NORTH CENTRAL REGIONAL TECHNICAL COMMITTEE FOR NEWCASTLE DISEASE
Dr. H. Macy, Minnesota, Administrative Adviser Dr. I. L. Baldwin, Wisconsin, Former Administrative Adviser
Illinois ...... Dr. P. D. Beamer
Indiana H • H H • ••••••• H • ...... Dr. H. E. Moses
Iowa ...... Dr. M. S. Hofstad
Kansas ...... Dr. J. 0. Harris* Dr. A. Eisenstar k Dr. L. M. Roderick* Dr. L. D. Bushnell*
Michigan ...... Dr. C. H. Cunningham
Minnesota ...... Dr. B. S. Pomeroy
Missouri ...... Dr. S. C. Benbrook* Dr. H. C. McDougle*
Nebraska .... .Dr. Carl Olson, Jr. Dr. F. R. Woodring
North Dakota ...... Dr. D. F. Eveleth* Dr. F. M. Bolin
Ohio ...... Dr. W. L. Ingalls* Dr. Earl N. Moore
South Dakota ...... Dr. G. S. Harshfield
Wisconsin ...... Dr. C. A. Brandly Dr. R. P. Hanson
Bureau of Animal Industry, United States Department of Agriculture ...... Dr. B. T. Simms Dr. H. C. McPhee Dr. H. W. Schoening Dr. 0. L. Osteen • Former members. CONTENTS
Importance to poultry industry 5 History. 6 Cause 6 Species of birds and animals affected 7 Modes of spread 7 Natural course of the disease 10 Period of incubation 10 Symptoms of Newcastle disease in chicks 10 Symptoms of Newcastle disease in growing stock 11 Symtoms of Newcastle disease in laying birds 11 Symptoms of Newcastle disease in turkeys 12 Symptoms of Newcastle disease in other poultry and birds 12 Factors modifying the course of Newcastle disease 12 Diagnosis . 13 What to do in case of outbreak 16 General recommendations 16 Recommendations for the hatchery 16 Recommendations for the farm 16 Baby chick flocks 16 Growing flocks 16 Laying flocks 17 The broiler plant 17 Prevention 17 Prevention by sanitary management 17 Hatchery 17 Farm flocks 18 Broiler plant 18 Produce plant 19 Feed manufacturer and dealer . 19 The veterinarian 19 Prevention by vaccination . 19 Two types of vaccines 20 Future goals and objectives ... 22
Submitted for publication December 1, 1952 36M-4-53 ~-1:·:1:;: DEATH LOSS
•1::!:1::!.!;~~:!;_l}:l':::l:~:::::.:;:::~:::l::.::::l~:::::.:l::~:::::·:~~.·!!l::··.:l ::·::·:·i·:~:::il:::::l.:':::i:!. LOSS IN GAIN AND EGG PRODUCTION
VACCINATION COSTS
YEARLY LOSS TO POULTRY INDUSTRY Facts about ll
il1••.
B.S. Pomeroy and C. A. Brandly1
EWCASTLE DISEASE is a specific, highly contagious disease N affecting chiefly chickens and turkeys. Other poultry, as well as various species of wild birds, may be attacked also.
Newcastle disease is now considered The greatest loss comes from the effect one of the most important diseases of of the disease on egg production and poultry and is by far the most serious egg quality. In breeder flocks, the dis disease encountered in the chicken ease has additional detrimental effect broiler industry. Experienced poultry on fertility and hatchability of the eggs. men know that Newcastle disease causes Further evidence of the losses to the severe losses directly but few realize poultry industry is the restriction on the hidden toll the industry pays to the exportation of live and dressed fowl disease each year. from the United States to certain for The actual loss of birds to the disease eign countries such as Canada, England, is felt keenly by the owner. Although and some countries of South America. practically 100 per cent of the birds This loss of export trade is of grave get the disease in any given outbreak, concern to the industry. the losses may vary from one outbreak The poultry and turkey industries to another, depending on several factors. have shown phenomenal growth in the In baby chicks the loss may be as high past few years. In 1952 about H2 billion as 100 per cent but the average loss chicks and 65 million turkeys were may be 30 to 40 per cent. hatched. An estimated 1 per cent mor The chicks that survive an outbreak tality to Newcastle disease means a loss ll'ill show poorer growth and lower ef of 15 million chickens. In addition to ficiency of feed utilization. Approxi the mortality, the loss from effects of mately two more weeks are required the disease would make a total loss to to finish birds in affected broiler flocks. the industry of 30 million dollars. In turkey poults, the loss is not as high In order to live with Newcastle dis as in chicks but may be 15 to 20 per ease about 500 million birds are vac cc·nt of a brood. cinated annually for this disease. Thus, In laying birds, the death loss may to get this protection the cost to the be only 1 to 2 per cent but occasionally industry is estimated at 10 million may be as high as 80 per cent or more. dollars.
1 Publications subcommittee of the North Central Regional Technical Committee for Newcastle Disease Project NC-6. Dr. B. S. Pomeroy is professor of veterinary medicine at the University of Minnesota, and Dr. C. A. Brandly is professor of veterinary science at the Untversity o£ Wisconsin. 6 STAT ION BULLETIN 419
Any figure for losses caused by New Although Newcastle disease is not a castle disease in poultry must be a serious threat to public health, man broad estimation. In arriving at a final may become infected with the virus estimate of around 40 million dollars and suffer a mild infection of the eyes. for the yearly losses suffered directly There is no evidence at the present and indirectly because of "Newcastle time that Newcastle disease virus has disease, every effort has been made to any relationship to nervous disorders lean toward the conservative side. in man such as poliomyelitis.
