Les examens sérologiques

Serological

HIV positive or negative? We all know these words, often related to AIDS, yet there are several infections that can be detected by serology. But how does it work? The detection of antibodies and antigens information on our immune status

What serology?

Serology is an examination of the blood serum. It is to detect and investigate antibodies to a specific disease present in the serum, while reflecting the immunity of the individual. The study of these antibodies is an indication of the presence of a pathogen in the body. These are antibodies that correspond to specific antigens. These antibodies are called immunoglobulins.

When to serology?

Serology is performed mainly for

screening,

diagnosis (an autoimmune disease, for example),

follow the evolution of a disease,

assessing the efficacy of vaccination.

However, serology can be performed for certain infectious diseases.

The main immunoglobulins involved in the immune response are the immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM). The presence of IgG usually means an old infection. Active infection is usually shown by the existence of IgM.

Les différentes sérologies	Les techniques utilisées
La sérologie virale
La sérologie de l’hépatite A	Recherche des anticorps anti- VHA (type IgM et IgG)
La sérologie de l’hépatite B	Recherche des anticorps anti-VHB Recherche de l’antigène HBs
La sérologie de l’hépatite C	Recherche des anticorps anti-VHC
La sérologie du VIH/sida	Recherche des anticorps anti-VIH
La sérologie bactérienne
La sérologie de la mononucléose infectieuse	Recherche des anticorps anti-Epstein-Barr virus (anti-EBV) du type IgM. Recherche d’anticorps correspondant à des antigènes spécifiques IgG-VCA, IgG-EBNA, IgG-EA
La sérologie des salmonelloses (fièvre typhoïde)	Sérodiagnostic de Widal et Félix : recherche des anticorps de type O et de type H
La sérologie de la syphilis	TPHA ou Treponema Pallidum Haemagglutination Assay: mise en évidence des anticorps contre les tréponèmes VDRL ou Venereal Disease Research Laboratory : mise en évidence des anticorps anticardiolipidiques
La sérologie de la rubéole	Recherche d’anticorps de type IgM, IgA mais aussi IgG
La sérologie parasitaire
La sérologie de la toxoplasmose	Recherche des anticorps IgM

The result

When serology is positive, it is called an HIV-positive person to infection. Otherwise, it is called a negative person.

Seropositivity means the presence of specific antibodies to an infectious disease in the blood. This antibody may reflect a former contact with the pathogen but may also sign the existence of a progressive disease.