Gumboro disease in poultry; cause. symptom, and prevention

Gumboro disease in poultry; cause. symptom, and prevention Due to the hardy nature of IBDV and the widespread distribution of the virus, prevention and contro See "Vaccination / Decline of MDA in Progeny".

Common Questions
Is day old vaccination against Gumboro Disease recommended? While probably doing no harm the benefits of a day old vaccination are questionable. The level of maternal derived antibody will be too high neutralising the vaccine virus. Despite vaccination we still see Gumboro related mortality. Are we vaccinating too late? The chances are that vaccination is done to early at a age wh

en maternally derived antibody levels are still high, neutralising the vaccine strain. See "Vaccination/Vaccination with live IBDV vaccines". Is it possible that we have variant strains against which the vaccines do not protect? All the IBDV strains, including vaccine strains, belong to a single serotype thus all vaccines should be efficacious. Vaccine failure is usually the result of incorrect vaccine administration, or vaccine administration at a time when the maternal derived antibody levels are still too high. By far the majority of Gumboro isolates made outside of North America are classical IBDV. See "Microbiology/VirusClassification"

Can the Gumboro vaccines be applied by spray administration? The preferred route of administration is drinking water application as this directs the virus into the digestive tract. However, spray vaccination is an alternative and if administered effectively will give comparable results. At what age should I vaccinate my chickens against Gumboro disease? I do not have access to a laboratory to determine antibody levels. Without knowing the antibody levels any decision made on age of vaccination is a gamble. However, some practical guidelines follow to improve the odds. Commercial broiler or layer chicks originating from parent birds vaccinated with an inactivated gumboro vaccine generally have maternal antibody titers in the range of 1,000 to 8,000 ELISA units. Based on this assumption we can predict that for:

Broilers
An intermediate plus vaccine (Nobilis Gumboro 228E) is effective from an age of round 12 days. An intermediate vaccine (Nobilis Gumboro D78) is effective from an age of round 18 days. Layers
An intermediate plus vaccine (Nobilis Gumboro 228E) is effective from an age of round 18 days. An intermediate vaccine (Nobilis Gumboro D78) is effective from an age of round 28 days. Further to this it is known that a chicken is protected within 5 - 7 days of successful vaccination with a live gumboro vaccine. (Successful vaccination implies that the vaccine crossed the maternal antibody barrier and entered the bursa.) A vaccination schedule should thus be designed to give the best possible chance of vaccine take 5 - 7 days before the expected gumboro break. Two vaccinations are recommended with a 5 - 7 day interval between the first and second vaccination. Examples:
My broiler flock had a spike in mortality due to Gumboro at 21 days of age. At what age should I vaccinate the next flock? Symptoms at 21 days. Need to vaccinate at least 5 - 7 days earlier, thus at 14 - 16 days of age. At this early age intermediate vaccines (Nobilis Gumboro D78) are not effective in broilers, thus an intermediate plus vaccine (Nobilis Gumboro 228E) is required. First intermediate plus vaccination at 12 days of age, second at 17 days of age. My layer flock had a spike in mortality due to Gumboro at 35 days of age. Symptoms at 35 days. Need to vaccinate at least 5 - 7 days earlier, thus at 28 - 30 days of age. At this age intermediate vaccines (Nobilis Gumboro D78) are effective in layers. First intermediate vaccination at 21 days of age, second at 28 days of age.

Control and Treatment of Infectious Bursal DiseaseThere is no treatment. Rigorous disinfection of contaminated farms aft...
30/09/2022

Control and Treatment of Infectious Bursal Disease
There is no treatment. Rigorous disinfection of contaminated farms after depopulation has achieved limited success. Live vaccines of chicken embryo or cell-culture origin and of varying low pathogenicity can be administered by eye drop, drinking water, or SC routes at 1–21 days of age. Replication of these vaccines and thus the immune response can be altered by maternal antibody, although the more virulent vaccine strains can override higher levels of maternal antibody. Vectored vaccines that express the IBDV VP2 protein in herpesvirus of turkeys (HVT) can be used in ovo or at hatch. These HVT-IBD vaccines are not affected by maternal antibodies. Vaccines that use live-attenuated viruses bound to antibodies (immune-complex vaccines) are also available for in ovo or at hatch administration.
High levels of maternal antibody during early brooding of chicks in broiler flocks (and in some commercial layer operations) can minimize early infection, subsequent immunosuppression, or both. Breeder flocks should be vaccinated one or more times during the growing period, first with a live vaccine and again just before egg production with an oil-adjuvanted, inactivated vaccine. Inactivated vaccines of chicken embryo, bursa, or cell-culture origin are available. The latter vaccines induce higher, more uniform, and more persistent levels of antibody than do live vaccines. The immune status of breeder flocks should be monitored periodically with a quantitative serologic test such as virus neutralization or ELISA. If antibody levels decrease, hens should be revaccinated to maintain adequate immunity in the progeny.
The goal of any vaccination program for IBD should be to use vaccines that most closely match the antigenic profile of the field viruses. Diagnostic testing for the genomic sequences of field strains can be used to select the most appropriate vaccination program.

