The causative agent in these alleged cases of infectious bursal disease was a virus of infectious bronchitis – Virus Gray.

The true etiologic agent of infectious bursal disease was isolated for the first time in 1962. And is called the “agent, infectious bursal”; it is a virus included within the type of the reovirus.

The virus of this disease is distributed throughout the world and is prevalent in many areas where there is a high concentration of birds.

The losses due to mortality caused by this disease are significant and result directly from the disease itself or from the immunosuppressive effect of the virus.

As a result of this treatment, the disease may be associated with dermatitis gangrenous, hepatitis inclusion body syndrome anemic or failures in the processes of other diseases.

Currently, the sequels that stops the infection by this virus are most important from the economic point of view that the disease itself.

As a general rule, the infectious bursal disease occurs in young animals.

Some time ago it was thought to be a disease of birds heavy, but it has been shown that in birds, light can also occur with the same gravity and a high degree of mortality.

The disease typically appears between three and six weeks of age, although subclinical infection may occur before three weeks of age.

The virus of the disease is highly contagious and is more prevalent in a lot of time in the holding which has been affected animals, including 125 days after casting.

It is not entirely proven vertical transmission via the egg, but some authors report that can occur at certain stages of the disease.

Similarly, doubting the existence of remaining animals carriers once that has happened, of the disease.

It has been noted that some genera of ticks and mosquitoes can be carriers of the virus infectious bursal disease and lead to an outbreak of this disease.

The virus can survive very well in the feed, drinking water, vessels of the chicken coop and clothes of the staff, which favors the maintenance of infection within an exploitation determined.

The incubation period for Gumboro disease is very short, with symptoms appearing two to four days after inoculation.

The presentation of the disease always occurs suddenly, with symptoms of general deaths and serious, with severe depression and not reacting the birds to external stimuli.

Appears watery diarrhea, and a foamy white-yellowish, messing up the feathers around the cloaca, and sometimes the upper edge of this is projected to the outside as a result of the enlargement of the bursal.

The severity of symptoms decreases as the chicks grow older, and the infection becomes subclinical after six weeks.

The depression gradually worsens to the point where the birds are unable to move, leading to dehydration and, ultimately, death.

In this phase preagónica the bird presents hypothermia.

The morbidity is very high, occurring in up to 70 % of sick birds, although mortality can vary between three and twenty percent.

The recovery of the animals is quick. The phenomenon of immunosuppression was observed since a long time ago and is a result of the damage the virus in the immune system.

This is manifested by:

—Increase: From susceptibility to other pathological conditions, including gangrenous dermatitis, infectious anemia, and inclusion body hepatitis.

—Decrease: Of the immune response to vaccines supplied to prevent other diseases.

There are no known chemotherapy treatment that may be useful for treating infectious bursal disease. On the other hand, the rapid recovery of the birds makes it uneconomical to any treatment.

The only way to prevent Gumboro disease is to implement vaccination programs that include breeding stock and their chicks.

Vaccination programs for breeding stock determine the vaccination schedule for chicks, as the residual natural immunity they possess at birth plays an important role in their immune response.

There are three types of live vaccines, based on the virulence of the strains used in their preparation:

—Those produced using attenuated avirulent strains:

Do not cause any injury to the tissues' lymphocyte subsets, and do not produce any immuno-suppressive effect.

They are only suitable for use with chicks that have no residual maternal immunity. The presence of maternal antibodies prevents the development of immunity.

—Those produced using strains of relatively low virulence:

They cause immunosuppression and damage to lymphoid organs, and vaccinated chicks may even exhibit clinical signs of disease.

—Those produced using strains of moderate virulence:

These are the most commonly used methods today, since all breeding stock is generally well protected. The virus is replicated in the presence of maternal antibodies.

It has a power of spreading horizontally from bird to bird.

Have not been identified effects of immunosuppression with the use of these strains.

Currently, these vaccines are supplied to the chicken to the twelve or fifteen days by the oral route.

If Gumboro disease occurs in chicks vaccinated at this age, vaccination should be brought forward—even to the first day of life—with a second vaccination administered three weeks later.

Implementing effective vaccination programs against Gumboro disease is essential, not only to prevent clinical cases of the disease but also to prevent subclinical infections that pave the way for secondary infections, which negatively impact the economic and health status of the flocks.