tuberculinization Flashcards
what are immunological methods
serological and allergological (tuberculin test)
what is hypersensitivity
the state of heightened or excessive immune response to repeated exposure to a specific antigen
how does sensitisation happen
on the first contact of a immunocompetent macro-organism and he substance with antigenic properties, the macroorganism is sensitised
ie it becomes hypersensitive so that it creates sensitised T lymphocytes or antibodies
what happens on second contact with substance
if in contact with same substance again, an antigen-antibody complex is created or antigen sensitised T lymphocytes and an excessive immune response, which leads to tissue damage or signs of inflammation
early phase hypersensitivity
seen quickly after repeat contact with the antigen/allergen
carriers = antibodies of all immunoglobulin classes
late phase hypersensitivity
seen in hours or days after contact between the previously sensitised macroorganism and the antigen/allergen
carriers = sensitised T lymphocytes
what is tuberculosis
chronic, contagious infectious disease
cause = mycobacterium complex - M.bovis, M.caprae, M.tuberculosis, M.africanum
most common zoonosis worldwide
immune response
when infected with mycobacteria cattle become hypersensitive to the protein antigen of the causative agent
cellular hypersensitivity leads to sensitised T lymphocytes leads to lymphokines which activate monocytes and mononuclear cells
consequences of immune response
the cascade immune response leads to inflammation and manifestation of hypersensitive reaction
best expressed 48-72h after introduction of the antigen to previously sensitised cattle
individual skin test testing for TB
fill out form
L neck - 10cm in front of shoulder and 20cm below ridge of neck
clip 5cm2
measure thickness of skin
apply 0.1ml of purified protein derivative of M.bovis intradermally
check it has been applied appropriately - rice size lump under finger
check reaction after 72h
what is assessment of reaction to tuberculin test based on
clinical exam of swelling at site of application
exam of regional lymph nodes - submandibular and prescapular
measure thickness of skin fold using cutimeter
negative reaction to individual skin test
only limited swelling at site, no sign of infection (edema, temp, redness, pain)
lymph nodes without signs
increase in skin fold not greater than 2mm
doubtful reaction individual skin test
no changes at site or on lymph nodes but increase in skin thickness is more than 2mm but less than 4mm
positive reaction individual skin test
inflammation seen at site of application or lymph nodes
or increase in skin fold greater than 4mm
descrive comparative intradermal test
at least 42 days after reading of individual test
clip 2 areas on neck
measure skin with cutimeter
0.1ml avian 10cm below ridge of neck
0.1ml bovine 15cm lower in line parallel with shoulder
read test after 72h
negative reaction comparative test
if reaction to bovine is the same or less than the reaction to avian and no clinical signs of inflam
doubtful reaction comparative test
reaction to bovine is 1-4mm larger than reaction to avian without clinical signs
positive reaction comparative test
reaction to bovine is more than 4mm larger than reaction to avian with or without clinical signs
tuberculinisation of goats
all goats older than 12 months kept on farms where there is dairy cattle must be tested by individual TB test
doing and reading the results the same as in cattle
tuberculinisation of pigs
intradermal application of bovine and/or avain on dorsal side of head, where ear joins head
0.1ml in each site
read results 48h after
positive pig reactions
if inflammation at site of application of either
erythema, sometimes necrosis
skin swelling with central necrosis = dominant signs hypersensitivity
pig reactions if TB to no TB
on pig farm with NO TB, positive reaction is a swelling larger than 20mm, and swelling 10-20mm is doubtful
on farm with confirmed TB, positive is when swelling large than 10mm and doubtful if less than 10mm
negative pig test
NO TB = negative if no reaction or less than 10mm swelling
TB farm = negative if no reaction
tuberculinisation in horses
performed the same as in cattle
usually caused by M.avium complex but can be M.bovis and M.tuberculosis
up to 70% of clinically healthy horses can have a positive test - v low specificity test