Newcastle disease was first recog channels of trade. All earlier outbreaks nized as a distinct and separate disease in a previously free continent were of chickens in 1926 after outbreaks oc near seaport towns. Evidence would cured in England and in the Dutch East suggest that the introduction came from Indies. Dr. T. M. Doyle showed that infected birds or their inedible parts the malady in a flock near Newcastle that had been brought to the country on-Tyne, England, was a virus disease by ship. which differed from fowl pest. He Newcastle disease apparently reached named the disease after the town of California about 1940. There, because Newcastle. of its unusual nature, it went unrecog The outbreak in England was prompt nized until 1944. Then the virus of ly stamped out by quarantine of the the new respiratory-nervous disorder premises, slaughter of infected and ex which the California workers called posed flocks, and disinfection of con pneumo-encephalitis was shown to be taminated material and equipment. identical with the virus of Newcastle Recognition of the disease in the Dutch disease. In 1945, Newcastle disease was East Indies was not followed by eradi found on the eastern seaboard-first cation and subsequently the disease in New Jersey and New York. By 1947 has eventually spread to every poultry the infection had been reported in 30 producing country of the world. states and within a year or two it had Newcastle disease appears to have spread to every state reached by traffic spread between continents largely along in poultry and poultry products.
Newcastle disease is caused by a studying the virus in the laboratory virus, an infectious agent too small to and making vaccines that may be used be seen with the ordinary microscope. in the control of the disease. The virus can be grown in the labora The virus of Newcastle disease causes tory in fertile chicken eggs that have certain changes in the embryonated been incubated for about 10 days. This chicken egg that gives us evidence of method of growing the virus provides its presence. Death of the embryo in a means by which the virus may be iso two to four days, small hemorrages on lated from affected fowl, animals, and the membrane around the yolk and on man. It also provides a method for the skin of the embryo are visible re- FACTS ABOUT NEWCASTLE DISEASE 7 actions. Another means of detecting This clumping phenomenon is known the presence of the virus is the ability as hemagglutination and is very useful of the fluid from an infected egg to in the study of Newcastle disease. The cause clumping of chicken red blood terms hemagglutination and hemag cells and other mammalian blood cells. glutination inhibition refer to this test.
Since Newcastle disease was first Other than chickens and turkeys, the identified as a disease of chickens, vari following species of birds have been ous species of poultry and birds, as reported as affected with Newcastle dis well as certain mammals including man, ease in nature: pheasants, ducks, geese, have been found to contract the dis guinea fowls, pigeons, swans, parrots, ease by natural exposure. The suscepti quail, partridges, sparrows, crows, ma bility of a variety of species to infection yas (martins), starlings, doves, owls, by inoculation with Newcastle disease and gannets. virus indicates that all species of birds So far the infection of human beings and some mammals are subject to in has been recognized only as a relatively fection. The wider prevalence of New mild pink-eye-like infection contract castle disease among chickens has led ed by handlers of sick or slaughtered to rather abundant and extensive ex birds or by diagnosticians or laboratory posure of other birds and mammals. personnel working with the virus. The expected result of such greater Ducks, geese, and other birds may show exposure is that the Newcastle disease little, if any, evidence of the disease virus or, at least those strains with upon being infected, yet they may act active abilities to do so, will have more. as carriers and spreaders of Newcastle opportunity to become adapted or ad disease virus. Persons as well as cats, justed to new hosts, perhaps in the way dogs, and other species perhaps may that pullorum disease has become a also serve as unrecognized or "blind" serious malady of turkeys as a result carriers and spreaders of Newcastle of contact with diseased chickens. disease infection.
The actively infected individual, as viduals that survive a more or less well as the apparently healthy carrier, severe attack of Newcastle disease sel is the reservoir of Newcastle disease dom have been shown to harbor or give virus. The virus is given off with the off the virus for periods longer than saliva, nasal secretions, and droppings three weeks. The virus has been re before symptoms of Newcastle disease covered from the lungs of chickens appear, frequently within one to two two to three months after recovery days after exposure to infection. Some from the natural infection and in one individuals may have a "silent" or hid case it was demonstrated in the lungs den attack and eliminate the virus for of a chicken about 17 months after an several days to a week or more. Indi- attack of Newcastle disease. Normal 8 STATION BULLETIN 419
hens placed in contact with a rooster 1 per cent lysol, and 0.1 per cent quar infected six months previously devel ternary ammonium compounds, are ef oped infection five weeks later. fective in destroying the virus in 5 to Other information suggests that the 10 minutes. These agents, however, will proportion of healthy recovered carriers not kill virus protected by dirt, drop of Newcastle disease virus is ;rdinarily pings, or body secretions or tissues. quite low but the persistence for a Lye solution (1 per cent) is useful as month or more of only a small per a cleansing and scouring agent prelimi centage of carrier cases is often suf nary to use of disinfectants as a spray ficient to set up new centers of infection or dip. However, lye solution should and thus to favor further spread of not be substituted for the usual disin Newcastle disease. fectants since Newcastle disease virus If contact of succeptible birds with is much more resistant to alkalies than the virus were to be prevented for a many other viruses. time, Newcastle disease would soon Fumigation of incubators with for disappear. Under conditions unfavor maldehyde by the usual method used able to the virus outside of the living against pullorum disease will destroy bird, Newcastle disease virus perishes Newcastle disease virus on exposed in a few minutes or hours. Where the surfaces but, of course, cannot