Looking for a head louse or a nit in the very early stages can be like looking for a needle in a haystack. In fact you would probably have more chance of finding a needle. As you can see in this photo a nit or egg can be so small that they can actually fit through the eye of a needle. They are up to approx 0.8mm x 0.3mm in size and an egg with a live nymph (baby louse) are tan or brown in colour, nits which are the empty shells appear white or cream in the hair.
Many people believe that the only way to tell if someone has head lice is that they itch, not so.....the fact is that only one in three people itch as they have an allergic reaction to the saliva when the louse bites the scalp to consume your blood. This is why we see so many long established infestations in our clinic.
The best way to prevent head lice infestations taking hold is to check for lice, nits and eggs once a week with a good quality nit comb. Which will make sure that you catch the infestation before the louse infestation takes hold.
Having read many scientific reports here is no need for pointless household sprays or prevention sprays, save your money. Keep your child's hair tide close to the head with plaits and buns and check your families hair once a week.