Seshan Vigna, Sarangan Gopalsamy, Sheriff Khaleefathullah, Krishnasamy Kaveri, Palani Gunasekaran, Srikanth Padma
Department of Microbiology, Sri Ramachandra Medical College and Research Institute, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, 600116, India.
King Institute of Preventive Medicine and Research, SIDCO Industrial Area, Guindy, Chennai, Tamil Nadu, 600032, India.
Arch Virol. 2017 Oct;162(10):2983-2988. doi: 10.1007/s00705-017-3429-7. Epub 2017 Jun 16.
Dengue disease is caused by dengue viruses 1-4 and has been ranked by the World Health Organisation (WHO) as the fastest spreading vector-borne viral disease. Dengue is often underreported and misdiagnosed due to a wide spectrum of clinical manifestations. Diagnosis of dengue is based on clinical case definitions and laboratory methods. Newer case definitions of dengue have been formulated by clinical studies in order to improve case detection. Owing to its epidemic potential, mortality and morbidity, there is a need for a rapid and accurate diagnostic assay for dengue in order to help the clinician in the early detection of cases and to prevent disease progression. A duplex real time PCR targeting the 3'UTR region for rapid and simultaneous detection of all dengue viruses serotypes (1-4) was standardized based on published literature. About 150 patients with acute undifferentiated febrile illness classified based on the 2009 WHO dengue case definition were tested using the duplex real time dengue PCR. Sequencing based PCR was performed on selected PCR positive samples for partial nucleotide sequence of the CprM gene and a phylogenetic tree was constructed. Statistical analysis was done using the MedCalc software. Out of the 126 patients classified as dengue disease positive, according to the 2009 WHO dengue case definition, 54% had "probable dengue", 43% had "dengue with warning signs" and 3% had "severe dengue". The performance of the duplex real time PCR was assessed among the various clinical groups of dengue and it was found that in the "dengue with warning signs group" PCR had a positive predictive value of 85.29% (range - 68.94% to 95.05%) when compared with dengue NS1 ELISA. The average time for PCR positivity was found to be four days from the onset of illness. The cycling threshold values obtained from real time PCR were used as a semi quantitative measure of viremia. Accordingly, there was a relatively low CT value among the "warning signs dengue group" when compared to the "probable dengue group". The use of the duplex PCR is suggested in the early diagnosis of dengue, especially in the 'warning signs' group of patients as they showed a higher positivity rate. Also, the use of the resultant CT value as a semi-quantitative measure of viremia will assist the clinician in early diagnosis and prevention of disease development.
登革热由1 - 4型登革病毒引起，世界卫生组织（WHO）已将其列为传播速度最快的媒介传播病毒性疾病。由于临床表现多种多样，登革热常常报告不足且误诊。登革热的诊断基于临床病例定义和实验室方法。为了提高病例检测率，临床研究制定了更新的登革热病例定义。鉴于其流行潜力、死亡率和发病率，需要一种快速准确的登革热诊断检测方法，以帮助临床医生早期发现病例并预防疾病进展。基于已发表的文献，对靶向3'UTR区域的双重实时PCR进行标准化，以快速同时检测所有登革热病毒血清型（1 - 4）。使用双重实时登革热PCR对约150例根据2009年WHO登革热病例定义分类的急性未分化发热性疾病患者进行检测。对选定的PCR阳性样本进行基于测序的PCR，以获取CprM基因的部分核苷酸序列，并构建系统发育树。使用MedCalc软件进行统计分析。根据2009年WHO登革热病例定义，在126例被分类为登革热疾病阳性的患者中，54%为“可能登革热”，43%为“有警示体征的登革热”，3%为“重症登革热”。在登革热的不同临床组中评估了双重实时PCR的性能，发现与登革热NS1 ELISA相比，在“有警示体征的登革热组”中，PCR的阳性预测值为85.29%（范围 - 68.94%至95.05%）。发现PCR阳性的平均时间为发病后四天。从实时PCR获得的循环阈值用作病毒血症的半定量指标。因此，与“可能登革热组”相比，“有警示体征的登革热组”的CT值相对较低。建议在登革热的早期诊断中使用双重PCR，特别是在“有警示体征”的患者组中，因为他们显示出更高的阳性率。此外，将所得的CT值用作病毒血症的半定量指标将有助于临床医生早期诊断和预防疾病发展。
