LICE

Lice are highly specialised external parasites of birds and mammals. They belong to Order Phthiraptera, which comprises of 3000 species worldwide, and around 200 are represented in Australia. Within this order, there are four distinct suborders.

1. Amblycera
2. Ischnocera
3. Rhyncophthirina
4. Anoplura

Human infesting lice have played a significant part in the transmission of epidemic typhus by the body louse has, during the history of mankind, had a significant impact on human health.

Adult lice are 1.5 – 3.5 mm long; they are wingless and have a flattened body shape. The antennae are usually short, they have small compound eyes, and legs usually carry conspicuous claws, this claw help with movement among hair.  Developing nymphs will resemble adults.

LIFE CYCLE

Lice undergo a gradual metamorphosis. The eggs are sometimes called “nits” and are usually glued to their host’s hair or in the case of body louse they are found in the seams of clothing that are in close contact with the body. The eggs can hatch in 5-10 days, and nymphs feed on blood from the host, they usually pass through three instars before reaching maturity.

The life cycle can take 3-4 weeks. Adults live for about a month, in this time the female may lay around 200 eggs. If the lice are separated from the host their span is usually short, this can be a few days.

HABITS

Lice spend their entire life on the host; both sexes and all developmental stages are obligate bloodsuckers and can feed intermittently throughout the day or night. Some lice species occupy certain regions of the host’s body. The head louse is mostly associated with the hair of the head. The grab louse is most often found infesting the pubic region. Lice are sensitive to temperature and tend to leave a dead or drying host to seek another. Temperature and smell play an important part in host detection. Lice can spread when there is close contact between hosts.

Body lice feeding involve breaking the skin and injecting saliva. This can cause irritation and scratching, in severe cases this can lead to local infection of bite wounds. Continuous injection of saliva in severe infestations can lead to weariness and irritability.

Where a situation of severe body louse infestation is detected, is usually combined with unhygienic conditions.

CONTROL OF LICE

Where a louse infestation has been discovered, persons that have been in contact with the infested person should be checked out immediately, as this can limit the spread.  If possible avoid contact with a person that has a lice problem. Frequent bathing and washing with soap and water, and frequent changing of underwear, create unfavourable conditions to louse infestations. Clothing and bedding should be washed in hot water, steam cleaning of carpets, upholstery, mattresses are advisable. Special designed combs can give partial control of head lice, and then physically remove.

Lice can be bought into a home from birds. Birds will nest in the roof void of a home and are carriers of lice. The most susceptible type of home for harbouring lice is the Queenslander. This is because they are very easy for birds to find their way into the roof space, usually from broken gutters or a rotten piece of wood on the exterior of the home.

Once the lice have made home in the roof, they can find their way into the rest of the home by cracks around the ceiling or even from down lights in the roof. To successfully treat lice, the roof void needs to be treated. This is done by using an electric blower to fill the roof with a permethrin dust. The dust will settle on the roof trusses and work its way into the insulation.

Gaps and excess holes need to be fixed to prevent any birds from nesting within the roof void once the treatment has been completed.