Published Feb 03, 2026 | 7:00 AM ⚊ Updated Feb 03, 2026 | 7:00 AM
Aedes aegypti mosquito. (Creative Commons)
Synopsis: Kerala has approved a long-term research project to closely track dengue and Zika infections, as the state continues to face a significant dengue burden and early signs that Zika could become locally entrenched. The study, proposed by the ICMR–Vector Control Research Centre, aims to understand how these infections spread, worsen, overlap and evolve, amid rising cases, seasonal surges and changing virus strains.
Kerala has cleared a major long-term research initiative to closely track two of the biggest mosquito-borne diseases that continue to take a heavy toll on the state each year: dengue and Zika.
The project, proposed by the ICMR–Vector Control Research Centre under the Union Ministry of Health and Family Welfare, will track clinical, epidemiological, genomic and immunological markers of dengue and Zika infections, including co-infections, through long-term follow-up studies in Kerala. It is scheduled to begin soon.
In other words, the study will track cases over time to see how dengue and Zika infections begin, how severe they become, how the viruses change and how the body responds, including what happens when a person is infected with both viruses at once.
Scheduled to begin in February, the study aims to deepen understanding of how mosquito-borne infections spread, evolve and overlap in the state.
The approval comes amid a persistent dengue burden. In the first month of 2026 alone, Kerala reported 378 confirmed dengue cases and four deaths.
No Zika cases have been detected so far in 2026. Dengue trends from recent years, however, show the scale of the problem: 10,886 cases and 56 deaths in 2025; 20,674 cases and 128 deaths in 2024; and 17,426 cases and 153 deaths in 2023.
Zika surfaced briefly in 2023, with 13 confirmed cases and no deaths. Earlier data show dengue claiming lives even in lower-incidence years, including 4,432 cases and 29 deaths in 2022.
Kerala’s long battle with mosquito-borne viral diseases has entered a more worrying phase. Fresh scientific evidence shows that dengue is now firmly endemic in the state, while the Zika virus may be evolving into a more resilient, locally established strain.
A group of researchers led by Alex Eapen, senior scientist of ICMR point to a dangerous mix of favourable climate conditions, dense population centres, ecological diversity and human-made breeding habitats that sustain transmission of these arboviral diseases.
Dengue fever, a mosquito-borne viral infection listed by the World Health Organization among its 20 prioritised Neglected Tropical Diseases, has risen steadily worldwide over the past two decades.
India is among the worst-affected countries, while Kerala is among the high dengue-burden states. The first confirmed dengue case in Kerala was reported from Kottayam in 1997.
In 2017 alone, the state reported about 21,993 dengue cases and 165 deaths, accounting for more than 10 percent of India’s total reported cases that year.
Thiruvananthapuram recorded the highest number of infections and was also the district where Zika cases were reported at the time.
Since then, dengue has entrenched itself across districts, with recurring outbreaks and seasonal surges that strain public health systems year after year.
Dengue cases in Kerala have risen gradually over the years, with major peaks every three to four years, according to a 2023 study published in the International Journal of Mosquito Research.
The study notes a sharp seasonal rise in cases between May and July, coinciding with the southwest monsoon. Researchers link the spread not only to climate, but also to geography, vegetation cover, urbanisation and population density.
Thiruvananthapuram, the state capital and its most densely populated district, has consistently recorded the highest number of cases.
Predictive modelling in the study shows that dengue cases in Kerala are likely to rise further in the coming years. This underlines the need for coordinated action by health authorities, local governments and the public.
A separate 2023 study on Zika identified five unique non-synonymous mutations, pointing to the emergence of a novel “Indian lineage” of the Asian strain of the Zika virus during the 2021 outbreak.
Zika belongs to the Orthoflavivirus genus of the Flaviviridae family, which also includes dengue, West Nile, Japanese encephalitis and Kyasanur Forest disease viruses. Many of these are classified by the World Health Organization as emerging or re-emerging threats.
The investigation confirmed that Zika transmission during recent outbreaks in Kerala was driven by local Aedes species, including Aedes albopictus, Aedes aegypti and Aedes vittatus.
Some of these mutations have since been found in other parts of India, raising concern that the lineage could become dominant and drive larger outbreaks in the future.
State health officials say Kerala’s climate plays a critical role in sustaining dengue transmission.
The hot season from March to May is often broken by pre-monsoon showers. This is followed by the southwest monsoon from June to early October and the northeast monsoon between October and December. Even January and February receive intermittent rainfall.
The southwest monsoon, in particular, creates ideal breeding conditions for dengue vectors such as Aedes aegypti and Aedes albopictus.
Rainwater not only creates new breeding sites but also triggers the hatching of dormant Aedes eggs, increasing mosquito density.
Scientists warn that this may also enable transovarian transmission of the dengue virus, raising the risk of outbreaks during and after the monsoon.
More worryingly for Kerala, a multi-district mosquito survey conducted in 2025 across five districts—Thiruvananthapuram, Kollam, Kozhikode, Wayanad and Idukki—identified 108 mosquito species across 28 genera from more than 12,500 specimens, including 14 known disease vectors.
Artificial, human-made habitats accounted for nearly 78 percent of breeding sites. These far outnumbered natural habitats such as tree holes, rock pools and ground depressions.
Discarded tyres, plastic containers, latex collection cups and household water storage items emerged as the main breeding sources, especially for Aedes albopictus, which was found breeding in 77 different habitat types. The species showed marked adaptability, thriving in both peri-domestic and forested environments.
Wayanad recorded the highest mosquito species diversity due to its forests, plantations and limited human disturbance, followed by Ernakulam and Pathanamthitta.
Thiruvananthapuram, despite moderate species diversity, showed a persistent presence of key vectors because of dense habitation and abundant artificial breeding sites.
(Edited by Dese Gowda)
