TABLE OF CONTENTS
Poultry Tapeworms: Species, Life Cycle, Pathogenesis, Diagnosis & Treatment
Poultry tapeworms (cestodes) are common gastrointestinal parasites of chickens, turkeys, pigeons, ducks, and other domestic and wild birds. These parasites inhabit the small intestine and require an intermediate host, such as ants, beetles, earthworms, flies, slugs, or crustaceans, to complete their life cycle. Although light infections are often subclinical, heavy infestations can lead to poor growth, weight loss, reduced egg production, enteritis, intestinal nodules, and decreased flock performance, resulting in significant economic losses in poultry production.
Several tapeworm species infect poultry, including Davainea proglottina, Raillietina tetragona, R. echinobothridia, R. cesticillus, Cotugnia digonopora, Amoebotaenia cuneata, Choanotaenia infundibulum, and Hymenolepis species. This article provides comprehensive veterinary notes on the major poultry tapeworms, including their morphology, hosts, intermediate hosts, life cycle, prepatent period, epidemiology, pathogenesis, diagnosis, treatment, and control.
The most common species of tapeworms affecting poultry are:
- Davainea proglottina
- Raillietina tetragona
- R. echinobothridia
- R. cesticillus
- Cotugnia digonopora
- Amoebotaenia cuneata
- Choanotaenia infundibulum
- Hymenolepis carioca
- H. contaniana
- H. lanceolata
1. Davainea proglottina
- Common Name: Dwarf tapeworm of poultry
- Host: Chickens and pigeons
- Location: Duodenum
- Intermediate Host: Slug (snail without shell). Limax and Arion species
Morphology
- The worms are microscopic in nature, about 0.5 to 3 mm in length. They have only 4 to 9 segments.
- The rostellum is retractable and armed with hammer-shaped hooks.
- Suckers are also armed with hooks.
- Each segment has a single set of genital organs.
- The genital pore opens in a regularly alternating pattern.
- In the gravid segment, the uterus is replaced by an egg capsule.
- Each egg capsule contains a single egg.
2. Raillietina tetragona
- Common Name: Largest poultry tapeworm
- Host: Chicken, pigeon and guinea fowl
- Location: Posterior half of the small intestine
- Intermediate Host: Ants (Pheidole spp. and Tetramorium spp.)
Morphology
- Adults are up to 25 cm in length. The scolex is smaller than that of R. echinobothridia. Rostellum is armed with 1 to 2 rows of hooks.
- Suckers are oval in shape and armed with hooks.
- Each segment has a single set of reproductive organs. The genital pore opens unilaterally in the anterior third of the segment.
- Each egg capsule contains 6 to 12 eggs.
3. R. echinobothridia
- Common Name: Nodular tapeworm of Poultry (It causes Nodular taeniasis)
- Host: Chicken and turkey
- Location: Small intestine
- Intermediate Host: Ants (Tetramorium spp. and Pheidole spp.)
Morphology
- The scolex is larger than that of R. tetragona.
- The rostellum is heavily armed with two rows of hooks. The suckers are circular.
- Each segment has a single set of genital organs. Genital pore unilateral at the posterior third of the segment.
- Gravid segments are separated in the middle forming small “windows” in strobila.
- Each egg capsule contains 6 to 12 eggs.
4. R. cesticillus
- Host: Chicken
- Location: Small intestine
- Intermediate Host: Dung beetles (Opatroides spp.)
Morphology
- Usually 4 cm long but may rarely reach 15 cm. Scolex is very wide.
- The large rostellum is armed with 400 to 500 small hooks.
- Suckers are indistinct and are not armed.
- Each segment contains single set of genital organs. Genital pore unilateral at the middle of the segment.
- Each egg capsule contains a single egg with funnel-shaped filaments at both ends.
5. Cotugnia digonopora
- Common Name: Double pored poultry tapeworm
- Host: Chicken
- Location: Small intestine
- Intermediate Host: Ants (Pheidole spp. and Monomorium floricola).
Morphology
- The rostellum is armed with two rows of hooks.
- It has cup-like muscular suckers.
- Each segment contains two sets of genital organs.
- Each egg capsule contains a single egg.
6. Amoebotaenia cuneata (A. sphenoides)
- Host: Domestic fowl
- Location: Small intestine
- Intermediate Host: Earthworms (Eisenia spp.).
Morphology
- It is small, measuring up to 4 mm in length (microscopic).
- Roughly triangular in shape.
- The rostellum is armed.
- A single set of genital organs is present, and the genital pores alternate regularly and are situated at the extreme anterior margin of the proglottids.
