There are several important types of worms or helminths as they are scientifically known in poultry production, that farmers need to know about. These worms are generally divided into two groups, Nematodes, which are generally rounded in shape. They measure between 10-50mm in length and are 1-3mm in thickness. Some need intermediate host to survive and they generally cause damage in the intestines of chickens and other types of birds. Members of these group include Ascarids, Capillaria, Heterakis and Syngamus. The other group is referred to as Cestodes, also known as tape worms. They are much longer, measuring 50-150mm, thinner and are more destructive to their host. Members of this group include Davainea and Raillietna.
1. Round worms (Ascarids)
These are the most common worms affecting chicken, turkeys, geese, ducks, and pigeons. They are found mostly in the intestinal lumen but can also be seen in the esophagus, the crop, gizzard, and oviduct in heavy infestation. They cause havoc in the intestinal wall by migration of larvae and ‘pluck feeding’ by adult worms resulting into hemorrhage and inflammation in the intestines. If the infection is not treated immediately, there will be intestinal obstruction by adult worms. The adult worms will disrupt any uptake of feed/ intestinal contents meant for the host, resulting into weight loss, diarrhea, and some production losses. An adult worm can produce up to 200,000 eggs per day. These eggs' maturation can be delayed by dry conditions, temperatures below 10-150C or above 340C and in absence of oxygen, but will be destroyed completely by dryness, heat, direct sunlight and extreme frost. This is very important in the control of worm infestation as humid conditions may extend the life of these eggs for 1-4 years, waiting for arrival of the next victim.
2. Tape worms (Cestodes)
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The most common are the species Davainea and Raillietina which inhabit chicken and turkeys, guinea fowls and quails. In affected laying flock, they cause a drop in egg production, production of small eggs with weak fragile shells. The birds lose body condition, weighing less than 1.3kg and showing a thin keel bone as sharp as a blade. Because of loss of blood, you will notice pale comb and wattles with some completely shrunken, probably due to anaemia and diarrhoea. Most of these types of birds would show no signs of egg laying. Some birds will exhibit dirty vent feathers while others will have their vents pecked by other birds. If not treated immediately some birds will have little or no appetite and appear ill thrift and listless. Fecal droppings will appear watery and foamy.
How infection is introduced in the farm
The route of infection is through direct ingestion of adult worms or ingestion of eggs or larval stages of the worms from the litter or manure. The worms or their eggs are normally introduced into the poultry shed by contaminated foot wear, clothing, feed bags, equipment and wild bird droppings. They can also be in the farm if you have free range birds kept in the yard.
Treatment and control
Treatment and control involve administration of registered anti-helminths such as Levamisole 7.5 per cent in drinking water under supervision of a registered veterinarian for tqo days every 3-4 weeks in severely infected flock and at intervals of two months in a healthy flock to avoid heavy build-up of infestation. Please note that during de-worming, egg production is likely to temporarily drop due to poor water intake. Another round of treatment with a Flubendazole like Panacur is recommended to avoid developing resistance.
Prevention
Ensure you concrete your poultry floor to help in ensuring a thorough cleaning and disinfection with appropriate disinfectant. Make sure the litter is always dry and friable and that there are no water leaks on the floor. Keep limited visits into the barns and keep the compound clean and tidy. Practice good biosecurity measures at all times.
