Internal Parasites

Nematodes INTRODUCTION Nematodes constitute the most important group of helminth parasites of poultry. In the number of species, the number of animals infected, and the amount of damage done, they far exceed the trematodes and cestodes.

Capillaria annulata is found in the mucosa of the esophagus and the crop. Burrowing into the crop mucosa causes a thickening of the crop wall and enlargement of the glands. Usually, there is inflammation of the crop and esophageal walls.

Capillaria contorta may be found in mucosa of the esophagus, the crop, and sometimes the mouth. When present in large numbers, these worms are extremely pathogenic. In light infections, the wall of the crop and esophagus becomes slightly thickened and inflamed.

Ascaridia columbae is found in the lumen of the small intestine, but sometimes may be found in the esophagus, proventriculus, gizzard, liver, or body cavity. Ascaridia galli may be found in the lumen of the intestine, occasionally in the esophagus, crop, gizzard, oviduct, and body cavity.

A. galli infection causes weight depression in the host, which correlates with increasing worm burden. Heterakis gallinarum Larval and adult H. gallinarum inhabit the ceca. The chief economic importance of the cecal worm lies in its role as a carrier of the blackhead organism Histomonas meleagridis.

Syngamus trachea may be found in the trachea, bronchi, and bronchioles Syngamus trachea may be found in the trachea, bronchi, and bronchioles. It is the causative agent of “gapes” (labored breathing due to parasites) in chickens, turkeys, peacocks, and pheasants. Young birds are most seriously affected with gapeworms.

PREVENTION AND CONTROL For most nematodes, control measures consist of sanitation and breaking the life cycle, rather than chemotherapy. Treatment of the soil or litter to kill intermediate hosts may be beneficial. Chemotherapy Label directions and dosages should be followed explicitly.

Ascaridia Piperazine compounds have been widely used in treatment for ascaridiasis. Piperazine may be administered to chickens in water (0.1— 0.2%) or as a single treatment (50—100 mg/bird).

A high concentration of piperazine in contact with worms at a given time is very important for maximum elimination. Therefore, to be most effective, piperazine should be consumed by birds in a period of a few hours. Fenbendazole at 8—10 mg/kg for 3 or 4 days was effective against A. galli.

Pyrantel tartrate has a high efficacy against A Pyrantel tartrate has a high efficacy against A. galli and some efficacy against C. obsignata. Fenbendazole had 100% efficacy in turkeys experimentally infected with H. gallinarum. Syngamus: Thiabendazole, Mebendazole

Cestodes A high percentage of chickens or turkeys may be infected with tapeworms if they are reared on range or in backyard flocks. Many species of tapeworms are now considered rare in intensive poultry-rearing regions because the birds do not come in contact with intermediate hosts.

Choanotaenia infundibulum: Houseflies and several species of beetles are proven natural hosts. Davainea proglottina: This parasite is one of the more harmful species in young birds. Uncontrolled reports include emaciation, dull plumage, slow movements, breathing difficulties, thickened mucosal membranes that produce hemorrhage and fetid mucus, leg weakness, paralysis, and death.

TREATMENT Butynorate (dibutyltin dilaurate) is approved for treatment of 6 species of chicken tapeworms —Raillietina cesticillus, R. tetragona, Choanotaenia infundibulum, D. proglottina, Hymenolepis carioca, and Amoebotaenia sphenoides). Intermediate host must be eliminated.

CONTROL If the life cycle is known and evidence of pathogenicity or economic loss is clear, changes in poultry management may prevent the problem.

Trematodes Prosthogonimus sp., popularly known as the oviduct fluke, has caused economic losses to poultry producers by 1) drastically reducing egg production after a recent infection and 2) occasionally being enveloped within a hen’s egg and later discovered by complaining customers.

CONTROL Directed at intermediate host Chemotherapy for control or prevention of trematode infections is not available for use in poultry.