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Tse Surveillance In Australia

Transmissible spongiform encephalopathies (TSE) are a group of fatal neuro-degenerative diseases of both humans and animals.

By Wellington Shire Council - 7th August 2003 - Back to News

Bovine spongiform encephalopathy (BSE) and scrapie are members of this group of diseases, and though it is known that these diseases affect only cattle and sheep, they have very serious implications in the world-wide incidence of a human form of TSE, variant Creutzfeldt-Jakob disease.

Australia is presently free from both BSE and scrapie. However, due to international edict requiring trading partners to prove the absence of disease, Australia has implemented a national strategy to monitor the national cattle and sheep populations for both clinical and histological evidence of disease. The National Transmissible Spongiform Encephalopathy Surveillance Program (NTSESP) is a jointly funded venture involving industry and government, specifically aimed at achieving on-going demonstration of Australia’s freedom from BSE and scrapie. Implementation of the program will also facilitate the early detection of these diseases should they occur in Australia, thus assisting in the maintenance of Australia’s market access.

NTSESP involves detailed examination of several hundred cattle and sheep nation-wide annually. Each state has a designated quota assigned depending on the size of the state’s herd and flock. Individual animals identified as potentially eligible candidates for inclusion in the program must meet several species dependant guidelines. In Victoria, these eligibility criteria include cattle 2 years of age or more, which do not recover after exhibiting one or more specific neuro-degenerative signs, or cattle of 4 years of age or more displaying a chronic progressive disease or wasting. Similarly, sheep of 2 years of age or more, which do not recover after displaying neuro-degenerative signs, or sheep which are 2 years of age or more and exhibiting chronic progressive disease or wasting, are preferred candidates for further examination.

Producers can assist in maintaining the program by reporting animals exhibiting suspicious behavioural patterns to their local veterinarian, DPI Veterinary or Animal Health officer. Incentive payments are available to producers for suitable candidates, however the animal must be examined initially while alive and a report prepared relating to clinical signs.

Further information of the risk of TSE’s in Australia’s livestock industries, and measures to counteract the risks can be provided by local DPI Animal Health staff and private veterinary practitioners. Alternatively, information and links to related sites can be found on Animal Health Australia’s web site, located at www.aahc.com.au.

SALMONELLOSIS IN CATTLE

Salmonellosis in cattle is a bacterial disease that is usually caused in Australia by either Salmonella typhimurium or Salmonella dublin. It causes either diarrhoea or septicaemia, and death can result if treatment is not prompt. Disease outbreaks can occur under certain circumstances, particularly following periods of stress.

The economic effects of salmonellosis include losses due to death of livestock, loss of milk production and growth in affected animals, abortion of pregnant animals, treatment and veterinary costs and the costs of control and prevention. Additionally, people can be infected with the bacteria and cases of salmonellosis are of human health concern.

Cattle are infected by taking in the bacteria when eating infected food or drinking infected water. Many are carriers of the bacteria, and only develop the disease when they are stressed. Other cattle develop the disease when exposed to large numbers of bacteria in the environment, such as occurs after there have been clinical cases of salmonellosis in the herd. The bacteria can be introduced onto farms by carrier animals, rodents, birds and contaminated feed. The bacteria can survive in the environment for long periods. Salmonella typhimurium can remain viable on pasture and in soil, still water and faeces for up to 7 months. Drinking water can remain infected for up to 9 months.

Clinical signs - For Salmonella dublin, sporadic cases occur when individual animals are exposed to stress. Severe outbreaks are rare, but occur when there is severe stress to the whole herd. For Salmonella typhimurium, it is usual to have a single animal or a small number of animals affected at one time. When disease occurs in calves it is usually much more severe, with many affected.
Diarrhoea is most commonly seen, in both calves and adult cattle. The affected animals become lethargic, completely lose their appetite and develop a fever (40-41^oC) in addition to having diarrhoea. The diarrhoea is watery, and may contain mucous, blood and sometimes sheets of intestinal lining. It often has a putrid smell. The animal loses weight and strength rapidly, becomes recumbent and dies within a few days if not treated.
There is also a septicaemic form. In this case the affected animal becomes depressed and dull, develops a very high temperature (40.5-42^oC) and generally becomes recumbent. Newborn calves often develop the septicaemic form of disease, and in this case nervous signs such as incoordination occur in addition to the signs mentioned above. Death is generally fairly rapid, within 24-48 hours, unless there is prompt treatment.
Pregnant cattle will often abort after developing salmonellosis, even if they recover.

A number of other diseases can cause signs similar to salmonellosis, such as other bacterial diseases, some viral diseases, and some parasitic diseases like worms or coccidiosis.
The history combined with faecal culture of affected cattle and post mortem of dead cattle can confirm that salmonellosis is the problem. It can be important to determine which strain of bacteria is involved in order to decide how best to control and prevent disease in the herd

One of the most important factors in treatment is to rehydrate affected cattle with electrolytes. In severe cases the cattle need to be given large quantities of electrolytes by either drenching or stomach tubing.
It is also important to treat affected cattle with the appropriate antibiotics, which can be given by either injection or by mouth, usually as a drench.

Good management and hygiene are key factors to preventing salmonellosis. Salmonellosis often follows times of stress, such as calving, transportation, overcrowding, induction or food deprivation. Minimising stress can be an important means of preventing this disease.
Taking care that water sources are not overly contaminated by faeces is another important preventive factor.

Cattle sick with salmonellosis should be isolated from the herd to reduce contamination.
A vaccine is available for the two most common types of salmonella in cattle. Some properties with a history of salmonellosis or which are bringing calves in from a number of different properties vaccinate routinely. Vaccination can also be used in an outbreak situation to reduce the likelihood of other cattle developing the disease if they are being exposed to the same stressful situation or large amounts of contamination.

Source: www.gippsland.com

Published by: news@gippsland.com