Thirteen years of official counts show Tamil Nadu reporting more dengue than ever while far fewer people die of it. Reading the numbers well means knowing how a case gets counted.
The numbers
Tamil Nadu recorded 27,378 dengue cases in 2024 and 23,407 in 2025, according to the National Center for Vector Borne Diseases Control (NCVBDC). Both are higher than the 23,294 cases of 2017, until then the state’s worst year. Yet the deaths tell a different story: 65 in 2017, 13 in 2024 and 12 in 2025.
The national picture moved the other way in 2025. India’s reported cases fell from 2,33,519 in 2024 to 1,21,824, while Tamil Nadu’s fell only modestly, so the state’s share of the national count rose to about one case in five. By 30 April 2026, Tamil Nadu had reported 4,973 of India’s 13,336 provisional cases, more than a third, before the northeast monsoon season that usually drives transmission here.
Thirteen years of official counts
| Year | TN cases | TN deaths | India cases | TN share of India |
|---|---|---|---|---|
| 2013 | 6,122 | 0 | 75,808 | 8.1% |
| 2014 | 2,804 | 3 | 40,571 | 6.9% |
| 2015 | 4,535 | 12 | 99,913 | 4.5% |
| 2016 | 2,531 | 5 | 129,166 | 2.0% |
| 2017 | 23,294 | 65 | 157,996 | 14.7% |
| 2018 | 4,486 | not in source | not in source | n/a |
| 2019 | 8,527 | not in source | not in source | n/a |
| 2020 | 2,410 | 0 | 44,585 | 5.4% |
| 2021 | 6,039 | 8 | 193,245 | 3.1% |
| 2022 | 6,430 | 8 | 233,251 | 2.8% |
| 2023 | 9,121 | 12 | 289,235 | 3.2% |
| 2024 | 27,378 | 13 | 233,519 | 11.7% |
| 2025 | 23,407 | 12 | 121,824 | 19.2% |
Source: CBHI National Health Profile 2018, Table 3.1.5 (2013-2017, 2017 provisional); Lok Sabha USQ 2753 of 6 March 2020 (2018-2019, cases only); NCVBDC, Dengue cases and deaths 2021-2026 (2021-2025); Lok Sabha USQ 972 of 8 December 2023 (2020). Shares calculated for this article
The series has three distinct phases. From 2013 to 2016, cases stayed between about 2,500 and 6,100 a year. The 2017 outbreak multiplied cases roughly ninefold over 2016, and deaths reached 65. After a quieter stretch, including the pandemic year 2020 when only 2,410 cases were reported, counts climbed again from 2023 and jumped in 2024.
The 2023 total is a useful lesson in how these figures firm up. A Lok Sabha answer in December 2023 gave 7,133 cases to 30 November; the final NCVBDC figure for the year is 9,121. Figures for the latest year are always provisional and tend to rise.
Share of Tamil Nadu’s 2024 dengue cases that ended in death (13 of 27,378), against 0.28% in 2017 (65 of 23,294), calculated from NCVBDC and CBHI figures.
How a dengue case gets counted
A case in these tables is a laboratory-confirmed case reported through the national programme, not every fever that might be dengue. The Union health ministry told the Lok Sabha in March 2020 that diagnosis is supported through a network of 680 sentinel surveillance hospitals linked to 16 apex referral laboratories, with IgM test kits supplied through the National Institute of Virology, Pune; it supplied 7,958 kits, each good for 96 tests, in 2019. By December 2023 the network had grown to 805 sentinel hospitals and 17 apex laboratories, with testing free.
This has a consequence for interpretation. A state that tests more, and reports promptly, will record more cases than a state that tests less, even with similar transmission. Tamil Nadu’s high count may partly reflect the reach of its testing and reporting, though the official tables alone cannot separate that effect from real transmission. Deaths are a harder number to inflate or miss, which is why the falling death count is the more telling trend.
Tamil Nadu against its neighbours
| State | 2021 cases (deaths) | 2023 cases (deaths) | 2024 cases (deaths) | 2025 cases (deaths) |
|---|---|---|---|---|
| Tamil Nadu | 6,039 (8) | 9,121 (12) | 27,378 (13) | 23,407 (12) |
| Karnataka | 7,393 (7) | 19,300 (11) | 32,886 (27) | 7,325 (0) |
| Kerala | 3,251 (27) | 17,426 (153) | 20,674 (128) | 10,923 (65) |
| Maharashtra | 12,720 (42) | 19,034 (55) | 19,385 (40) | 14,168 (24) |
Source: NCVBDC, Dengue cases and deaths in the country, 2021 to 2026 (till 30 April)
Kerala reported fewer cases than Tamil Nadu in 2024 but almost ten times as many deaths. Karnataka had a larger 2024 outbreak, then reported only 7,325 cases in 2025. These differences reflect testing, reporting and clinical care as well as mosquitoes, so the death column is the safer basis for comparison.
What these tables cannot tell you
The national tables stop at the state. They do not show which districts or Chennai zones drive Tamil Nadu’s count, whether cases are concentrated in children or adults, or how many people were admitted to hospital. Deaths are reported through the same system and can be revised after review, and the 2018 and 2019 death figures were not in the parliamentary answer used here. For a local picture, residents have to rely on the Corporation’s and the Directorate of Public Health’s own bulletins, which are not published as a long series. A careful reader should therefore treat the state totals as a measure of the season’s scale, and the death count as the best available measure of how well cases are being caught and treated.
It’s often said a year with record dengue cases must also be a year of record deaths.
The record shows Tamil Nadu’s highest case count, 27,378 in 2024, came with 13 deaths, against 65 deaths in 2017 when cases were lower (NCVBDC, CBHI).
The legal duty to stop breeding
Control in Tamil Nadu rests on the Public Health Act, 1939, whose Chapter IX (sections 83 to 88) deals with mosquito breeding and gives health authorities powers over premises where mosquitoes breed. Dengue is one of the diseases targeted under the national vector-borne disease programme, which the state’s 2024-25 health policy note lists among the programmes run by the Directorate of Public Health. In practice this means house-to-house source reduction by field workers, which is why water stored in drums, discarded containers and construction sites draw notices and fines.
What this means for you
- Treat any high fever during October to January seriously and get tested at a government facility, where dengue tests are free.
- Most dengue deaths follow late presentation. Warning signs such as abdominal pain, persistent vomiting or bleeding need hospital care the same day.
- Empty or cover stored water weekly. Breeding on private premises is an offence under the 1939 Act, and inspectors can act on it.
- When you read a dengue figure, check whether it is final or provisional; current-year counts are revised upward.
What to watch
October to December 2026
The northeast monsoon months, when Tamil Nadu usually records its highest weekly dengue counts.
Pending
NCVBDC’s full-year 2026 table, which will show whether the state’s early-2026 share of national cases held through the season.
Checked against official sources on 23 October 2026. Figures and rules change; confirm on the linked official pages before relying on them.
Sources
- Dengue cases and deaths in the country, 2021 to 2026 (till 30 April) (NCVBDC, Ministry of Health and Family Welfare)
- National Health Profile 2018, Table 3.1.5: State/UT-wise dengue cases and deaths, 2013-2017 (CBHI, DGHS)
- Lok Sabha Unstarred Question 2753, Dengue Cases, 06.03.2020 (Ministry of Health and Family Welfare)
- Lok Sabha Unstarred Question 972, Cases of Dengue, 08.12.2023 (Ministry of Health and Family Welfare)
- The Tamil Nadu Public Health Act, 1939, text via FAOLEX (FAO)
- Health and Family Welfare Department Policy Note 2024-25 (Government of Tamil Nadu)
