Also known as Infectious bursal disease (IBD)
Gumboro is very common worldwide. It affects mainly chickens (serotype 2 only in USA, in chickens, turkeys and ducks) of 2-16 weeks. Infectious bursal disease virus is a birnavirus. It is highly stable and resistant to many physical and chemical agents. It is highly contagious and is be spread by contaminated faeces, water and feed. It can also be carried by vectors such as darkling beetles and rats.
Causes of Gumboro
Mode of transmission
IBD spreads by contaminated faeces, water and feed.
It is a highly contagious and hardy agent. Other vectors can harbour the virus including the lesser meal worms and rats.
Effects of Gumboro
Elevated body temperature (111oF/44oC) watery urate diarrhoea, anorexia, depression, ruffled feathers, head trembles, sleepiness and lameness can occur.
Morbidity approaches 80% in white leghorns and 50% in broilers.
Hypervirulent strains occur and can cause up to 100% morbidity and 80% mortality in laying hens. Normal mortality is not more than 40% in laying hens and 20% in broilers. It is immunosuppressive and very common throughout the world.
Postmortem lesions
The bursa is enlarged (2-4 times), haemorrhagic and/or oedematous early (3-5 days) in the course of the infection.
Other lesions include an increase in kidney urates, a swollen necrotic spleen and increased mucous in the intestine.
Later in the infection the bursa is atrophic (7 days), ¼-½ normal size. Thymus may also be atrophic. The bursa remains atrophic through the life of the bird, whereas the thymus can regenerate.
Muscle haemorrhage, rickets, dehydration, haemorrhages at the junction of the proventriculus and gizzard may also be seen especially with the hypervirulent strains.
Diagnosis of Gumboro
Oedematous involvement of the bursa of Fabricius in young birds is diagnostic.
Treatment & Control of Gumboro
Prevention
Vaccinate parents at 2 and 6 weeks with live vaccine and at 10 and 18 weeks with killed vaccine. Live vaccine can be given between 10-26 days, depending on level of maternal antibodies and type of vaccine used. Virulent strains can be given approximately 5 days broilers. For problem farms, it is recommended to measure maternal antibody levels of ELISA and calculate day(s) of vaccination accordingly.
For breeders, in addition one killed vaccine around 16-18 days in common.
Vaccinate progeny between 1 and/or 14-21 days with attenuated vaccine on problem farms by spray or drinking water. Some vaccine can be given in ovo at 18 days of embryonation mixed with MD vaccine.
There are two serotypes of IBDV. Serotype 1 viruses are pathogenic, whereas serotype 2 viruses are not pathogenic. Serotype 1 viruses are divided into 6 subtypes.
Treatment
Vitamins and minerals and/or sugar in drinking water to prevent dehydration, replace lost electrolytes and provide and energy burst.