reach virus is protected to some degree virus covered by masses of dirt and against heat, light, moisture, and other down or the virus within infected eggs. factors that destroy it, it may survive It is often hard to determine just how for months. Newcastle disease gets into a brood The earlier reports from England in or flock. Obviously there are many ways clude an instance where day-old chicks, that it arrives from the original reser placed in dirty battery brooders seven voir in another bird or animal. The weeks after the removal of infected flock owner himself may introduce it by chicks contracted Newcastle disease. carrying the virus home on his shoes Others have reported that healthy stock and clothing after a visit to an infected has remained free of Newcastle disease flock, hatchery, or produce plant. Baby when placed in uncleaned houses as chicks are sometimes exposed to New early as three weeks after removal of castle disease during shipment by rail, an infected flock. Such an interval truck, or air. The local produce buyer must be considered extremely short in may trade chicken crates with the flock view of the resistance of Newcastle owner at the time his cull or broiler disease virus and would not justify birds are picked up. These may be a reuse of houses or quarters without source of infection. Reused feed sacks an intervening period of time and from infected premises may carry New thorough cleaning and disinfection. castle disease to clean flocks. Study by Newcastle disease virus is quite re one investigator has shown that New sistant to heat and can withstand a castle disease virus can survive on temperature of 132° F. for at least 30 strips of burlap bagging for 20 days at minutes. Boiling water temperatures a temperature varying from 29 to 72 will, however, destroy it immediately. F. but another research worker later Newcastle disease virus in droppings reported survival of the virus on bur and secretions may survive exposure lap for as long as 49 days in a room to direct sunlight for several days or at 68 to 86° F. and for 129 days in a longer. hen house at 12 (-11' C.) to 45° F. The common chemical disinfectants Newcastle disease can be "purchased'' such as 1 per cent saponified cresol, with started chicks, especially with FACTS ABOUT NEWCASTLE DISEASE 9
INFECTED BIRDS
POULTRY CRATES TRANSPORTATION
SHOES EGG CASES
FREE-FLYING BIRDS FEED SACKS
HATCHERY
those bought at "bargain'' rates. Free The virus seldom, if ever, may be flying birds have been responsible for expected to pass from a recovered hen bringing Newcastle disease to certain through the egg to the chick. Few, if farms and flocks. any, infected eggs will hatch. Since a Flock -selecting and pullorum-testing high proportion of eggs from flocks in crews have spread Newcastle disease the early stages of the disease contain from farm to farm as a result of failure the virus of Newcastle disease, an in to observe proper sanitary precautions. cubator or hatchery can become con Cats and dogs can act indirectly as car taminated by such eggs. Virus on the riers of the virus from one place to surface of dirty eggs, feathers, and another, especially after eating infected crates can contaminate the hatchery carcasses or contacting contaminated and incubator as can the breaking of ll1aterial. infected eggs from such premises. 10 STATION BULLETIN 419
PERIOD OF INCUBATION three weeks. The chicks that develop .. nervous symptoms seldom recover . Newcastle disease tends to be an acute infection in all species of birds and in eye infections of man. The period of incubation is the interval of time between the entrance of the virus into the host and the appearance of mani festations of disease. In Newcastle dis ease, evidence of disease may be noted by respiratory or nervous symptoms or a reaction to the hemagglutination inhibition or serum neutralization test as conducted in the laboratory. The minimum incubation period for the on set of respiratory or nervous symptoms is 2 days and may be as long as 7 to 10 days. It has been reported that the incubation period may be as long as 15 days with the average period being from 5 to 6 days.
FIG. l. Chick showing respiratory symptoms SYMPTOMS OF NEWCASTLE of Newcastle disease. DISEASE IN CHICKS
In chicks the most common symptoms are gasping, coughing, and hoarse chirps, while some chicks may lose their chirp entirely. The chicks are depressed with loss of appetite and tend to huddle under the brooder. Ner vous symptoms of twisting head move ments and paralysis usually follow respiratory symptoms. The bird may assume peculiar attitudes and move ments including lateral or downward twisting of the neck, convulsive sei zures, somersaulting, rearing, and walk ing in circles. While symptoms of diffi cult breathing occur in most chicks in an infected flock, the nervous symptoms may occur in only a small percentage of the chicks or may be completely absent FIG. 2. Chick showing nervous symptoms that in the flock. The respiratory symptoms follow respiratory phase of Newcastle usually persist in a flock for two or disease. FACTS ABOUT NEWCASTLE DISEASE 11
eggs w ith no shells, and eggs with shell membranes are found. These mal formed eggs may be found under the roosts, on the floor, and in the nests. The birds appear to have no control over where the egg may be laid. The color of the shell may change from w hite to brown or brown to white, depending on the breed. Under farm conditions about 20 per cent of the FIG. 3. Young chicken showing twisting of flocks will never return to their normal head associated with Newcastle disease. rate of laying. On an individual bird basis, it may be from tw o weeks to SYMPTOMS OF NEWCASTLE six weeks before a bird comes back DISEASE IN GROWING STOCK into laying. On a flock basis it requires from one to two months for a flock to The disease affects this group in regain normal production, and in some much the same manner as the chicks. instances the flocks never regain nor Respiratory symptoms may vary from mal production. The influence on egg flock to flock from very mild symptoms quality is considerable. Eggs with ab that may go unnoticed, to severe signs normal sh ells (thin shell, abnormal of respiratory distress. Nervous symp shape, small size) are consistently en toms, as noted in chicks, may be absent. countered after a flock has recovered In some flocks, few birds will show egg production. Eggs are found with characteristic involvement of the head abnormal air cells, that is, the air or paralysis. The symptoms of New castle disease appear to be milder in the summer months and increase in severity in the winter months.
