EXTERNAL PARASITES OF POULTRY
Preliminary notes on treatment of these parasite problems:
Sevin is the product name for carbaryl. It is available as a spray and powder. As of 8/13 carbaryl is not approved for use on poultry. It is still commonly used in this way, and is generally considered to be very safe, despite the lack of federal approval.
Permethrin is another insecticide that can be used instead of Sevin. It is available under many brand names as a spray or powder. Unlike Sevin, some permethrin products are approved for use on poultry; these products often have dilution and application instructions on the label.
There are systemic (oral, injectable, or absorbed-through-the-skin topical) medications that are very safe and effective for parasite treatment. Unfortunately, none of them are approved for use in or on poultry. If neither the bird or its eggs will ever be eaten then use of these medications is reasonable, in our opinion. We cannot recommend their use if the eggs or bird will be eaten.
Parasites can be detected on the external surfaces of the body by way of a thorough physical examination. Periodical examination of the flock can help to detect an early infestation and can help to prevent a larger flock outbreak. It is important to detect infestations early because of the restrictions on treatments available for food-producing birds. Moreover, many of the parasites have an environmental component so treating the environment is also necessary for controlling infestations. Prevention and early detection are the keys to successful treatment and control of external parasites in poultry flocks. The most common external parasites seen in poultry are lice and mites.
Poultry lice are tiny, wingless, 6-legged, flat-bodied, insects with
broad, round heads. They lay their eggs on the host bird’s feathers, especially near the base of the feather shaft (Figure 1). A female louse will lay 50 to 300 eggs at a time, which she cements to the feather shaft. There are several species of lice that affect poultry, and multiple species can affect a bird at any given time. Some species can be localized on specific locations like the quill lice; or others can be found over most of the body surface like the chicken body lice. The lice found on poultry do not suck blood as the lice found in other species of animals; rather they feed on dry skin scales, feathers, and scabs. However, they will ingest blood extruding from irritated skin. The entire life cycle of the lice occurs on the host bird, primarily in the feathers. Poultry lice are host specific and cannot be transferred to humans.
Fall and winter are the most common times to observe lice infestations. Inspect the ventral region of the bird for live lice crawling on the bird and for nits (lice eggs) as most infestations start in this area of the bird’s body. Eggs are white and commonly appear in bunches on the lower feather shaft. Feathers of infested birds may have a moth-eaten appearance. Due to the feather damage, the bird may have a dull or roughened appearance.
There are two major types of mites found on the body of poultry. They are the Northern Fowl Mite (or in tropical environments, the Tropical Fowl Mite) and the Chicken Mite (or Red Roost Mite).
The Northern Fowl Mite is the most common external parasite in poultry, especially in cool weather climates. It sucks blood from all different types of fowl and can live in the temperate regions of the world. As compared to the Chicken Mite, the Northern Fowl Mite primarily remains on the host for its entire life cycle. These mites can live off the host bird for 2 to 3 weeks. These mites are small and black or brown in color, have 8 legs, and are commonly spread through bird-to-bird contact. The Tropical Fowl Mite is comparable to the Northern Fowl Mite but lives in the tropical regions.
The Chicken Mite is a nocturnal mite that is primarily a warm weather pest. These mites suck the blood from the birds at night and then hide in the cracks and crevices of the houses during the day. Chicken Mites are dark brown or black, much like the Northern Fowl Mite.
The life cycle of mites can be as little as 10 days, which allows for a
quick turnover and heavy infestations. Mites can be transferred between flocks by crates, clothing, and wild birds. Mites are capable of living in the environment and off the host bird for a period of time. Diagnoses of mite infestations are similar to that of lice; however since mites can live off the bird and some are nocturnal, inspect birds and housing facilities at night especially if you suspect that the Chicken Mite is the cause of the infestation. Observable signs may include darkening of the feathers on white feathered birds due to mite feces; scabbing of the skin near the vent; mite eggs on the fluff feathers and along the feather shaft (Figure 2); or congregations of mites around the vent, ventral abdomen, tail, or throat. Since mites congregate around the ventral region, they can also reduce a rooster’s ability of successful matings.
Flocks infested with lice or mites show similar general symptoms. Birds will have decreased egg production; decreased weight gain; decreased carcass-grading quality; increased disease susceptibility; and decreased food intake. If any of these generalized symptoms are observed, a visual evaluation is recommended. Inspect birds around the ventral region for signs of lice or mites since infestations usually start in this area of the bird.
Sanitation and cleanliness are the keys to lice and mite control. Sanitation includes cleaning and disinfecting housing facilities and equipment between flocks. Moreover, reducing people traffic through housing facilities is recommended. Eliminating the contact between flocks and wild birds can reduce the potential transfer of external parasites. Chemical control can include the use of carbaryl (Sevin®). Treat the walls, floors, roosts, nest boxes, and the birds simultaneously. When dusting an entire house, be careful to avoid feed contamination. One treatment method for small flocks or individual birds is the use of a dusting bath with Sevin®. Place the bird into a garbage bag containing the medicated powder with the birds’ head out and rotate/shake the bag to completely cover the bird with powder. Be sure not to inhale the medicated powder during treatments. The use of a facial mask is recommended to prevent inhaling this medicated powder. Because the life cycle of lice and mites is. approximately 2 weeks, treatments should be repeated every 2 weeks as needed. Carefully read all labels prior to treatment to make sure withdrawal times are followed for food-producing poultry. Severe lice or mite infestations can be treated initially with a kitten strength dose of a pyrethrin-based medicated spray on the birds to reduce the initial numbers. If problems persist, contact a veterinarian for treatment with such medications as Ivermectin�. Prevention is the best method of treatment. For poultry used in exhibition or for new poultry entering the flock, a minimum quarantine period of 2 weeks is recommended. During this time birds should be physically examined and treated if necessary.
Table 1. Comparison chart to distinguish between lice and mites.
||2-3 millimeters long
||1 millimeter diameter (ground pepper)
||Straw-colored (light brown)
||Dark reddish black
||Base of feather shaft
||Along feather shaft
||White or off-white
|Best detection time
||Nighttime or Daytime
||Lives only on host
||Lives on host and in environment
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 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 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, 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.
The scaly-leg mite is 8-legged and lives under the scales of the legs
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.