Diagnosis of Infectious Bursal DiseaseDiagnosis can be accomplished by clinical evaluation of the cloacal bursa for macr...
30/09/2022

Diagnosis of Infectious Bursal Disease
Diagnosis can be accomplished by clinical evaluation of the cloacal bursa for macroscopic and microscopic lesions followed by molecular detection of the viral VP2 gene using RT-PCR
Sequence analysis of the VP2 gene is used to identify the IBDV genotype
Virus isolation in chicken embryos or chicken embryo fibroblast cell cultures is possible but often not necessary
Initial diagnosis of infectious bursal disease is accomplished by the observation of gross lesions in the cloacal bursa. This is followed by microscopic analysis of the bursa for lymphocyte depletion in the follicles. Molecular diagnostic assays are most often used to identify IBDV in diagnostic samples. The reverse-transcriptase-PCR assay is used to identify the viral genome in bursa tissue. Sequence alignments and phylogenetic analysis of the VP2 coding region has been used to further characterize the viruses into genogroups. Samples for molecular diagnostic testing are typically collected after maternal antibodies have waned.
IBDV may be isolated in 8- to 11-day-old, antibody-free chicken embryos with inocula from birds in the early stages of disease. The chorioallantoic membrane is more sensitive to inoculation than is the allantoic sac. Some strains of IBDV may also be isolated in cell cultures that include chicken embryo fibroblasts, cells from the cloacal bursa, and established avian and mammalian cell lines. Cell culture–adapted strains of IBDV produce a cytopathic effect and may be used for quantitative titration of the virus and virus-neutralization assays.
Serology can be used to detect the presence of antibodies to IBDV in convalescent chicks. Commercially available ELISA kits are most often used to quantitate IBDV antibodies. The presence of IBDV antibodies in chicks is not always an indication of infection because most young chicks have maternal antibodies.

Etiology and Transmission of Infectious Bursal DiseaseInfectious bursal disease is caused by a birnavirus (infectious bu...
30/09/2022

Etiology and Transmission of Infectious Bursal Disease
Infectious bursal disease is caused by a birnavirus (infectious bursal disease virus; IBDV) that is most readily isolated from the bursa of Fabricius but may be isolated from other organs. It is shed in the f***s and transferred from house to house by fomites. It is very stable and difficult to eradicate from premises.
Two serotypes of IBDV have been identified. The serotype 1 viruses cause disease in chickens and, within them, antigenic variation can exist between strains. Antigenic drift is largely responsible for this antigenic variation, but antigenic differences can also occur through genome homologous recombination. Serotype 2 strains of the virus infect chickens and turkeys but have not caused clinical disease or immunosuppression in these hosts. IBDVs have been identified in other avian species, including penguins, and antibodies to IBDV have been seen in several wild avian species. The contribution of IBDV to disease in these wild birds is unknown.

30/09/2022

Infectious bursal disease (IBD) is seen in young domestic chickens worldwide and is caused by infectious bursal disease virus (IBDV). Symptoms of the clinical disease can include depression, watery diarrhea, ruffled feathers, and dehydration. Depending on the IBDV strain and presence of maternal immunity, the disease can also present as a clinical or subclinical disease in young chicks. For both clinical and subclinical forms of the disease, all pathogenic IBDVs cause lesions in the bursa of Fabricious. The cloacal bursa can become enlarged, with a yellowish colored transudate on the surface. Hemorrhages on the serosal and mucosal services are sometimes observed. Atrophy of the bursa, which includes the loss of B-lymphocytes, occurs approximately 7-10 days after infection. Immunosuppression is directly related to this loss of B-lymphocytes, but immunosuppression and related secondary infections are typically seen in birds that recover from the disease. Severity of the immunosuppression depends on the virulence of the infecting virus and age of the host.

