Sheep measles can eat into your profit.
According to DPI monitoring programs, 36% of sheep consignments at various NSW abattoirs are affected by this parasite. On infected premises as many as one in 4 lambs have been found to have the small oval white cysts, 3 to 10mm long, in various muscles. At slaughter affected carcasses will be partly or wholly condemned. These cysts, commonly known as sheep measles, are the intermediate stage of a particular tape worm – Taenia ovis. It occurs in Australia wherever there are sheep or goats, as well as dogs.
Dogs are the final hosts of Taenia ovis. The adult tapeworm lives in its intestines, where it can grow to 2 meters long. The dog’s health is generally unaffected by the tapeworm.
Eggs are shed in the dog’s droppings and infest the pasture. Grazing sheep ingest the eggs. These eggs hatch and tiny larvae developed and migrate to the muscles where they become cysts. Dogs get infected with Taenia ovis by eating viable tapeworm cysts in sheep or goat tissues, e.g. raw meat.
Domestic dogs are the most important definitive host for Taenia ovis. Dingoes and wild dogs are only very occasionally affected.
Foxes are rarely affected with this tapeworm. They are more likely to get different species of tapeworm from rabbits (T.pisiformis and T. serialis) and less commonly the tapeworm Spirometra erinacea from eating reptiles and amphibians.
Sheep measles threaten your wealth and does not develop in humans.
Another dog tapeworm Echinococcus granulosus, or the hydatid tapeworm, is a human health hazard. The adult hydatid tapeworm is tiny – only 4 to 6mm. Its lifecycle is similar to Taenia ovis. However, if humans ingest the eggs – usually due to close contact with dogs – cysts can develop in their organs – such as the liver, lungs or even brain, with life threatening results. Cysts also develop in the organs of sheep or goats.
To control sheep measles and hydatid tapeworm one needs to break the sheep-dog lifecycle.
· Control dog movements
· Prevent dogs from eating raw sheep or goat meat or offal.
· Treat dogs regularly with an efficient tapewormer such as praziquantel (eg Droncit) which can be purchased from a vet.
Thursday, July 31, 2008
Monday, July 21, 2008
Bovine Pestivirus
Bovine Pestivirus under Extensive Farming Conditions in Australia
Cause:
Pestivirus or Bovine Viral Diarrhoea Virus belongs to the Flaviviridae family and the Pestivirus genus. Human Hepatitis C belongs to the same family of viruses, but is a member of the Flavivirus genus. Only Type 1 occurs in Australia. It is less aggressive than Type 2, which occurs in the USA and UK, amongst others.
History and prevalence:
It has been known to be present in Australia for about 40 years. Approximately 90% of herds have animals that test positive for antibodies against this disease, therefore it is widely distributed.
How does it spread:
Calves which survive in utero infection between 30 and 90 days of gestation are born persistently infected. Their developing immune systems do not recognise the virus as a foreign entity and do not produce any antibodies against the disease. Occasionally infection between day 90 and 125 can also result in the birth of a PI. These so-called PI calves are a potent and constant source of virus, excreting vast amounts in every secretion and excretion - eg saliva, urine, faeces, semen etc.
In the general population 0.5% to 1% of animals at 1 to 2 years of age may be PI's. In certain infected mobs of calves it may be as high as 50%.
PI animals often have deranged nervous systems and are more likely than other animals to be aggressive and jump fences, therefore posing a risk to neighbouring herds and farms.
In an average herd situation, in a herd of 100 calves running together and occasionally being yarded together, all should be infected by the time they are 12 months old is there is a single PI present. This in itself is not a big problem, as the disease's main impact is on the developing foetus. An animal infected before breeding under extensive conditions rarely show symptoms. Once infected, all (except the PI's) develop antibodies and are immune for life.
A problem develops when pregnant susceptible animals are exposed to the PI animal, for instance by mixing groups of cattle that were previously separated, or by a PI animal jumping a fence. The pregnant animals come into contact with the infected animal and its excretions/secretions and become infected. Bulls may also be PI's and infect the cows they mate with.
Depending on conditions the virus can survive for a few hours to a few days in the environment. If a cow aborts an infected foetus, the foetus and placenta are a source of the virus for a short period.
Animals which become infected after birth, regardless of their age, rarely show symptoms, but they are viraemic for 7 to 10 days. They secrete small numbers of virus; usually insufficient to infect other animals, though there have been instances of the Type 1 virus spreading from transiently infected animals. Type 2 is more likely to spread to in contact animals in this way.
Symptoms:
If breeding cows are infected close to the time of mating, there will be reduced conception and cows will return to service. Infection later in the 1st trimester of pregnancy causes embryonic death, abortion, stillbirth, the birth of weak non-viable calves and the birth of PI's.
Infection in the second trimester leads to congenital defects, such as eye defects and cerebellar hyperplasia.
Infection in the third trimester does not cause any problems. The foetus mounts an immune response and is born immune to BVDV and is seropositive (has antibodies in his bloodstream)
PI calves are often small, are poor do-ers and immunological cripples. They are prone to common infections such as ringworm, and are reservoirs of other infections.
A PI cow will always give birth to a PI calf.
Young animals that contact BVDV may show mild transient respiratory symptoms, but are often asymptomatic. They have antibodies 13 to 19 days after exposure and remain immune for life. The exception is animals in feedlots. They can develop severe respiratory disease and diarrhoea.
