.
adult
Life Cycle
The cat flea life cycle is one of complete metamorphosis, involving the stages of an egg, larva, pupa, and adult. This cycle usually lasts 30 to 75 days, yet may vary due to external factors, such as temperature and humidity.
Medical and Economic Significance
Cat fleas are capable of transmitting plague and murine typhus to humans, though such reports are rare. There are also varied allergic responses to their bites, depending upon the sensitivity of the host. Cat fleas serve as the intermediate host to an intestinal parasite, the dog tapeworm (Dipylidium caninum), which is transmitted to the pet when a flea carrying a tapeworm cyst is ingested. Mostly, fleas simply act as a nuisance, since they feed on any warm-blooded animal. A common problem for the host is flea allergy dermatitis (FAD), which pet owners in the United States annually spend millions of dollars to treat. An estimated $2.8 billion is spent annually on flea-related veterinarian bills. Pet owners spend an estimated $1.6 billion annually for flea treatment through groomers, $4 billion for over the counter treatments, and $348 million professional flea control.
Action Threshold
Fleas can be detected early on by observing the behavior of the pet (i.e. noticing the pet scratching). FAD is a costly and uncomfortable ailment for both animals and humans, and early detection and treatment is the key to minimization of suffering. Though cat fleas can act as vectors for disease, action is usually taken due to the great annoyance caused by the itching and biting of the fleas, rather than for health purposes.
Management
In order to effectively control an infestation, fleas must be removed from the pet, the home, and the yard. Removal of fleas from the animal alone is futile. Immature fleas which have developed into adults off the animal simply jump on, causing subsequent reinfestation. Flea combs may be used to treat the pet, yet they only remove ten to sixty percent of the fleas. By shampooing the animal, the dried blood and skin flakes which provide food for the larvae are removed.
Shampoos contain certain pesticides such as pyrethrins, carbamates, and citrus peel derivatives. Pennyroyal oil, another natural product, is also available in shampoos. Pulegone, the active ingredient in the oil has dose related toxicity to mammals and may induce lethargy, vomiting, diarrhea, nose bleeds, seizures, and, possibly, death due to liver failure.
The most recent advances in flea adulticides are topical treatments, such as imidacloprid (AdvantageTM) or fipronil (FrontlineTM). When using a pesticide, always consult the label.
Insect growth regulators (IGR) and insect development inhibitors (IDI) disrupt egg and larval development, but do not kill adult fleas. Methoprene (Precor) and pyriproxyfen (Nylar, Archer, Biospot) are IGRs sold through veterinarians and pest control operators which are available in sprays and fleas collars. Lufenuron (ProgramTM), an IDI sold through veterinarians, is orally administered to the pet.
Scientific evidence regarding dietary supplementation with vitamin B, Brewer's Yeast, or garlic suggest these methods are of little value. Scientific evidence has also shown that ultrasonic and insecticidal flea collars are not very effective.
For effective control, the home must also be treated, primarily in areas most frequented by the animal; eggs and larvae are developing here. This can be done by way of vacuuming, washing bedding and rugs, and using sprays containing insecticides on the carpet. Vacuuming, however, will only remove eggs and food sources from the carpet. Larvae curl up around carpet fibers and pupae stick to the carpet.
Borate carpet treatment (boric acid), applied either by the home owner or a professional, works as an intestinal poison upon ingestion by the flea larvae. Diatomaceous earth has been used as a chafing agent to control larvae in carpets, but it contains silica which is known to cause lung disease in humans if inhaled in excessive quantities. Light traps placed around the home, especially where the pet frequents, may collect fleas upon emergence from their cocoons. Yet it is doubtful that this trap will attract fleas off the pet. Cedar chips and leaves from wax myrtles have repellent properties according to some homeowners, but have not been scientifically proven. It is important to restrict pet access from areas that are hard to treat, such as children's playrooms, crowded garages, and work areas. Sheds and dog houses should be treated the same way as the home.
