Notes for the Poultry Farmer

New Zealand Journal of Agriculture, Volume 64, Issue 1, 15 January 1942, Page 63

Notes for the Poultry Farmer

Pullorum Disease, or Bacillary White Diarrhoea of Chicks

PULLORUM disease, or “8.W.D.” as it is often called, is primarily a disease of baby chicks. Fortunately, it has not become a scourge in New Zealand, and furthermore, when it has occurred, Pullorum appears to be milder in form than is experienced in, say, England or the United States. The fact remains, however, . that this disease is existent in the Dominion, and might easily become firmly established, even in a more severe form, unless steps are taken immediately to bring it under control. Can “B.W.D” Be Easily Recognised? It should be clearly understood that poultrykeepers are not in a position to recognise or diagnose “8.W.D.” among chickens. The disease may be suspected, but only a complete laboratory examination can determine beyond doubt the presence of “8.W.D.” in a chicken. It will be shown. later that this disease is also carried by adult stock, but here again it is impossible to recognise its presence in a bird while still alive on the farm. In fact, it is possible to have apparently healthy birds in full lay carrying the germs of this disease. Poultrykeepers should not attempt, therefore, to recognise “8.W.D.” in either their chickens or laying birds. Even the presence of a white diarrhoea does - not necessarily mean that a bird is affected. When to Suspect “B.W.D” “8.W.D.” is caused by a minute .organism, the technical name for which is Salmonella pullorum. With infected laying birds, it is usually found only in the ovaries (yolks), and in most instances has no serious effect upon the bird. With chicks, however, the germs may spread to many of the organs, with fatal results. Certain .chicks will recover from an attack of “8.W.D.” and often then retain the germs, ( which finally become centred in their ovaries. Is There a Cure? „ . The answer is an emphatic—NO! Any attempt to cure infected chicks or adult birds is a waste of time and money.

By

F. C. BOBBY,

Superintendent of Poultry Husbandry, Wellington.

How Infection Is Spread Infection in the case of baby chicks comes through the eggs at hatching time. Laying birds whose ovaries are infected are referred to as “carriers,” and during the breeding season a certain number of their eggs carry germs of this disease.' If these germ-infected eggs are hatched, then the resultant chicks are infected with “8.W.D.” organisms. Should these organisms multiply, the chicks are attacked by the disease, and in most cases die, but before doing so will pass droppings laden' with germs. These droppings may, in turn, infect other . healthy chicks, and so the disease is spread. It has also been established that .adult stock “carriers” pass droppings containing “8.W.D.” germs, and in this way a gradual increased ection may develop among a laying flock. It should be noted, however, . that the poultrykeeper will see no signs of the increased infection, and will be totally unaware of this growing trouble. That trouble exists will become obvious only when mortality among his baby chicks becomes excessive. Control of “B.W.D” As there are no means of curing either infected hens or chicks, it is fortunate that there is a satisfactory method of detecting “carriers.” which are responsible for spreading this disease. Once detected, these “carriers” may be removed from the flock and killed for table purposes. They ar* in no way unsuitable for human consumption. “Carriers” may be detected by what is usually called “blood testing” the flock, and this test may be made in two ways: (a) For the first method, it is' necessary to have every bird to be tested leg-banded with a numbered' ring. A small sample of blood is drawn into a glass tube from a vein in the wing, and a label on the tube is marked with the bird’s number. Samples from each .

bird are forwarded to the laboratory, and the poultrykeeper is subsequently informed which numbers reacted to the test. The birds , whose leg ' bands correspond with numbers given are 'then removed from the flock as “reactors,” being, in fact, “carriers.” This is known as the “tube" test” method. J (b) For the second method, a large drop of blood is ' obtained from the comb or vein in the wing, and placed on 'a glass slide. To this-; blood is added a specially-prepared liquids referred. to as “antigen,” and within a minute or two the tester is able to say whether the bird is a “reactor” ..(“carrier”) .or not, according ,to the effect of the blood upon the antigen. This method is referred to as the whole-blood “rapid test.” While ; satisfactory,' this second method is not as accurate as the “tube test,” but helps the poultyrkeeper in that less labour is involved and no numbered rings are required. Poultrykeepers are strongly advised to “blood test” their birds once an outbreak of “8.W.D.” has been diagnosed among their chickens. It is. the only satisfactory method known at the present time of controlling and eventually eliminating this disease. When to “Blood Test” Assuming that an outbreak of “8.W.D.” has occurred, the first essential is to blood test the breeding stock. This may be done immediately if the outbreak occurs at the beginning of a rearing season. In this way, further losses with chicks from “8.W.D.” may be avoided during that season.

