Chang, C. leptospiral immunoglobulin CGS 35066 M (IgM) antibodies have exhibited high diagnostic accuracy (1, 4, 8, 10, 11). However, a recent study in Viet Nam suggested a poor diagnostic power of such assessments there (9). Here we report the diagnostic accuracy of a commercial ELISA and an ICT for the detection of IgM antibodies among adults with fever in the Lao People’s Democratic Republic (Laos), where leptospirosis is usually endemic. Human sera were collected after informed oral consent was obtained as part of a study to determine the causes of unexplained fever for patients presenting at Mahosot Hospital, Vientiane, Laos, between November 2001 and October 2003 (7). Paired admission and convalescent-phase serum specimens were available from 186 patients (total sample, = 372) and stored at ?85C until tested. Unpaired sera were not included. Ethical approval was granted by the Ethical Review Committee of the Faculty of Medical Sciences, National University of Laos, Vientiane, Laos. A commercial ELISA (Panbio Pty, Ltd., Australia) for the detection of IgM antibodies against species was performed according to the manufacturer’s instructions. The results were calculated as Panbio models with results of 9.0, 9.0 to 11.0, and 11.0 defined as unfavorable, equivocal, and positive, respectively. Samples that initially returned an equivocal result were Rabbit Polyclonal to FGFR1/2 retested. An ICT (Leptotek; Organon-Teknika, The Netherlands) for the detection of IgM antibodies was performed according to the manufacturer’s instructions. All results were read by vision by the same operator and recorded as positive, equivocal, or unfavorable for the presence of specific IgM antibody. The MAT for antibodies was performed by reference laboratories in The Netherlands and Australia. Samples 1 to 36 were assessed at WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis, KIT Biomedical Research, Amsterdam, The Netherlands (2). Samples 37 to 186 were assessed at the WHO/FAO/OIE Collaborating Centre for Reference and Research on Leptospirosis in Australia. A patient was considered to have a current or recent contamination if a serum showed a CGS 35066 titer of 1 1:400 or if paired sera demonstrated a fourfold rise over two specimens. The diagnostic accuracy was calculated for ICT and ELISA by comparing results with the acute- and convalescent-phase MAT results for each patient as an individual case diagnosis. Only admission samples were tested by the ICT. For both ICT and ELISA, equivocal results were regarded as unfavorable. Standard diagnostic accuracy indices of sensitivity, specificity, unfavorable predictive values (NPVs) and positive predictive values (PPVs) with exact 95% confidence intervals (CI), positive and negative likelihood ratios, interquartile (IQR) ranges of days of fever and area under the receiver-operator characteristic curves (AUROCC) were calculated by using Stata/SE 8.0 (Stata Corp., College Station, Texas). The percentage of patients with a true leptospirosis contamination (as defined by MAT diagnostic criteria) was 12.4% (23 of 186). Of these, 78.2% (18 of 23) and 100% had admission and convalescent-phase sample titers of 1 1:400, respectively. The five patients with titers of 1:400 on admission exhibited a 4-fold rise in titer in the convalescent-phase sample. On admission, patients had been ill for a median of 9 days (IQR 7 to 13), and the median interval between admission and convalescent-phase serum collection was 4.5 days (IQR 2 to 8). The diagnostic sensitivity of both assays was poor (Table ?(Table1).1). Overall, the sensitivity of the ELISA was 63.0%, with only a marginal increase in sensitivity when using convalescent-phase sera (65.2%) in comparison to admission sera (60.9%). The sensitivity of the ICT (47.8%) was lower than that of the ELISA. The specificities of the ELISA (55.5%) and ICT (75.5%) CGS 35066 were also low, with a lower specificity for convalescent-phase sera than for the admission sera. In comparison to serum from all patients, samples from patients with only 1 1 to 7 days of fever had higher sensitivity (70.0%) and specificity (70 to 75%) in both assays but with very wide CIs (Table ?(Table11). TABLE 1. Sensitivities and specificities of the Panbio IgM ELISA and Leptotek IgM lateral flow test for the detection of IgM antibodies compared to the MATIgM ELISA versus the MAT for admission (A) and convalescent-phase (B) specimens. TABLE 2. Diagnostic accuracy indices at different positivity cutoff points for the Panbio IgM ELISAis endemic and where a high proportion of clinically well individuals gave positive IgM results (9). The Viet Nam study differed from that presented here since the reference.