สถาบันวิจัยวิทยาศาสตร์สาธารณสุข

National Institute of Health of Thailand

Diagnostic Tools for Leptospirosis in Thailand: Evaluation of Rapid Tests

Authors : Wimol Petkanchanapong*, Pathom Sawanpanyalert*, Pimjai Naigowit*, Scott Dowell**,****, Paul Levett****, Waralak Tangkanakul*****, Piyada Wangroongsarb*, Khanchit Limpakarnjanarat**,Wanna Wongjindan**,Saithip Sutthirattana**, and Tamara Fisk**,***

 

Affiliations :      *National Institute of Health, Ministry of Public Health, Thailand
**International Emerging Infections Program, Thailand
***Emory Univ. School of Medicine
****CDC, Atlanta, USA
***** Department of Disease Control, Ministry of Public Health, Thailand
 
Source:         Proceeding of. International Conference on Emerging Infectious Diseases, February 29 - March 3, 2004, Atlanta, GA
 
Language:     English
 
Abstract:
 
Leptospirosis presents as a non-specific febrile illness with clinical features similar to other tropical diseases. Early diagnosis of leptospirosis would allow clinicians to initiate effective therapy sooner in the course of illness. Although many kits are available for rapid testing in the acute setting, data on use of these tests in the field compared to gold standard testing are limited. As part of a prospective observational cohort of febrile illness patients in two areas of Thailand, acute and convalescent serum and acute urine samples were collected. At the rural hospitals, sera were tested with Panbio Multi-SDLST (MULTI) and Thailand NIH latex agglutination test (LAT). MAT testing of paired sera, the gold standard for diagnosis of leptospirosis, was performed at Thai NIH as was blinded repeat LAT testing of 88 samples. Urine samples were tested for leptospiral antigen using Leptodot. Paired sera from 749 febrile patients were tested using MAT. Sixty-six febrile patients had a four-fold rise by MAT. These patients had clinical evidence of leptospirosis (conjunctival suffusion in 24% compared to 7.2% of MAT – (<4x rise), p<0.01; elevated creatinine in 50% vs. 21%, p<0.01; elevated bilirubin in 26% vs. 9%, p<0.01) as well as compatible risk factors (water or mud exposure in 83% vs 49%, p<0.01; lower extremity cuts or abrasions in 42% vs. 25%, p=0.01). Sensitivity of rapid tests at the acute visit were as follows: MULTI 12%, LAT at hospital 6%, LAT at NIH 26%, Leptodot 20%. For the convalescent visit, sensitivity improved to 33% for LAT at the hospital, 78% at NIH, and73% for MULTI. MULTI and LAT were 91-94% specific at each visit at the hospitals. LAT at NIH was 57% specific and Leptodot was 90% specific. MAT testing identified patients with clinical findings and risk factors compatible with leptospirosis. No rapid test had very good sensitivity at the acute visit. Quality control is important for accuracy of rapid tests.