- Uterus is sac-like and slightly lobed.
7. Choanotaenia infundibulum
- Host: Chicken and turkey
- Location: Upper half of the small intestine
- Intermediate Host: Dung beetles, Dermestes spp., and Musca domestica.
Morphology
- The rostellum is armed with 15 to 20 slender hooks.
- Segments are wider posteriorly than anteriorly, giving a bell-shaped or saw-tooth appearance.
- Each segment has a single set of genital organs, and the genital pore opens in an irregularly alternating pattern.
- The uterus is sac-like and is not replaced by egg capsules.
- Egg has filaments on both poles.
8. Hymenolepis carioca
- Common Name: Thread worm
- Host: Chicken
- Location: Small intestine
- Intermediate Host: Dung beetles, flour beetles, and the stable fly (Stomoxys calcitrans).
The cysticercoid may possess a tail and is known as a cercocystis.
Morphology
- The worms are slender, thread-like, and approximately 8 cm long.
- The rostellum is armed with spanner-shaped hooks.
- Segments are very small. Each contains a single set of reproductive organs. Genital pore is unilateral.
- Each segment contains three testes: one on the poral side and two on the aporal side.
- Eggs are covered by three layers and are rugby ball-shaped.
9. H. cantaniana
- Host: Chickens and other birds
- Location: Small intestine
- Intermediate Host: Aquatic crustaceans.
- Morphology: Similar to H. carioca
10. H. lanceolata
- Host: Ducks
- Location: Small intestine
- Intermediate Host: Aquatic crustaceans
- Morphology: Similar to H. carioca
Life Cycle of Poultry Tapeworms
Gravid segments are passed in the droppings of infected birds and crawl over the surface of the feces, releasing eggs during this process. Each egg contains a hexacanth embryo.
The eggs are ingested by the intermediate host (I/H), where they hatch and develop into cysticercoids in approximately 3 weeks. Poultry become infected by ingesting infected intermediate hosts.
Prepatent Period
- D. proglottina: 14 days
- R. tetragona: 21 days
- R. echinobothridia: 20 days
- R. cesticillus: 13 days
- A. cuneata: 28 days
- C. infundibulum: 15 days
- C. digonopora: 20 days
- Hymenolepis spp.: 20 days
Epidemiology
Tapeworm infections are more common in free-range birds than in birds raised under intensive production systems. This is because free-range birds have greater access to intermediate hosts than birds reared in confined environments.
Heavy tapeworm infections may also occur in intensive management systems (cages or deep litter) because these systems provide favorable conditions for intermediate hosts such as flies, beetles, and ants. Under these management systems, Choanotaenia infundibulum and R. cesticillus infections are more common.
Pathogenesis
- D. proglottina is the most pathogenic tapeworm. The worms penetrate deeply between the villi, causing necrosis and hemorrhagic enteritis. Sometimes death may occur.
- Chronic infections are characterized by reduced growth rate, emaciation, paralysis, catarrhal enteritis, and weakness.
- Of the Raillietina species, R. echinobothridia is the most pathogenic species causing nodule formation in the intestine, and the condition is known as “Nodular taeniasis” in poultry. Hyperplastic enteritis may also occur. All other tapeworm species are less pathogenic, but heavy infections result in reduced egg production and general weakness.
Diagnosis
- Macroscopic (gross) examination of droppings for the presence of gravid segments.
- Postmortem examination of representative birds from the affected flock.
- Microscopic examination of intestinal mucosal scrapings for small cestodes such as Davainea and Amoebotaenia spp.
Treatment
Old Drugs
- Butynorate: 75–150 mg/kg body weight
- Lead arsenate (Di-N-Butyl tin dilaurate): 1.5–1.75 g/kg body weight
- Dichlorophen: 300 mg/kg body weight
- Aricoline hydrobromide (Arica nut)
New Drugs
- Niclosamide: 75 mg/kg body weight
- Fenbendazole: 5 mg/kg body weight
- Praziquantel: 15 mg/kg body weight
- Closantel: 7.5 mg/kg body weight
Control
Elimination of intermediate hosts (I/H) is essential and can be achieved by:
- Maintaining good hygiene in poultry houses.
- Beetle, earthworm and crustacean control is very difficult. Alteration of the ranges of free-range birds may be useful.
- Using metaldehyde bait for slug control.
- Applying chemical agents such as BHC and HCH.
- Insect growth regulators such as cyromazine, a chitin synthesis inhibitor (Larvadex/Laris), may be used against Musca spp.
- Bio-control agents such as Bacillus thuringiensis may be used against I/H.