SYMPTOMS OF NEWCASTLE DISEASE IN LAYING BIRDS In the laying flock, the disease af fe cts the birds suddenly and the entire flo ck seems to become affected at once. The disease starts with difficult and noisy breathing, coughing, and sneezing. The birds are depressed and feed con sumption goes down. They sit around on the floor and on roosts. The respira tory symptoms usually last in a flock fo r one to two weeks. Occasionally birds with nervous symptoms (twisting of the head or paralysis) are encoun tered but these symptoms may be com pletely absent. Egg production drops abruptly and FIG. 4. Adult hen showing twisting of the may go to zero within a few days after head that is occasienally seen in a symptoms are noted. Soft-shelled eggs, Newcastle disease infected flock. FIG. 5. Soft-shelled, malformed eggs are commonly encountered in laying fl ocks affected with Newcastle disease. present in the egg occurs as free-float production and if the disease hits dur ing bubbles. The albumen becomes ing the egg laying period the loss in egg watery; this quality may persist for production is disastrous. The disease several weeks. The yolks appear nor produces respiratory symptoms of diffi mal. Newcastle disease has a detrimen cult breathing such as gasping and tal effect on the keeping quality of eggs coughing. Nervous symptoms are usu in storage. ally absent. The effect on egg quality usually is not as severe as in flocks of laying chickens. SYMPTOMS OF NEWCASTLE 4. Breeder flocks-In chicken- or tur DISEASE IN TURKEYS key-breeder flocks that contact New castle disease during the period eggs Newcastle disease occurs in turkeys are saved for hatching, the disease has of all ages. a serious effect on hatchability and in 1. Poul.ts-The disease in young most cases the flocks never regain good poults takes on the same form as in production to warrent their use as hat chicks; however, the symptoms are not chery-supply flocks. as pronounced and may be easily mis sed. The respiratory phase appears to be mild and nervous symptoms (twist SYMPTOMS OF NEWCASTLE ing of head and paralysis) are only DISEASE IN OTHER POULTRY occasionally encountered. The birds are AND BIRDS depressed and feed consumption is de creased. Th symptoms of Newcastle disease 2. Growing stock-Because turke:YS in other fowl such as ducks, ph asants, have more natural immunity to New guinea fowl, sparrows, and pigeons are castle disease than chickens, the disease similar to those which occur in chickens in growing birds may go completely but are milder, less apparent, and may unnoticed. However, the disease in this be overlooked unless laboratory studies age does produce depression, lack of are attempted. appetite, and intestinal disturbances as manifested by loose droppings. Only rarely are birds encountered with ner FACTORS MODIFYING THE vous symptoms. COURSE OF NEWCASTLE 3. Laying flock-The diseas can pro DISEASE duce an adverse effect on a laying flock of turkeys. The disease has a more Certainly th re are factors that play important economic effect because lay an important role in modifying the ing flocks are only h eld for poult natural course of the disease. This FACTS ABOUT NEWCASTLE DISEASE 13 modification of Newcastle disease will killed virus) develop an active immun become more apparent as the vaccina ity. Active immunity means that the tion procedures become more widely defenses in the body of the bird are used. stimulated to protect it against the It has long been recognized that virus of Newcastle disease when it chicks or poults hatched from immune enters the host. This protection is hens receive some degree of protection relative and not complete. Thus, the from the dam. This protection is often course of the natural infection in referred to as "passive immunity." The vaccinated birds is sometimes so modi chick receives the passive immunity by fied that the characteristic symptoms the absorption of the Newcastle disease of Newcastle disease are completely antibodies from the yolk sac. These lacking yet the flock has gone through antibodies may persist and give pro re-infection that can be determined tection to the chick for as long as three only by laboratory studies. Birds from weeks. Not all of the chicks from an such a flock may act as carriers for immune flock will be protected for this a short period of time. The other im interval or even for a week. portant factor in the modification of The symptoms of a natural outbreak the symptoms produced by Newcastle of Newcastle disease may be modified disease virus is the variation that in chicks by some degree of passive occurs in the strains of the Newcastle immunity. The respiratory symptoms disease virus. Some strains of the virus, may be very mild and nervous symp in natural or experimental outbreaks, toms may be completely absent. produce very mild respiratory symp Birds vaccinated with one of the toms and no nervous symptoms and a\~ailable vaccines (live-virus intra therefore an outbreak may not be diag nasal, wing-vveb, intramuscular, or nosed as Newcastle disease.
