HomeAboutusEditorial BoardCurrent issuearchivesSearch articlesInstructions for authorsSubscription detailsAdvertise

  Login  | Users online: 1685

   Ahead of print articles    Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size  

 Table of Contents    
Year : 2015  |  Volume : 40  |  Issue : 2  |  Page : 135-138

Dengue Fever Outbreak in Delhi, North India: A Clinico-Epidemiological Study

1 Department of Laboratory Medicine, Delhi State Cancer Institute, New Delhi, India
2 Department of Microbiology, Sri Sri Gobind Tricentinary Medical College Hospital and Research Institute, Gurgaon, Haryana, India

Date of Submission12-Feb-2014
Date of Acceptance22-Jul-2014
Date of Web Publication24-Mar-2015

Correspondence Address:
Dr. Shobha Broor
Department of Microbiology, SGT Medical College-Hospital and Research Institute, Gurgaon - 122 505, Haryana
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-0218.153884

Rights and Permissions



Background: Dengue viruses, single-stranded positive polarity ribonucleic acid (RNA) viruses of the family Flaviviridae, are the most common cause of arboviral disease in the world. We report a clinico-epidemiological study of the dengue fever outbreak of 2010 from a tertiary care hospital in Delhi, North India. Objectives: Objectives of the study were to know the incidence of laboratory-confirmed dengue cases among the clinically suspected patients; to study the clinical profile of dengue-positive cases; and to co-relate the above with the prevalent serotype and environmental conditions. Materials and Methods: Four thousand three hundred and seventy serum samples from clinically suspected cases of dengue infection were subjected to μ-capture enzyme-linked immunosorbent assay (ELISA) for detection of dengue-virus-specific IgM antibodies. Virus isolation was done in 55 samples on C6/36 cell mono-layers. Clinical and demographic details of the patients were obtained from requisition forms of the patients or from treating clinicians. Results: Out of the 4,370 serum samples, 1,700 were positive for dengue-virus-specific IgM antibodies (38.9%). Prevalent serotype was dengue virus type-1. Thrombocytopenia and myalgia was seen in 23.1% and 18.3% of the 1,700 dengue IgM-positive patients, respectively. Also, 10.3% of 1,700 were dengue hemorrhagic fever (DHF) patients; and the mortality in serologically confirmed dengue fever cases was 0.06%. Conclusions: A change in the predominant circulating serotype, unprecedented rains, enormous infrastructure development, and increased reporting due to improved diagnostic facilities were the factors responsible for the unexpected number of dengue fever cases confronted in 2010.

Keywords: Dengue virus, prevalent serotype, μ-capture ELISA

How to cite this article:
Ahmed NH, Broor S. Dengue Fever Outbreak in Delhi, North India: A Clinico-Epidemiological Study. Indian J Community Med 2015;40:135-8

How to cite this URL:
Ahmed NH, Broor S. Dengue Fever Outbreak in Delhi, North India: A Clinico-Epidemiological Study. Indian J Community Med [serial online] 2015 [cited 2022 Jul 4];40:135-8. Available from: https://www.ijcm.org.in/text.asp?2015/40/2/135/153884

   Introduction Top

Dengue viruses, single-stranded positive polarity ribonucleic acid (RNA) viruses of the family Flaviviridae, are the most common cause of arboviral disease in the world. Dengue viruses have four serotypes, designated dengue types 1-4; and are transmitted mainly by bite of Aedes aegypti mosquito and also by Aedes albopictus. More than two-fifths of the world's population (2.5 billion) live in areas potentially at risk for dengue. [1],[2] The global incidence of dengue fever (DF) and dengue hemorrhagic fever (DHF) has increased dramatically in recent decades, and has turned this disease into a serious public health problem, especially in the tropical and sub-tropical countries. [3],[4],[5]

Dengue infection is endemic in many parts of India. In India, the first epidemic of clinical dengue-like illness was recorded in Madras (now Chennai) in 1780. The first virologically proven epidemic of DF in India occurred in 1963-1964, outbreaks have been reported from different parts of the country at regular intervals. [6],[7],[8],[9],[10],[11],[12]

Delhi, a city in North India, is endemic for dengue infection and has experienced eight outbreaks of dengue virus infection since 1967; with the last reported in 2006. [11],[12],[13] We report the experience of All India Institute of Medical Sciences (AIIMS), a tertiary care hospital in Delhi city, in the 2010 dengue outbreak.

