Immunodeficiency

The struggle for existence is the law of nature and acquisition of the efficient weaponry paves the way for the survival of the fittest. Immune system is one of the most complex, ubiquitous, sensitive and specific arsenal acquired by living creatures to sustain the onslaughts of the physical, chemical, biological and environmental adversities. The alterations, which decrease the effectiveness or destroy the capabilities of the system to respond to various antigens, are collectively designated as immunodeficiency disorders. The animal may acquire the suppression of immune system due to drugs, genetic defects, diseases or infections, deficiency of nutrition, neoplasm or environmental pollution etc. which is clinically manifested by increased susceptibility to infectious diseases. The immunodeficiencies in animals can be broadly classified into congenital (primary) and acquired (secondary) immunodeficiencies. Acquired immunodeficiency is more common than congenital immunodeficiencies. Many infectious agents are known to cause immunosuppression in animals and poultry either by directly acting on immunocytes or through action on cytokines and activation of T-suppressor cells. The diagnosis of immunodeficiency diseases can be made by detection of immune responses against any kind of antigen or nonspecifically by measuring gamma globulins and antibody levels in the serum.