The symptoms as described under (encephalomalacia or crazy chick dis Natural Course of the Disease (page 10) ease), and sometimes deficiencies of closely resemble or are identical with vitamin D (rickets) and vitamin A those of a number of other infectious (starvation). diseases. Bronchitis, laryngotracheitis, A distinction between Newcastle dis coryza, leukosis, mycosis, pullorum dis ease and bronchitis is particularly diffi e~se, and chronic respiratory disease cult in most flocks of growing and lay (sinusitis) cause gasping and other ing birds where the rather characteris respiratory signs indistinguishable from tic nervous symptoms of Newcastle dis those seen in many Newcastle disease ease are often absent. Even in broods infected flocks. The common nervous of baby chicks nervous symptoms are symptoms of Newcastle disease-lame not always seen or they may appear ness, paralysis, twisted necks - are late in the disease, thus complicating much the same as those seen in cases or preventing an early diagnosis. The of the following diseases: neurolympho early sudden drop and cessation of pro matosis (fowl paralysis), epidemic duction among layers and the develop tremor, riboflavin deficiency (curled ment of nervous symptoms following toe paralysis), vitamin E deficiency. initial respiratory symptoms in baby 14 STAT ION BULLETIN 419
chicks often suggest Newcastle disease. Isolation of the virus: Birds in the The changes or lesions of Newcastle incubative and early stages of the dis disease seen at postmortem examina ease are usually necessary for this pur tion differ greatly in location, severity, pose. The most suitable specimens are and extent from bird to., bird and those showing symptoms of impaired among flocks and outbreaks. The le breathing during the first week of the sions, even in severe active infections, infection in a brood or flock. After the differ with age and are altered some flock has passed through the initial what by partial immunity to the dis respiratory stage of the disease it is ease. The rapidly developing and acute usually too late for virus isolation. cases may show prominent hemor Tissues are collected from several rhages (bleeding) of the proventriculus birds. The spleen, lungs, and trachea (glandular stomach) and of the lym contain the most virus and are there phoid patches and follicles of the in fore preferable to other tissues for testine. Sometimes the heart and lung virus isolation. The suspected tissues membranes of the body cavities are are ground in broth and inoculated into more or less hemorrhagic. In the acute several fertile eggs that have previ forms of Newcastle disease the spleen ously been incubated for 10 to 12 days. may be mottled or quite pale and After inoculation the eggs are further shrunken. The rather severe hemor incubated. If Newcastle disease is pres rhages in the body tissue of some cases ent the virus will usually kill the em account for the paleness and small size bryos in 48 to 96 hours after inocula of the spleen. tion. The dead embryos yield fluid fo r The similarity or identity of lesions serum and other tests to identify the as well as symptoms of Newcastle dis virus. ease to those of a number of other dis Virus neutralization tests: These tests eases may not allow even the veteri are based on the fact that Newcastle narian or experienced pathologist to disease causes the birds to develop reach a final diagnosis. Hence, a diag antibodies which will neutralize or in nosis often requires laboratory assist activate the Newcastle disease virus. ance. The methods of recognizing the Before setting up and reading a test disease include: (1) isolation of the it is important to know whether the virus, (2) serum tests, and (3) histo flock has been vaccinated and, if so, logic (microscopic) examination of when, since vaccination also causes suspected tissues. antibodies to form and a positive test
FIG. 6. Diagnosis of Newcastle disease re· quires isolation of the virus from infected tis· sues. This is done by inoculating these tis· sues into embryonated chicken eggs. FIG. 7. In the late sta ges of infection, Newcastle disease can be detected by the m (hemagglutination inhibition) test.
to persist for a considerable time. Tests prevent the virus from killing the em with serum from a flock that has been bryo. Negative serum, i.e., that from infected or vaccinated as late as six to a Newcastle disease susceptible bird, seven days previously will give a posi does not contain antibodies to neutra tive test. The serum of birds recovered lize the virus and thus, it kills the from a natural attack often remains embryo. This test is reliable a nd per positive for· a year or longer; vacci mits diagnosis of Newcastle disease in nated birds commonly show a weaker fection that has occurred as recently as reaction and may become negative to one to two weeks, or, it determines the neutralization test within three to earlier infection or vaccination. four weeks. It is well to remember that 2. Test for virus neutralization in the not all vaccinated or r ecovered birds test tube (hemagglutination inhibition develop a positive serum reaction and tests): hence, 5 per cent, or in smaller flocks This test is not as dependable as the 10 per cent, of the birds should be virus neutralization test with eggs but sampled and tested to avoid errors in takes less time and is more economical appraisal. of materials. It is based on the principle There are two methods or procedures that Newcastle disease virus will ag for testing the serum for virus neu glutinate (clump) chicken red blood tralization. They are : cells. The serum to be tested, either 1. Test for virus neutralization with undiluted or diluted, is mixed with eggs: equal quantities of virus, which is con The serum of the test bird is mixed stant strength or diluted, and a suspen with an equal quantity of various ten sion of chicken red blood cells. If the fo ld dilutions of a known Newcastle serum contains Newcastle disease anti disease virus. The mixtures are inoc bodies the virus will be neutralized and ulated into embryonating eggs. If po it will be unable to clump the red sitive for antibodies, i.e., if the serum blood cells. In contrast, a negative is from a bird that has been infected serum, i.e., one without Newcastle dis with or vaccinated against Newcastle ease antibodies, permits the virus to disease, antibodies which are present agglutinate the red blood cells. 16 STATION BULLETIN 419
