Pullorum Disease of Chickens and Turkeys

J. E. WILLIAMS, PAUL B. ZUMBRO, AND A. D. MACDONALD.

PULLORUM DISEASE, which occurs in all parts of the world, is caused by a microscopic organism, Salmonella pullorum. The chicken seems to be the natural host of the organism, but the disease has become increasingly serious among turkeys as the commercial hatching of turkey eggs has increased.

Pullorum disease may also strike ducks, guinea fowl, pheasants, sparrows, quail, bittern, geese, pigeons, doves, parakeets, and canaries. The organism, which was discovered in 1899, is rarely found in mammals.

Pullorum disease causes heavy death losses in chicks and poults and reduces the productivity of adult birds. The deaths occur mainly during the first 3 weeks after hatching. Losses may be as high as 80 to 90 percent of the brood. Pullorum disease is not commonly encountered in the acute form in birds more than 1 month old. The infected adults usually show no outward evidence of infection.

Once commonly known as bacillary white diarrhea (B.W. D.) of chicks, pullorum disease for more than a half- century has been recognized as one of the worst of all poultry diseases.

Great strides have been made toward eradicating it through a national program of blood testing adult breeding flocks, supplemented with the widespread practice of sound sanitation.

The main reservoirs of pullorum infection are the egg-producing organs of the infected hen. The disease is transmitted from her to the chick or poult directly through the egg.

The infection may be spread among the brood through breathing or consuming contaminated dust, down, or other material in the incubator, shipping box, brooder, or pen. The disease is transmitted also through consumption of litter, feed, or water contaminated with infected droppings. One infected chick or poult at hatching time may be responsible for transmitting the disease to the entire brood. The infection is usually spread during the first few days. Unsanitary conditions, improper heating or ventilation, and the occurrence of other diseases hasten the spread.

Infected chicks or poults that do not die of the disease may grow to maturity and remain lifetime carriers. Infected hens may lay infected eggs that may hatch diseased chicks; thus the cycle is repeated. Transmission sometimes happens among adult fowl through consumption of infected droppings or broken eggs.

THE SYMPTOMS exhibited by infected chicks and poults are by no means specific but may lead one to suspect the disease. Losses may start in the incubator or shortly after hatching, when infected eggs are the source of the disease. As a general rule, however, several days elapse before heavy losses start. Losses tend to decline during the third and fourth weeks.

Pullorum-infected chicks and poults show symptoms of extreme depression, huddling together with closed eyes and with drooping heads and wings, ruffled feathers, frequent passages of liquid feces, which results in pasty vents, shrill chirping, and loss of appetite.

When the infection reaches the lungs, the birds may breathe with difficulty and extend their heads in an effort to breathe. Surviving birds may be runts.

Listlessness, a lack of appetite, diarrhea, increased water consumption, and a paleness of the comb may be observed when the infection is acute among adults.

Postmortem findings in chicks and poults are usually observed in the liver, spleen, heart, and lungs as a generalized infection. Those organs are enlarged and often covered with streaks of hemorrhage or minute white spots, in which the organisms are centered. Larger areas of infection in the form of abscesses lumps may occur in the heart wall and through the lungs. The lumps may be observed also along the intestines and in the muscle of the gizzard. The sac covering the heart may be thickened and cloudy. The contents of the yolk sac often are dry and cheesy. The blind sacs (ceca), located toward the end of the intestinal tract, frequently contain a dry core.

The findings in maturing and adult birds that die of acute pullorum infection are like those in young birds. The more frequently observed lesions of adults are in the chronic carrier. On Postmortem examination, one generally finds the most clear-cut lesions in the ovary of the chronic carrier. The ova are thickened, misshapen and discolored, and filled with a cheesy or watery material. Diseased ova may be clustered among normal ova or suspended on stemlike extensions from the main body of the ovary. Ovarian lesions are suggestive of pullorum disease. Other lesions in chronically infected adults include abscesses on the heart wall, thickening of the heart sac, and generalized infection of the abdominal cavity, with an accumulation of fluid and pus.

For accurate diagnosis, bacteriological tests must be made in a laboratory, because the symptoms and postmortem findings merely suggest the infection.

Adult or maturing birds that react suspiciously to the pullorum blood test and chicks and poults that show symptoms of acute pullorum disease should be submitted to a State diagnostic laboratory for examination.

This service is available at most State agricultural colleges. The laboratory culture tests are essential in distinguishing pullorum disease from fowl typhoid and paratyphoid infections, which are also eggborne diseases closely related to pullorum. Birds infected with fowl typhoid react to the pullorum test. Occasionally birds infected with certain paratyphoid types, as well as other micro-organisms, may react to the test. After the organisms have been isolated in the laboratory, their biochemical activity can be determined and a detailed report can be issued on the exact type of infection involved. This information is often useful in guiding the pathologist in making recommendations regarding treatment and control.

When an acute disease outbreak occurs, it is usually best for the owner to take several live birds and several dead ones to the laboratory for examination. The laboratory procedures for pullorum diagnosis generally take 48 to 96 hours to complete.

CONTROL AND ERADICATION Of pullorum disease must be based on breaking the cycle of transmission. That is done by detecting and eliminating adult carriers, because the disease is largely eggborne. Such a procedure makes the owner reasonably sure that only noninfected eggs are set and non-infected chicks and poults are hatched.

Blood testing of adult chickens and turkeys in breeding flocks is done throughout the United States. The agglutination test, used in detecting pullorum carriers, is conducted by one or more of the three officially recognized methods; namely, the tube agglutination test, the rapid whole-blood plate test, and rapid serum plate test.

Each test is based on the fact that infected birds carry in their blood stream immune substances (antibodies), which will clump (cause to stick together in a compact mass) a liquid suspension of killed-pullorum organisms (antigens) when the test suspension is mixed with the serum or the whole blood of the infected bird. The clumps are visible to the unaided eye and indicate that the living organisms and the antibodies that they stimulate are present in the bird. The blood of noninfected birds does not contain any antibodies, and therefore no clumps form when the whole blood or serum of such birds is mixed with the antigen.

The rapid whole-blood test has been most widely used for testing chickens. The test is easily conducted in the field by anyone trained in its use.

State agricultural colleges for years have held schools to train poultrymen in conducting blood tests and practicing other procedures for controlling pullorum disease.

The three agglutination tests mentioned as being used for diagnosing pullorum disease are described in The National Poultry Improvement Plan and National Turkey Improvement Plan and Auxiliary Provisions. This publication is available from the Agricultural Rem search Service, Washington 25, D. C.

A VARIANT TYPE of pullorum disease was recognized in Canada in 1941. Outbreaks occurred in chicks in flocks that tested negative to the standard agglutination test and were maintained on uninfected premises. The outbreaks had the same history and symptoms as typical pullorum disease. Cultures were isolated and studied. All were identical to Salmonella pullorum, except that they varied in their antigenic makeup from the official pullorum strains that were used to produce antigens (liquid testing fluids containing killed-pullorum organisms). These usual or so-called "standard" antigens often did not react in the presence of serum from the outbreaks noted. This new form of pullorum disease was designated "variant type." It has been found in many sections of the United States.

In order to detect both the standard (usual) and the variant forms of pullorum infection, a polyvalent-type whole-blood antigen has been widely used in testing. The polyvalent antigen consists of a mixture of both standard and variant-type cultures of Salmonella Pullorum organisms; the standard antigen contains only standard-type cultures. Both standard and polyvalent whole-blood type antigens are available commercially.