Fleas are small, wingless insects that feed on blood. Their mouthparts are designed to penetrate skin and suck a victim’s blood. Although the reddish-brown adults are only 2 to 4mm long, they are famous for their jumping ability. They have been known to leap 18cm high or a distance of 33cm.
There are about 80 species of fleas in Australia but the main ones humans come into contact with are:
- Cat fleas (Ctenocephalides felis)
- Dog fleas (Ctenocephalides canis)
- Human fleas (Pulex irritans)
- Stickfast fleas (Echidnophaga gallinacea)
The Cat flea is the most common flea afflicting pets and people. Dog fleas and Human fleas are rarely found in Australia. The Stickfast flea is sometimes incorrectly identified as Ceratophyllus gallinae. It is an important pest in hen houses but can also be found on pets, such as cats and dogs.
Fleas go through a complete metamorphosis: eggs, larva, pupa and adult.
Female fleas can lay up to 50 eggs a day, either on the host or, in the home environment, dropped on carpets and bedding. She will only lay eggs after her first meal of blood. During her life, she can lay between 2,000 and 5,000 eggs.
The larvae hatch two to fourteen days later and eat organic debris. They are blind and avoid light, moving deep into carpets or other dark places. Flea development can take as little as two to three weeks but may last anything up to six months. The average lifespan of an adult is between three and six months but can extend to over a year in some situations.
An adult flea can live more than three months without food if undisturbed. They can remain dormant until they detect that a host is nearby through vibrations, heat, and carbon dioxide
In a normal flea population, only 5% are adult with the rest in various stages of immaturity. This can make eradication more difficult.
An adult female flea may consume 15 times her own body weight in blood during one feeding.
The most immediate problem with fleas is their bite which irritates its victim, whether human or animal. Secondary infection from scratching can cause further problems. Allergies and dermatitis are complications associated with flea bites.
Fleas are known to be vectors of disease, the most infamous case being the Bubonic Plague in Europe in the Middle Ages. Fleas not only transmit viral and bacterial diseases but can also pass on helminth eggs (tapeworms, hookworm, etc.).
Although the transmission of disease by fleas in Australia is uncommon, in 2011 a case of cat-flea typhus, Rickettsia felis, affected a family in Melbourne. Murine typhus is occasionally transmitted from rats to humans by rat fleas but mainly in South West Australia.
Signs of infestation
Dogs that are constantly scratching or cats that are grooming excessively indicate the presence of fleas. Bites on humans typically appear as red spots, often surrounded by a reddish ring. Unlike bedbug and mosquito bites, they itch immediately. People are most frequently bitten on their feet and ankles but flea bites can occur anywhere on the body.
It is possible to see the fleas moving in the fur of pets. A flea comb can be used to confirm if fleas are present.
If you can't see any but suspect a problem, try holding the animal over a large sheet of white paper and brush or ruffle its fur. Black specks might appear on the paper, which may be flea droppings, or there may be small streaks of red on the paper.
The home owner should be encouraged to vacuum daily, especially around furniture, beds, curtains and where their pets sleep. This will pick up many of the flea larvae and eggs. If the vacuum has a dust bag it should be disposed of, preferably by burning, to avoid the reintroduction of hatched eggs. If it is a bag-less vacuum, it should be thoroughly cleaned after each use.
A water-based insecticide such as Cislin can be used to treat carpets, floorboards and most areas around the home. Cislin is a synthetic pyrethroid, so is safe for humans and pets. Caution should be exercised if there are aquariums in the home or ponds nearby as it is fatal to fish.
Treatments such as Cislin will kill the adults but not all the immature stages. A repeat treatment is needed roughly ten days later.
Pets should be treated with a topical anti-parasitic chemical such as Advantage, Frontline and Revolution. These work well in preventing further infestation. Pets can also be washed regularly with flea shampoos.
The pet’s bedding should be thoroughly washed on a regular basis, preferably in bleach and left to air.
Stickfast fleas are normally found in a hen house rather than in human dwellings. The larvae go underground to pupate, making it possible to break the lifecycle by having a concrete base to the hen house. The surrounding soil can be treated with a chicken-safe pesticide.