Roundworms

Roundworms produce eggs which are laid in the bird's intestines and pass out through the faeces. They then undergo a maturation process lasting a week or more, after which they may be picked up by another bird, hatch in the intestine and here develop to a mature worm up  to 12cm in length.

The Signs of Roundworm Infestation in Poultry

• Loss of condition.

• Poor growth.

• Listlessness.

• Diarrhoea.

• Wasting, (mainly in young birds).

Roundworms in intestine

Tapeworms are flattened, ribbon-shaped worms, usually segmented. Theses cestodes use arthropods and   other invertebrates as their intermediate hosts. Poultry become infected by swallowing infected snails, slugs     or insects. In turn, the invertebrate hosts become infected by ingesting the eggs or egg-bearing segments of the worm, along with their food. Following ingestion by the intermediate host, the eggs hatch in the intestinal wall and enter the body cavity. After a few days they become transformed into small, white cysts (cysticercoids). These cysts are visible to the naked eye when removed from the host. Microscopic examination will show the head of the tapeworm near the centre of the cyst.

The cysts take approximately three weeks after the initial ingestion to develop into this embryonic form.          No further development occurs in the intermediate host, although the cysticercoids may remain alive for      much longer than this. The host may remain infective to birds for many months.

When the invertebrate host is ingested by poultry, the cysticercoid is freed from the body of the host by the action of digestive juices. The tapeworm head then becomes attached to the intestinal wall. New segments  begin to form and within 3 weeks of ingestion of the host a mature tapeworm has developed. Therefore, the entire life-cycle can take 6 weeks for completion, although this may be longer under unfavourable conditions.

Microscopic image of a cysticercoid
(The larval stage of tapeworms).

Numerous tapeworms attached to the
intestinal tract of an infected bird.

The tapeworm's scolex ("head").
This attaches to the intestine of the definitive host.

Gapes is a condition caused by the pathogenic nematode roundworm Syngamus trachea and is most likely to     be seen in free-range systems where chickens may be kept together with infected pheasants, or on infected pasture. The condition, which is common in both wild and domestic birds, results in paralysis and physical blockage of the respiratory tract, leading to difficulty in breathing. Infected birds respond with outstretched necks and open mouths. The disease is called 'gapes' from the characteristic gaping mouth of an afflicted bird. The disease can occur sporadically and can result in severe loss of condition and high rates of mortality.

The life cycle of the nematode most frequently involves the earthworm, although it can be more direct.           In the earthworm, infections can persist for long periods and soils can become heavily infected for many years. Infective larvae may live as long as several years in infected intermediate hosts. There is evidence that the passage of the larvae through earthworms renders them more highly infective to chickens. Game and wild birds provide a reservoir for the parasite.

The worms are bright red, with the male measuring 2 to 6mm and the female 5 to 20mm. The male becomes firmly attached to the tracheal wall and is in almost permanent copulation with the females, forming an easily distinguishable Y-shape. Eggs produced by the female worm are carried by the mucus of the trachea to the pharynx where they are swallowed and eventually passed out of the bird in faeces. Under optimal temperature and humidity levels, the egg undergoes a third stage, moulting to produce an infective larva. Eggs containing larvae have been reported to survive on pasture and up to 9 months in soil.

Syngamus trachea (gapeworm)
male and female in permanent copulation.

Syngamus trachea (gapeworm)
in the trachea of a pheasant

Syngamus trachea (gapeworm)
Adult worms in the trachea of a turkey.

After ingestion of the worm larva, either in the form of an intermediate host or as a free egg, the larva migrates  in the bird from the bowel to the lungs via the blood stream. Larvae undergo a fourth stage moult at about the third day after ingestion, and undergo a fifth larval stage in the bronchi of the lungs on the fifth day of infection. Copulation starts at this time. By the seventh day of infection the parasite is found in the trachea. They reach sexual maturity twelve days after this and eggs can be found in poultry faeces 18 to 20 days after infection.

Although gapeworms are only rarely found in mature layers, the parasites can survive in poultry birds for long periods. They are more often found in adult turkeys.

Gape worms are not commonly seen in poultry reared on impervious floors. Only chicks up to 8 weeks of age    are susceptible. Since most commercial systems now involve rearing of chicks in systems where they are not in constant contact with their droppings and not ingesting earthworms, the incidence of gapes is not widespread. The disease can be found in turkeys kept on dirt floors.

Hairworm / Threadworm

The Capillaria species of nematode, or roundworm, are intestinal worms that can cause severe symptoms such     as diarrhoea, weakness, weight loss and a drop in egg production. The condition is sometimes referred to as capillariasis. There are several species of Capillaria, and they cause paralysis of different parts of the alimentary tract, including the crop, oesophagus and the intestinal tract. Commonly, the Capillaria species are referred to      as the threadworm or hairworm, and they can be highly pathogenic, causing severe disease.

The Capillaria are a small species of worms, and some tend to be restricted to free-range birds, as the intermediate host is the earthworm. Others have a more direct life cycle. Capillaria bursata is found only in chickens and its life cycle is dependent on the earthworm as an intermediate host. Capillaria caudinflata has a similar life cycle and can be found in a number of domestic poultry species. Capillaria obsignata can be a problem in deep-litter systems.  This worm does not have an intermediate host and can be found in a number of poultry species.

The main site of infection of Capillaria bursata, Capillaria caudinflata and Capillaria obsignata is the small intestine.

Capillaria anatis is a parasite of the caecum and is found mainly in ducks.

The main species afflicting turkeys and game birds are Capillaria annulata and Capillaria contorta.

Capillary worm

Capillary worm (Capillaria obsignata)

Capillary worm

Like many other stresses, these worms can cause an outbreak of Marek's disease, especially in young growing birds.

Treatment

An affected flock suffering from any of the above parasites will need treating immediately with Flubendazole. Flubendazole is a compound belonging to a group of chemical compounds called benzimidazole carbamates
which are effective in controlling intestinal parasites.

Flubendazole can be administered using either :

Janssen's  Flubenvet 1% Medicated Premixture or Marriage's Layers Pellets with Flubenvet .  

                                                                                                                             Marriages - Layers Pellets with Flubenvet - 20kg
1.2kg of Flubenvet medicated pre-mixture added per                                         tonne, gives 30mg/kg Flubendazole in the finished                                              feed as a broad spectrum anthelmintic.