Immunity Against Parasites in Animals - The Veterinary Site

Immunity Against Parasites in Animals

Immunity Against Parasites


Host Defense and Immunity
       Host evolve many behavioural  and other strategies to reduce the risk of succumbing to parasitism.
       The most powerful form of defence is the immune system.
Susceptibility and resistance
A host is susceptible to a parasite if the host cannot eliminate the parasite before the parasite can become established.
The host is resistant if its physiological status prevents the
establishment and survival of the parasite.
Similarly, from the parasite’s point of view it would be infective and noninfective.
These terms are relative and not absolute
       The term immunity has been, on the one hand, often used as synonymous with resistance and, on the other hand, associated with the sensitive and specific immune response exhibited by vertebrates.
       However, because invertebrates can be immune to infection with various agents, a more general yet concise statement is that an animal demonstrates immunity if it possesses cells or tissues capable of recognizing and protecting the animal against nonself invaders.
       Frequently the resistance conferred by immune mechanisms is not complete. In some instances a host may recover clinically and be resistant to specific challenge, but some parasites may remain and reproduce slowly, as in toxoplasmosis Chagas’ disease, and malaria. The parasites are held in check by the host’s immune system, and the host is asymptomatic. This condition is called premunition
Concomitant immunity
       In some infections a parasite may elicit a protection against reinfection, but the parasite itself may remain in the host, unaffected by the immune response (concomitant immunity), as in schistosomiasis. In this case the host may suffer significant morbidity.
       Ideally, immunity should protect against reinfection after the invading parasites have been eliminated. This is called ‘sterile Immunity ’. It can last for a lifetime              but often wanes with time.
Mucosal Immunity
       Mucosal immunology is the study of immune system responses that occur at mucosal membranes of the intestines, the urogenital tract and the respiratory system, i.e., surfaces that are in contact with the external environment
       A preparation containing antigenic material which may consist of
       Dead microorganisms
       Attenuated (weak or harmless) microorganisms
       Toxoid (harmless form of toxin)
       Preparation of harmless stages

Immunity Against Parasites in Animals Immunity Against Parasites in Animals Reviewed by Maaz ahmed siddiqui on 09 May Rating: 5

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