Cross-sectional antibody prevalence studies

Cross-sectional prevalence studies involve collecting biological samples at a point in time that are representative of a population of interest and subsequently screening them for a marker that relates to a disease. They are relatively simple to conduct, take only a short time and are relatively cheap.

Serum is often the sample of choice with specific IgG the marker chosen, as the presence of this antibody indicates previous exposure (or vaccination) to the disease for which it is specific. If samples collected at several different time points are able to be used it is possible to estimate how the epidemiology of a particular disease may be changing.

Not only can markers be considered qualitatively in terms of their presence or absence, but also quantitatively. For example, high titres of IgG specific to pertussis toxin are considered indicative of a recent Bordetella pertussis infection (Nardone et al. Vaccine 2004;22:1314-1319). In the absence of a reliable IgM assay, this provides valuable additional information.

Similarly, high titres of H.pylori specific IgG have been shown to be indicative of an active infection with this bacterium at the time of sample collection ( Vyse et al, Epidemiol. Infect. 2002;128:411-417 ). Such analyses often yield important information that can contribute to understanding the epidemiology of a disease.

Regular cross-sectional IgG prevalence studies form the basis of serological surveillance, an important technique for continually monitoring the behaviour of a disease within a population.