Introduction

Various species of lice are common external parasites of poultry worldwide. They are spread by direct contact between birds and by litter etc. Away from birds adults survive about 4-5 days. The parasites are 1-6 mm in size and their life cycle takes about 3 weeks. Menocanthus stramineus is the most pathogenic and is said to be capable of causing anaemia in heavy infestations. Check flocks regulary for rapidly moving insects at the base of the feathers on the abdomen or around the vent. Crusty clumps of eggs ('nits') may be visible at the base of feathers.

Signs

• Lack of thrift in young birds.
• Lice eggs stuck to feathers.
• Parasites on birds, especially around vent.
• Irritation.
• Loss of vent feathers.
• Scabs around vent.
• Loss of condition.
• Drop in egg production.

Post-mortem lesions

• Usually none, may be some feather damage and crustiness of skin.

Diagnosis

Identification of the parasites. Differentiate from mites, bedbugs.

Treatment

Malathion powders and pyrethroid sprays where approved for bird application.

Prevention

Avoid direct contact with wild and backyard poultry. Examine for lice regularly, especially in autumn and winter and treat if required. It is usually necessary to treat twice at a 7-10 day interval to fully control the condition, as the larvae within eggs are not killed by most products. Effective removal of all organic material at flock depletion should be practised in all-in/all-out production systems.