Lice

Lice

Causative Agent

Lice are small, flattened, wingless insects that are external parasites of mammals and birds.
Lice are of two general types:
- lice that chew on fur, feathers and skin debris
- lice that suck on blood

Distribution

Geographic:

Seasonality:

Lice populations undergo seasonal fluctuations that vary according to the biology of the louse and affected host.
Found at higher numbers on affected animals in winter and early spring, and are generally absent or extremely rare in summer and autumn.

Click on a photo to enlarge.

Photomicrograph of a chewing louse.

Lice with the fur of an Arctic fox.

Hosts, Transmission and Life Cycle

Hosts:

Transmission and Life Cycle:

Lice vary from 0.3 to 10 mm long with a head much broader than the rest of the body.
The entire life cycle of lice occurs on the host.
Lice lay eggs directly onto fur or feathers.
Transfer of lice between hosts occurs from physical contact.
Lice are very well adapted to a particular host and even to specific areas on a host’s body; lice will not survive on other host species.
Lice may serve as vectors for other wildlife diseases such as Lyme Disease, brucellosis, hemobartonella, ringworm, salmonellosis and certain tapeworms.
A generation of lice usually lasts 45 days.

Signs and Symptoms

Small infestations of lice are commonplace on animals and do not often cause harm to the host.
Large numbers of lice may be found on: older or young animals, animals in poor nutritional condition, those suffering from a concurrent illness, or those that are inefficient at grooming.
Lice leave the host 1-2 days following death of the host.
Animals may become immune to the effects of lice infestation resulting in reduced survival of eggs, fewer eggs being produced, and a reduction in feeding on host tissues.
Lice may cause the following in animals:
- anemia
- itching
- inflammation of the skin
- skin sensitivity
- allergic reactions
- intense grooming
- fur mats
- loss of hair
- secondary infections at the location of bites
- reduced survival in winter due to hair loss
Death may result from heavy infestations in young animals or those in poor condition from other disease conditions.

Meat Edible?

Human Health Concerns and Risk Reduction

Rubber gloves and protective clothing should be worn when handling wildlife with skin conditions.
Although lice from animals cannot be transferred to humans, if wildlife are handled lice may initially crawl onto humans, causing a minor irritation, but do not remain for long.

Samples for Diagnosis

Collection of a whole louse placed in 70% ethanol is sufficient for identification

Similar Diseases

Ticks and mites are also external parasites but are very different in appearance.