Browsing by Author "Khan, B."

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A Comparative retrospective study of novel Reverse-Transcription Polymerase Chain Reaction-based Liquid Hybridization (RT-PCR-LH) assay with Polymerase Chain Reaction (PCR) amplification, virus isolation and serological techniques for early, definitive laboratory diagnosis of dengue infection
(Malaysian Society of Parasitology and Tropical Medicine, 2007) Hapugoda, M.D.; de Silva, N.R.; Khan, B.; Gunasena, S.; Dayanath, M.Y.D.; Abeyewickreme, W.
Dengue is an important vector borne viral infection in South East Asia. Dengue virus is responsible for dengue fever, dengue haemorrhagic fever and dengue shock syndrome. Early diagnosis of infection helps in monitoring the disease, determining when hospital admission is necessary and in reducing case fatalities. The objective of the study was to carry out a comparative retrospective study of a novel Reverse Transcription-Polymerase Chain Reaction-based Liquid Hybridization (RT-PCR-LH) assay with PCR amplification, virus isolation and serological techniques for laboratory diagnosis of dengue infection. Amplified products of Non Structural-3 gene were hybridized with a mixture of the 4 dengue type-specific Deoxyribonucleic Acid (DNA) probes in liquid phase. The assay was validated in a comparative retrospective study using acute serum samples collected from 88 patients with dengue confirmed by Haemagglutination Inhibition (HAI) assay. The assay was highly specific for diagnosis of dengue infection. As an early (<5 days of fever) laboratory diagnostic method, this assay had 100% sensitivity for detection of dengue patients confirmed by HAI assay. A high analytical sensitivity of 2 fluorescent focus units of dengue virus/reaction was achieved. Novel RT-PCR-LH assay using a single serum specimen offers distinct advantages of specificity and sensitivity over other diagnostic techniques for early definitive laboratory diagnosis of dengue infection at the time during which serological methods cannot be used.
A Comparative retrospective study of RT-PCR-based liquid hybridization assay for early, definitive diagnosis of dengue
(Oxford University Press, 2010) Hapugoda, M.D.; de Silva, N.R.; Khan, B.; Dayanath, M.Y.D.; Gunesena, S.; Prithimala, L.; Abeyewickreme, W.
Dengue is an important flaviviral infection in tropical and subtropical regions. Early diagnosis of dengue infection helps in monitoring the disease, determining when hospital admission is necessary and reducing case fatalities. The objective of this study was to carry out a retrospective comparison of an RT-PCR-based liquid hybridization (RT-PCR-LH) assay with PCR amplification, virus isolation and serological techniques for laboratory diagnosis of dengue infection. Amplified products of non-structural 3 gene were hybridized with a mixture of four dengue type-specific DNA probes in liquid phase. The assay was validated in a comparative retrospective study using acute serum samples collected from 119 fever patients with or without dengue, confirmed by haemagglutination inhibition (HAI) assay, the gold standard assay for diagnosis of dengue infection. The RT-PCR-LH assay was highly specific for dengue and, as an early laboratory diagnostic method, had 100% sensitivity in detecting dengue patients confirmed by HAI assay. A high analytical sensitivity of two fluorescent focus units of dengue virus/reaction was achieved. This RT-PCR-LH assay using a single serum specimen offers distinct advantages of specificity and sensitivity over other diagnostic techniques for early definitive laboratory diagnosis of dengue infection when serological methods are of little value.
Correlation between clinical and laboratory diagnosis of dengue in Sri Lanka.
(Faculty of Tropical Medicine, Mahidol University, 2007) Hapugoda, M.D.; Khan, B.; de Silva, N.R.; Gunasekera, J.; Abeyewickreme, W.
BACKGROUND: In Sri Lanka, diagnosis of dengue mainly depends on clinical signs and symptoms. Very few suspected patients from the state and private sector health institutions are tested by laboratory diagnostic assays compared to the number of dengue cases recorded all over the island. OBJECTIVES: To correlate clinical parameters with laboratory diagnosis in confirmation of dengue. RESEARCH DESIGN: Patients, clinically suspected of having dengue (n=201) were selected based on WHO criteria. Serum samples were tested using major 3 types of laboratory diagnostic assays; molecular, virus isolation and serology. Differences in clinical and laboratory data were analyzed on the basis of the final diagnosis assigned as dengue or non-dengue. Chi-square test was used for comparison of data. RESULTS: The proportion of laboratory diagnosed dengue patients were 80% (162/201). Mean platelet value and PCV in laboratory confirmed dengue patients were 92 247/mm3 (range 20 000-318 000) and 45% (range 31-59%) respectively. On comparison of the presence of clinical features that are used by the WHO for diagnosis of dengue, headache (129/162 vs 18/39, x2=23, p=0.00), limb pain (107/162 vs 18/39, x2=4.56, p=0.03) and external bleeding (67/162 vs 00/39, X2=27, p=0.00) showed significant association, with dengue infection. The infection was confirmed as definitive dengue in 75% (121 /162) and probable dengue in 25% (41/162). DISCUSSION: Surveillance based on clinical diagnosis may result in over estimation of the disease as clinical diagnosis is not specific enough. Laboratory confirmation of dengue suspected patients is important to measure the real incidence of the disease is needed in country like Sri Lanka.