“I lost my son last year to dengue. It started with a severe headache accompanied by a high fever. Initially, we thought it was just exhaustion from the particularly intense hot summer days that year,” shares Anumita Ranjan, a Delhi resident and mother of two sons. However, the situation quickly worsened, and her son was hospitalized for over a month and a half.
Living in Delhi’s Badarpur area, she and her family are among the thousands who annually confront the dengue menace—a challenge that escalates as the city struggles with recurring outbreaks.
According to data from the Municipal Corporation of Delhi (MCD), the number of reported dengue cases in 2023 skyrocketed to 4,965. This staggering figure not only surpasses last year’s statistics but also represents the highest number recorded in the past five years.
Dr. Kavita Singh, South Asia Director at the Drugs for Neglected Diseases initiative (DNDi) highlights the persistent threat of dengue both in urban and rural settings in India, “The incidences of dengue are rapidly increasing in India every year.”
The annual incidence of Dengue has increased five-fold in the last decade in India. In 2023, India officially recorded nearly 95,000 cases and 91 deaths as reported by MoHFW, however, the count of unreported cases is manifold.
“This increase can be due to many causes such as globalization, urbanization, travel, trade, climate change, and mostly, viral evolution and the fact that this virus has 04 serotypes,” Dr. Singh adds.
Urban dynamics in Dengue resurgence
The resurgence of dengue in densely populated areas such as Delhi can be attributed to a confluence of environmental and urban factors. T. Jacob John, former head of the ICMR Virology Research Center and a public health expert, explains, “The mosquito Aedes aegypti is the primary vector for dengue. Once this virus establishes itself in a region, it tends to become endemic, thriving under environmental conditions that promote mosquito breeding. While often mild, dengue can escalate to severe, even life-threatening levels in a small proportion of cases.”
Dr. John further notes the presence of multiple dengue serotypes, emphasizing the complexity of immunity: “There are four recognized dengue serotypes. Immunity to one type does not guarantee protection against the others, allowing for up to four potential infections per individual over their lifetime.”
Dr. Kavita Singh adds a crucial dimension by highlighting the rapid evolution of the virus. “The evolution of the virus accelerates with intense transmission. This rapid evolution leads to the emergence of new variants or serotypes, which can trigger massive outbreaks in endemic regions, thereby increasing the disease’s severity,” she adds.
In urban settings, the unchecked sprawl contributes significantly to the dengue crisis. Stagnant water from irregular monsoons, a common issue in cities like Delhi, creates ideal breeding grounds for mosquitoes. This problem is compounded by the city’s high density, which facilitates the rapid spread and transmission of the disease.
Moreover, water management issues play a critical role in exacerbating these challenges. Inadequate drainage systems coupled with irregular water supplies compel residents to store water in open containers, inadvertently creating potential mosquito breeding sites. These urban planning shortcomings are particularly pronounced in rapidly developing areas like Badarpur, in Delhi, where environmental management has struggled to keep pace with growth.
How is Climate Change impacting Dengue trends?
“Dr. Singh remarks, “Climate change is altering patterns for dengue fever and other diseases. Previously, we didn’t see as many cases or as many deaths.”
Environmental changes, such as increased temperatures and altered rainfall patterns due to climate change, have intensified the breeding cycles of the Aedes mosquitoes.
Rev Ngaihthe, a resident of Dimapur, admitted to initially underestimating the severity of dengue, saying, “When I contracted dengue, I didn’t take it very seriously, thinking I had battled colds and even COVID-19, so I’d be fine. But this experience was unlike anything I’ve ever encountered.”
In Manipur, the incidence of dengue has risen significantly in recent years. The first cases in the state were reported in 2007, and there has been a steady increase ever since. In October 2023, the state health directorate released a report covering the period from January 1 to October 13. The report revealed that Manipur recorded 1,338 dengue cases, which was 835 more than what was reported in the previous year, 2022.
According to the National Centre for Vector Borne Disease Control (NCVBDC), the number of dengue cases in Uttarakhand exceeded 3,000 in 2023, marking the highest count in the past five years. The capital, Dehradun, reported over 1,000 cases, while Pauri district had an additional 736 cases.
John explained the link between these rising numbers and environmental changes, stating, “It is the result of the impact of climate change on Manipur’s weather. The vector, Aedes mosquitoes, has been significantly affected by climate change. As the atmosphere warms, there is consequently increased rainfall. High temperatures stimulate the growth of mosquito larvae and provide a very favorable atmosphere for the Aedes mosquitoes to multiply rapidly. This change can lead to outbreaks if proper measures are not taken to minimize the spread of the vector and the virus. The dengue vector thrives in all tropical conditions, which would lead to an increase in its multiplication. Hence, warmer temperatures, high humidity, excess precipitation, storms, and flooding all create conducive conditions for the vector to grow.”
Challenges in developing effective dengue treatments
Developing effective treatments and vaccines for dengue presents a significant challenge that spans decades and involves complex virological hurdles. Dr. Singh, emphasizes the struggles faced by endemic countries. “All dengue-endemic countries are facing great difficulty in fighting the disease. Even after almost two decades and many complications and casualties to date, there is no all-effective therapy or vaccine for the dengue virus.”
Amidst these challenges, there are promising developments on the horizon. Indian Immunologicals Limited (IIL), a subsidiary of the National Dairy Development Board, is currently advancing a dengue vaccine that is expected to be available commercially by mid-2026. Having completed the first phase of clinical trials, which focused on safety, IIL is moving forward with the second and third phases to test the vaccine’s efficacy. This development is part of a broader effort to combat vector-borne diseases, also including initiatives for vaccines against the Zika virus and Kyasanur Forest Disease.
Dr. Singh further explains the broader efforts and progress in this area: “Numerous groups have already made intensive efforts and made good progress in developing a safe, affordable, and effective vaccine against all serotypes for global public health.” These efforts signify the global scientific community’s commitment to overcoming the biological challenges presented by dengue.
“India’s health challenges are complex, but effective strategies include mobilizing communities, building capacity, and promoting community health. Unfortunately, community voices are often missing from the dengue narrative. Innovative ways to disseminate information are needed to ensure communities are informed participants and equal stakeholders,” Dr. Singh remarks.
(We reached out to the National Vector Borne Disease Control Programme (NVBDCP) multiple times for comment but were denied any statements regarding the issue.)
