Reticuloendotheliosis(RE)

It is a viral disease that causes severe immunocompromise, stunting, and acute and chronic tumors in chickens, turkeys, and ducks. It is caused by reticuloendotheliosis virus (REV), which belongs to the retrovirus family.

Clinical Symptoms

In chickens, trichoendotheliosis can be broadly classified into acute trichoendothelioma, which is an acute onset of tumors, running disease syndrome, which is an immunocompromised condition characterized by damage to the thymus and Fabricius sac, and chronic trichoendothelioma, which is a chronic onset of tumors.

The first pathology, acute reticulocyte tumor, is caused by infection with REV-T isolated from turkeys, and although it has not yet been confirmed whether it actually occurs in outdoor chickens, experimental infections at the age of 1 day cause 100% of chickens to develop acute tumors (Figure 1) in various internal organs such as liver, kidney, and spleen within 3 weeks of infection and die.

The second pathology, dwarfism syndrome, is a pathology characterized by severe decrease in growth rate and decrease in immunity, which can cause proctitis, enteritis, and anemia, and a symptom called Nakanuke (Figure 2), in which the middle part of the feathers are curled on the pterygoid axis, and when the wings are spread, it is observed as if there is a hole in the middle of the wing.

Individuals with dwarfism syndrome are severely immunocompromised due to the destruction of primary immune organs such as the thymus and Fabricius gland, which greatly reduces their resistance to fungal diseases, parasitic diseases such as coccidiosis, and diseases such as pox and infectious laryngotracheitis.

The third pathology, the chronic tumor type (Figure 3), is similar to other neoplastic diseases such as Marek's tumor and leukemia in terms of clinical manifestations and tumor growth period, and is divided into Follicular lymphoma and non-Follicular lymphoma according to the presence or absence of tumor formation in the F follicle and the latent period of tumor formation.

Follicular lymphoma is similar to leukemia with a latent period of tumor formation of more than 17 weeks, and the tumor growth period is often seen in the liver and spleen, but most tumors are also formed in the F follicle.

Non-follicular lymphoma, on the other hand, is similar to Marek's disease with an incubation period of 6 weeks, and tumors often appear in the thymus, liver, and spleen, but are not formed in the follicle.

Diagnosis

Poor growth rate, severe vaccine sequelae, and decreased resistance to other diseases may lead to suspicion of infection with a xenotropic agent, but confirmation requires virus isolation.

Virus isolation is possible from embryonic fibroblasts but requires a long time.

Recently, it has become possible to detect the genes of the disease in blood cells or tumor tissue of infected individuals using gene amplification methods, making it relatively easy to diagnose the disease.

Prevention and treatment

A vaccine is not available because no vaccine has been developed.

Infectious strains should not be used as breeding stock.