Alternatively, all possible breeders for the following season may be tested just before the birds go into the annual moult. If the number of reactors proves to be high, then it is advocated that the remainder be retested after the moult to ensure the elimination of any reactors which failed to show up in the first test. This is the only effective way to control this disease. Furthermore, it is a wise precaution to test, when on the point of lay, all pullets which have survived an outbreak of “8.W.D.” The elimination of “carriers” at this stage appreciably lessens the chance of infection spreading among the adult stock. It is

also strongly recommended that “bloodtesting” be carried out for more than one year following an outbreak of “8.W.D.” Poultrykeepers are warned that testing for one year only does not necessarily protect their birds from a further mild infection, which in time is likely to become serious again. What To Do With y “Reactors” / All “reactors” or “carriers” .discovered by “blood testing” are, in fact, a source of danger to healthy birds. For this reason, the Department stipulates that they must not leave the farm unless for killing purposes. It

is obvious that, if sold on the market or direct to another farm, such birds could easily be responsible for starting a fresh outbreak of this disease. If they are retained on the farm after a test has been conducted, then it is equally obvious that they must be kept quite separate from the tested or healthy stock. Carelessness in this respect can easily lead to a re-infec-tion of the non-reactors or healthy birds. Precautions Apart from blood testing, there are certain precautions which should be taken when “8.W.D.” occurs among chicks:— (1) Remove as often as possible all dead and sickly chicks from the brooders. These should /be destroyed by burning. (2) Change the litter at weekly intervals for the first three weeks in all pens where the disease has appeared. This litter should be burned. (3) Drinking vessels and hoppers should be kept clean and disinfected frequently during the first three weeks. The use of caustic soda and boiling water is strongly recommended for this purpose. (4) No chicks from an infected brood should be allowed to mix with other healthy broods. (5) An incubator which has hatched chicks subsequently proved to be suffering from “8.W.D.” should be thoroughly disinfected (see notes on fumigation). (6) All chick boxes which have carried baby chicks subsequently proved 'to' be suffering from “8.W.D.” should be burned. (7) Pullets surviving an outbreak should be treated with suspicion, as there are almost certain to be “carriers” among such birds. On no account should these birds be bred from, either as pullets or hens, until they have been “blood tested.” Such a practice would be helping to spread the disease. - ' Fumigating Incubators There is ample evidence to show that “8.W.D.” can be spread in an incubator during hatching time, more especially in cabinet incubators, where a fan is employed for forced air ventilation. Fluff and other dry material,, which may be carrying disease germs, is distributed throughout the hatching compartment, and can in this way spread the disease to healthy chicks. To prevent this spread of infection, formalin (40 per cent, formaldehyde) may be used as a disinfectant at the time of hatching. Fumigation of incubators in ' this way is a method of reducing the spread of “8.W.D.,” but is not a satisfactory means of eliminaating the disease from a farm.

It is essential that fumigation should be carried out with care, and only when 'the poultry keeper has a full knowledge of the > correct procedure. While the Department does not recommend that fumigation should be carried out as a routine practice, full details will be supplied on request to any poultrykeeper who wishes to use this method of control for “8.W.D.” Evidence collected in New Zealand does not support the view that serious trouble from the spread of this disease in cabinet incubators is being experienced. This is probably due to the mild form of infection at present existent in the Dominion. Where Help Can Be Obtained Poultrykeepers are urged not to accept undue losses among their young chickens without requesting help from the Department. Where losses are heavy during the first ten days of brooding, about four or six dead chicks should be forwarded immediately to— The Chief Diagnostic Officer, Animal Research Station, Wallace ville. A report upon the chicks will be supplied free of charge. Should this report state that the chicks died of “8.W.D.,” then it is essential to consider “blood testing” all breeding stock involved. A request to “blood test” should then be made to the Superintendent of Poultry Husbandry, Department of Agriculture, P. 0., Box 3004, Wellington, when particulars concerning a supply of antigen for “blood testing” will be forwarded without delay.