The objectives of the study were to know the incidence of laboratory confirmed dengue cases among the clinically suspected patients, to study the clinical profile of dengue-positive cases, and to co-relate the above with the prevalent serotype and environmental conditions.

   Materials and Methods Top

The study included clotted blood specimens received in virology laboratory, from clinically suspected cases of dengue infection, from 1st May 2010 to 31st December 2010. Serum was separated aseptically and was stored at -70°C until further processing.

Serotype identification

For the identification of serotype, virus isolation followed by indirect fluorescent antibody assay (IFA) was done. As isolation could be done only in the acute phase samples for which proper cold chain was maintained throughout the transport, it was done in only 55 samples which were collected within 6 days of fever from the suspected dengue cases and were transported to the virology laboratory in ice. Virus isolation was carried out in the C6/36 clone of Aedes albopictus cell lines as described earlier. [11] IFA was performed using specific monoclonal antibodies to dengue virus types 1-4 (provided by Dr. D.J. Gubler, then at CDC, Atlanta, during the 1996 outbreak). [14]

Diagnosis of dengue infection

The serum samples from patients having ≥ 5 days of fever (n = 4370) were tested for dengue-specific IgM antibodies. μ-capture dengue IgM enzyme-linked immunosorbent assay (ELISA) kit was used (supplied by the National Institute of Virology, Pune; under the National Vector Borne Disease Control Program). Manufacturer's instructions were strictly followed for performing the test and interpreting the results. Optical Density (O.D) was measured at 450 nm using ELISA reader (BioTek R , Winooski, United States).

Recording clinical and demographic details of patients

Clinical and demographic details of the patients were obtained from the patients' requisition forms, or from treating clinicians if required. The details were recorded in microsoft-excel sheets and those of dengue IgM ELISA-positive patients were analyzed to discern the pattern.

   Results Top

Prevalent dengue serotype

Out of 55 specimens subjected to virus isolation, 33 (60.0%) were positive for dengue-1, while one specimen (1.8%) was positive for dengue-2. Thus, the prevalent serotype (97.1% of the 34 culture-positive DF cases) was dengue virus (DENV) serotype-1.

Demographic profile of the dengue IgM antibodies-positive cases

Dengue IgM antibody test was done on a total of 4,370 samples, of which 1,700 were positive for DENV-specific IgM antibodies (38.9%). In the 1,700 serologically confirmed dengue cases, male-to-female ratio was 1.6:1. The largest number of positive samples (30.8%) was from the age-group 21-30 years [Table 1]. The youngest patient was a 1-month-old male child and the oldest was an 87-year-old male patient.
Table 1: Age-wise distribution of dengue-positive patients

Click here to view

Clinical profile and month-wise distribution of dengue cases [Table 2]
Table 2: Clinical profile and month-wise distribution of dengue-positive patients in 2010

Click here to view

Out of 1,700 serologically confirmed dengue cases, 175 (10.3%) were DHF patients, of which 158 (9.3%) were DHF Grade I/II, and 17 (1.0%) were DHF Grade III/IV (dengue shock syndrome). Only one serologically confirmed dengue patient died (0.06%). Thrombocytopenia (platelet count < 100,000 cells per microliter of blood) was seen in 393 (23.1%) dengue IgM-positive patients and 311 (18.3%) patients presented with myalgia.

The first dengue IgM sero-positive case was in the last week of May, a 5-year-old male child from Jharkhand - a state in east-central India. Indigenous cases from Delhi appeared from third week of June. Maximum number of specimens was received in September (n = 1745; 39.9% of 4,370), followed by October (n = 1330; 30.4% of 4,370). The maximum cases diagnosed were also in September (n = 782; 46.0% of 1,700), followed by October (n = 448; 26.4% of 1,700). Percentage positives of the suspected cases peaked in September and August (44.8% and 44.2%, respectively).

