Some causes of Salmonella

by Various

If the birds do have salmonella. It is a very serious disease for birds and even those that live, in my opinion, should never be bred again. Some causes of salmonella are mixed aviaries, too crowded an aviary, contaminated food, contact with outdoor birds or rodents. Some ways that new born babies can become affected.

Contamination of food at source, proprietary egg food is a potential danger.

Contamination of food or water by rodents or wild birds in the aviary or store.

Contact with a newly-acquired infected bird.

Less commonly, infection is spread at shows or as the result of handling by visitors who have been in contact with the bacteria. Spread throughout an establishment is aided by overcrowding, allowing food to become stale, scattering seed and food where it can attract vermin, and other unhygienic practices. Flies and some parasites are also capable of transmitting the disease, while some strains of salmonella are able to live for almost four months in stagnant water in temperate climates.

CLINICAL SIGNS:

In an outbreak, the initial picture may depend on the source of infection and the age groups first affected. The severity may also depend to some degree on the type of Salmonella responsible. The severest and most acute outbreaks are usually seen in young chicks, for example, when infected egg food is fed to parents and later to offspring. The parents at this stage may show little evidence of disease. However, low hatchability rates, dead-in-shell or weak newly-hatched chicks, and chicks "fading" during the first few days of life are strongly suggestive of the infection. The blood, other tissues and droppings of such chicks as well as the parents excreta, are rich sources of the organisms. As little as 10 per cent of all eggs incubated may hatch, and all of these chicks may die before leaving the nest. Signs range from sudden death to gradual onset of depression over one to three days, accompanied by huddling of the birds, fluffed up feathers, unsteadiness, shivering, loss of appetite, markedly increased or absence of thirst, rapid loss of weight, accelerated respiration, and watery yellow, green, or occasionally blood-tinged droppings. The vent feathers become matted with excreta, the eyes begin to close, and immediately before death some birds show apparent blindness, inco-0rdination, staggering, tremors, or other nervous signs including convulsions.

DIAGNOSIS:

Diagnosis cannot be made on clinical signs alone. Confirmation depends on isolating the bacteria from the heart blood or lesions of dead birds and the droppings of live, recovered carriers, but this can only be done in a properly equipped laboratory. This is called a NECROPSY or a form of autopsy for birds. In an establishment where occasional losses have been experienced in several age groups, examination of droppings from birds which have been in close contact with the dead birds should be made because salmonellosis can be well established before it is even suspected. When an infection is well distributed throughout the stock and established, but not causing heavy losses, it is said to be endemic or enzootic. When an infection suddenly wreaks havoc in an aviary, causing a high incidence of clinical disease and deaths, it is referred to as an epidemic or epizootic. Blood testing methods for antibodies is a useful means of identifying carrier birds harbouring a particular strain of organism.

TREATMENT AND PREVENTlON:

It must be stressed that, short of destroying all infected birds, carriers and those in contact, it is unlikely that an establishment can be entirely cleared of the infection. If rodents or wild birds can gain access, they will soon be acting as a reservoir of the organism. Because of the individual financial, and sentimental value of cage birds, treatment is more generally attempted than in the case of poultry. This reduces mortality and greatly slows the onset of new cases of clinical illness but masks infected birds by turning them into symptomless carriers. Treatment must be prolonged, and repeated at intervals in all valuable birds. Breeding should also be discontinued for the current year. Some would say that once birds are infected they should never be used for breeding again. Minor or major fresh outbreaks are to be expected in following seasons, especially if sudden change of food occurs, also during a cold spell or breeding, or indeed during any conditions of stress. The greatest success in treatment has occurred with the drugs furazolidone and spectinomycin. Sulphonamides, particularly sulphadimidine and sulphadiazine are also quite effective in reducing losses and checking clinical signs. The tetracyclines, chloramphenicol and neomycin generally appear to be less effective, although some strains respond reasonably well. It is advisable therefore to combine or alternate two or more of these drugs. Where drug-sensitivity tests are available, which indicate the particular efficiency of either one or more drugs, these drugs should of course be used. No commercial vaccines are available, but some success has been reported with vaccines made from Salmonella isolated from birds on the affected premises. These "auto-genous vaccines" are said by their advocates to be helpful in controlling outbreaks where the infection is established. The most important factors for prevention are cleanliness, care in the choice and origin of foodstuffs, vermin-proof premises, isolation of new stock and all stock after visits to shows.

This article is not intended to diagnose, treat, cure or prevent any disease. It is intended to be educational and thought provoking. Neither BSSA, or any of its officers, director, employees, or representatives will be liable for any direct or indirect, consequential or incidental damages arising from any information contained herein. The limitation of liability is comprehensive and applies to damage of any kind.