Sensitivity and specificity of single IgA and IgG antibody concentrations for early diagnosis of pertussis in adults: an evaluation for outbreak management in public health practice

Table 1 Outcome of clinical and laboratory investigations in absolute numbers in the convent population (N = 99)

Outcome of laboratory tests for pertussis infection	Clinical Outcome				Total
	Clinical pertussis coughing > 14 days	Clinical pertussis coughing 7–13 days	Pre-epidemic cough	No cough
	(n = 47)^c	(n = 3)^c	(n = 2)	(n = 47)^e	(N = 99)
Laboratory confirmed pertussis infection:	45^b	1^b	0	12^f	58
IgA or IgG 4-fold increase or decrease between week 9, 13 and 60 of the epidemic	41	1	0	9	51
IgG ≥ 100 U/ml at week 9 or 13 of the epidemic, no IgA or IgG 4-fold increase or decrease	4	0	0	3	7
Details of laboratory confirmed pertussis findings:
- IgG ≥ 100 U/ml	41	0	0	6	47
- IgA 4-fold increase	8	1	0	2	11
- IgA 4-fold increase or decrease	22	1	0	5	28
- IgG 4-fold increase	6	1	0	2	9
- IgG 4-fold increase or decrease	39	1	0	9	49
- PCR or culture positive ^a	5	0	0	0	5
No laboratory confirmed pertussis infection	2	2	2	35^d	41

^a All culture and PCR positive subjects had a significant increase of IgA or IgG as well
^b Pertussis cases for sensitivity calculation
^c Subjects for calculations of spectrum bias in sensitivity
^d Internal controls for specificity calculation
^e Subjects with no cough for calculations of spectrum bias in specificity
^f Subjects with asymptomatic pertussis infection

ISSN: 1471-2334