[Show abstract][Hide abstract] ABSTRACT: Methods:
We analyzed influenza surveillance data from nine countries around southern and southeastern Asia spanning latitudinal gradient from equatorial to temperate zones to further characterize influenza type specific seasonality in the region. We calculated proportion of positives by month out of positives during that year and adjust for variation in samples tested and positivity in these countries.
Influenza A epidemics were identified between November-March during winters in areas lying above 30(o) N latitude; during monsoon months of June-November in areas between 10(o) -30(o) N latitude, and no specific seasonality for influenza A virus circulation in areas lying closer to the equator. Influenza B circulation coincided with influenza A circulation in areas lying above 30(o) N latitude; however in areas south of 30(o) N Asia, influenza B circulated year round at 3-8% of annual influenza B positives during most months with less pronounced peaks during post-monsoon period.
Even though influenza B circulates round the year in most areas of the tropical southern and southeastern Asia region, the most appropriate time for influenza vaccination would be prior to the monsoon season conferring protection against influenza A and B peaks using the most recent WHO recommended vaccine. This article is protected by copyright. All rights reserved.
Full-text · Article · Jan 2016 · Influenza and Other Respiratory Viruses
[Show abstract][Hide abstract] ABSTRACT: Detection of respiratory viruses using polymerase chain reaction (PCR) is sensitive, specific and cost effective, having huge potential for patient management. In this study, the performance of an in-house developed conventional multiplex RT-PCR (mRT-PCR), real time RT-PCR (rtRT-PCR) and Luminex xTAG® RVP fast assay (Luminex Diagnostics, Toronto, Canada) for the detection of respiratory viruses was compared. A total 310 respiratory clinical specimens predominantly from pediatric patients, referred for diagnosis of influenza A/H1N1pdm09 from August 2009 to March 2011 were tested to determine performance characteristic of the three methods. A total 193 (62.2%) samples were detected positive for one or more viruses by mRT-PCR, 175 (56.4%) samples by real time monoplex RT-PCR, and 138 (44.5%) samples by xTAG® RVP fast assay. The overall sensitivity of mRT-PCR was 96.9% (95% CI: 93.5, 98.8), rtRT-PCR 87.9% (95% CI: 82.5, 92.1) and xTAG(®) RVP fast was 68.3% (95% CI: 61.4, 74.6). Rhinovirus was detected most commonly followed by respiratory syncytial virus group B and influenza A/H1N1pdm09. The monoplex real time RT-PCR and in-house developed mRT-PCR are more sensitive, specific and cost effective than the xTAG® RVP fast assay. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
No preview · Article · Jun 2015 · Journal of Medical Virology
[Show abstract][Hide abstract] ABSTRACT: Background:
Influenza surveillance is an important tool to identify emerging/reemerging strains, and defining seasonality. We describe the distinct patterns of circulating strains of the virus in different areas in India from 2009 to 2013.
Patients in ten cities presenting with influenza like illness in out-patient departments of dispensaries/hospitals and hospitalized patients with severe acute respiratory infections were enrolled. Nasopharangeal swabs were tested for influenza viruses by real-time RT-PCR, and subtyping; antigenic and genetic analysis were carried out using standard assays.
Of the 44,127 ILI/SARI cases, 6,193 (14.0%) were positive for influenza virus. Peaks of influenza were observed during July-September coinciding with monsoon in cities Delhi and Lucknow (north), Pune (west), Allaphuza (southwest), Nagpur (central), Kolkata (east) and Dibrugarh (northeast), whereas Chennai and Vellore (southeast) revealed peaks in October-November, coinciding with the monsoon months in these cities. In Srinagar (Northern most city at 34°N latitude) influenza circulation peaked in January-March in winter months. The patterns of circulating strains varied over the years: whereas A/H1N1pdm09 and type B co-circulated in 2009 and 2010, H3N2 was the predominant circulating strain in 2011, followed by circulation of A/H1N1pdm09 and influenza B in 2012 and return of A/H3N2 in 2013. Antigenic analysis revealed that most circulating viruses were close to vaccine selected viral strains.
Our data shows that India, though physically located in northern hemisphere, has distinct seasonality that might be related to latitude and environmental factors. While cities with temperate seasonality will benefit from vaccination in September-October, cities with peaks in the monsoon season in July-September will benefit from vaccination in April-May. Continued surveillance is critical to understand regional differences in influenza seasonality at regional and sub-regional level, especially in countries with large latitude span.
