PULLORUM DISEASE OF CHICKS

Transcription

1 PULLORUM DISEASE OF CHICKS (Bacillary White Diarrhea) By ROBERT GRAHAM Young chicks fatally affected with pullorum disease UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURE : AGRICULTURAL EXPERIMENT STATION AND EXTENSION SERVICE Circular 432

2 PULLORUM DISEASE is a chronic infection of the yolks or ova of mature fowls which is transmitted thru the egg to baby chicks. In young chicks the same infection is often fatal. Chicks that apparently recover are chronically infected and should never be used for breeding purposes. As pullets they again spread the disease to young chicks thru infected eggs, as well as to mature fowls thru association. Fig. 1.- Transmission of Pullorum Disease in Breeding Stock Thru the Egg to Young Chicks Special attention to feeding and management, as well as to incubator hygiene, is necessary in flocks infected with pullorum disease. For information on these subjects see Illinois Agricultural Experiment Station Circular 275, "Feeding for Egg Production;" Circular 329, "Raising Chicks at a Profit;" Circular 374, " Keeping the Farm Flock Healthy; " and Circular 403, "Incubator Hygiene in the Control of Pullorum Disease." U rbana, Illinois March, 1935 Printed in furtherance of the Agricultural Extension Act approved by Congress May 8, H. W. MVMf9RD, Director, Agricultural Extension Service, University of Illinois.

3 Pullorum Disease of Chicks (Bacillary White Diarrhea) By ROBERT GRAHAM, Chief in Animal Pathology and Hygiene PULLORUM DISEASE is a highly fatal and contagious disease of young chicks. A large percentage of losses from disease in chicks under three weeks of age appears to be traceable to this cause. Its ravages have rendered many flocks unprofitable. The disease is one of the few affecting adult fowls that may be transmitted directly thru the egg to the newly hatched chick. It is rare that mature sto~k infected with the disease show any symptoms, yet when infected hens are killed and the body cavity opened, abnormal or diseased yolks are found. Infected parent stock and contaminated incubators and brooders are largely responsible for the presence of the disease in young chicks. The specific cause of pullorum disease is a microscopic germ known as Salmonella pullorum. This organism gains entrance to the chick thru the respiratory or alimentary tract with contaminated air, feed, or water, or, as indicated above, it may have been in the egg from which the chick was hatched. The germ is found in the blood, in the unabsorbed yolk, and in the internal organs of baby chicks following death from the disease. The droppings of affected chicks, as well as infertile or unhatched eggs from infected breeding fowls, often contain Salmonella pullorum in large numbers. Conditions which tend to weaken the vitality of baby chicks are regarded as important factors in susceptibility to the disease. Proper brooding and handling of chicks from infected stock or of those exposed to the disease are regarded as helpful in reducing losses. Symptoms in Baby Chicks Chicks are most susceptible to the disease before they are five days old, tho symptoms may not be observed for several days after exposure. Heavy losses in chicks under three weeks of age are often traceable to an acute type of the disease. Affected chicks are weak and unsteady in standing or walking. The feathers are ruffled, the, eyes closed, and the wings drooping. Diarrhea usually develops, with a "pasting up behind," and death follows in a few hours. Chicks suffering from an acute type of the disease, however, may die before symptoms of diarrhea appear. The absence of diarrhea, therefore, cannot be regarded as definite evidence of the absence of pullorum disease. An accurate diagnosis of pullorum disease can be made only by laboratory examination. A flock owner who suspects the presence of 3

4 4 CIRCULAR No. 432 the disease should send typically affected live chicks to a properly equipped laboratory for examination. Specimens in limited numbers will be examined without charge by the Laboratory of Animal Pathology and Hygiene, University of Illinois, Urbana. Surviving Chicks Should Not Be Used as Breeders Chicks that suffer a temporary setback from a mild attack of pullorum disease, followed by apparent recovery, develop a low-grade, chronic type of the disease in the yolks or ovaries and, as mature birds, will pass on the infection to young chicks in subsequent hatching seasons. Therefore such chicks should not be kept for breeders. Symptoms of unthriftiness and lameness and a tendency to develop large abdomens are often observed in chicks that survive an acute attack of the disease. How the Disease Spreads The part which mature infected fowls play in transmitting the disease to baby chicks thru the egg has been established in experimental tests and confirmed in outbreaks of the disease in farm flocks. In fact repeated heavy losses of baby chicks unexplained by other causes are often the first suggestion of the disease in mature fowls. Pullorum disease may thus be regarded as being transmitted thru the egg to the chick, and from egg-infected chicks to healthy chicks thru contaminated droppings in incubators, brooders, and water and feed containers. One chick infected with pullorum disease at hatching time is capable of contaminating incubators and spreading the disease to the entire brood. While it is not definitely established that pullorum disease is commonly spread among adult hens thru association with infected hens or by an infected male in breeding, it is possible that the rapid progress of the disease in some breeding flocks may be accounted for in this way. Control of Pullorum Disease The control of pullorum disease depends largely upon two factors: first, the detection of infected breeding fowls by means of certain tests and their removal from the flock; second, the sanitary protection of healthy chicks against infection in incubators, brooder houses, and contaminated runways. The greatest progress in freeing flocks from pullorum disease has been made by owners who have removed infected breeding stock and applied the fundamentals of chick sanitation. In healthy, vigorous flocks, properly managed, the complete extermination of the disease is possible. In fact, several clean flocks have been established and the amount of infection greatly reduced in other flocks in which pullorum disease was found.

