FLEAS
Fleas are insects that are of major importance to veterinary medicine. Their significance lies in their blood feeding abilities as adults, their broad host range, and their ability to transmit several important disease agents. Some fleas can also serve as intermediate hosts for helminth infections.
Fleas can be differentiated from other insects by the following features:
The general life cycle involves eggs being laid while adults are on the host but they do not become attached. Instead, the eggs fall off to the floor or bedding. Eggs are white in color and rounded on both ends (above left). Eggs hatch in a few days to weeks and a 13 segmented larvae (looks like a fly larvae) emerges (above right). Larvae feed on feces, blood, etc. The larval period lasts 1 to 2 weeks but may be extended to several months. The larvae then pupates. The pupal period may last from 1 week to a year. Adults emerge from the pupa and are ready to feed and reproduce.
There are several anatomical features that will allow you to differentiate between the different genera of fleas. These include the presence or absence of genal (mustache) and pronotal (collar) bristles on the head of fleas (left) and the shape of the spermatheca (sperm storage) in the female (right).
Important species of fleas:
Pulex irritans. Human flea. This flea is cosmopolitan in distribution and may infest many domestic animals as well as man. Swine are also commonly infested with this flea. Adults can be identified by the presence of neither pronotal or genal combs, and a mesopleuron that is not divided. This flea is an important flea in the transmission of plague.
Ctenocephalides felis. Dog and cat flea. This flea is a common pest of dogs, cats and man. It is also important as an intermediate host for the cestode, Dipylidium caninum. Adults can be identified by the presence of a sharp horizontal genal comb and pronotal combs. This genus is probably the most common flea pest of domestic animals.
Xenopsylla cheopis. Oriental rat flea. This flea is world-wide in distribution, often being associated with rats and man. It is a common biological vector for plague and murine typhus. It is imilar in appearance to Pulex only with a divided mesopleuron (right).
Echidnophaga gallinacea. Stick-tight flea. This is a flea that attaches firmly while feeding. It is a common pest of poultry, cats, dogs, horses and man. Ulcers and wart-like lesions are often associated with attachment site. This flea can also serve as an intermediate host for the cestode Dipyllidium caninum. The shape of the head of this flea is often used in identification.
Tunga penetrans. Tropical flea. This flea is common in S. America, West Indes and Africa. The adult female burrows under the skin resulting in nodular swelling and ulceration.
Flea bite allergy
The allergic reaction to flea bites results after repeated exposure over time. The allergen, in the saliva of the flea, appears to be incomplete and of low molecular weight. Flea allergy dermatitis is usually observed in dogs and cats which are infested with a small number of fleas and animals that are "defleaed" frequently. The condition is seldom seen in heavily infested animals.
Animals are usually presented with an observable pruritis with alopecia. Diagnosis may be complicated by concurrent infestation with other arthropods (mites) and/or bacterial or micotic infections. Treatments vary depending on a definitive diagnosis and the length of time the condition has existed. Intradermal allergy testing and/or serologic evaluation are common. Treatment designed to deal with the specific type(s) of allergic reaction are most successful.
Treatment:
Control of fleas is best effected through a system of integrated pest management that is based on a understanding of the biology of the flea and treatments available for the animal and its environment.
Control and elimination of fleas must be directed at eliminating adult fleas on the animal and immature stages in the environment. Treatment of the environment is important and control of both newly emerged adults and prevention of development in immature stages is essential The use of collars, dips and sprays are useful in controlling adult stages on the animal (see section on tick control). Currently, pyrethrin and pyrethroid insecticides are commonly used for treatment on the animal. Often, a growth regulating compound is used simultaneously so that both adults are killed and flea eggs are prevented from hatching. The residual effects of products now available is about 4 weeks. New products that use nematode larvae that feed on and kill immature fleas have proven successful as a part of environmental control using a non-toxic biological system.
OUTDOOR ENVIRONMENTAL INSECTICIDES TRADE NAME INGREDIENT FORMULATION Sevin Carbaryl Dust Several Malathion Liquid, Granules Knox Out 2 Diazion Liquid Vet Kem Yard Chlorphyrifos Liquid INDOOR PREMISE SPRAYS AND FOGGERS TRADE NAME INGREDIENT FORMULATION Vet Fog Permethrin Fogger Many Permethrin Sprays Many Malathion Liquids PRODUCTS FOR USE ON THE ANIMAL TRADE NAME INGREDIENT FORMULATION Adams Pyrethrins Dust VIP Chlorpyrifus Dips, etc. Many Carbaryl Dusts Many Permethrin Sprays