Research Article: A Prospective Assessment of the Accuracy of Commercial IgM ELISAs in Diagnosis of Japanese Encephalitis Virus Infections in Patients with Suspected Central Nervous System Infections in Laos

Date Published: July 01, 2012

Publisher: The American Society of Tropical Medicine and Hygiene

Author(s): Catrin E. Moore, Stuart D. Blacksell, Thaksinaporn Taojaikong, Richard G. Jarman, Robert V. Gibbons, Sue J. Lee, Vilada Chansamouth, Soulignasack Thongpaseuth, Mayfong Mayxay, Paul N. Newton.


Japanese encephalitis virus (JEV) is a major cause of encephalitis in Asia. We estimated the diagnostic accuracy of two anti-JEV immunoglobulin M (IgM) enzyme-linked immunosorbent assays (ELISAs) (Panbio and XCyton JEVCheX) compared with a reference standard (AFRIMS JEV MAC ELISA) in a prospective study of the causes of central nervous system infections in Laos. Cerebrospinal fluid (CSF; 515 patients) and serum samples (182 patients) from those admitted to Mahosot Hospital, Vientiane, were tested. The CSF from 14.5% of acute encephalitis syndrome (AES) patients and 10.1% from those with AES and meningitis were positive for anti-JEV IgM in the reference ELISA. The sensitivities for CSF were 65.4% (95% confidence interval [CI] = 51–78) (Xcyton), 69.2% (95% CI = 55–81) (Panbio), however 96.2% (95% CI = 87–100) with Panbio Ravi criteria. Specificities were 89–100%. For admission sera from AES patients, sensitivities and specificities of the Panbio ELISA were 85.7% (95% CI = 42–100%) and 92.9% (95% CI = 83–98%), respectively.

Partial Text

The Japanese encephalitis virus (JEV) is an important cause of encephalitis in Asia, with an estimated 35,000–50,000 cases and 10–15,000 deaths annually.1–6 Despite being surrounded by countries with documented JEV infections, there is very little information about JEV in the Lao People’s Democratic Republic (Laos). Anti-JEV immunoglobulin M (IgM) has been described in the cerebrospinal fluid (CSF) of 5 of 26 patients with viral encephalitis in Vientiane hospitals (Innis and others, unpublished data) and anti-JEV antibodies occur in 50% of healthy adults in central Laos.7 There is no routine JEV vaccination in Laos, and there are insufficient data to inform Lao public health and vaccination policy.8–12