Lalit Dar

Concurrent infections by all four dengue virus serotypes during an outbreak of dengue in 2006 in Delhi, India.

BackgroundCo-circulation of multiple dengue virus serotypes has been reported from many parts of the world including India, however concurrent infection with more than one serotype of dengue viruses in the same individual is rarely documented. An outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) occurred in and around Delhi in 2006. This is the first report from India with high percentage of concurrent infections with different dengue virus serotypes circulating during one outbreak.ResultsAcute phase sera from patients were tested for the presence of dengue virus RNA by RT-PCR assay. Of the 69 samples tested for dengue virus RNA, 48 (69.5%) were found to be positive. All the four dengue virus serotypes were found to be co-circulating in this outbreak with DENV-3 being the predominant serotype. In addition in 9 of 48 (19%) dengue virus positive samples, concurrent infection with more than one dengue virus serotype were identified.ConclusionThis is the first report in which concurrent infections with different dengue virus serotypes is being reported during an outbreak from India. Delhi is now truly hyperendemic for dengue.

The changing epidemiology of dengue in Delhi, India.

BackgroundA major DHF outbreak occurred in Delhi in 1996. Following this another outbreak was reported in the year 2003. In the years 2004 and 2005, though no outbreak was reported, a definitely higher number of samples were received in the virology laboratory of A.I.I.M.S. from suspected cases of dengue infection. This study was designed to compare the serological and virological profiles of confirmed dengue cases in the years 2003, 2004 and 2005.ResultsOut of 1820 serum samples received from suspected cases in all three years, 811 (44.56%) were confirmed as dengue infection serologically. Out of these confirmed dengue cases maximum cases, in all three years, were seen in the age group 21–30 years. There was an increase in the number of samples received in the post monsoon period (September to November) with a peak in the second and third week of October. More samples were received from DHF cases in the year 2005 than 2004 and 2003. All four dengue serotypes were seen co-circulating in the year 2003, followed by complete predominance of dengue serotype 3 in 2005.ConclusionEpidemiology of dengue is changing rapidly in Delhi. Dengue infections are seen every year thus making it an endemic disease. After co-circulation of all serotypes in 2003, now dengue serotype 3 is emerging as the predominant serotype.

Co-infections with Chikungunya Virus and Dengue Virus in Delhi, India

Aedes aegypti mosquitoes are common vectors for dengue virus and chikungunya virus. In areas where both viruses cocirculate, they can be transmitted together. During a dengue outbreak in Delhi in 2006, 17 of 69 serum samples were positive for chikungunya virus by reverse transcription–PCR; 6 samples were positive for both viruses.

Respiratory viral infections detected by multiplex PCR among pediatric patients with lower respiratory tract infections seen at an urban hospital in Delhi from 2005 to 2007

BackgroundAcute lower respiratory tract infections (ALRI) are the major cause of morbidity and mortality in young children worldwide. Information on viral etiology in ALRI from India is limited. The aim of the present study was to develop a simple, sensitive, specific and cost effective multiplex PCR (mPCR) assay without post PCR hybridization or nested PCR steps for the detection of respiratory syncytial virus (RSV), influenza viruses, parainfluenza viruses (PIV1–3) and human metapneumovirus (hMPV). Nasopharyngeal aspirates (NPAs) were collected from children with ALRI ≤ 5 years of age. The sensitivity and specificity of mPCR was compared to virus isolation by centrifugation enhanced culture (CEC) followed by indirect immunofluorescence (IIF).ResultsFrom April 2005–March 2007, 301 NPAs were collected from children attending the outpatient department or admitted to the ward of All India Institute of Medical Sciences hospital at New Delhi, India. Multiplex PCR detected respiratory viruses in 106 (35.2%) of 301 samples with 130 viruses of which RSV was detected in 61, PIV3 in 22, PIV2 in 17, hMPV in 11, PIV1 in 10 and influenza A in 9 children. CEC-IIF detected 79 viruses only. The sensitivity of mPCR was 0.1TCID50 for RSV and influenza A and 1TCID50 for hMPV, PIV1, PIV2, PIV3 and Influenza B. Mixed infections were detected in 18.8% of the children with viral infections, none detected by CEC-IIF. Bronchiolitis was significantly associated with both total viral infections and RSV infection (p < 0.05). History of ARI in family predisposed children to acquire viral infection (p > 0.05).ConclusionMultiplex PCR offers a rapid, sensitive and reasonably priced diagnostic method for common respiratory viruses.

Rapid detection of respiratory viruses by centrifugation enhanced cultures from children with acute lower respiratory tract infections.

BACKGROUND Acute respiratory tract infection (ARI) is the major cause of morbidity and mortality in young children in developing countries. Information on viral aetiology in ARI in India is very limited. OBJECTIVE The aim of the study was to define the role of viruses in acute lower respiratory tract infections (ALRTI) in children in India using centrifugation enhanced cultures followed by indirect immunofluorescence (IIF). STUDY DESIGN Nasopharyngeal aspirates (NPAs) were collected from children from September 1995 to April 1997, attending paediatric clinic of All India Institute of Medical Sciences (AIIMS) with symptoms of ALRTI. Virus isolation was done by centrifugation enhanced cultures using HEp-2, LLC-MK2 and MDCK cells. The viruses were identified at 24-48 h post inoculation by IIF staining using monoclonal antibodies to respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus and adenovirus. RESULTS Of 200 NPA samples, 89 (44.5%) were positive for one or more viral pathogens. RSV was detected in 34 (17%) of all ALRTI cases followed by influenza viruses in 29 (14.5%), PIVs in 23 (11.5%) and adenoviruses in three (1.5%). In 79 children with bronchiolitis, RSV was most frequently isolated (25%) pathogen, while in bronchopneumonia cases (101) the most common viral pathogen was influenza virus (17%). In eight cases (4%) of ALRTI dual infections were detected. In 100 NPA specimens IIF staining on direct cell smears was carried out and viruses were detected in only 17%. RSV and influenza virus infection peaked from September to December, where as PIV infections were more frequent from January to April. CONCLUSION Respiratory viruses accounted for 44.5% of cases of ALRTI in India and the results of viral aetiology could be given in 24-48 h using centrifugation enhanced cultures. RSV was the most common viral agent associated with ALRTI in children under 5 years of age with greater association with bronchiolitis.

Can human papillomavirus DNA testing of self-collected vaginal samples compare with physician-collected cervical samples and cytology for cervical cancer screening in developing countries?

BACKGROUND To determine human papillomavirus (HPV) types by polymerase chain reaction (PCR)-reverse line blot assay and examine the concordance between HPV by Hybrid Capture 2 (HC2) and PCR on self-collected vaginal and physician-collected cervical samples and cytology. METHODS This was a cross-sectional study of 546 sexually active women aged > or =30 years with persistent vaginal discharge, intermenstrual or postcoital bleeding or an unhealthy cervix. Participants self-collected vaginal samples (HPV-S) and physicians collected cervical samples for conventional Pap smear and HPV DNA (HPV-P) testing and performed colposcopy, with directed biopsy, if indicated. HPV testing and genotyping was done by HC2 and PCR reverse line blot assay. Concordance between HC2 and PCR results of self- and physician-collected samples was determined using a Kappa statistic (kappa) and Chi-square test. RESULTS Complete data were available for 512 sets with 98% of women providing a satisfactory self-sample. PCR detected oncogenic HPV in 12.3% of self- and 13.0% of physician-collected samples. Overall, there was 93.8% agreement between physician-collected and self-samples (kappa=76.31%, 95% confidence interval [CI]: 64.97-82.29%, p=0.04)-complete concordance in 473 cases (57 positive, 416 negative), partial concordance in seven pairs and discordance in 32 pairs. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of self-sampling for detection of cervical intraepithelial neoplasia (CIN)2+ disease were 82.5%, 93.6%, 52.4% and 98.4%, respectively; for physician-sampling they were 87.5%, 93.2%, 52.2% and 98.9%, respectively; and for cytology they were 77.5%, 87.3%, 34.1% and 97.9%, respectively. Concordance between HC2 and PCR was 90.9% for self-samples (kappa=63.7%, 95% CI: 55.2-72.2%) and 95.3% for physician-collected samples (kappa=80.4%, 95% CI: 71.8-89.0%). CONCLUSIONS Self-HPV sampling compares favourably with physician-sampling and cytology. A rapid, affordable, HPV self-test kit can be used as the primary method of cervical cancer screening in low-resource situations.

Congenital cytomegalovirus infection in a highly seropositive semi-urban population in India.

To determine the incidence and natural history of congenital cytomegalovirus (CMV) infection in a population of women with near universal serologic reactivity for CMV, a prospective study of 423 women attending the antenatal clinic of the Comprehensive Rural Health Center in northern India was conducted. All 9 (2.1%) CMV positive infants were born to mothers who were CMV seropositive at the first antenatal visit. One child had hepatosplenomegaly at birth and another child had mild unilateral hearing loss at 4 months of age.

Dengue virus therapeutic intervention strategies based on viral, vector and host factors involved in disease pathogenesis

Dengue virus (DV) is the most widespread arbovirus, being endemic in over 100 countries, and is estimated to cause 50 million infections annually. Viral factors, such as the genetic composition of the virus strain can play a role in determining the virus virulence and subsequent clinical disease severity. Virus vector competence plays an integral role in virus transmission and is a critical factor in determining the severity and impact of DV outbreaks. Host genetic variations in immune-related genes, including the human leukocyte antigen, have also been shown to correlate with clinical disease and thus may play a role in regulating disease severity. The hosts immune system, however, appears to be the primary factor in DV pathogenesis with the delicate interplay of innate and acquired immunity playing a crucial role. Although current research of DV pathogenesis has been limited by the lack of an appropriate animal model, the development of DV therapeutics has been a primary focus of research groups around the world. In the past decade advances in both the development of vaccines and anti-virals have increased in dramatically. This review summarises the current understanding of viral, vector and host factors which contribute to dengue virus pathogenesis and how this knowledge is critically important in the development of pharmaceutical interventions.

Human papillomavirus-type distribution in women with and without cervical neoplasia in north India.

Our objective was to determine the human papillomavirus (HPV)-type prevalence in cervical samples in women with and without cervical neoplasia in an opportunistic hospital-based cancer-screening program. A cross-sectional study of 524 women presenting from January 2003 through June 2005 with symptoms of persistent vaginal discharge, intermenstrual bleeding, and postcoital bleeding or detected to have an unhealthy cervix underwent HPV genotyping by consensus polymerase chain reaction and reverse line-blot hybridization assay, conventional Pap smear, and colposcopy, with directed biopsy from all lesions detected. The prevalence rates of HPV infection among women with normal, low-grade cervical neoplasia (CIN 1) and high-grade CIN (>CIN2) were found to be 7.6%, 42.3%, and 87.5%, respectively. Seventeen high-risk and 6 low-risk HPV types were identified by the reverse line-blot assay. Multiple infections were seen in 20% of women. In normal women, the 6 commonest types were HPV-16, HPV-89, HPV-39, HPV-52, HPV-62, and HPV-18, whereas in high-grade disease, these were all high-risk types HPV-16, HPV-18, HPV-33, HPV-39, HPV-35, and HPV-56. HPV-16 was the commonest type in all groups, seen in 49.4% cases overall and in 74.3% of high-grade squamous intraepithelial lesion. It was followed by HPV-18 (7.4%) and HPV-33 and HPV-39 (4.9% each). HPV-89 was the commonest low-risk type (9.9%). HPV-16/18 were associated with 34.3% of normal, 45.4% of low-grade and 65.7% of high-grade lesions. A wide spectrum of HPV types is seen in north Indian women, with the majority being HPV-16 in all grades of histology. A vaccine against HPV-16 and HPV-18 could prevent two thirds of cases of high-grade cervical neoplasia.

Dynamics of influenza seasonality at sub-regional levels in India and implications for vaccination timing.

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. Methods 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. Results 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. Conclusions 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.