   Discussion Top

In the year 2010, four years after the last epidemic of 2006, India witnessed a massive wave of dengue fever, involving almost all states, except those in the extreme north and extreme north-east. The total number of serologically confirmed dengue cases from all over India in 2010 was 28,066, the highest on records. Total dengue IgM-positive cases from Delhi were 6,259 (22.8% of 28,066), considerably higher than those reported in the previous years (548, 1312, and 1153 in 2007, 2008, and 2009, respectively). [15] As per the epidemiological definition, as the number of dengue fever cases clearly exceeded all previous records, which was definitely greater than expected, it constituted an outbreak.

Over the last one and half decades, outbreaks and sporadic cases have been ascribed to different serotypes of dengue virus. The 1996 epidemic was mainly due to dengue-2 virus. [11],[12] In 2003 outbreak, all four DENV serotypes were found to be co-circulating. [13] In 2005, dengue-3 was identified as the predominant serotype in Delhi. [16] In the year 2010, the predominant serotype found was dengue-1, which seemed to have replaced the previous circulating serotype. It is known that infection with one dengue serotype provides lifelong homologous immunity, but only transient cross-protection against other serotypes. The change in prevalent serotype is the major factor responsible for the enormous number of dengue cases witnessed, as the exposed population was by and large non-immune and thus susceptible to serotype-1.

Dengue affects humans of all age-groups. In 1996, maximum number of cases was in the 5-20 year age-group, while in 2003, maximum number of positive cases was in 21-30 year age-group. [11],[12],[13] In our study, maximum dengue cases (524; 30.8% of 1,700) were from the age group 21-30 years. The shift from pediatric/adolescent population to young adults getting affected reflects the presence of non-immune adult population falling prey to the circulating serotype of dengue virus.

Classical DF is characterized by sudden onset of high grade fever, accompanied by headache, retro-orbital pain, myalgia, and thrombocytopenia. In our study, myalgia was seen in 18.3% and thrombocytopenia in 23.1% cases. Thus, most of dengue cases were clinically indistinguishable from other febrile illnesses, and could be missed lacking the clinical suspicion and timely diagnosis.

The risk of developing DHF/DSS is greatest following an anamnestic dengue infection, particularly if the most recent infection was with dengue-2 virus. [17],[18] Dengue-2 virus was the predominant serotype in 1996 outbreak of DF/DHF/DSS, and was responsible for the witnessed severity and mortality (10.8%). In 2003, a mortality of 1.3%was reported from AIIMS; and in 2006, 1.5% mortality was reported from India. [11],[13],[19],[20] In 2010, total number of deaths was 110 all over India (mortality 0.4% of 28,066 cases), with 8 from Delhi (mortality 0.13% of 6,259 cases). [15] At AIIMS, with only one death, the mortality was even lower (0.06%). And, 10.3% of the cases were of DHF of which only 1.0% were DSS. This suggests that the present dengue outbreak was larger in scale, but lesser in severity.

The role of environmental factors in infectious diseases is well-known. In most countries, dengue epidemics are reported to occur, during the warm, humid, and rainy seasons, which favor abundant mosquito growth and shorten the extrinsic incubation period as well. [21],[22],[23] In our study, the largest proportion of serologically positive cases was recorded in the post-monsoon period, which is in agreement with previous studies. [22],[24]

The reason for large number of DF cases can also be related to the fact that in 2010, Delhi witnessed one of the wettest monsoons recorded. Delhi obtained 997.2 millimeters (mm) of rainfall between July 1 and September 30. The total rainfall in these three months in 2010 was not only notably higher than that of the previous 4 years (412.1 mm, 408.2 mm, 268.3 mm, and 468.2 mm in 2006, 2007, 2008, and 2009, respectively) but also appreciably exceeded the 25-year average of 530.8 mm (1981-2005). [25] The prolonged and heavy rains led to a rise in mosquito growth, thus increasing transmission of mosquito-borne infections.

The huge amount of infrastructure development which took place prior to Commonwealth Games (October 2010), may also have made growth environment more conducive for mosquitoes. Another factor which would have contributed to the number of dengue cases could be an increase in the reporting of cases due to improvement in diagnostic settings.

