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LICE – ALL YOU NEED TO KNOW

They’re relatively uncommon pests, but would you know how to identify and treat a lice infestation?

 

When a customer phones and complains about being bitten and having itchy skin, it could be caused by a number of pests. Perhaps fleas and bed bugs would be the most likely culprits, but it could also be caused by lice. Although a less frequent pest, it’s important for pest managers to know how to identify and deal with a lice problem. There are three types of lice that are associated with humans: head lice (Pediculus capitis), body lice (Pediculus humanus) and pubic lice or ‘crabs’ (Pthirus pubis).

Head lice and body lice are very similar in appearance. They are flattened, wingless insects, up to 4 mm in length and grey/brown in colour, although they become red after feeding. Determining whether someone has head lice or body lice can be assumed by their location. Head lice only occur on the scalp and body lice actually live in clothing, only emerging onto the skin to feed.

Pubic lice (main picture, above) are also flattened, wingless insects but are noticeably smaller than head and body lice (up to 2 mm long) and have a short, ‘stumpy’ abdomen compared to the elongated abdomen of head and body lice. Essentially, they have a crab-like appearance. Although predominantly found in the pubic areas, they can also infest other areas of coarse hair on the body including beards, eyebrows and eyelashes, but not the scalp.

It’s worth pointing out that lice are very different from mites, which are not insects but arachnids (eight-legged arthropods). Although some pest managers refer to bird ‘lice’, these are actually bird mites, Ornithonyssus bursa. The basic lice life cycle involves the female louse laying eggs (nits) after a blood meal. Although head lice and pubic lice nits will be found in the hair, body lice nits are generally laid within the clothing. The eggs hatch in 1-2 weeks and the nymphs that emerge look like smaller versions of the adults. The nymphs mature into adults in around 9-12 days, moulting three times. The adults can live for around a month, but if they fall off the body or cannot access a blood meal, they will die in a day or two.

 

Head louse (Pediculus capitis)

 

Lice infestations can cause intense itching as a result of their feeding activity. Body lice bites tend to result in swelling and red welt-like marks, whereas pubic lice bites produce discrete, round, slate-gray swellings. When body lice have been present for an extended period, heavily bitten areas of skin can become thickened and discoloured. Scratching affected areas can lead to the introduction of bacteria and fungi, leading to secondary infections. Although uncommon in developed countries with good hygiene practices, in some countries body lice can spread diseases such as epidemic typhus, trench fever and louse-borne relapsing fever.

Lice are wingless and do not jump – they can only crawl. As such they can only be spread by direct physical contact with an infested person or through contact with infested clothes, linen or towels.

If when investigating a pest problem you suspect a potential lice issue, you should recommend that the customer consults a health professional or pharmacist to get the correct diagnosis and treatment. Recommend that any clothing, linen and towels should be washed in hot water and ironed to kill lice and their eggs. Placing affected garments and sheets in sealed plastic bags in the sun for several hours will also kill any lice present. Depending on the level of infestation, mattresses, floor coverings and wardrobes and drawers can be vacuumed and treated with a suitably labelled spray or dust, before placing clothes back in the wardrobes and drawers and re-opening the room.

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