[Infectious serology: interpretation of the results and traps to avoid]

In Medical Microbiology, in addition to the direct methods of indentification of infectious agentss, the serologic indirect techniques by quantification of antibodies have extremely useful in infectiology, for the diagnosis and the therapeutic or vaccination follow-up as well as for epidemiologic enquiries, serodiagnosis methods have significantly improved. Meanwhile, results may reveal hard to interpret, especially when are tries to specify the time of the beginning of an infection. The results require in the majority of the cases to be compared on two subsequent serum samples, to observe a possible increase in antibodies level. In addition, the infectious serology results may not be considered as the only element of final diagnosis. In all cases, they have to be interpreted and challenged against the clinical context.