5 PULLORUM DISEASE OF CHICKS 5 FIG. 2.-NoRMAL OVA OF A HEALTHY HEN FIG. 3.-0VA HARBORING Salmonella pullorum. THE DARK RED ANGULAR OVA ARE VISIBLY DISEASED

6 6 CIRCULAR No. 432 It is to be expected that some flock owners will be more successful than others in stamping out this disease, yet anyone can reduce losses by adopting approved methods of sanitation and testing his flock regularly. Tests for Detecting the Disease The testing of flocks for pullorum disease is usually done in the late fall, after culling. The value of the tests in detecting infected breeding stock over one year of age is well established, altho it must be acknowledged that no biological test is perfect and that repeated tests are more valuable than a single test. The tests for pullorum disease represent but one part of the control program. In order that they may give the best results, they should be applied by skilled persons. FIG. 4.-Box FOR WHOLE-BLOOD STAINED-ANTIGEN TEST This wooden box can be carried with ease and may be operated by one person. Properly identified slides on which the blood and antigen are mixed are placed in trays, each tray holding six slides. The glass plate protects the samples from dust and rapid drying. When the samples are ready to be read, the trays can be removed. The Whole-Blood Stained-Antigen Test The whole-blood stained-antigen test is used extensively in Illinois by veterinarians and technicians in preference to the tube and pullorin tests because, when properly conducted and interpreted, it can be more quickly dispatched and is less expensive. Fowls may be tested by this method in from Yz to 3 minutes and reactors removed from the flock in a single handling. Collecting and sending samples to the laboratory for

7 PULLORUM DISEASE OF CHICKS 7 FIG. 5.-TEST! G TABLE A table with adjustable legs and sufficient table space for materials employed in the test is convenient. the tube test, and the necessity of handling the fowls a second time, are eliminated. Equipment.-Various testing boxes for the whole-blood stainedantigen test have been used. A simple box such as that used in Illinois (Fig. 4) has proved satisfactory and economical. Additional equipment (Fig. 5) needed includes restraining table, blunt-pointed sharp scissors, clean microscope slides, toothpicks, paper and pencil for re

8 8 CIRCULAR No. 432 cording results, container for used slides, hot water for testing box, cold water for cleaning slides, and clean towels. Procedure.-Hold the fowl with the left arm, and grasp the head firmly. Snip the comb with-a pair of sharp scissors (Fig. 6), and turn the head to one side so that a drop of blood will fall on the center of the slide (Fig. 7). If the chicken has a single, well-developed comb, the end of one point may be snipped. Small combs or rose combs may be snipped just above the beak. As soon as the drop of blood is collected, place an approximately equal amount of stained antigen near the drop of blood (Fig. 8) and thoroly mix the two with a clean toothpick. It is important to avoid touching the tip of the antigen dropper to the drop of blood. If a sample becomes gelatinous and fails to mix evenly, it should be discarded and another sample collected. Immediately after mixing the sample, place the slide in the slide tray of the box. The temperature of the box is maintained by hot water (Fig. 9). The temperature of the tray should approximate body temperature. If the trays are too hot, the antigen-blood mixture will dry too rapidly and the results may be unreliable. Removing the FIG. 6.-SHARP} BLUNT-POINTED SCISSORS ARE USED FOR SNIPPING C01\1B In collecting a blood sample, hold the fowl against the body under the left arm, holding the head in the left hand. Snip the comb at the base. One large or two small drops of blood are sufficient for the test. If the bleeding persists from the comb, tincture of chlorid of lime may be applied to stop the flow of blood.

