Lice
and Mites in Poultry - the less well known ones!
By Carrie L. Pickworth & Teresa Y. Morishita
Carrie
and Teresa carry on their look at mites and lice. Following on
from the last article they wrote (the more common types of live
and mites) they now look at the less common ones....
Although lice and mites are the most common external
parasites of poultry, below are other external parasites that
may be occasionally seen in poultry. The external parasites that
will be discussed are chiggers, stick-tight fleas, fowl ticks,
and scaly-leg mites.
Chiggers
Chiggers form clusters on the skin around the wings, neck, and
breast of poultry and inject a substance that causes allergic
skin reactions. The young chiggers in the larval stages are the
ones that do most of the biting. They are 0.16mm in diameter,
yellow-orange, and have 6 legs. Adult chiggers have a dense feathery
hair coat that gives them a velvety appearance. They are bright
red in color and can grow to 1 to 2mm in length. The lifecycle
for a chigger is 50 days. These chiggers are the same chigger
pests that can affect humans and cause similar problems. Chiggers
are primarily a problem in poultry that are raised on pasture.
Poultry that are infested with chiggers are droopy and emaciated.
They may have abscesses and extensive skin inflammation. It takes
birds at least three weeks to heal after a chigger problem. If
chiggers infest a market poultry flock, the carcass quality will
be greatly reduced. Chiggers cause red scabby lesions on the carcass.
In severe cases, death may result due to secondary bacterial infections.
Infested birds should be treated with a kitten-strength dose
of a pyrethrin-based spray and removed from the infested pastures.
Stick-tight Fleas
Stick-tight fleas are the smallest type of fleas (half the size
of a cat or dog flea). They are a burrowing and stationary flea
as compared to most fleas, which are jumping fleas. These fleas
lay their eggs around the eyes and wattles of chickens causing
nodules. Once the flea larvae hatch, they drop off the bird to
live in the soil for approximately two weeks. Stick-tight fleas
feed off the host bird causing skin irritations and ulcerations.
Severe infestations may lead to blindness. Stick-tight fleas often
congregate into groups of at least 100 fleas. These fleas are
capable of being transferred to other animals like dogs, cats,
horses, and even humans.
Infested birds will have small brown dots clinging to or embedded
into the fleshy portions of the head. The head will become very
inflamed and red due to the irritation of the flea living under
the skin. Egg production and feed efficiency will decline greatly
and birds will become anemic and emaciated. Secondary bacterial
infections may develop because of the birds’ weakened immune
system. In severe cases, stick-tight flea infestations may kill
young birds.
Stick-tight flea treatments include using carbaryl (Sevin®)
to dust the litter and facilities; removal of the fleas using
tweezers; or by smothering them with petroleum jelly. In addition,
even after treatment, although the fleas have died, they will
remain attached to the bird. Raising birds in wire cages at least
three feet above the ground is an alternative prevention method.
Fowl Ticks
Fowl ticks, also known as "blue bugs," are a soft-bodied
tick belonging to the Argas genus of ticks. These ticks are very
different from the common dog or cat tick. Ticks are a light reddish-brown
to a dark brown in color with wrinkled leathery skin. The 8-legged
tick has a thin, flat, egg-shaped body measuring 6 to 9mm in length.
The ticks require a blood meal just prior to reproduction but
can live for over one year without a blood meal. They feed off
their host’s blood primarily at night. The life cycle of
a tick includes 3 weeks for the egg to hatch and then 30 days
to reach the adult stage. Females lay 25 to 100 eggs at a time
for a total of about 700 eggs in her lifetime. Ticks lay their
eggs in the cracks and crevices of the housing facility.
Fowl tick infestations can cause a decrease in egg production;
an increase in disease incidence; weight loss; emaciation; and
in severe cases, death.
Treatment for ticks include a thorough cleaning and sanitizing
of the poultry house.
Scaly-Leg Mite
The scaly-leg mite is 8-legged and lives under the scales
of the legs
Figure 1. Toes that have fallen off a chicken’s feet
due to a severe scaly-leg mite infestation.
and feet of the birds. This mite is pale gray and has a flat
round body. They burrow under the leg scales to feed on connective
tissue. The life cycle of this mite is 1 to 2 weeks.
This mite is different from other mites in that they cause itching
and irritation of the legs. The scales lift and there is subsequent
scabbing or crusting. The diameter of a bird’s leg shaft
may double in size due to scaly-leg mite infestations. White dusty
scabs can be observed. In severe cases, birds will develop leg
and joint problems making walking difficult. In addition, toe
necrosis has been observed (Figure 1).
There are several treatment methods available to control scaly-leg
mites. Treatment with Ivermectin® is recommended. In addition,
coating the entire leg shaft with petroleum jelly will help to
moisturize the scales and revert the scales back to normal in
less severe cases.
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