PreventionVaccination, including passive protection via breeders, vaccination of progeny depending on virulence and age ...
29/09/2022

Prevention
Vaccination, including passive protection via breeders, vaccination of progeny depending on virulence and age of challenge. In most countries breeders are immunised with a live vaccine at 6-8 weeks of age and then re-vaccinated with an oil-based inactivated vaccine at 18 weeks. A strong immunity follows field challenge. Immunity after a live vaccine can be poor if maternal antibody was still high at the time of vaccination.
When outbreaks do occur, biosecurity measures may be helpful in limiting the spread between sites, and tracing of contacts may indicate sites on which a more rebust vaccination programme is indicated.This shows the anatomical relationship between the bursa, the re**um and the vent. This bursa is from an acutely affected broiler. It is en­larged, turgid and oedematous.

SignsDepression.Inappetance.Unsteady gait.Huddling under equipment.Vent pecking.Diarrhoea with urates in mucus.Post-mort...
29/09/2022

Signs
Depression.
Inappetance.
Unsteady gait.
Huddling under equipment.
Vent pecking.
Diarrhoea with urates in mucus.
Post-mortem lesions
Oedematous bursa (may be slightly enlarged, normal size or reduced in size depending on the stage), may have haemorrhages, rapidly proceeds to atrophy.
Haemorrhages in skeletal muscle (especially on thighs).
Dehydration.
Swollen kidneys with urates.
Diagnosis
Clinical disease - History, lesions, histopathology.
Subclinical disease - A history of chicks with very low levels of maternal antibody (Fewer than 80% positive in the immunodifusion test at day old, Elisa vaccination date prediction < 7 days), subsequent diagnosis of 'immunosuppression diseases' (especially inclusion body hepatitis and gangrenous dermatitis) is highly suggestive. This may be confirmed by demonstrating severe atrophy of the bursa, especially if present prior to 20 days of age.
The normal weight of the bursa in broilers is about 0.3% of bodyweight, weights below 0.1% are highly suggestive. Other possible causes of early immunosuppression are severe mycotoxicosis and managment problems leading to severe stress.
Variants: There have been serious problems with early Gumboro disease in chicks with maternal immunity, especially in the Delmarva Peninsula in the USA. IBD viruses have been isolated and shown to have significant but not complete cross-protection. They are all sero-type 1. Serology: antibodies can be detected as early as 4-7 days after infection and these last for life. Tests used are mainly Elisa, (previously SN and DID). Half-life of maternally derived antibodies is 3.5- 4 days. Vaccination date prediction uses sera taken at day old and a mathematical formula to estimate the age when a target titre appropriate to vaccination will occur.

Differentiate clinical disease from: Infectious bronchitis (renal); Cryptosporidiosis of the bursa (rare); Coccidiosis; Haemorrhagic syndrome.

A viral disease, seen worldwide, which targets the bursal component of the immune system of chickens. In addition to the...
29/09/2022

A viral disease, seen worldwide, which targets the bursal component of the immune system of chickens. In addition to the direct economic effects of the clinical disease, the damage caused to the immune system interacts with other pathogens to cause significant effects. The age up to which infection can cause serious immunosuppression varies between 14 and 28 days according to the antigen in question. Generally speaking the earlier the damage occurs the more severe the effects.
The infective agent is a Birnavirus (Birnaviridae), Sero-type 1 only, first identified in the USA in 1962. (Turkeys and ducks show infection only, especially with sero-type 2).
Morbidity is high with a mortality usually 0- 20% but sometimes up to 60%. Signs are most pronounced in birds of 4-6 weeks and White Leghorns are more susceptible than broilers and brown-egg layers.
The route of infection is usually oral, but may be via the conjunctiva or respiratory tract, with an incubation period of 2-3 days. The disease is highly contagious. Mealworms and litter mites may harbour the virus for 8 weeks, and affected birds excrete large amounts of virus for about 2 weeks post infection. There is no vertical transmission.
The virus is very resistant, persisting for months in houses, faeces etc. Subclinical infection in young chicks results in: deficient immunological response to Newcastle disease, Marek's disease and Infectious Bronchitis; susceptibility to Inclusion Body Hepatitis and gangrenous dermatitis and increased susceptibility to CRD.

