The head louse is a tiny parasitic insect that lives in human hair and subsists on small amounts of blood drawn from the scalp. Human head lice likely evolved right along with people. Head lice are host specific. Neither able to fly nor jump, head lice are unlikely to leave a host and most often hatch and spend their entire lives on a single individual. Human lice won’t infest your pets, and lice on pets usually don’t infest people.
Head lice are common worldwide. Infestation isn’t an indication of poor hygiene. Head lice are acquired from other infested people. In North America and Europe, children are more frequently infested than are adults, females more often than males, and Caucasians more frequently than other ethnic groups.
Generally, a host has fewer than a dozen active lice on the scalp, but may have dozens of viable eggs. Head lice neither cause nor transmit infections or diseases.
What Head Lice Look Like
There are three forms of lice: the nit or egg, the nymph, and the adult.
Nits are very small and easily confused for dandruff or dried drops of hair spray. They are oval in shape and usually yellow to white in color. Without magnification it is difficult to determine whether nits are viable (fertilized and under development) or just the remaining shells of hatched nymphs. The female louse cements each nit to the base of a hair shaft near the scalp. The nits take about one week to hatch.Nymphs are newly hatched nits. Nymphs look like adult head lice, but are much smaller. Nymphs mature in about a week.
The adult louse is about the size of a sesame seed, has six legs, and is tan to gray-white. Adult lice can live up to 30 days but need to feed on blood several times daily. Without a host, a louse typically dies within a day or two.
Symptoms of Head Lice
Head lice are most commonly found on the scalp, behind the ears and near the neckline at the base of the head. Unless seen, symptoms of infestation are easy to miss:
Tickling sensation or feeling something move through the hair.
Allergic reaction to the bites, which causes itching.
Scratching the itch can result in sores, which lead to infection and general irritability.
Viable eggs are usually located within 1/4 inch of the scalp. Normal hair growth transports the nits away from the scalp. Eggs more than one-half an inch away from the scalp are usually not viable. Unless adults, nymphs or viable eggs are noticed, the presence of nits doesn’t signify an active infestation. An infestation is diagnosed by looking closely through the hair and scalp for nits, nymphs, or adults and is usually best done by an experienced health care provider.
Head lice are common worldwide. Infestation isn’t an indication of poor hygiene. Head lice are acquired from other infested people. In North America and Europe, children are more frequently infested than are adults, females more often than males, and Caucasians more frequently than other ethnic groups.
Generally, a host has fewer than a dozen active lice on the scalp, but may have dozens of viable eggs. Head lice neither cause nor transmit infections or diseases.
What Head Lice Look Like
There are three forms of lice: the nit or egg, the nymph, and the adult.
Nits are very small and easily confused for dandruff or dried drops of hair spray. They are oval in shape and usually yellow to white in color. Without magnification it is difficult to determine whether nits are viable (fertilized and under development) or just the remaining shells of hatched nymphs. The female louse cements each nit to the base of a hair shaft near the scalp. The nits take about one week to hatch.Nymphs are newly hatched nits. Nymphs look like adult head lice, but are much smaller. Nymphs mature in about a week.The adult louse is about the size of a sesame seed, has six legs, and is tan to gray-white. Adult lice can live up to 30 days but need to feed on blood several times daily. Without a host, a louse typically dies within a day or two.Symptoms of Head Lice
Head lice are most commonly found on the scalp, behind the ears and near the neckline at the base of the head. Unless seen, symptoms of infestation are easy to miss:
Tickling sensation or feeling something move through the hair.Allergic reaction to the bites, which causes itching.Scratching the itch can result in sores, which lead to infection and general irritability.Viable eggs are usually located within 1/4 inch of the scalp. Normal hair growth transports the nits away from the scalp. Eggs more than one-half an inch away from the scalp are usually not viable. Unless adults, nymphs or viable eggs are noticed, the presence of nits doesn’t signify an active infestation. An infestation is diagnosed by looking closely through the hair and scalp for nits, nymphs, or adults and is usually best done by an experienced health care provider.
I think that the itchy scalp of your sister is caused by allergic reaction or sensitivity to the Hairspray she used due to some ingredients of hairspray that causes AN INFLAMMATORY REACTION OF THE SKIN UNDERNEATH THE HAIR Like : (methylchloroisothiazolinone, parabens (preservatives), DMDM hydantoin (an antimicrobial formaldehyde releasing agent), Quarternium-15 (an ammonium salt preservative), formaldehyde, phenoxyethanol, and imidazolidinyl urea (antimicrobial preservative).
RépondreSupprimerAn itchy scalp can occur by itself or with other symptoms, such as a rash or visible bumps on the scalp and nape of the neck. In addition, excessive scratching of an itchy scalp can introduce bacteria or fungus into the layers of the scalp, resulting in secondary infections.