Gumboro disease is a viral infection that mainly affects chicks between the first 3 and 6 weeks of life. It can also affect other birds such as ducks and turkeys, which is why it is one of the most common diseases in poultry. The disease is characterized by affecting the lymphoid organs, with particular severity in the bursa of Fabricius in birds, causing immunosuppression by affecting the production of immune cells. In addition, type III hypersensitivity processes occur with damage to the kidneys or small caliber arteries.
Keep reading this article on our site to find out exactly what is Gumboro disease in birds, its symptoms and treatment.
What is Gumboro disease?
Gumboro disease is a infectious and contagious disease of birds, clinically affecting chicks 3 to 6 weeks old. life, although it can also affect turkeys and ducks. It is mainly characterized by atrophy and necrosis of the bursa of Fabricius (a primary lymphoid organ in birds that is responsible for producing B lymphocytes), which causes immunosuppression in these birds.
This is a disease of great he alth and economic importance that affects poultry farming. It presents a high morbidity, infecting between 50 and 90% of the birds. Due to its great immunosuppressive action, it favors secondary infections and compromises vaccination.
The infection is carried out by contact with the feces of infected chickens or by water, fomites and food contaminated by them.
What virus causes Gumboro disease in birds?
Gumboro disease is caused by the avian infectious bursal disease virus, belonging to the family Birnaviridae and the genus Avibirnavirus. It is a very resistant virus in the medium, to temperature, to pH between 2 and 12 and to disinfectants.
It is an RNA virus that has a pathogenic serotype, serotype I, and a non-pathogenic one, serotype II. Serotype I includes four pathotypes:
- Classic strains.
- Mild and vaccinal field strains.
- Antigenic variants.
- Hypervirulent strains.
Pathogenesis of Gumboro disease in birds
The virus enters orally, reaches the intestine where it replicates in the macrophages and T lymphocytes of the intestinal mucosa. Then, the first viremia (virus in the blood) begins 12 hours after infection. It passes to the liver where it replicates in hepatic macrophages and immature B lymphocytes in the bursa of Fabricius.
After the above process, the second viremia occurs and then replicates in the lymphoid organs of the bursa of Fabricius, thymus, spleen, harder glands of the eye and cecal tonsils. This causes destruction of lymphoid cells, which causes an inability of the immune system. In addition, type 3 hypersensitivity occurs with deposition of immune complexes in the kidney and small arteries, causing nephromegaly and microthrombi, hemorrhages, and edema, respectively.
Gumboro disease symptoms in birds
In birds two clinical forms of the disease can occur: subclinical and clinical. Depending on the presentation, the symptoms of Gumboro disease can vary:
Subclinical form of Gumboro disease in birds
The subclinical form occurs in chicks less than 3 weeks old that have low maternal immunity. In these birds there is a low conversion rate and average daily gain, that is, as they are weaker, they need to eat more but, however, they do not gain more weight. Likewise, there is an increase in water consumption, immunosuppression and mild diarrhea.
Clinical form of Gumboro disease in birds
This form appears in chickens from 3 to 6 weeks, characterized by showing the following symptoms:
- Fever.
- Depression.
- Ruffled Feathers.
- Pica.
- Prolapse of the cloaca.
- Dehydration.
- Small hemorrhages in the muscles.
- Ureter dilation.
In addition, there is an increase in the size of the bursa of Fabricius in the first 4 days, later congestion and hemorrhages occur from 4 to 7 days and finally it decreases in size due to atrophy and depletion lymphoid, causing the immunosuppression that characterizes the disease.
Diagnosis of Gumboro disease in birds
The clinical diagnosis will make us suspect Gumboro disease, or infectious bursitis, in the presence of symptoms similar to those indicated in chicks from 3 to 6 weeks of age, making a differential diagnosis with the following poultry diseases:
- Avian infectious anemia.
- Marek's disease.
- Lymphoid leukosis.
- Avian Influenza.
- Newcastle disease.
- Avian infectious bronchitis.
- Avian coccidiosis.
The diagnosis will be made after extracting samples and sending them to the laboratory for direct laboratory tests in search of the virus and indirect tests in search of antibodies. The direct tests include:
- Viral isolation.
- Immunohistochemistry.
- Antigen capture ELISA.
- RT-PCR.
The indirect proofs consist of:
- AGP.
- Viral seroneutralization.
- Indirect ELISA.
Treatment for Gumboro disease in birds
Treatment for infective bursitis is limited. Due to the damage that occurs to the kidneys, many drugs are contraindicated due to their side effects on the kidney. Therefore, the use of preventive antibiotics for secondary infections can no longer be done today.
Because of all this, There is no treatment for Gumboro disease in birds and control of the disease must be done through preventive measures and biosafety measures, such as:
- Vaccination with live vaccines in growing animals 3 days before loss of maternal immunity, before those antibodies drop below 200; or inactivated in breeders and laying hens to increase maternal immunity for future chicks. Thus, there is a vaccine against Gumboro disease, but not to combat it once the chick has been infected, but to prevent it from developing.
- Cleaning and disinfection of the farm or home.
- Control access to the farm.
- Insect control in feed and bedding that can carry the virus.
- Prevention of other debilitating diseases (infectious anemia, marek, nutritional deficiencies, stress…)
- Measurement of all in-all out, which consists of separating the chicks from different places into different spaces. For example, if an animal sanctuary rescues chicks from different farms, it is preferable to keep them separate until they are all he althy.
- Serological monitoring to assess vaccine responses and field virus exposure.
