BORDETELLA PERTUSSIS IGG/IGM, BY ELISA WITH IMMUNO

Code
900.0701
Name
BORDETELLA PERTUSSIS IGG/IGM, BY ELISA WITH IMMUNO
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
CPT Codes
86615 X2; If indicated add 86615 for each immunoblot
Site
SBMF
Reference Test
44426
ATLAS Test Code

BORD PERT

Specimen Information

Type

Gold, SST

Volume

1.0 ml

Transport Info

Centrifuge and immediately transfer serum to separate plastic tube Refrigerated

Fasting Required?
False
Patient Instructions

Reference Range

See Report

Methodology

Semi-Quantitative Enzyme-Linked Immunosorbent Assay (ELISA) Qualitative Immunoblot

Clinical Significance

Bordetella pertussis is a fastidious gram-negative pleomorphic bacillus that requires special media for culture. Infection of the tracheobronchial epithelium produces pertussis (whooping cough), a prolonged disease marked by paroxysmal coughing. Transmission of pertussis is by airborne spread of respiratory secretions. Pertussis is highly infectious and the spread of disease is often not recognized due to the mildness of symptoms in immunized persons. Secondary spread in families and schools is common. Adult cases with symptoms resembling the common cold are a significant reservoir of the organism, and have been the source of outbreaks in highly susceptible populations, such as unimmunized infants. After an incubation period of 7-10 days, pertussis follows a prolonged course consisting of three overlapping stages: catarrhal, paroxysmal coughing, and convalescent. Partially immune persons and infants under six months of age may not show all the typical features of pertussis. Paroxysmal coughing may be absent in these cases. The number of annual cases of pertussis has dropped significantly since the introduction of the whole-cell vaccine in the 1940s. The number of reported cases has been rising, however, with an average of 4,619 reported cases per year during 1990 to 1995. The proportion of cases of pertussis involving adolescents and adults rose from 15.1 percent between 1977 and 1979 to 26.9 percent between 1992 and 1993 (Centers for Disease Control and Prevention). This rise in cases in adults appears to be due to a combination of waning immunity to childhood vaccination, increasing B. pertussis in the community, and increased recognition of the disease in older individuals. Culture: A clinical diagnosis of pertussis is confirmed by isolation of B. pertussis from a nasopharyngeal swab. The organism is not found in blood or at distant sites. Specimens collected during the initial catarrhal or early paroxysmal stage provide the greatest chance of successful isolation. Unfortunately, the diagnosis is frequently not considered until the paroxysmal coughing has been present for some time, and the number of organisms has decreased significantly. Direct immunofluorescence antibody test (DFA): A direct immunofluorescence antibody technique can be applied to nasopharyngeal smears for rapid diagnosis of pertussis. Positive smears should always be confirmed by culture, if possible. Studies of adults with pertussis have indicated that the vast majority will have a negative DFA (Mink CM, Wright SW). Serology: The sensitivity of isolating B. pertussis by culture decreases progressively during the disease, and there is decreased sensitivity of culture overall in adults. For these reasons, a combination of culture and serologic assays may be useful for the diagnosis of pertussis. The sensitivity with culture or serology, however, remain quite low, 55 percent and 45 percent, respectively (Hallander HO). Antibodies to pertussis toxin and filamentous hemagglutinin have been commonly used as a serologic indicator of pertussis. Antibodies to pertussis toxin have also been effective in detecting infection in children. A recent study suggests, however, that the detection of IgG antibody to fimbriae 2/3 may be more useful for diagnosing pertussis in adults (Jansen DL). Additionally, a significant correlation between clinical protection after household exposure and the presence of IgG antibodies to pertactin, fimbriae 2/3, and pertussis toxin were demonstrated in the Swedish vaccine trial I (Storsaeter J). IgA does not appear to contribute to the diagnostic sensitivity of serology if paired sera are available. In almost all cases in which an IgA antibody level increase occurred, an increase in IgG level occurred as well (Hallander HO). Culture for B. pertussis is the "gold standard" for diagnosis of pertussis in children. However, culture is rarely positive in adults with pertussis. Serologic measurement of pertussis antibodies, therefore, may be helpful in the diagnosis of pertussis in cases where paroxysmal coughing has been present for a long time or in adults in whom the typical features of pertussis are absent. An acute and convalescent specimen is recommended since there is no single reference value that will distinguish acute from past infection or immunization. A twofold or greater change in antibody level is suggestive of acute infection. The CDC does not recognize serologic testing as a criterion for the definitive diagnosis of pertussis. Caution should be exercised in making the diagnosis of pertussis infection with serology alone, since antibodies to filamentous hemagglutinin and pertactin due to infection with B. parapertussis or other Bordetella species can also occur. Detectable levels of IgG antibodies to B. pertussis may be seen in the serum of vaccinated individuals of all ages, in early infancy as the result of placental transfer, and in the convalescent phase of a recent infection. IgG antibodies can only be used to diagnose active infection when paired sera are available and a rise in antibody level can be demonstrated. A significant rise may not always be demonstrated as peak levels of IgG may be reached before the first sample is collected. Therefore, IgA and IgM antibody levels should be measured to diagnose active disease.

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