   Conclusion Top

We report our experience of the dengue fever outbreak of 2010. The event was of a large magnitude, but was comparatively less severe. A change in the predominant circulating serotype, unprecedented rains, enormous infrastructure development, and increased reporting due to improved diagnostic facilities all accounted for the observed multitude of people affected.

   Acknowledgement Top

We thank Dr. D. J. Gubler for providing specific monoclonal antibodies to dengue virus types 1, 2, 3, and 4.

   References Top

Available from: http://www.who.int/mediacentre/factsheets/fs117/en/ [Last accessed on 2011 Feb 28].  Back to cited text no. 1
Gubler DJ. Dengue and dengue hemorrhagic fever. Clin Microbiol Rev 1998;11:480-96.  Back to cited text no. 2
Teixeira MD, Costa MC, Guerra Z, Barreto ML. Dengue in Brazil: Situation-2001 and trends. Dengue Bull 2002;26:70-6.  Back to cited text no. 3
Sukri NC, Laras K, Wandra T, Didi S, Larasati RP, Rachdyatmaka JR, et al. Transmission of epidemic dengue hemorrhagic fever in easternmost Indonesia. Am J Trop Med Hyg 2003;68:529-35.  Back to cited text no. 4
Barrera R, Delgado N, Jimenez M, Valero S. Eco-epidemiological factors associated with hyper endemic dengue hemorrhagic fever in Maracay city, Venezuela. Dengue Bull 2002;26:84-95.  Back to cited text no. 5
Carey DE, Myers RM, Reuben R, Rodrigues FM. Studies on dengue in Vellore, South India. Am J Trop Med Hyg 1966;15:580-7.  Back to cited text no. 6
Sarkar JK, Pavri KM, Chatterjee SN, Chakravarty SK, Anderson CR. Virological and serological studies of cases of haemorrhagic fever in Calcutta. Indian J Med Res 1964;52:684-91.  Back to cited text no. 7
Bhattacharjee N, Mukherjee KK, Chakravarti SK, Mukherjee MK, De PN, Sengupta M, et al. Dengue haemorrhagic fever (DHF) outbreak in Calcutta-1990. J Commun Dis 1993;25:10-4.  Back to cited text no. 8
Padbidri VS, Mahadev PV, Thakare JP, Pant U, Ilkal MA, Varghese GG, et al. Virological and entomological investigations of an outbreak of dengue fever in Dhule district, Maharashtra. Indian J Med Microbiol 1996;14:25-32.  Back to cited text no. 9
Parida MM, Dash PK, Upadhyaya C, Saxena P, Jana AM. Serological and virological investigation on an outbreak of dengue fever in Gwalior, India. Indian J Med Res 2002;116:248-54.  Back to cited text no. 10
Broor S, Dar L, Sengupta S, Chakaraborty M, Wali JP, Biswas A, et al. Recent dengue epidemic in Delhi, India. In: Saluzzo JF, Dodet B, editors. Factors in the Emergence of Arboviruses Diseases. Paris: Elsevier; 1997. p. 123-7.  Back to cited text no. 11
Dar L, Broor S, Sengupta S, Xess I, Seth P. The first major outbreak of dengue haemorrhagic fever in Delhi, India. Emerg Infect Dis 1999;5:589-90.  Back to cited text no. 12
Gupta E, Dar L, Narang P, Srivastava VK, Broor S. Serodiagnosis of dengue during an outbreak at a tertiary care hospital in Delhi. Indian J Med Res 2005;121:36-8.  Back to cited text no. 13
Henchal EA, McCown JM, Seguin MC, Gentry MK, Brandt WE. Rapid identification of dengue virus isolates by using monoclonal antibodies in an indirect immunofluorescence assay. Am J Trop Med Hyg 1983;32:164-9.  Back to cited text no. 14
Available from: http://nvbdcp.gov.in/Doc/Dengue-CD-December 2010.pdf [Last accessed on 2011 Feb 28].  Back to cited text no. 15
Gupta E, Dar L, Kapoor G, Broor S. The changing epidemiology of dengue in Delhi, India. Virol J 2006;3:92.  Back to cited text no. 16
Thein S, Aung MM, Shwe TN, Aye M, Zaw A, Aye K, et al. Risk factors in dengue shock syndrome. Am J Trop Med Hyg 1997;56:566-72.  Back to cited text no. 17
Vaughn DW, Green S, Kalayanarooj S, Innis BL, Nimmannitya S, Suntayakorn S, et al. Dengue viremia titer, antibody response pattern, and virus serotype correlate with disease severity. J Infect Dis 2000;181:2-9.  Back to cited text no. 18
Sharma RS, Panigrahi N, Kaul SM, Shivlal, Barua K, Bhardwaj M. Status report of DF/DHF during 1998 in the National Capital Territory of Delhi, India. Dengue Bull 1999;23:109-12.  Back to cited text no. 19
Available from: http://en.wikipedia.org/wiki/2006_dengue_outbreak_in_India [Last accessed on 2011 Feb 28].  Back to cited text no. 20
Gibbons RV, Vaughn DW. Dengue: An escalating problem. BMJ 2002;324:1563-6.  Back to cited text no. 21
McBride WJ, Bielefeldt-Ohmann H. Dengue viral infections: Pathogenesis and epidemiology. Microbes Infect 2000;2:1041-50.  Back to cited text no. 22
Katyal R, Singh K, Kumar K. Seasonal variations in A. Aegypti population in Delhi, India. Dengue Bull 1996;20:78-81.  Back to cited text no. 23
Chakravarti A, Kumaria R. Eco-epidemiological analysis of dengue infection during an outbreak of dengue fever, India. Virol J 2005;2:32.  Back to cited text no. 24
Available from: http://www.imd.gov.in/section/hydro/distrainfall/webrain/delhi/delhi.txt [Last accessed on 2011 Jun 27].  Back to cited text no. 25