Control and Prevention of Gumboro DiseaseIf Gumboro is an issue, vaccination is the most effective control method, eithe...
29/09/2022

Control and Prevention of Gumboro Disease
If Gumboro is an issue, vaccination is the most effective control method, either through enhanced MDA in parent stock or through active immunity by means of direct vaccination of chicks. Vaccination policy against Gumboro disease tends to vary by area and the degree of challenge – in cases where the level of challenge is low, birds can develop immunity and vaccination will not be required. However, where vaccination is used, all protocols strive to provide passive protection to the hatching chick, followed by active immunization and a series of boosts in layer and breeder flocks (Saif, 1998).
Broilers drinking
Live vaccines are usually administered in drinking water when the birds are 12 – 21 days old.
If there is a challenge to birds from Gumboro, live vaccines are normally administered through drinking water or eye-drops to chicks at 12-21 days. Saif (1998) refers to unpublished data that casts some doubt on this controversial practice. A live vaccine at 4-10 weeks, followed by an inactivated oil-adjuvanted vaccine at approximately 16 weeks, may be used on parent birds in order to achieve high levels of MDA. Repeated vaccination of chicks is practised in some flocks to counteract declining levels of MDA. It is important that vaccination of chicks is given when MDA levels are low so as to avoid MDA neutralizing the effect of the vaccine.
Removal of the virus from contaminated sites can be difficult, as large quantities are excreted and the virus is stable. An all-in all-out housing policy, coupled with stringent disinfection with formaldehyde and iodophors, can prove effective in reducing challenge to levels and enhancing the impact of vaccination.
Spread of the disease has been associated with the use of infected manure on fields adjoining poultry housing. It is therefore advisable to locate poultry manure away from poultry houses and to store for more than 3 months. Protecting manure heaps from wildlife could also be desirable in controlling infection. Outbreaks of recent virulent epidemics of IBD have been spread rapidly by litter taken from infected houses. There are MAFF and Department guidelines concerning manure handling.
Routine blood testing can be conducted to assess the immune status of flocks.

13/11/2021

Clinical Findings of Infectious Bursal Disease
Infectious bursal disease is highly contagious; results of infection depend on age and breed of chicken and virulence of the virus. Infections may be subclinical or clinical. Infections before 3 weeks of age are usually subclinical. Chickens are most susceptible to clinical disease at 3–6 weeks of age when immature B cells populate the bursa and maternal immunity has waned, but severe infections have occurred in Leghorn chickens up to 18 weeks of age.
Early subclinical infections are the most important form of the disease because of economic losses. They cause severe, long-lasting immunosuppression due to destruction of immature lymphocytes in the bursa of Fabricius, thymus, and spleen. The humoral (B cell) immune response is most severely affected; the cell-mediated (T cell) immune response is affected to a lesser extent. Chickens immunosuppressed by early IBDV infections do not respond well to vaccination and are predisposed to infections with normally nonpathogenic viruses and bacteria. Common diseases are usually exacerbated by IBDV infections. Some strains of IBDV can cause subclinical infections in older birds (3–6 weeks old), which leads to losses from poor feed efficiency and longer times to market. In these cases, the immunosuppression is usually transient, and convalescent birds may recover most or all of their humoral immune function. However, secondary infections that occur during the transient immunosuppression can cause significant economic losses.
In clinical infections, onset of the disease occurs after an incubation of 3–4 days. Chickens may exhibit severe prostration, incoordination, watery diarrhea, soiled vent feathers, vent picking, and inflammation of the cloaca. Flock morbidity is typically 100%, and mortality can range from 5% to greater than 60% depending on the strain of virus and breed of chicken. Mortality is typically higher in layer breeds compared with broiler chickens. Recovery occurs in 20%) were first detected in Europe. They spread throughout the Middle East, Asia, and Africa, were detected in South and Central America in 1999, and in the USA in 2009

13/11/2021

GUMBORO DISEASE in Chickens , Infectious Bursal Disease Symptoms, IBD, Poultry Diseases
Key Points
Infectious bursal disease, caused by infectious bursal disease virus, is a disease of young chickens. The virus infects immature B-lymphocytes and causes an immune suppression that leads to secondary infections in convalescent birds.
The virus is found worldwide, and diagnosis is through clinical evaluation of the cloacal bursa and molecular identification of the viral genome.
Control of IBD is accomplished using vaccination of breeder flocks to induce maternal immunity in young chicks. Antigenic drift requires the use of vaccines that closely match the antigenic structure of the infecting virus. Vaccination in ovo or young chicks using vectored or live-attenuated vaccines can help boost protection as maternal antibodies wane.

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