Seroconversion 604783 222327780 2008-06-28T19:16:19Z WhatamIdoing 1998764 Merge pages '''Seroconversion''' is the development of detectable specific [[antibodies]] to [[microorganism]]s in the [[blood plasma|blood serum]] as a result of [[infection]] or [[immunization]]. [[Serology]] (the testing for antibodies) is used to determine antibody positivity. Prior to seroconversion, the blood tests ''[[seronegative]]'' for the [[antibody]]; after seroconversion, the blood tests ''[[seropositive]]'' for the antibody. The word is often used in reference to blood testing for anti-[[HIV]] antibodies. '''Seroreversion''' is the opposite of seroconversion. This is when the tests can no longer detect [[antibody|antibodies]] in a patient’s serum.<ref>Tantalo et al, JID 2005:191; "''Treponema pallidum'' strain-specific differences in neuroinvasion and clinical phenotype in a rabbit model"</ref> == Background == The [[immune system]] maintains an "immunological memory" against past pathogens to facilitate early detection and to confer protective immunity against a [[Challenge-dechallenge-rechallenge|rechallenge]]. This explains why many childhood diseases never recur in adulthood (and when they do, it generally indicates [[immunosuppression]] or failure of a vaccine). In the initial (primary infection) phase of the infection, [[Immunoglobulin M]] (IgM) antibodies are produced and as these levels drop (and become undetectable) [[Immunoglobulin G]] (IgG) levels rise and remain detectable. Upon reinfection, IgM antibodies usually do not rise again but IgG levels will increase. Thus an elevated IgM [[titre]] indicates recent primary infection, while the presence of IgG suggests past infection or [[immunization]]. ==References== {{reflist}} [[Category:Serology]] [[de:Serokonversion]] [[id:Serokonversi]]