Head lice - parasites are very narrowly specialized not only in the nature of nutrition, but in the place of their existence. They can live only on the scalp of a person and his closest relatives - some species of monkeys. Accordingly, the life cycle and features of biology, including the incubation period of head lice, are largely adapted and depend on the lifestyle of the person himself.
On a note
You should immediately decide on the terms. The incubation period of a disease is usually understood as the time between infection with it and the first clinical manifestations. To infect a person with head lice, this definition does not work - parasites will begin to bite a person immediately after infection, but due to a small number of them the patient may not feel this or not attach importance to some unpleasant sensations.
The incubation period of lice in biology is the time of development of lice eggs. Considering the fact that lice eggs are called nits, for an entomologist the incubation period of lice and nits is essentially the same thing. Given that many readers view lice as a disease, in describing the incubation period of lice, we will further consider it in a biological, and so to speak, popular sense.
The incubation period in lice: how quickly they begin to pester after infection
After infection, the first bites of lice occur in the first hours after the parasites get on the human hair - these insects can not do without food for more than a few days. However, the bites of one or two individuals that managed to creep onto a healthy person are not particularly felt and often do not attract attention. Because at this time to talk about any manifestation of lice is early.
The real symptoms of lice on the head begin to be felt after three to four weeks. During this time the nymphs of the first generation manage to withdraw and grow up, which already massively begin to bite the scalp of a person.
Under favorable conditions, the second generation of lice appears on the head in three weeks, and due to the large number of them they already cause severe itching and well-expressed discomfort.
On a note
Pediculosis is a complex of symptoms characteristic of people with severe lice infestation. In medical practice, pediculosis is considered a disease and manifests itself in the form of dissimilar symptoms caused by the activity of lice: itching, pustules, the appearance of spots and allergic rashes.
Thus, in this case, such an incubation period in lice can be considered equal to three weeks. It is during this period that all the signs of pediculosis appear on the head: nits, irritations, itching, and the possibility of infecting other people.
It is interesting
Depending on the conditions of life, the incubation period for the development of pediculosis may vary. For example, in winter or northern latitudes, when the head of a man is constantly covered with a hat, and the room is sufficiently heated, lice develop faster - sometimes a full cycle of their reproduction takes place in 16 days. In the middle latitudes, when a person's head is often open, parasites develop usually longer.
Reproduction of lice: details about nits and nymphs
The head louse is an insect with incomplete transformation. A larva hatching from her egg resembles an adult in appearance, but much smaller and incapable of reproduction. It feeds on the same things that adult insects feed - human blood - three times molts and turns into an adult insect.
On a note
Do not confuse the concept of "nits" and "egg lice." Nit is the formation of an egg and a cocoon from a sticky substance that ensures the retention of the structure on the hair. You can say that this is a kind of cocoon.
Such a larva, which is generally similar to an adult insect, is called a nymph. The stage of the nymph is also characteristic of other insects, for example, for cockroaches, grasshoppers and bedbugs.
What is important is that each stage of development in lice lasts relatively briefly, and therefore the life span of these insects is small, and the rate of reproduction is quite large. In parasitologists, it is customary to call an insect, only released from the egg, a larva, and already a moult larva - a nymph.
Breeding times and incubation period of lice
The timing of the development of lice at each stage is different:
- The maturing period of nits is from 5 to 8 days, depending on the temperature. Optimum conditions for nits providing a minimum incubation period of nits - average air humidity and temperature of about 31 ° C. At temperatures above 40 ° C and below 22 ° C, egg development ceases and the larvae do not hatch.
- The larva of the first age develops from one day at a temperature of 30 ° C to ten days at a temperature of 10 ° C.
- The nymph of the first age develops 5 days.
- Nymph of the second age develops for eight days and turns into a adult-adult insect.
- Adult insects begin to multiply after the first meal after moulting. Usually within 1-2 days after the transformation of the nymph into an adult insect, the females and males mate, after which the females lay 3-4 eggs each day.
The fact that the lice from eggs hatch after a long time is significantly affected by the temperature. At 25-26 ° C, lice hatch for 7-8 days, and at 32-33 ° C for 5-6 days.
How quickly lice are hatching does not depend on how often the head is washed or the hair becomes wet.
The time of the general reproductive cycle of insects depends on how many nits are ripening. The minimum development time from egg to egg is 16 days, the maximum can be stretched to two months.
On a note
There are almost no periods of hunger in head lice. They constantly live on the scalp, never leaving the human body. Therefore, there are practically no such factors as the presence or absence of food in the life of these parasites.
The maximum life of an adult head louse is 46 days. During this time the female manages to postpone up to 140 eggs.
And what about other species?
The incubation period of lice of other species differs little from that of head lice.
Thus, in a clothing louse belonging to the same species, but adapted to life on clothing, the nymphs hatch after 5-8 days. And the average development time is 3-4 weeks - like head lice.
On a note
Sometimes the expression "hatched nits" is in principle incorrect. Lice hatch nymphs, and the nits themselves are deposited by the female. Therefore, instead of "nits hatch" should be said "larvae hatch from the nits."
The incubation period of pubic lice is about 6 days, and the development of the larva is about 18 days. Their difference from head lice is that the adult pubic louse lives no more than 30 days, and one female can lay a maximum of 50 eggs.
In pubic lice, larvae of nits do not hatch at temperatures below 22 ° C.
Methods of fighting nits
To destroy and to drain nits is quite possible and even necessary at any stage of their development. This is usually done using special shampoos with effective insecticides - Pedilin, Parasidosis, Nittifor, Pedex, Chigia. Earlier, even kerosene was used against lice, but of course, it is significantly inferior to modern shampoos for its effectiveness and convenience of use.
It is important that even after shearing your head, you need to wash your hair with shampoo and hold it under a plastic bag, since nits and lice themselves can stay on the skin and near the hair bulbs. And when using a shampoo that does not have the ability to kill louse eggs - you need to rinse your head again after 5-6 days.
And of course, always and everywhere you must follow the rules of hygiene: do not wipe yourself with another's towel, do not use someone else's comb. It is known that head lice can survive in the water for two days, so even bathing in public places can be fraught.
Getting rid of lice and nits at home for 1 procedure: