title: An epidemiological study of dengue in Delhi, India.
abstract: Delhi, the capital of India, is an important metropolitan hub for major financial and sociocultural exchanges, offering challenging threats to current public health infrastructure. In recent past, an upsurge of dengue cases in Delhi posed a significant menace to the existing dengue control policies. To reform the control strategies and take timely intervention to prevent future epidemics, an epidemiological study on the proportion of both asymptomatic and symptomatic dengue infections in selected population was conducted. The aim of the study was to investigate and assess the epidemiology of dengue infection and to estimate the proportion of asymptomatic and symptomatic dengue infections in Delhi. In this study, around 50 confirmed dengue cases, a total of 2125 individuals as household and neighbourhood contacts, with or without dengue febrile illness, were finger pricked and serologically detected as dengue positive or negative using SD Duo Bioline Rapid Diagnostic Test (SD Inc, Korea) with NS1, IgM & IgG combo test, which detected dengue virus antigen and antibodies to dengue virus in human blood. Out of 2125 individuals, 768 (36.1%) individuals showed positive dengue test with past (25.5%), primary (1.88%) or secondary (8.8%) dengue infections. Higher percentage of IgG was found in age groups 15-24 years and 25-50 years (36% each). Infants (<1 year) presented higher incidence of new infections (22% of NS1+IgM positives) as compared to adults. Further analysis revealed that out of the 226 newly infected cases (including NS1 and IgM positives), 142 (63%) were asymptomatic and 84 (37%) were symptomatic, as per WHO guidelines. Our findings also suggest that out of the total population screened, 10.6% dengue infection was either primary or secondary. On the basis of these results, it may be hypothesized that there are large number of asymptomatic dengue infections in the community as compared to reported symptomatic cases in Delhi. For the effective control of dengue transmission in such community like Delhi where dengue epidemics have frequently been encountered, it is essential to ascertain the proportion of asymptomatic dengue infections which may act as a reservoir for dengue transmission, as well as threat for developing dengue haemorrhagic fever (DHF).
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Kumar
authors.initials: K
authors.lastname: Vikram
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India. Electronic address: bnnagpal57@gmail.com.
authors.forename: B N
authors.initials: BN
authors.lastname: Nagpal
authors.affiliation: Kumaun University, Nainital, India.
authors.forename: Veena
authors.initials: V
authors.lastname: Pande
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Aruna
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Rekha
authors.initials: R
authors.lastname: Saxena
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Anup
authors.initials: A
authors.lastname: Anvikar
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Aparup
authors.initials: A
authors.lastname: Das
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Himmat
authors.initials: H
authors.lastname: Singh
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.lastname: Anushrita
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Municipal Corporation of Delhi, India.
authors.forename: N R
authors.initials: NR
authors.lastname: Tuli
authors.affiliation: Institut Pasteur, Paris, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Telle
authors.affiliation: Municipal Corporation of Delhi, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Yadav
authors.affiliation: National Institute of Malaria Research (ICMR), Delhi, India.
authors.forename: Neena
authors.initials: N
authors.lastname: Valecha
authors.affiliation: Institut Pasteur, Paris, France.
authors.forename: Richard
authors.initials: R
authors.lastname: Paul
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000453:epidemiology*; D003716:Dengue Virus / Q000302:isolation & purification*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007223:Infant; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D055815:Young Adult
keywords: Asymptomatic infection; Dengue; Index case; Primary dengue infection; Secondary dengue infection