Head lice are transmitted by direct contact between human heads. Other ways of transmission is highly unlikely. In what stage of a lice infestation, lice is most infectious is not known. Biologically speaking, it is logical that the lice migrate as soon as possible, once they have established themselves in the head, and when they are most numerous. We select, in fact, the lice that are most proficient at infection time before they are discovered.
Perhaps, the infestation phase is already over when the lice make us aware of their presence. Until we know more about it, lice remain a snap experience, where you treat the infected as soon as the lice are detected. Of course infestation can be avoided by cutting the almost all the hair off, by avoiding other people and by constantly treating hair with insecticide. However, these solutions that are not proportionate to the little danger, lice pose.
Loose lice. Sometimes, lice can fall out of the hair and pop up elsewhere, however, this almost always only happen to individuals who, because of illness or high age, have released its grip on the hair. Naturally, these lice cannot be infectious.
Loose nits. Hair with live nits can also fall off into the surroundings. The chance of a nit, which ends up on the floor or furniture, hatches and the nymph finds a head before dying of starvation or dehydration and afterwards survives until adulthood and find a partner of the opposite sex in the same head, is so small that, in actuality, this is not a possible chance of infection.
For the same reason, there is no point in spraying, dusting or gassing rooms and furniture against head lice.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)