• Outbreak of hepatitis E virus infection in Darfur, Sudan: effectiveness of real-time reverse transcription-PCR analysis of dried blood spots

      Mérens, Audrey; Guérin, Philippe Jean; Guthmann, Jean-Paul; Nicand, Elisabeth; National Reference Laboratory for Hepatitis E, Hospital Val-de-Grâce, Paris, France; Epicentre, Paris, France (2009-04-01)
      Biological samples collected in refugee camps during an outbreak of hepatitis E were used to compare the accuracy of hepatitis E virus RNA amplification by real-time reverse transcription-PCR (RT-PCR) for sera and dried blood spots (concordance of 90.6%). Biological profiles (RT-PCR and serology) of asymptomatic individuals were also analyzed.
    • Reducing the Number of Sputum Samples Examined and Thresholds for Positivity: An Opportunity to Optimise Smear Microscopy.

      Bonnet, M; Ramsay, A; Gagnidze, L; Githui, W; Guerin, P J J; Varaine, F; Epicentre, Paris, France. maryline.bonnet@geneva.msf.org (International Union Against TB and Lung Disease, 2007-09)
      SETTING: Urban health clinic, Nairobi. OBJECTIVE: To evaluate the impact on tuberculosis (TB) case detection and laboratory workload of reducing the number of sputum smears examined and thresholds for diagnosing positive smears and positive cases. DESIGN: In this prospective study, three Ziehl-Neelsen stained sputum smears from consecutive pulmonary TB suspects were examined blind. The standard approach (A), > or = 2 positive smears out of 3, using a cut-off of 10 acid-fast bacilli (AFB)/100 high-power fields (HPF), was compared with approaches B, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3, one of which is > or = 10 AFB/100 HPF; C, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3; D, > or = 1 positive smear (> or = 10 AFB/100 HPF) out of 2; and E, > or = 1 positive smear (> or = 4 AFB/100 HPF) out of 2. The microscopy gold standard was detection of at least one positive smear (> or = 4 AFB/100 HPF) out of 3. RESULTS: Among 644 TB suspects, the alternative approaches detected from 114 (17.7%) (approach B) to 123 cases (19.1%) (approach E) compared to 105 cases (16.3%) for approach A (P < 0.005). Sensitivity ranged between 82.0% (105/128) for A and 96.1% (123/128) for E. The single positive smear approaches reduced the number of smears by 36% compared to approach A. CONCLUSION: Reducing the number of specimens and the positivity threshold to define a positive case increased the sensitivity of microscopy and reduced laboratory workload.
    • Use of filter paper as a transport medium for laboratory diagnosis of cholera under field conditions

      Page, Anne-Laure; Alberti, Kathryn P; Guénolé, Alain; Mondongue, Vital; Lonlas Mayele, Sylvaine; Guerin, Philippe J; Quilici, Marie-Laure; Epicentre, Paris, France; Institut Pasteur, Centre National de Reference des Vibrions et du Cholera, Unite des Bacteries Pathogenes Enteriques, Paris, France; Ministry of Health, Kinshasa, Democratic Republic of Congo; Medecins Sans Frontieres, Brussels, Belgium; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom (American Society for Microbiology, 2011-06-22)
      Confirmation of a cholera epidemic is based on bacteriological identification of the agent and requires the sending of samples to a culture laboratory, often in countries with limited resources. Comparison of the use of filter paper with the use of Cary-Blair reference medium for stool transport showed that this simple transport medium is appropriate for the recovery of Vibrio cholerae.