Occurrence: Worldwide.   Species affected: All.   Age affecetd: All.

Causes: Lice are common external parasites of birds, belonging to the order Mallophaga. More than 40 species have been reported for the domestic fowl. Transmitted from one bird species to another if they come in contact.

Effects: Eat feather products and may consume blood by puncturing soft quills near the bases and gnawing through the covering layers of the skin. Not highly pathogenic to mature birds, but infected chicks may die. Frequently accompanies manifestations of poor health, such as internal parasitism, infectious disease and malnutrition.

Lice are common external parasites of birds. They belong in the order Mallophaga, the chewing lice and are characterised by chewing-type mandibles located ventrally on the head, incomplete metamorphosis, no wings, dorsoventrally flattened body, and short antennae with 3-5 segments. More than 40 species have been reported from domesticated fowl. Lice will transfer from one bird species to another if these hosts are in close contact.

Bird lice eat feather products and may consume blood by puncturing soft quills near the bases and gnawing through the covering layers of the skin itself. Hence birds may appear agitated and have ruffled or damaged feathers. Not highly pathogenic to mature birds, but infected chicks may die. Frequently accompanies manifestations of poor health, such as internal parasitism, infectious diseases and malnutrition. In sever infestations, laying birds may refuse to sit on the nest.

Pediculosis (lice infestation) of birds is diagnosed by finding the straw-coloured lice on skin or feathers of birds. Lice of domestic birds vary in size from less than 1 mm to over 6 mm in length. Mallophaga up to 10 mm long occur on wild birds. Lice spend their entire life cycle on the host. Eggs are attached to the feathers, often in clusters and require 4.7 days to hatch.

Galliform wild or domestic birds should never be allowed contact with poultry flocks. Lice tend to increase during autumn and winter, so flocks should be examined for lice on a regular basis (two times/month minimum) and treated if needed. Birds should be treated twice on a 7-10 day interval. Only the mature and immature forms will be controlled, as none of the available chemicals are ovicidal (egg are not killed). Re-treatment is necessary to control the lice that will hatch after the initial treatment.

In houses, the egg-laden feathers will be a source of re-infestation and when the house is depopulated, a thorough cleanup should be completed. Spraying of birds is the most practical means.

Care should be taken when spraying to ensure that the whole bird is treated, as it is common for lice to move to the neck from the vent when populations are large. In caged-layer flocks it is important that the birds are checked on a regular basis.

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