Whooping cough is an acute and very contagious infection of the respiratory tract. It causes inflammation and necrosis of the respiratory tract ciliated epithelium and it produces immunological and pathophysiological reactions.
Pertussis toxin (PT) is a protein produced by the Bordetella pertussis Gram-negative bacterium and it is one of the main virulent factors of the disease.
It is typically characterized by an incubation phase of 15-20 days, followed by a catarrhal stage of about 2 weeks, and in the end by a paroxysmal stage lasting 2 or 3 weeks. In young children more serious complications are constituted by further infections that can lead to otitis, pneumonia, bronchitis, or even neurological diseases.
The serological test is based on the determination of specific antibodies through the ELISA principle. IgA antibodies, specific for PT, can be detected after 1-2 weeks and persist for 6-24 months depending on the age. The IgA production is slower in children. IgA antibodies, in suckling infants, can be detected after 6-8 weeks.
IgG antibodies are not detectable before 2-3 weeks from the beginning of the disease and reach their maximum after 6-8 weeks.
Immunoenzymatic method for the quantitative determination of IgG and IgA class antibodies against Bordetella pertussis toxin in human serum, using a disposable device applied on the Chorus and Chorus TRIO instruments. The test is based on the ELISA principle (Enzyme Linked ImmunoSorbent Assay) which uses the reaction between the antibodies present in the tested sample and the immobilized antigen bound to solid phases. The immunoglobulins bind to the antigen through incubation with diluted human serum. The disposable devices contain all the reagents to perform the test when applied on the Chorus instruments. The results are expressed in International Units (IU/ml) calculated in reference to (WHO 1st IS NIBSC 06/140).