  [Table 1], [Table 2]

This article has been cited by
Vaishali Gupta, Kuldeep Singh, sanyogita Jain
[Pubmed] | [DOI]
2 In silico Investigation of Natural compounds identified from Ocimum species as Dengue NS3 and NS5 Protein Inhibitors
Jeyabaskar Suganya, G. Rajesh Kumar, Mahendran Radha, Dhananya S
Research Journal of Pharmacy and Technology. 2021; : 6621
[Pubmed] | [DOI]
3 Circulation of dengue virus serotypes in hyperendemic region of New Delhi, India during 2011–2017
Arshi Islam,Mohd. Abdullah,Ayesha Tazeen,Irshad H. Naqvi,Syed Naqui Kazim,Anwar Ahmed,Salman Freeh Alamery,Ajamaluddin Malik,Shama Parveen
Journal of Infection and Public Health. 2020; 13(12): 1912
[Pubmed] | [DOI]
4 WITHDRAWN: Circulation of dengue virus serotypes in hyperendemic region of New Delhi, India during 2011-2017
Arshi Islam,Mohd Abdullah,Ayesha Tazeen,Irshad H. Naqvi,Syed Naqui Kazim,Anwar Ahmed,Salman Freeh Alamery,Ajamaluddin Malik,Shama Parveen
Sustainable Cities and Society. 2020; : 102560
[Pubmed] | [DOI]
5 Circulation of single serotype of Dengue Virus (DENV-3) in New Delhi, India during 2016: A change in the epidemiological trend
Nazish Parveen,Arshi Islam,Ayesha Tazeen,Malik Hisamuddin,Mohd Abdullah,Irshad H. Naqvi,Md I. Faizan,Divya Gulyani,Anwar Ahmed,Shama Parveen
Journal of Infection and Public Health. 2019; 12(1): 49
[Pubmed] | [DOI]
6 Potential of medicinal plants to treat dengue
Dulanjalee Neelawala,Sanjaya Rajapakse,Wikum Widuranga Kumbukgolla
International Journal of One Health. 2019; : 86
[Pubmed] | [DOI]
7 Dengue infection in India: A systematic review and meta-analysis
Parasuraman Ganeshkumar,Manoj V. Murhekar,Veeraraghavadoss Poornima,Velusamy Saravanakumar,Krishnendu Sukumaran,Anandan Anandaselvasankar,Denny John,Sanjay M. Mehendale,Isabel Rodriguez-Barraquer
PLOS Neglected Tropical Diseases. 2018; 12(7): e0006618
[Pubmed] | [DOI]
8 Global dengue death before and after the new World Health Organization 2009 case classification: A systematic review and meta-regression analysis
Gary Kim-Kuan Low,Simon A. Ogston,Mun-Hin Yong,Seng-Chiew Gan,Hui-Yee Chee
Acta Tropica. 2018; 182: 237
[Pubmed] | [DOI]
9 An epidemiological study of dengue and its coinfections in Delhi
Deepali Savargaonkar,Swati Sinha,Bina Srivastava,B.N. Nagpal,Abhinav Sinha,Arshad Shamim,Ram Das,Veena Pande,Anupkumar R. Anvikar,Neena Valecha
International Journal of Infectious Diseases. 2018; 74: 41
[Pubmed] | [DOI]
