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Davainea proglottina does not affect dogs, cats, cattle, sheep, pigs, horses or other mammals. Davainea proglottina is a small tapeworm, usually not longer than 4 mm with only 4 to 7 segments proglottids. The head scolex has numerous hammer-shaped hooks and suckers armed with spines, and numerous hooks.
The segments are whitish to translucent. Only the last one is gravid, i. E ach segment has its own reproductive organs of both sexes i. Each segment has also excretory cells known as flame cells protonephridia. The reproductive organs in each segment have a common opening called the genital pore. In young segments all these organs are still rudimentary.
They develop progressively, which increases the size of the segment as it is pushed towards the tail. In Davainea tapeworms o nly the last segment is gravid, i. Otherwise, as other tapeworms, they have neither a digestive tube , nor circulatory respiratory systems. They don't need them because each segment absorbs what it needs directly through its tegument.
The eggs measure about 35x50 micrometers, have a capsule and are embryonated, i. Davainea proglottina , has an indirect life cycle with certain birds chicken, turkey, guineafowl, pigeons, etc. The gravid segments of adult tapeworms are shed with the birds' feces usually one gravid segment per tapeworm per day. The gravid segments are motile and capable of climbing upwards on the vegetation.
By mild and humid weather the eggs can remain infective for slugs and snails during several days. The slugs and snails ingest the gravid segments, which release the eggs after digestion. The eggs then develop to cysticercoids in the body cavity of the intermediate hosts. The birds ingest such contaminated snails or slugs. After digestion, the cysticercoids release the young tapeworms that attach to the gut's wall.
The time between infection and shedding of the first eggs prepatent period is 2 to 3 weeks. Davainea proglottina is highly pathogenic for young birds. It is very seldom an issue in modern industrial operations. But in numerous regions in Africa and Asia almost all traditionally kept poultry are more or less infected with this parasite or related tapeworms.
Free-ranging poultry are more at risk if they have free access to humid environments with abundant slugs and snails that can be inefected. Davainea proglottina can attach deeply into intestinal villi. Sudden massive infections can cause hemorrhagic enteritis and intestinal necrosis that can be fatal for the young birds. Chronic infections lead to reduced weight gains, diminished egg production, malnutrition, general weakness and even paralysis.
Diagnosis is usually done only after necropsy. It is important to examine a representative sample of the flock and to analyze intestinal smears under the microscope. Gravid segments can be found in the birds' feces, but not always, i. Frequent change of the birds' bedding and keeping it dry can help to avoid infections because it shortens the survival of the eggs and is unattractive for slugs and snails. Free-ranging birds should be kept off humid environments that are supportive of slugs and snails.
Chemical control of the snails and slugs with molluscicides i. It is virtually impossible to treat every place where they can survive and they reproduce extremely quickly. Cleaned pastures would become re-infested very fast. In addition it would be also very harmful for the environment. In fact, such molluscicides mainly niclosamide are approved only in a few countries as an aid in the prevention of human schistosomiasis also called bilharziosis or snail fever.
WARNING : niclosamide is toxic for geese , and the combination of praziquante l with pyrantel tartrate is toxic for chicken! There are so far no vaccines against Davainea proglottina. To learn more about vaccines against parasites of livestock and pets c lick here. Biological control of Davainea proglottina i. You may be interested in an article in this site on medicinal plants against external and internal parasites.
Ask your veterinary doctor! If available, follow more specific national or regional recommendations for Davainea control. Junquera All rights reserved. Control: Introduction Biol.
Control of Flies Biol. Control of Ticks Biol. Biology, prevention and control. It is closely related to Raillietina spp , another genus of bird tapeworms.
Details Written by P. Junquera Last Updated: July 15 Other interesting articles.
Davaineidae is the name of a family of tapeworms that includes helminth parasites of vertebrates. Members of the family are characterized by the presence of a crown rostellum at the tip of the scolex , and the rostellum is made up of mattock- or hammer -shaped hooks. The rostellum is surrounded by suckers which are armed with spines. Intermediate hosts are small insects such as ants. Slugs are the intermediate hosts. From Wikipedia, the free encyclopedia.
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