Gumboro Disease also known as Infectious bursal disease (IBD) threatens poultry farmers mostly because it is a killer type of disease. It is an acute infectious disease that is common with chicks of 3-6 weeks old. Gumboro disease disturbs the growth of broilers in most severe manners.
Symptoms: Birds infected with Gumboro disease would not be able to feed well and start to pass out watery whitish diarrhea. The feathers would become ruffled and appear very sluggish.
Prevention: To prevent the outbreak of Gumboro disease, you must make sure that you improve your sanitary measures by disinfecting all poultry equipment and cleaning of every place in the house regularly.
As there is no treatment for Gumboro disease outbreak only a vaccination, poultry farmers should always advised to follow strictly the vaccination program of their birds and administer each drugs and vaccines accordingly and also to contact a nearby veterinary clinic for special advice whenever this disease is suspected.
Note: you should not apply any drug or vaccine without the advice of an expert unless you are sure of what to do to avoid vaccination failure or mistakes.
Now let’s explain Gumboro Disease in details below:
(Anatomy of Chicken: The virus which causes Gumboro disease usually affects the lymph cells in the cloaca, tonsils and spleen).
Infectious bursal disease (IBD), also known as Gumboro, is a highly contagious viral infection that is found in chicken flocks in most countries. The severity of the disease will depend on the age and breed of chicken (White Leghorns are more susceptible than broilers and brown-egg layers) and the virulence of the virus.
Signs of the disease can include a rapid drop in feed and water consumption, mucoid (slimy) diarrhoea with soiled vent feathers, ruffled feathers, listless chicks with unsteady gait or sitting in hunched position, picking at own vent and sleeping with beak touching the floor.
Infections before 3 weeks of age are usually subclinical (no detectable symptoms). Chickens are most susceptible to clinical disease at 3-6 weeks and severe infections have occurred in Leghorn chickens up to 18 weeks old.
Early subclinical infections are the most economically important as the disease can cause severe, long-lasting suppression of the immune system. Chickens that are immunosuppressed by early IBD infections do not respond well to vaccination and are more susceptible to other diseases, including those that don’t normally affect healthy chickens.
In clinical infections, onset of the disease is sudden after an incubation of 3-4 days. Mortality is usually low but has been reported to be as high as 20%. Recovery from the disease usually occurs in less than a week, however broiler weight gain is delayed by 3-5 days.
The presence of maternal antibody (antibody passed to the chick from the mother) will modify the way the disease progresses. The virulence of field strains varies considerably. Very virulent (vv) strains of the virus that cause high mortality and morbidity were first detected in Europe, and have not yet been detected in Australia.
What causes infectious bursal disease?
Infectious bursal disease is caused by a birnavirus (IBDV) that is most readily isolated from the bursa of Fabricius which is an organ of the immune system. The virus can also be isolated from other organs. It is shed in the faeces and spreads between birds or by contact with a contaminated environment and is possibly also carried in dust.
The virus can be transferred from house to house on fomites (any inanimate object or substance that is capable of carrying infectious organisms from one individual to another) and rodents. The virus is very stable and difficult to eradicate.
There is no vertical transmission (from parents directly to offspring) and mealworms and litter mites may harbour the virus for 8 weeks. Infected birds shed large amounts of virus for up to 2 weeks after infection.
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).
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.
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.
Routine blood testing can be conducted to assess the immune status of flocks.
Prevention and treatment of infectious bursal disease
There is no treatment for IBD but support therapies such as vitamin and electrolyte supplements and antibiotics to treat any secondary bacterial infections, may reduce the impact of the disease.
Depopulation and rigorous disinfection of contaminated farms have achieved some limited success in preventing disease spread. Prevention is through good biosecurity and vaccination, including passive protection via breeders and 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.
Birds that have recovered from a natural infection have a strong immunity. If maternal antibody was still high at the time of vaccination, immunity in chicks that receive live vaccine can be poor.
Due to the high degree of variation between naturally occurring IBD viruses there are a number of vaccines available. Vaccines need to be selected based on the types of viruses present in the area.
Gumboro disease cannot be successfully treated, so if there is a risk of this disease, vaccination is the best policy. The virus is resistant to a number of disinfectants.
Pattison (1993) recommends the following disinfection procedure after contagious and infectious disease:
- The buildings should be closed and isolated from all visitors
- The bedding, litter and all areas in intimate contact with the birds should be sprayed with a disinfectant at adequate concentration
- The litter should subsequently be removed from the building and may be burnt or buried so there is no possible contact with poultry or other livestock
- Portable equipment and fittings should be given the same treatment, preferably in the house, and later be taken out and aerated
- The floors and lower part of the walls are treated with a detergent disinfectant
- Surfaces should then have a disinfectant applied with a wide spectrum of activity, capable of killing all types of pathogens present
- It may be advisable to skim off the top few inches of the soil around a heavily infected area
- The approaches to the building should be treated with disinfectant; foot dips should be provided for personnel and wheel-dips for vehicles
Good Practice based on Current Knowledge
- If there is a risk of Gumboro, vaccinate all birds at a week old
- Operate an ‘all-in, all-out’ policy between batches of birds
- Maintain high standards of hygiene, particularly with regard to disinfection between batches
- Store poultry manure for at least 3 months before spreading
- Do not spread manure on land used for poultry
- Protect manure heaps from wildlife
Here are some poultry farming books to guide and assist you further: