Hairworms and roundworms are widespread in pigeon flocks, whereas tapeworms are
less common. These worm types live as parasites in the small intestine of pigeons.
Pathogen:
The hairworm, Capillaria obsignata - a very slender, hair-like parasite - infests
various poultry species in addition to pigeons. Hairworm eggs become infective in the
environment after 8-9 days.
The pigeon roundworm, Ascaridia columbae, only occurs in pigeons. The eggs become
infective in the environment after 2-3 weeks.
Two types of tapeworm, Hymenolepis columbae and Raillietina columbae, infest pigeons.
Their emergence is dependent on suitable intermediate hosts (snails, beetles, ants),
which they require in order to develop. Pigeons only become infected if they ingest an
intermediate host.
The interval between ingestion of infective worm eggs, sexual maturation of the new
generation of worms and the first excretion of eggs in the faeces (prepatent period) is
5-6 weeks for roundworms, 3-4 weeks for hairworms and approx. 2 weeks for
tapeworms. All types of worms may also appear at the same time.
Symptoms of the disease:Affected pigeons produce droppings of varying consistency 10-12 days after ingesting
infective eggs or an intermediate host. Appetite is initially increased, but diminishes as
infestation progresses. The birds lose weight. Heavily infested pigeons usually show
impaired general condition and are listless and apathetic with dull, ruffled plumage.
Recognition of the disease:Hairworm and roundworm infestation is identified by microscopic examination of faecal
samples (prepared according to the flotation method). When the intestine is cut open
during the cadaver examination, the yellowish-white roundworms are clearly visible,
whereas the fine, white hairworms require a smear preparation, which is floated in a
flat dish with a dark base.
In many cases, the intestinal mucosa also reveals inflammatory lesions and focal
haemorrhages caused by the burrowing of parasites. Tapeworm infestation is
demonstrated by the identification of tapeworm segments or eggs in the faeces.