Mariem Gdoura1,2, Wasfi Fares3, Souha Bougatef4, Amine Inoubli3, Henda Touzi3, Nahed Hogga3, Imen Ben Dhifallah3, Naila Hannachi5, Aida Argoubi6, Saoussen Kacem7, Hela Karray8, Nissaf Ben Alaya4,9, Henda Triki3,9. 1. Laboratory of Clinical Virology, Institut Pasteur de Tunis, University Tunis El Manar, 13 Place Pasteur, Tunis Belvédère, BP 74, 1002, Tunis, Tunisia. mariem.gdoura@pasteur.tn. 2. Faculty of Pharmacy of Monastir, University of Monastir, Monastir, Tunisia. mariem.gdoura@pasteur.tn. 3. Laboratory of Clinical Virology, Institut Pasteur de Tunis, University Tunis El Manar, 13 Place Pasteur, Tunis Belvédère, BP 74, 1002, Tunis, Tunisia. 4. National Observatory for New and Emerging Diseases, Tunis, Tunisia. 5. Laboratory of Microbiology, CHU Farhat Hached, Sousse, Tunisia. 6. Laboratory of Microbiology, CHU Fattouma Bourguiba, Monastir, Tunisia. 7. Laboratory of Microbiology, CHU Sahloul, Sousse, Tunisia. 8. Laboratory of Microbiology, CHU Habib Bourguiba, Sfax, Tunisia. 9. Faculty of Medecine of Tunis, University Tunis El Manar, Tunis, Tunisia.
Abstract
INTRODUCTION: Routine laboratory screening is based on the detection of WNV specific IgM and IgG in blood and cerebrospinal fluid. Confirmation is then classically applied by real time RT-PCR (rRT-PCR) in Cerebrospinal fluid (CSF), which often gives negative results due to too short virorachia and late sampling. rRT-PCR was applied-for the first time for routine diagnosis purpose-on urine samples. METHODS: During 2018 outbreak in Tunisia, 107 patients presented WNV neurologic symptoms and were positive for WNV serology. Of them, 95 patients were sampled for urine and 35 were sampled for CSF. Qualitative rRT-PCR was performed on both type of samples. RESULTS: WNV RNA was detected in 50.5% of urine samples (48/95) and in 2.8% of CSF samples (1/35). WNV RNA was detectable from day 1 to day 41 from symptom onset, however, positive urine rate was 53.1% during the first 10 days from symptom onset. The proportions of urine-positive and urine-negative samples, based on day of collection, showed no statistical difference (p > 0.005). Cycle threshold (Ct) values ranged from 12 to 39, with no correlation with the day of collection. The lowest Ct value was detected for urine sampled on day 5 after symptom onset. A statistically significant difference was found between age groups of confirmed and non confirmed cases (p < 0.001). DISCUSSION/ CONCLUSION: Our study reported the use of rRT-PCR on urine samples as a confirmatory diagnostic tool for WNV "probable cases" during an outbreak. Our findings underlined the reliability and the rapidity of this confirmatory tool, even late, and showed its superiority on CSF investigation.
INTRODUCTION: Routine laboratory screening is based on the detection of WNV specific IgM and IgG in blood and cerebrospinal fluid. Confirmation is then classically applied by real time RT-PCR (rRT-PCR) in Cerebrospinal fluid (CSF), which often gives negative results due to too short virorachia and late sampling. rRT-PCR was applied-for the first time for routine diagnosis purpose-on urine samples. METHODS: During 2018 outbreak in Tunisia, 107 patients presented WNV neurologic symptoms and were positive for WNV serology. Of them, 95 patients were sampled for urine and 35 were sampled for CSF. Qualitative rRT-PCR was performed on both type of samples. RESULTS: WNV RNA was detected in 50.5% of urine samples (48/95) and in 2.8% of CSF samples (1/35). WNV RNA was detectable from day 1 to day 41 from symptom onset, however, positive urine rate was 53.1% during the first 10 days from symptom onset. The proportions of urine-positive and urine-negative samples, based on day of collection, showed no statistical difference (p > 0.005). Cycle threshold (Ct) values ranged from 12 to 39, with no correlation with the day of collection. The lowest Ct value was detected for urine sampled on day 5 after symptom onset. A statistically significant difference was found between age groups of confirmed and non confirmed cases (p < 0.001). DISCUSSION/ CONCLUSION: Our study reported the use of rRT-PCR on urine samples as a confirmatory diagnostic tool for WNV "probable cases" during an outbreak. Our findings underlined the reliability and the rapidity of this confirmatory tool, even late, and showed its superiority on CSF investigation.
Authors: Steven A Baty; Katherine B Gibney; J Erin Staples; Andrean Bunko Patterson; Craig Levy; Jennifer Lehman; Tricia Wadleigh; Jamie Feld; Robert Lanciotti; C Thomas Nugent; Marc Fischer Journal: J Infect Dis Date: 2012-03-20 Impact factor: 5.226
Authors: L Barzon; M Pacenti; E Franchin; T Martello; E Lavezzo; L Squarzon; S Toppo; F Fiorin; G Marchiori; G P Scotton; F Russo; M Cattai; R Cusinato; G Palù Journal: Euro Surveill Date: 2012-09-06
Authors: Michael P Busch; Sally Caglioti; Eugene F Robertson; Joan D McAuley; Leslie H Tobler; Hany Kamel; Jeffrey M Linnen; Venkatakrishna Shyamala; Peter Tomasulo; Steven H Kleinman Journal: N Engl J Med Date: 2005-08-04 Impact factor: 91.245