[Show abstract][Hide abstract] ABSTRACT: Influenza is an RNA virus that belongs to the Orthomyxoviridae family. It causes a highly contagious acute respiratory illness, has been recognized since ancient times, and is a major health threat throughout the world. An outbreak of influenza-like illness (ILI) was reported from Alappuzha district of Kerala State between late June and July 2011. This investigation was conducted to determine the clinical picture, causative agents, and epidemiological characteristics of the illness.
The World Health Organization (WHO)'s case definition for ILI was followed throughout the investigation. Nasal or throat swabs were collected from 204 suspected patients. Real-time reverse transcription polymerase chain reaction (RT-PCR)-based diagnosis was performed to detect influenza A and B viruses and their subtypes. Madin-Darby canine kidney (MDCK) cell line was used for virus isolation. One-step RT-PCR was performed to amplify the HA1 gene of influenza A(H3N2). The amplicons for the HA1 gene of influenza A(H3N2) were sequenced, and phylogenetic analysis was done.
Analysis of the data revealed that 96 (47.05%) of the 204 respiratory specimens collected were influenza A(H3N2) and only 6 (2.94%) were A(H1N1)pdm09. Phylogenetic analysis revealed that the isolated A(H3N2) was closely related to the 2012-2013 northern hemisphere vaccine strain (A/Victoria/361/2011/H3N2).
An influenza A(H3N2) outbreak was confirmed in Alappuzha district of Kerala state with a co-circulation of A(H1N1)pdm09. No substantial difference in the sequence was observed in the etiological agent, and the virus was found to be sensitive to oseltamivir.
Full-text · Article · Apr 2015 · The Journal of Infection in Developing Countries
[Show abstract][Hide abstract] ABSTRACT: Background: Rapid point-of-care (POC) tests provide an economical alternative for rapid diagnosis and treatment of inﬂ uenza, especially in public health emergency situations. Objectives: To test the performance of a rapid inﬂ uenza diagnostic test, QuickVue (Quidel) as a POC test against a real-time polymerase chain reaction (RT-PCR) assay for detection of inﬂ uenza A and B in a developing country setting. Study Design: In a prospective observational design, 600 patients with inﬂ uenza-like illness (ILI) or with severe acute respiratory illness (SARI) who were referred to the Inﬂ uenza Clinic of a tertiary care hospital in Srinagar, India from September 2012 to April 2013, were enrolled for diagnostic testing for inﬂ uenza using QuickVue or RT-PCR. All inﬂ uenza A-positive patients by RT-PCR were further subtyped using primers and probes for A/H1pdm09 and A/H3. Results: Of the 600 patients, 186 tested positive for inﬂ uenza A or B by RT-PCR (90 A/ H1N1pdm09, 7 A/H3 and 89 inﬂ uenza B), whereas only 43 tested positive for inﬂ uenza (inﬂ uenza A = 22 and inﬂ uenza B = 21) by QuickVue. Thus, the sensitivity of the QuickVue was only 23% (95% conﬁ dence interval, CI: 17.3-29.8) and speciﬁ city was 100% (95% CI: 99.1-100) with a positive predictive value (PPV) of 100% (95% CI 91.8-100) and a negative predictive value (NPV) of 74.3% (95% CI: 70.5-77.9) as compared to RT-PCR. Conclusions: The high speciﬁ city of QuickVue suggest that this POC test can be a useful tool for patient management or triaging during a public health crisis but a low sensitivity suggests that a negative test result need to be further tested using RT-PCR
Full-text · Article · Feb 2015 · Indian Journal of Medical Microbiology
[Show abstract][Hide abstract] ABSTRACT: The seasonality of influenza in the tropics complicates vaccination timing. We investigated influenza seasonality in northern India and found influenza positivity peaked in Srinagar (34.09°N) in January–March but peaked in New Delhi (28.66°N) in July–September. Srinagar should consider influenza vaccination in October–November, but New Delhi should vaccinate in May–June.
Full-text · Article · Oct 2014 · Emerging infectious diseases
[Show abstract][Hide abstract] ABSTRACT: Background
The global burden of influenza is increasingly recognized, but data from India remain sparse. We conducted a multi-site population-based surveillance study to estimate and compare rates of influenza-associated hospitalization at two rural Indian health and demographic surveillance system (HDSS) sites at Ballabgarh and Vadu during 2010-2012.