Non pregnant adult animals show no symptoms.
However, BVDV does suppress the immune system and makes animals more susceptible to other infections for up to two months after the initial infection.
Mucosal Disease:
This condition only occurs in PI's after a superinfection with a cytopathogenic strain of BVDV which arises as a mutant form of the persisting virus in a given PI animal. It causes ulceration of the buccal cavity and alimentary tract and leads to the death of the animal. As is the case with their original infection, they do not recognize the mutant virus as foreign and do not mount an immune response. This mutant strain only needs to arise in one PI in a herd and will rapidly spread to other PI's in the mob, due to their immune tolerance. This results in sudden death of clusters of PI's.
The mutant virus does not pose a risk to the rest of the herd.
50% of PI's will usually die in the first year of life. Half or more of the remainder die in the following year. Sometimes a PI will survive for a number of years. A female PI can breed successfully, but her calf will always be a PI.
sources:
www.bvdvaustralia.com
Dr. Peter Kirkland, Alison Bradford, Bruce Watt, David Gardiner and other Rural Land Protection Board District Veterinarians in NSW. E-mail communications.
Cause:
Pestivirus or Bovine Viral Diarrhoea Virus belongs to the Flaviviridae family and the Pestivirus genus. Human Hepatitis C belongs to the same family of viruses, but is a member of the Flavivirus genus. Only Type 1 occurs in Australia. It is less aggressive than Type 2, which occurs in the USA and UK, amongst others.
History and prevalence:
It has been known to be present in Australia for about 40 years. Approximately 90% of herds have animals that test positive for antibodies against this disease, therefore it is widely distributed.
How does it spread:
Calves which survive in utero infection between 30 and 90 days of gestation are born persistently infected. Their developing immune systems do not recognise the virus as a foreign entity and do not produce any antibodies against the disease. Occasionally infection between day 90 and 125 can also result in the birth of a PI. These so-called PI calves are a potent and constant source of virus, excreting vast amounts in every secretion and excretion - eg saliva, urine, faeces, semen etc.
In the general population 0.5% to 1% of animals at 1 to 2 years of age may be PI's. In certain infected mobs of calves it may be as high as 50%.
PI animals often have deranged nervous systems and are more likely than other animals to be aggressive and jump fences, therefore posing a risk to neighbouring herds and farms.
In an average herd situation, in a herd of 100 calves running together and occasionally being yarded together, all should be infected by the time they are 12 months old is there is a single PI present. This in itself is not a big problem, as the disease's main impact is on the developing foetus. An animal infected before breeding under extensive conditions rarely show symptoms. Once infected, all (except the PI's) develop antibodies and are immune for life.
A problem develops when pregnant susceptible animals are exposed to the PI animal, for instance by mixing groups of cattle that were previously separated, or by a PI animal jumping a fence. The pregnant animals come into contact with the infected animal and its excretions/secretions and become infected. Bulls may also be PI's and infect the cows they mate with.
Depending on conditions the virus can survive for a few hours to a few days in the environment. If a cow aborts an infected foetus, the foetus and placenta are a source of the virus for a short period.
Animals which become infected after birth, regardless of their age, rarely show symptoms, but they are viraemic for 7 to 10 days. They secrete small numbers of virus; usually insufficient to infect other animals, though there have been instances of the Type 1 virus spreading from transiently infected animals. Type 2 is more likely to spread to in contact animals in this way.
Symptoms:
If breeding cows are infected close to the time of mating, there will be reduced conception and cows will return to service. Infection later in the 1st trimester of pregnancy causes embryonic death, abortion, stillbirth, the birth of weak non-viable calves and the birth of PI's.
Infection in the second trimester leads to congenital defects, such as eye defects and cerebellar hyperplasia.
Infection in the third trimester does not cause any problems. The foetus mounts an immune response and is born immune to BVDV and is seropositive (has antibodies in his bloodstream)
PI calves are often small, are poor do-ers and immunological cripples. They are prone to common infections such as ringworm, and are reservoirs of other infections.
A PI cow will always give birth to a PI calf.
Young animals that contact BVDV may show mild transient respiratory symptoms, but are often asymptomatic. They have antibodies 13 to 19 days after exposure and remain immune for life. The exception is animals in feedlots. They can develop severe respiratory disease and diarrhoea.
Non pregnant adult animals show no symptoms.
However, BVDV does suppress the immune system and makes animals more susceptible to other infections for up to two months after the initial infection.
Mucosal Disease:
This condition only occurs in PI's after a superinfection with a cytopathogenic strain of BVDV which arises as a mutant form of the persisting virus in a given PI animal. It causes ulceration of the buccal cavity and alimentary tract and leads to the death of the animal. As is the case with their original infection, they do not recognize the mutant virus as foreign and do not mount an immune response. This mutant strain only needs to arise in one PI in a herd and will rapidly spread to other PI's in the mob, due to their immune tolerance. This results in sudden death of clusters of PI's.
The mutant virus does not pose a risk to the rest of the herd.
50% of PI's will usually die in the first year of life. Half or more of the remainder die in the following year. Sometimes a PI will survive for a number of years. A female PI can breed successfully, but her calf will always be a PI.
sources:
www.bvdvaustralia.com
Dr. Peter Kirkland, Alison Bradford, Bruce Watt, David Gardiner and other Rural Land Protection Board District Veterinarians in NSW. E-mail communications.
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