GENERAL RECOMMENDATIONS 6. Visitors handling chicks in the ~ battery room. 1. Prevent the disease from spread Newcastle disease can be eliminated ing to other flocks in the neighborhood. from the hatchery by completely de The flock should be isolated and visi populating the battery rooms, cleaning tors should not be allowed near the and disinfecting equipment, and fumi flock. Poultry equipment must not be gating the rooms with formaldehyde. removed from the farm unless cleaned The hatchery probably can continue and disinfected. The flock should not to operate if only day-old chicks are be marketed while in the acute respi sold during the clean-up period, other ratory stage of the disease since this wise, it may be necessary to stop all could endanger many flocks and con hatchery operations. taminate the produce plant. 2. Obtain a diagnosis of the problem. This can be done by contacting the RECOMMENDATIONS FOR THE local veterinarian or the state veteri FARM nary diagnostic laboratory. Live, sick birds showing various symptoms should Baby Chick Flocks not be sent by common carrier but brought to the laboratory. The most serious outbreaks of New castle disease are encountered in chicks under four to six weeks of age. When RECOMMENDATIONS FOR THE Newcastle disease occurs in a group of HATCHERY chicks, it may be advisable to destroy the flock. If a hatchery is the source of New There is no specific treatment except castle disease infected chicks, the dis to maintain adequate brooder house ease will be found existing in the bat temperature and encourage the chicks tery room where started chicks are to eat and drink. The use of sprays and being brooded. Newcastle disease is inhalants have little influence on the rarely encountered in chicks obtained course of the disease in a flock. from a hatchery selling day-old chicks If the flock is destroyed, clean and only. disinfect the brooder house; it may be How is Newcastle disease virus. in restocked again within a few we2ks. troduced into a hatchery? There are Otherwise clean and disinfect the several possible means: house after the flock has recovered. 1. Operation of a dressing plant in Take care to avoid spreading the conjunction with a hatchery. disease to other susceptible poultry on 2. Obtaining hatching eggs or market the farm. In many instances the owner eggs from a flock in the active stages carries the infection to the laying flock of the disease. before he realizes the chicks are ar 3. Introduction of chicks from out fected with Newcastle disease. side source that may have been exposed to Newcastle disease virus in transit Growing Flocks or at the point of origin. 4. Reuse of chick boxes. When Newcastle disease affects bircls 5. Sick poultry brough to the hatch older than six weeks of age, the actu;tl ery for diagnosis. loss in these birds is not as serious PREVENTION BY SANITARY disease into a hatchery. The following MANAGEMENT are important safeguards: 1. Isolate the hatchery from broiler plant and dressing plant. Hatchery 2. Use separate labor for the started !;;very precaution must be taken to chick brooding plant. a\·oid the introduction of Newcastle 3. Brood started chicks and surplus 18 STATION BULLETIN 419 chicks in another building away from safer to crate your own birds and take the hatchery. them to the produce plant. Clean and 4. Sell day-old chicks rather than disinfect the crates before returning started chicks. them to the farm. 5. Obtain weekly report9" from flock 4. Maintain all pullet flocks. For the owner and keep a close watch on egg average poultry farm it is best to mar records for any drop in egg production ket the flock at the end of the laying in supply flocks. season so that old birds are not mixed 6. Do not have used feed sacks or with the pullet flock because there is chick boxes returned to the hatchery. the danger that they may be carriers 7. Dispose of hatchery wastes prop of Newcastle disease or some other erly. respiratory infection. 8. Discourage visitors and other traf 5. Remove manure to fields :that will fic into the hatching and brooding not be used for poultry. Storage pits rooms. or sheds are often indispensable. 9. Change wearing apparel before 6. Use a burial pi:t, incinerator. or entering the chick room. deep burying to dispose of dead birds. Don't feed dead birds to the hogs or Farm Flocks leave them lying around the yard. 7. Have your own chicken crates :to To safeguard the farm flocks against be used only in your flock. If crates Newcastle disease, practice these essen are used away from the farm, clean tial rules: and disinfect them thoroughly and al 1. Isolate the farm flock from visi low them to dry in the sun for several tors. The poultryman should be careful days before storing them. about going to neighboring flocks and 8. Replace :the Ii:t:ter after an outbreak should he do so, his outer clothing of infectious or parasitic disease. should be changed and shoes and boots 9. Clean and disinfect feed bags thor disinfected before tending his own oughly if they are to be returned for flock. reuse. 2. Buy only day-old chicks from a re 10. Clean and disinfect :the laying liable local hatchery. Started chicks house :thoroughly af:ter it has been de have a greater chance to be exposed populated of chickens. Use lye and an to Newcastle disease or other respira approved disinfectant. Treat the roosts tory diseases and consequently, you with mite paint. After the brooder may be buying a disease with the house and range shelters have been started chicks. Rear the replaceiTlent vacated, clean and disinfect them for flock away from the adult birds on the next season's brood. clean range not only to lessen the dan 11. Control rodents and wild birds. ger of transmission of Newcastle dis Rats, mice, and free-flying birds may ease from old birds, but also avian leu spread a number of poultry diseases cosis, infectious bronchitis, fowl chol such as Newcastle disease. era, and other respiratory diseases. 3. Use precautions in marketing birds. It is a common practice to sell Broiler Plant the culls to poultry buyers. These poultry buyers and their crates, etc., The observation of strict sanitary should be restricted from the house in practices as outlined above is the ]{('Y order to prevent the introduction of to successful broiler operation. Imma Newcastle disease and other contagious ture birds, birds for slaughter, or birds diseases into the flock. It would be for visceration from an outside source, FACTS ABOUT NEWCASTLE DISEASE 19 should not be introduced into the broiler against further inroads of serious poul plant. try problems such as Newcastle disease is an early recognition and application of effective sanitary measures. Produce Plant Sometimes chickens or turkeys in the active stages of Newcastle disease are PREVENTION BY VACCINATION marketed. These birds may infect other birds in the feeding station, and the Vaccination, properly and judiciously produce plant may serve as a source employed, is a valuable supplement to of infection to the neighboring hatch a basic, sound, long-range program of ery, broiler plant, and poultry farms. sanitary management for the prevention One of the principal means of spread and eradication of Newcastle disease. is contaminated poultry crates. The