In production practice, there is always troubled by the disease, and often complicated with various diseases or secondary infections manifest themselves, resulting in a large number of dead poultry or eliminated, resulting in huge losses. Close look at this is that the presence of immunosuppressive diseases and infections and multiple infections. Therefore, the majority of poultry must attach great importance to the poultry industry immunosuppressive diseases.
Poultry immunosuppressive diseases occurring factors: We usually poultry immunosuppressive diseases are divided into primary and secondary categories. Many secondary immunosuppression in different growth stages after hatching, feeding a variety of improper management or infection caused a variety of infectious factors. Young poultry, especially the first week in infection, more prone to immune suppression secondary issue. Scale, intensive poultry rearing secondary immunosuppression of primary greater than the harm caused.
Production practice, improper use of drugs, nutritional deficiencies and mold toxins can cause immune suppression, we are more concerned about the infectious factor induced immunosuppression. Endanger their descending order, followed by infectious bursal disease (IBD), reticular endothelial hyperplasia within the virus (REV) infection, Marek’s disease (MD), leukemia, chicken infectious anemia (CIA) and reovirus (ReoV) infection. These viruses are often persistent and subclinical infection, the immune suppression caused by difficult to identify. Recent studies show that the prevalence of immunosuppressive virus surface increasingly common. The following brief overview:
1, infectious bursal disease virus (IBDV)
Naturally occurring virulence of IBDV very different. Does not cause death from almost all the dead until the fatal range, but even a low death rate of strain can also cause bursal atrophy. The bursa of Fabricius 3 days from hatching to 14 days before maturity, has been charged with the outside peripheral immune organs (spleen, lymph nodes) transport B cell functions. This time infection IBDV, less high mortality occurred, but would reduce the number of B cells to make antibodies also reduced the secretion of so difficult to have a good variety of other vaccine response, antibody titer is not high. Experience has shown, the occurrence of infectious bursal disease of chickens, resistance to various diseases have dropped significantly. In addition, many clinical observation and practice data show that some of the strong side of medium virulence attenuated vaccine can also cause varying degrees of immune suppression.
2, reticuloendothelial hyperplasia virus (REV) REV is a type of retrovirus, can infect a variety of birds. We are in the broiler and breeder serological testing found that 90% of antibodies in chickens REV 20-90% positive rate, indicating that indeed widespread poultry population REV infection problem. Recent research also shows that a day-old artificially infected with REV in chickens, attenuated vaccine against Newcastle disease and Newcastle disease, avian influenza inactivated vaccine antibody response to different degrees of inhibition. Although the vaccine can be spread through contaminated However, the immunosuppressive effects REV especially vertical hatched 1-3 days after infection or early infections the most significant. In fact, a considerable proportion of chickens infected with REV REV life does not generate antibodies, showing tolerance of sexually transmitted diseases known as toxemia (ie, long-term do not produce antibodies of viremia) in continuous or intermittent detoxification. These do not produce antibodies against REV chickens, poor immune response, it is easy to become infected with other pathogens in chickens susceptible host. And REV with Marek’s disease virus or were infected with chicken leukemia virus is present in the tumor breeder important reasons.
3, Marek’s Disease Virus (MDV)
Marek’s disease is a highly contagious avian tumors. It is outside the peripheral nerves, gonads, the internal organs, skin and muscles, tissues and organs of the characteristics of lymphocyte infiltration occurs, in which the immune organs and tissues are also affected. Since MDV target cells to lymphocytes induced cytotoxicity, resulting in infection of chickens professional immunosuppression. In addition, MDV in the bursa of Fabricius, thymus, spleen and other organs and tissues such as lymphocytes and macrophages in the proliferation of target cells, may reduce the functional activity, is one of the causes immune suppression occurs.