ROUNDWORMS (Nematodes):

These are probably the most common parasites of all and include the gapeworms, threadworms, proventricular and gizzard worms, caecal and filarial worms. The worms are cylindrical, smooth and unsegmented with tapered ends. In birds they are usually well-adapted and therefore non-pathogenic to their host so that the presence of small numbers is not suspected by the owner. The parasites have no eyes, heart or lungs, but a simple tube-like alimentary tract running the entire length of the worm from the mouth to the anus. A reproductive tract capable of producing thousands of eggs daily, liberally ensures future generations of worms in spite of the great hazards awaiting eggs and larvae in the outside world. Roundworms of birds are mainly small and threadlike, the largest being a few centimeters long and about 2 mm. thick. The habits of roundworms vary greatly and their life cycles may involve an intermediate host or be direct. Most can only exist as adults inside the host's body. Just as size, shape, and habits vary, so does the shape, size, and form of the eggs, although large groups of worms produce identical eggs.

Although some roundworms are harmless in moderate numbers, they are undesirable because they are always liable to multiply rapidly, especially if the condition of the host is lowered in some way, such as by the presence of an infectious disease or due to incorrect feeding.

Large Roundworms (dsearidia spp.):
Ascaridia hermaphrodita and closely related roundworms are common in psittacines, especially the larger Australian parakeets. Their importance as a cause of disease in these birds has only recently been realized. The very similar Ascaridia columbae is common in pigeons and A. galli in gallinaceous birds. The worms, which are probably cosmopolitan in distribution are easily visible to the naked eye on post-mortem examination or when they are passed in the feces. They can measure as much as 10 cm. in length, are whitish in colour and round in cross section, being about as thick as an ordinary pin. The life cycle of the worm is direct. The eggs are passed in the feces and the larvae develop in the egg outside the body of the bird. Within 1 to 2 weeks the eggs become infective to the host, but they can remain viable for over three months under suitable conditions of warmth and moisture. Direct sunlight kills the eggs, however. When the eggs are ingested by a suitable host the larvae are released in the small intestine. The larvae live in the gut and also penetrate the wall of the intestine. After moulting they reach the adult stage, produce eggs and the cycle is repeated. Young birds of most species are more susceptible to infestation than adults, but in parakeets this is not necessarily the case. Parakeets lose condition and may develop apparent paralysis of the legs, because the worms in these birds most frequently cause trouble by impacting and blocking the small intestine. In a small parakeet, only a few worms may produce trouble, since they are relatively large and often difficult for the bird to pass; this is because the diameter of the lower part of the small intestine is smaller than that of the duodenum where the worms are most frequently found.

Treatment and control:
In pigeons and gallinaceous species which normally drink liberally, the worms can be successfully treated by the addition of piperazine adipate to the drinking water. Parakeets, however, need to be dosed individually with piperazine or tetramisole by mouth, using a stomach tube. It may also be necessary to administer an intestinal lubricant such as liquid paraffin (NOT paraffin oil or kerosene) to help the passage of the paralyzed worms through the gut. Prevention and control of infestations is based on the same principles as those recommended for other worms such as Capillaria.


E-Mail: berniehansen@sympatico.ca



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Hamilton & District Budgerigar Society Inc.