To treat the outdoors, pyrethroids may be sprayed in dry shaded areas which the animal frequents, as well as insect growth regulators such as pyriproxyfen (Archer, Nylar) and fenoxycarb (Logic, Torus), which are the most effective outdoor treatments. Methoprene (Siphotrol, Precor) is also commonly used outdoors, but is not stable in sunlight. Since larvae prefer shaded, dry areas, spraying the entire yard is wasteful and irresponsible. If possible, control access of feral animals, such as skunks and opossums, to your yard as they bring new fleas with them. For outdoor areas which are difficult to treat (i.e. under decks), pet access should be restricted. 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. (if in doubt, check with your local hardware store - they will know what to use)
Biological control using the beneficial nematode Steinernema carpocapsae has been investigated in several areas around the United States. These nematodes are applied to the lawn as a spray to destroy the flea larvae by parasitizing them. If label directions are followed carefully, this should reduce flea populations. However, simply spraying the yard with water is enough to reduce flea populations.
Handling a Flea Emergency
If your home is heavily infested with fleas, take these steps to get the situation under control.
Inside the Home
1. Locate heavily infested areas and concentrate efforts on these areas.
2. Wash throw rugs and the pet's bedding.
3. Vacuum upholstered furniture. Remove and vacuum under cushions and in cracks and crevices of furniture.
4. Vacuum carpets, especially beneath furniture and in areas frequented by pets. Use a hand sprayer to treat all carpets with an insecticide that contains an insect growth regulator (check with your hardware store).
5. Allow carpet to dry and vacuum a second time to remove additional fleas that were induced to emerge.
6. Continue to vacuum for 10 days to 2 weeks to kill adult fleas that continue to emerge from pupal cocoons.
On the Pet
1. Use a spot-on treatment, which can be purchased in pet stores or from vets, or a systemic oral treatment, which is available from vets only.
Outside the Home
1. Sprays are only necessary outdoors if you detect lots of fleas.
2. Locate and remove debris in heavily infested areas, especially where pets rest. Concentrate treatment in these areas with a spray containing a residual insecticide and the insect growth regulator pyriproxyfen. Open areas to sunlight by removing low hanging vegetation.
Still not convinced that you should continually treat your pet for fleas? Read this:
Humans as Tapeworm Hosts
Human tapeworm infestations are most common in regions where there is fecal contamination of soil and water and where meat and fish are eaten raw or lightly cooked. In the case of the human tapeworm most common in the United States (the beef tapeworm, Taenia saginata) the usual intermediate host is a cow, which ingests the proglottid while drinking or grazing. The round-bodied embryos, equipped with sharp hooks, hatch and bore through the cow's intestinal wall into the bloodstream, where they are carried to the muscles. Here each embryo encloses itself in a cyst, or bladder; at this stage it is called a bladder worm. During the bladder worm stage the embryo develops into a miniature scolex; it remains encysted until the muscle is eaten by a primary host, in this case a human. If the scolex has not been killed by sufficient cooking of the meat, it sheds its covering and attaches to the intestinal wall, where it begins producing proglottids.
A human tapeworm common in Mexico, the pork tapeworm (T. solium), has a similar life cycle, with a pig as the usual intermediate host. The fish tapeworm, Diphyllobothrium latum, transmitted to humans from fish, especially pike, is common in Asia and in Canada and the northern lake regions of the United States. This tapeworm has a more elaborate life cycle, involving both a fish and a crustacean as intermediate hosts. The dwarf tapeworm, Hymenolepsis nana, is transmitted through fecal contamination and is common in children in the southeastern United States. There are also several tapeworms for whom humans the usual intermediate host; among these, the dog tapeworm, Echinococcus granulosis, spends its adult phase in the intestines of dogs.
Intestinal tapeworm infestation frequently occurs without symptoms; occasionally there is abdominal discomfort, diarrhea, constipation, or weight loss. The presence of tapeworm proglottids in clothing, bedding, or feces is the usual sign of infestation. Treatment is with quinacrine hydrochloride (Atabrine) or niclosamide, which kill the worm.
The most serious tapeworm infestation in humans is caused by the ingestion of T. solanum eggs through fecal contamination, which results in the person serving as the intermediate, rather than the primary, host. The embryos migrate throughout the body, producing serious illness if they lodge in the central nervous system. The embryos of the dog tapeworm encyst in various internal organs of humans, most commonly in the liver. The cysts produced by these embryos are called hydatid cysts, and the infestation of the liver is called hydatid disease.
Every dog at Paw's Place gets treated with Frontline every month! Why? Because we care!