A major limitation of vaccination as poultry crates should be so constructed applied to the control of Newcastle and handled that they can be easily disease and several other highly con cleaned and disinfected after daily use. tagious diseases is that the poultryman It is the duty of the operator of the frequently depends too much upon it. produce plant to take all precautions Often, vaccination is substituted en to avoid the spread of Newcastle dis tirely for the necessary sanitation and ease and other infections by means of management measures without which produce crates, egg cases, and contami serious difficulty and disappointment nated wearing apparel and footwear of commonly ensue. his employees. Finally, the degree of risk that a brood or flock may be exposed to New castle disease should decide whether Feed Manufacturer and Dealer vaccination is necessary or desirable. (Mill and Store) Farm flocks at a considerable distance from other flocks and centers of infec The feed manufacturer and dealer can tion are least likely to become exposed. bE· of considerable aid in preventing the Such flocks and premises are not often spread of Newcastle disease by en visited by poultry buyers, salesmen, couraging stricter application of the and others that may have come from principles of good management and diseased flocks and areas. The chances sanitation. A void the reuse of feed of exposure of such flocks by contami sacks, unless properly cleaned and nated feed bags, crates, and trucks is st Vaccination against Newcastle dis munizing effect. The vaccines must be ease, pox, and laryngotracheitis requires tested for safety and potency and be separate vaccines usually given at dif given a "use expiration" date before ferent times. With each additional vac release. cine the cost of vaccinatid'fl per bird Each % to 1 milliliter dose of the is increased several cents. vaccine contains a large quantity of Finally, the problem of vaccination killed virus, the reaction to which gov may be not only one of time, labor, erns directly the degree and duration and spacing between the several opera of the immunity which the bird can tions, but a question as to whether the develop. Usually this immunity is not bird can respond properly to the con as strong or durable as that from live stantly increasing number of vaccines. virus vaccination, which, to be effec Eventually, the decision whether vac tive, must actually produce an attack cination is or is not to be practiced of Newcastle disease. must constitute a calculated risk Killed Newcastle disease vaccine af against: (1) the possibility of exposure fords protection by a blocking effect to Newcastle disease, and (2) an un within a week after injection. Specific satisfactory response to vaccination. immunity against Newcastle disease Vaccination may not result in a sub develops within a week after vaccina stantial immunity if the flock is suffer tion and it is well advanced at two ing from other diseases or devitalizing weeks in healthy birds six weeks of influences. The reaction to living vac age or older. The immunity may wane cines may be unduly marked or severe. considerably during the period of two In spite of the most careful stand to six months after vaccination. Revac ardization of the vaccine, the circum cination at two weeks to several stances of its use, the environment of months strengthens and prolongs the the flock, and the health status and immunity and the ability to respond response of the birds and flocks into more quickly and effectively to later which it is introduced differ very Newcastle disease exposure. greatly and can never be standardized. Living Virus Vaccine/ Living New Hence, the results may be variable and castle disease virus vaccines are pre disappointing and the need for major pared by growing, on embryonating dependence on a basic and realistic eggs, single modified or -"weakened" sanitary management program of dis strains of Newcastle disease virus. Great ease prevention is more apparent. care is required to keep the vaccine virus at a satisfactory stage of modifi cation and to avoid contamination with Two Types of Vaccine other viruses and bacteria. The infected Two general types of Newcastle dis embryo material is dried to powd<·r ease vaccine, the killed virus and the from the frozen state. Further refrig living virus, are available: eration before it is used and proper care Killed Virus Vaccine. Killed New during its use are required to keep the castle disease virus vaccines are pre vaccine virus alive and capable of pro pared by growing suitable strains of ducing satisfactory results. virus in embryonating eggs, harvesting The living Newcastle disease vac the dead or dying embryos and tissues, cines now available from commercial and inactivating the virus with formal sources are administered by different dehyde or ultraviolet light. Substances routes, namely the "stick" or skin and such as alumina gel are sometimes the "drop" or intranasal and the intra added to increase and prolong the im- muscular. Other routes include drop- " Certain states restrict the use of live virus vaccines. FACTS ABOUT NEWCASTLE DISEASE 21 ping the vaccine into the eye or spray Likewise, use of killed vaccine in birds ing or atomizing the vaccine for inha of low vitality may fail to produce a lation. satisfactory degree of immunity al The modified virus employed in the though the health is not further im "stick" method vaccine usually pro paired, as may be the case with live duces a mild form of Newcastle disease virus vaccination. with a large majority of healthy birds While a stronger and more lasting of four to six weeks of age or older. immunity usually may be expected Given by other routes, e.g., intranasally with the living than with the killed or intramuscularly, it may cause rather Newcastle disease vaccine, these ad severe shock or fatal infection, especi vantages of the living vaccine are often ally in young chicks or devitalized offset by a relatively severe vaccina birds of any age. tion-disease reaction even in broods and The virus employed in the intranasal flocks of suitable age and production method vaccine is adapted to growth status that appear to be in normal in the respiratory tract and to stimu health when vaccinated. The use of late a moderate degree of immunity Jiving vaccines may also present the in a large majority of healthy birds. problem of introducing Newcastle dis While its use has been advised in baby case infection into previously clean chicks and laying flocks, the systemic flocks and areas. The possibilities that reaction in some cases has been so the vaccine virus may become fully severe as to impair production appre active and destructive are not great ciably and to contribute heavily to but cannot be overlooked. chick mortality. Another factor that may alter the Because of the relatively