Prospective facility-based surveillance for all hospitalizations (excluding those for trauma, elective surgery and obstetric, ophthalmic or psychiatric reasons) was conducted at 72 health facilities. After collection of clinical details, patients had nasopharyngeal swabs taken and tested by reverse transcription polymerase chain reaction for influenza viruses. Annual healthcare utilization surveys (HUS) were conducted in HDSS households to identify proportion of hospitalizations occurring at non-study facilities to adjust for hospitalizations missed through facility-based surveillance.
HUS showed that 69% and 67% of hospitalizations occurred at study facilities at Ballabgarh and Vadu respectively. Overall, 6,004 patients hospitalized with acute medical illness at participating facilities were enrolled (1,717 from Ballabgarh; 4,287 from Vadu). The proportion of patients with influenza was higher at Vadu than Ballabgarh annually (2010: 21% vs. 5%, p<0.05; 2011: 18% vs. 5%, p<0.05; 2012: 23% vs. 5%, p<0.05). Annual adjusted influenza-associated hospitalization rates were 5-11 fold higher in Vadu (20.3-51.6 per 10,000) versus Ballabgarh (4.4-6.3 per 10,000). At both sites, influenza A/H1N1pdm09 and B predominated during 2010, A/H3N2 and B during 2011, and A/H1N1pdm09 and B during 2012.
The markedly different influenza hospitalization rates by season and across communities in India highlight the need for sustained multi-site surveillance system for estimating national influenza disease burden. That would be the first step for initiating discussions around Influenza prevention and control strategies in the country.
Full-text · Article · Sep 2014 · Journal of Infection
[Show abstract][Hide abstract] ABSTRACT: Objective:
To characterize influenza seasonality and identify the best time of the year for vaccination against influenza in tropical and subtropical countries of southern and south-eastern Asia that lie north of the equator.
Weekly influenza surveillance data for 2006 to 2011 were obtained from Bangladesh, Cambodia, India, Indonesia, the Lao People's Democratic Republic, Malaysia, the Philippines, Singapore, Thailand and Viet Nam. Weekly rates of influenza activity were based on the percentage of all nasopharyngeal samples collected during the year that tested positive for influenza virus or viral nucleic acid on any given week. Monthly positivity rates were then calculated to define annual peaks of influenza activity in each country and across countries.
Influenza activity peaked between June/July and October in seven countries, three of which showed a second peak in December to February. Countries closer to the equator had year-round circulation without discrete peaks. Viral types and subtypes varied from year to year but not across countries in a given year. The cumulative proportion of specimens that tested positive from June to November was > 60% in Bangladesh, Cambodia, India, the Lao People's Democratic Republic, the Philippines, Thailand and Viet Nam. Thus, these tropical and subtropical countries exhibited earlier influenza activity peaks than temperate climate countries north of the equator.
Most southern and south-eastern Asian countries lying north of the equator should consider vaccinating against influenza from April to June; countries near the equator without a distinct peak in influenza activity can base vaccination timing on local factors.
Full-text · Article · May 2014 · Bulletin of the World Health Organisation
[Show abstract][Hide abstract] ABSTRACT: Abstract:
Background and Objective:
Recent antiviral studies from South East Asia, Europe and the United States showed the presence of neuraminidase inhibitor (NAIs) resistance in pandemic influenza 2009 viruses. The study was undertaken to evaluate neuraminidase inhibitor (NAI) resistance of pandemic Influenza virus isolated from India.
Pandemic Influenza viruses, isolated from 2009 to 2013 were analyzed genetically for known resistance markers in NA gene. Pandemic (H1N1) (n= 493) isolates were tested for H274Y mutation by rRT-PCR. Randomly selected resistant and sensitive viruses were confirmed by phenotypic assay.
All Pandemic A/H1N1 isolates remained sensitive except single 2013 isolate. Genetic analysis of single 2013 isolate as well as original clinical material showed H274Y mutation responsible for reduce susceptibility to Oseltamivir and were also confirmed by phenotypic assay.
Emergence of pandemic influenza strain resistant to oseltamivir emphasizes the need for monitoring antiviral resistance as part of National Influenza Program