10 Genetic signatures coupled with lineage shift characterise endemic evolution of Dengue virus serotype 2 during 2015 outbreak in Delhi, India
Manish Chandra Choudhary,Ekta Gupta,Shvetank Sharma,Nadeem Hasnain,Pragya Agarwala
Tropical Medicine & International Health. 2017; 22(7): 871
[Pubmed] | [DOI]
11 Circulating Genotypes of Dengue-1 Virus in South West India, 2014–2015
Shetty Pooja,Sasidharanpillai Sabeena,Bhaskar Revti,Ramachandran Sanjay,Aithal Anjali,Kumar Rajendra,Sushama Aswathyraj,Dsouza Giselle,Maity Hindol,Govindakarnavar Arunkumar
Japanese Journal of Infectious Diseases. 2017; 70(6): 663
[Pubmed] | [DOI]
Saurabh Chhotalal Gamit,Hitesh Kantilal Shingala,Mala Sinha
Journal of Evidence Based Medicine and Healthcare. 2017; 4(94): 5883
[Pubmed] | [DOI]
Jayashree Naik D,Swapnil Jain R,Sandeep Babar,Sachin Sharma,Madhuri Mathurkar P,Vishwanath G R,Sandesh Kamble V,Vivek Patil
Journal of Evolution of Medical and Dental Sciences. 2016; 5(29): 1488
[Pubmed] | [DOI]
14 Cost Burden of Dengue Fever in a Rural Ramanagara District of Karnataka State
Naveen Kumar, AC Shyam, Vidya LNU
The Journal of Medical Sciences. 2016; 2(4): 59
[Pubmed] | [DOI]
15 Differentiating secondary from primary dengue using IgG to IgM ratio in early dengue: an observational hospital based clinico-serological study from North India
Khalid Hamid Changal,Ab Hameed Raina,Adnan Raina,Manzoor Raina,Rehana Bashir,Muzamil Latief,Tanveer Mir,Qayum Hamid Changal
BMC Infectious Diseases. 2016; 16(1)
[Pubmed] | [DOI]
16 Dengue research: a bibliometric analysis of worldwide and Arab publications during 1872–2015
Sa’ed H. Zyoud
Virology Journal. 2016; 13(1)
[Pubmed] | [DOI]
17 Dengue fever among Israeli expatriates in Delhi, 2015: implications for dengue incidence in Delhi, India
Ami Neuberger,Avigail Turgeman,Yaniv Lustig,Eli Schwartz
Journal of Travel Medicine. 2016; 23(3): taw003
[Pubmed] | [DOI]


Print this article  Email this article


    Similar in PUBMED
    Search Pubmed for
    Search in Google Scholar for
  Related articles
    Article in PDF (428 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  

    Materials and Me...
    Article Tables

 Article Access Statistics
    PDF Downloaded664    
    Comments [Add]    
    Cited by others 17    

Recommend this journal

  Sitemap | What's New | Copyright and Disclaimer | Privacy Notice
  © 2007 - Indian Journal of Community Medicine | Published by Wolters Kluwer - Medknow
  Online since 15th September, 2007