Seasonal Trends & Short-Term Fluctuations of Aedes Larval Indices and Their Climatic Correlates Across Locality Types in South Zone, Delhi, India

Amar Nath  Pandey; Arun  Chauhan; Rohit Sagar; Neera  Kapoor; Sukhvir Singh; S.K.  Sagar

Amar Nath Pandey Research Scholar, IGNOU, Maidan Garhi, Delhi, India
Arun Chauhan Entomologist, National Centre for Vector Borne Disease Control, Delhi, India
Rohit Sagar Shri Ram Murti Gupta Govt P G College, Chharra, Aligarh, Uttar Pradesh, India
Neera Kapoor Professor, School of Life Sciences, IGNOU, Maidan Garhi, Delhi, India
Sukhvir Singh Ex-Join Director, National Centre for Vector Borne, Diseases Control, Delhi, India
S.K. Sagar Department of Zoology, Swami Shraddhanand College, University of Delhi, India

Keywords: Aedes aegypti, Aedes albopictus, larval indices and entomological surveillance

Abstract

Introduction: Dengue infects an estimated 390 million people annually, though underreporting is widespread due to asymptomatic cases. It is endemic in 129 countries, including nearly all of India, causing 20,000 deaths and 264 disability adjusted life years (DALYs) per million population yearly. Its vectors, Aedes aegypti and Aedes albopictus, differ in habitat and behaviour.

Method: Breeding habitats across eight localities (slum settlements, urban villages, high-income colonies, and government institutions) in five wards of South Zone, Delhi, were surveyed from January 2024 to December 2025. Monthly door-to-door surveys of 360 households and two institutions, examined water holding containers across nine categories for Aedes immatures.

Results: All localities showed larval indices lowest in Winter, peaking in Monsoon, and declining post- Monsoon. In 2024, HI rose from 2.5%–13.6% (Slums), 1.1%–12.2% (Urban Villages), and 0.6%–11.4% (High-Income Areas). In 2025, HI, CI and BI increased during Monsoon and post-Monsoon (HI plus 75% to plus 115%), coinciding with rainfall rising from 200.5–257.2 mm (Monsoon) and 70.8–99.3 mm (post- Monsoon), and humidity from 72%–81%. Positive containers rose from 418 to 587 (40.4%).

Conclusion: This two-year survey reveals a repeatable seasonal cycle peaking in Monsoon, tracking rainfall and humidity more than temperature. Locality ranking (Slums greater than Urban Village greater than High-Income greater than Govt. Institutions) suggests housing density and water-storage habits as key drivers. Locality-specific, container-targeted interventions during Winter and Pre-Monsoon are likely more effective than uniform measures, though findings need validation with adult mosquito and case data.

DOI: https://doi.org/10.24321/0019.5138.202655

How to cite this article:
Pandey A N, Chauhan A, Sagar R, Kapoor N, Singh S, Sagar S K. Seasonal Trends & Short-Term Fluctuations of Aedes Larval Indices and Their Climatic Correlates Across Locality Types in South Zone, Delhi, India. J Commun Dis. 2026;58(3): 55-67.

References

Bhatt S, Gething PW, Brady OJ, Messina JP, Farlow AW, Moyes CL, Drake JM, Brownstein JS, Hoen AG, Sankoh O, Myers MF. The global distribution and burden of dengue. Nature. 2013 Apr 25;496(7446):504-7. [Google Scholar] [Pubmed]

Halstead SB. Dengue. The lancet. 2007 Nov 10;370(9599):1644-52. [Google Scholar] [Pubmed]

Gubler DJ. Epidemic dengue and dengue hemorrhagic fever: a global public health problem in the 21st century. Emerging infections 1. 1997 Nov 6:1-4.doi: 10.1128/9781555816940.ch1. [Google Scholar]

Ten Bosch QA, Clapham HE, Lambrechts L, Duong V, Buchy P, Althouse BM, Lloyd AL, Waller LA, Morrison AC, Kitron U, Vazquez-Prokopec GM. Contributions from the silent majority dominate dengue virus transmission. PLoS pathogens. 2018 May 3;14(5):e1006965. [Google Scholar] [Pubmed]

Baruah K, Arora N, Sharma H, Katewa A. Dengue in India: Temporal and spatial expansion in last two decades. J Med Arthropodol & Public Health. 2021 Jun 1;1(1):15-32. [Google Scholar]

National Guideline Dengue Case Management during Covid 19 pandemic https://nvbdcp.gov.in/Doc/ National%20Guideline%20for%20Dengue%20case%20 management%20during%20COVID-19%20pandemic. pdf 7. Global strategy for dengue prevention and control 2012-20

https://www.who.int/immunization/sage/meetings/2013/april/5_Dengue_SAGE_Apr2013_Global_Strategy.pdf

Ducheyne E, Tran Minh NN, Haddad N, Bryssinckx W, Buliva E, Simard F, Malik MR, Charlier J, De Waele V, Mahmoud O, Mukhtar M. Current and future distribution of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in WHO Eastern Mediterranean Region. International Journal of Health Geographics. 2018 Feb 14;17(1):4. [Google Scholar] [Pubmed]

Ngoagouni C, Kamgang B, Nakouné E, Paupy C, Kazanji M. Invasion of Aedes albopictus (Diptera: Culicidae) into central Africa: what consequences for emerging diseases?. Parasites & Vectors. 2015 Mar 31;8(1):191. [Google Scholar] [Pubmed]

SK G. Observation on possible competitive displacement between populations of Aedes aegypti Linaeus and Aedes albopictus Skuse in Calcutta. Bull World Health Organ. 1967;37:437-46. [Google Scholar] [Pubmed]