small quan response to vaccination is the immunity tity of virus introduced with the living the hen that has had Newcastle disease Newcastle disease vaccines, the block or has been vaccinated against it trans ing effect is seldom as substantial as it mits to her chicks. Where the hen's is with the killed Newcastle disease immunity is of high grade, the chick vaccines. The specific immunity en will carry a yolk-borne immunity up gendered by living vaccine infection to 30 days of age. If the hen has a should appear within a week after vac partial immunity the passive immunity cination and should be of substantial of the chicks may be lost at two weeks ctegree after the second week. The im or earlier. The immunity gives the munity from living vaccine begins to chicks a degree of protection against wane within 21/z months and proper natural infection and also prevents a revaccination is usually recommended "take" or immunity from vaccination. within two months to a year. Failure to recognize the influence of That neither the killed nor living the previous Newcastle disease status vaccines have given fully satisfactory of the breeding flock and the degree rPsults is apparent from the continuing of immunity which the chick or flock dforts to improve them. While the may carry at any time may lead to killed vaccines can be used in birds of apparent failure of vaccination. any age or status of production or Obviously the indiscriminate, care health, the immunity produced by them less, and improper use of vaccines will has not been as strong or durable as result in difficulty, confusion, and loss. desired. Nevertheless, vacination of Only when vaccination is praticed as haby chicks, or those less than six a supplement to a long-range sanita weeks of age, may not be expected to tion program of a community, state, give a maximum immunity to a satis and national scope can it be fully ef [actory proportion of the brood or lot. fective. 22 STATION BULLETIN 419 The final goal or objective e~f a sound distance apart. Vaccination may be re disease-control program is eradication quired as a supporting measure of sani of the disease. The older as well as tation and, if so, it should be so em the newer methods and information, ployed as a weapon towards eradica however, must be accepted and applied tion. If it is not used properly and on a large and comprehensive scale if wisely, vaccination will continue to be a well-established disease is to be era a considerable year-after-year expense. dicated. Authorities on disease recog Effective treatments against New nize that education toward the means, castle disease and many other diseases necessity, and economy of stamping out have not been developed. Furthermore, a disease are at least of equal import no matter how effective possible "mira ance to the research and investigation cle drugs" of the future may be against required to develop newer and more Newcastle disease, the "remedy" cost effective methods of combatting such must be added to the toll already taken a malady. by disease before treatment can be The simplest and most logical control instituted. measure against infectious diseases like The effectiveness of the sanitation Newcastle is to prevent contact of the program is limited only by the extent infectious agent or virus with the sus of participation by all those concerned ceptible bird or animal. A second and with the poultry industry. Organization indirect method, applicable against at the community level usually depends some diseases, is vaccination. The latter upon the foresight and enthusiasm of gives the animal a degree of protection one or more forward-looking indivi against the infection in case of expos duals. The interest and effort of others ure. The third, and generally least can be enlisted readily. satisfactory and least economical pro The local county agent and veteri cedure, is to treat the animal after it is narian, agricultural extension service, exposed or has become affected. representatives of state and federal A combination of the first two meth agencies, as well as poultry, hatchery, ods may be required at the outset for dealer, and other organizations can be a highly contagious disease such as counted upon to aid in expanding and Newcastle that has become widespread strengthening the sanitary program. in a community, region, or country. At the outset, 75 per cent of the farm However, both phases must be carried ers or poultrymen in an area will par out on a sufficiently thorough and wide ticipate. The remainder may require basis. At least 70 per cent of the flocks further contact, urging, or even pres in an area must be included in the rigid sure. sanitary program along with a satis The effort towards developing and factory twice-a-year vaccination pro applying a sound, long-range sanitary gram. program is now, more than ever before, Compliance with the sanitary pro necessary to protect the future of our gram often prevents Newcastle disease poultry industry against the inroads of where the poultry population is rela Newcastle disease and a host of other tively small and the flocks are some infectious and parasitic diseases. EFFECT OF NrEWCASTU DISEASE ON LAYING HENS (The results of a survey of what happened in 100 farm flocks affected with Newcastle disease) 11Jiud wc;.,i ike wnrpe ra./ death lo.Jaeci /wm A!ewcadl.e dueoAe? PERCENTAGE OF DEATH LOSS PERCENTAGE OF FLOCKS 0 O.S-5 !,,,,,,.,.,,,.,.,.·.·.·.·.·.· ·· ··· ··· ·· · ·· ·· ·· ·· · · ··· ·· ·· · ···· ··· ·. ··· ·.·.· ·.·.·.·.·.·.· .. ·.. ·.· ·.·.· ·.·.·.· ·.-.,.,.,.,.-.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,,,,,,,,,,,,,,,,<,:':':':''''4 26 °/o 6-10 f,,,,,,,,,,,,.,.-.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.-.,.,.,.,.,.,.,.,.,.,,,,,,,,,,,.,,,,,,,,,,,,,,,,,.,,,,_,,,_,,,,,,,,,,,,,,,>,''''''''d 1 S o/o 11-1 s (,,,,,,.,,,,,,,,,.,.,.·.·.,.·.·.· ·.· ·······-·.·.·.·.·.·.·.·.·.·.·.·.·.·.·., .... ·.·.···'· ·.·.·.·.-.·.·.·.-.-.,.,.,.-.,.,.,.,.,.,.,,,,,,,,J 1 4 °/o 16-20 21-25 k:':''''':':':' ,,,,,,,.,,,,,,,,,,,,,,,,,,,,:':':'n 6 °/o OVER 26 v,;,,,,,,,.,.,,,.,., ..·.·.-.·.·.·.-.-.-.-.,.,., ..... ,.,.,.,,,,,,,,,,,,) 8 °/o RAPID DROP SLIGHT DROP I] 1% NO EFFECT 0 TIME REQUIRED PERCENTAGE OF FLOCKS 1 MONTH 2 MONTHS V,,,.,., . .-.-.-.-.-.-.-.-.-.-.-.-... ·.·.·.-.-.-.·.·.·.·.·.-.-.-.-.--.-.-.-.-.-.·.-.-.-.-.-.·.,.,.,.,.,.,.,.,.,.,.,_..,.,.,.,.,.,.,.,.,.,.,.,.,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1 38°/o NEVER v,,,.,.,.,.·.·.·.·· ...... •,•,•,·,•,·,•.-.-.-.-.-.·.· .... ,.,.,•,•,• ...... ,.,.,.,.,,,,,,,,,! 20 °/o Wk~A-t e./feci did Ike Ji~e.c;.,M; lu:u.J.e OFt !Lhe!J '/Juc;.,/i/1 duck a4 miuhc;.,ru;;n, o/J-~, OJt dc-/;f-4/nlle.J ~? SHELL QUALITY PERCENTAGE OF FLOCKS AFFECTED POOR SHELL QUALITY NO EFFECT The survey reported here was conducted in Minnesota during 1949-50 by the School of Veterinary Medicine, University of Minnesota.