9 PULLORU M DISEASE OF CHICKS 9 FIG. 7.-SINGLE DROP OF BLOOD ON MICROSCOPE SLIDE After snipping the comb, turn the head of the fowl as illustrated above, collecting the blood sample on a slide held in the right hand. It is important that the blood for the test be delivered on the center of the slide. FIG. S.-SINGLE DROP OF ANTIGEN ADDED TO SLIDE Place an amount of stained antigen on the slide with a pipette, adjacent to the drop of blood. The amount of antigen delivered should approximate the size of the drop of blood.

10 10 CIRCULAR No. 432 tray from the box frequently and tilting it hastens agglutination and facilitates the reaction. After the results are read, drop the used slides in water, and thoroly wash and dry before using them again. Interpretation of the Test.-Experience is required to interpret correctly the results of the test. If the mixture of blood and antigen remains homogenous and shows no clumping, the test is negative and FIG. 9.-HoT-WATER TANK SUPPLIES NECESSARY HEAT The water tank is placed in the lower compartment of the testing box. Hot water is added thru the opening in the end of the tank. The thermometer on the top of the box permits a careful check of the temperature. The slide trays should be kept at or near body temperature. the fowl free from pullorum disease; if the antigen is agglutinated, curdled, or clumped in small particles, the test is positive and the fowl is infected with pullorum disease and should be removed from the flock. Decidedly positive or negative samples are easily read (Fig. 10), but doubtful reactions, such as ropiness and flakiness in bloodantigen mixtures, are difficult to interpret. If natural light is not available from a window or open door during testing, good artificial light must be provided. Results cannot be read satisfactorily in a dark poultry house, especially late in the afternoon. It is necessary to confine the birds in a systematic manner in order that the results on each may be identified. A wooden table with restraining blocks at each side is very satisfactory for this purpose (Fig. 11). This table holds 24 birds; it is constructed in four sections, each holding 6 birds and corresponding with the four trays in the box. The fowls can thus be identified by numbering the trays to correspond with the sections on the table, or by painting the trays and the sections on the table in corresponding colors. Efficiency of the Whole-Blood Stained-Antigen Test.-The efficiency of this test for pullorum disease in fowls is dependent upon

11 PULLORUM DISEASE OF CHICKS 11 FIG. 1O.-NEGATIVE AND POSITIVE TESTS Slides should be carefully rotated in proper light in order not to overlook a positive reaction. If the mixture of blood and antigen remains homogenous and shows no clumping, the test is negative (upper slide). If the antigen is agglutinated, curdled, or clumped in small particles, the test is positive (lower slide). FIG. 11.-RESTRAINING TABLE FOR FOWLS The posltion of the fowl on the table identifies it with the blood sample number on the slide. The table is constructed in four sections, each of which holds six fowls, twelve on each side of the table. These four sections correspond with the four trays in the testing box.

12 12 CIRCULAR No. 432 many factors. The antigen must be properly diluted, the technic of applying the test must be acceptable, the air should be dust-free, and the light must be good. The Illinois State Department of Agriculture accredits properly qualified veterinarians to assist flock owners in giving the official whole-blood stained-antigen test. Where the service of accredited veterinarians is not available, technicians have been authorized to conduct the test. This procedure protects flock owners against imposters and enables them to obtain the most reliable diagnosis possible in the control of pullorum disease in breeding flocks. In badly infected flocks monthly tests need to be made until all reactors are eliminated. An annual test of flocks, particularly where infection is high, is not sufficient for the satisfactory control of pullorum disease. Ten Essentials in Sanitation and Testing To combat pullorum disease successfully, a flock owner must adhere carefully to the following practices: 1. Avoid purchasing eggs or breeding stock from infected flocks. 2. Disinfect incubators, brooders, houses, and equipment. 3. Do not hatch eggs from tested and nontested birds in the same incubator. 4. Arrange to grow newly hatched chicks on clean grass range which has not been occupied by fowls for a period of one year, or spade up old ground frequently. S. Brood and feed chicks carefully to maintain vigor and resistance to disease. 6. Avoid feeding infertile uncooked eggs. 7. Destroy all dead chicks by burning. S. Test annually all breeding flocks that have been freed from the disease and infected flocks monthly until all reactors are detected. 9. Promptly remove all reactors. 10. Keep houses and water and feed containers clean and disinfect once a month, or as often as necessary to hold the disease in check. Infected Hens Lay Fewer Eggs In mature stock, loss in egg production due to pullorum disease is more serious than the death loss. Infected hens are apt to lay fewer eggs than hens that are free from disease, other factors being equal. There is also evidence that eggs from hens that are free from pullorum disease have a higher hatching rate than eggs from infected stock. The increased livability of chicks from healthy stock over chicks from infected stock has been observed experimentally and repeatedly confirmed by farmers and hatcherymen who have used sanitary measures and testing in attempts to wipe out the disease M SM- 7768