Fleas (Siphonaptera)
The parasites have no wings and live on and around people and animals. They suck blood by biting and this causes reddening, irritation, and strong itching for several days after the bite. Extinction of fleas in the home and nearest surroundings is possible although a somewhat troublesome affair.
Flea species
Fleas are quite similar in build and it is impossible to tell the different species apart with the naked eye; it requires a microscopic examination. There are more than 2000 different flea species in the world. In the western part of the world, however, it is mostly the dog flea (Ctenocephalides canis), the cat flea (Ctenocephalides felis), and the human flea (Pulex irritans) which are a nuicance to people.
The Appearance of the Flea
Fleas are most often brownish black and 1 - 3 mm. long. They consist of a head, a thorax, and an abdomen. The six legs are all attached to the thorax, but what separates the flea from most other insects are the hind legs which are much longer than the other pairs of legs. These specially designed hind legs make the flea capable of jumping up to 20 cm. straight up in the air and thereby onto its host. This ability is strictly necessary as the flea is located in the surroundings for 98% of the time and only jumps onto the host to "eat".
Habitat
Fleas are most frequently occuring in places where people and their pets live close together and in cases of poor hygienic conditions. It is only resident animals and -humans who have fleas as the survival of the flea depends on the host regularly returning to the same places. In humans, flea bites are most often caused by fleas who temporarily leave their hosts (domestic animals). Even though fleas prefer their original host, most fleas are not host specific, i.e. on occasion the can suck blood from several different species. The cat flea, for example, can sting both cats, dogs, and people.
Propagation
An adult female flea can lay up to 8 eggs a day which are hatched in 2 - 14 days (2 - 3 days in room temperature) and turn into larvae. The larvae pupate after about 2 weeks and become adult fleas in another 3 weeks in room temperature. However, they can lie waiting for a long time in a seasonal inhabited house and be hatched when the heat is turned on or the weather is getting warmer - typically in spring. The eggs can lie in the cracks in wooden floors, for example.
The flea as a disease carrier (vector)
In some cases, bites can be the cause of transmission of disease agents like tapeworm and plague bacteria between humans and animals.
The Plague (Yersinia pestis)
Can be transmitted via fleas. This happens because rats who are infected with this bacteria die in city sewers which makes the fleas of the dead rats seek towards people and live on them instead - and thereby transmit the plague bacterium from rats to people.
Tapeworm (Dipylidum caninum)
Can be transmitted via fleas which contain the eggs of the worm. When the flea is eaten by e.g. a dog (dogs bite fleas in two with their front teeth), the dog can become infected. People - in particular children - can become infected by eating an infected flea.
The following signs indicate that you have fleas in your house:
- Pets - dogs, cats, rabbits, etc. - are more restless and itch more than usual, often around the tail area.
- You have red, itching stinges after having been in contact with your pet.
- You find black "grains" (flea faeces) or living fleas on the animal, mostly in the neck area.
