Dengue prevalence in India – A perspective

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Dengue prevalence in India - A perspective

Dengue is a viral, mosquito borne disease that is prevalent in tropical and subtropical regions across the world. In India, dengue is endemic and is most commonly reported during the Monsoon season. Symptoms typically appear 4 – 10 days after the mosquito bite and can last from 2- 7 days. Symptoms may include high fever, severe headache, nausea, vomiting, pain in bone & joint etc.

Recurrent dengue infections over the years may lead to severe dengue fever with more symptoms such as abdominal pains, bleeding from gums and nose, fatigue, and restlessness etc.

Dengue infection is diagnosed by detection of NS1 antigen in the first 4-5 days of onset of symptoms, followed by detection of IgM antibodies. Detection of IgG antibodies may indicate an infection which is more than one month old. Samples for this study were tested using both Rapid and ELISA methods wherein the confirmatory ELISA tests performed constituted two thirds of the total volume.

 In 2024, we observed some interesting trends in the data of samples tested for dengue.

Dengue cases in india

The positivity rate amongst 87,156 patients tested PAN India in 2024 was 17.63% which was similar to the previous year’s positivity rate of 18.48% out of 1,00,800 patients tested. Dr. Hardeep Vora (PhD. –  Immunology) highlighted that  “The spike in the positivity rate started in the month of May in 2024 compared to June in 2023, indicating an early onset of this disease in 2024”.

Dengue cases in indiaState Wise Insights

Dengue cases across states in india

In 2024, the states with the highest dengue positivity rates included Chandigarh, Jammu & Kashmir, Punjab, Haryana, Kerala and Karnataka. (States with less than 250 samples tested are excluded). 

A noteworthy year on year increase in positivity rates was seen in Punjab from 12.35% in 2023 to 31.5% in 2024 followed by Chandigarh (26.8% to 36.8%), Kerala (15.9% to 24.9%) and Maharashtra (7.8% to 14.5%) 

In contrast,  Tripura saw a decline in positivity rate from 27% in 2023 to 2% in 2024 along with Uttarakhand from 34.3%  to 18.5%. The same trend was observed in Odisha (23.9% to 10.8%) and West Bengal (22% to 10.6%). 

In  June’2024, states like Kerala (38.16%), Karnataka (35.92%), and Goa (34.78%) exhibited the highest positivity rates suggesting localized outbreaks potentially due to the onset of Monsoon compared to the average positivity rate of around 13% for the rest of India. 

The months from August to September’2024 saw a surge in positivity rates across most states, with significant rise in Gujarat and Haryana, suggesting that monsoon may have exacerbated dengue infections. 

Positivity peaks were observed in many states in the month of October’2024, notably Jammu & Kashmir (42.14%), Chandigarh (47.2%) as well as Punjab (43.72%) against the country average of 21% demonstrating the effects of the post-monsoon environment on dengue transmission.

Age and Gender prevalence:

Within the tested population, people under the age of 40 years in 2024 showed a higher positivity rate of 39.46% in comparison to 25.14% in people over the age of 40 years which was similar to last year’s trend. 

In general, the tested male subjects had a slightly higher positivity than females.

Positivity cases in india

Impact of Dengue on other Laboratory parameters:

Impact of Dengue on other Laboratory parameters:

In 2024, among the dengue- positive cases, platelets were found to be out of the normal range in 36.90% of patients, substantially lower than 44.19% in 2023 while plateletcrit levels were abnormal in over half the positive cases affecting 50.23% patients. Other blood parameters such as Hemoglobin, total number of RBCs, packed cell volume (PCV) etc. were outside normal ranges in 25-30% of the dengue-positive patients. Moreover, elevated liver enzymes such as SGPT and SGOT levels were abnormal in 44.92% and 71.39% of dengue-positive patients respectively.

Dr. Preet Kaur (MD Pathologist, Vice President – Lab Operations & Quality) said that “This is one of the largest retrospective clinical study and analysis of dengue positivity across the country from a diagnostics laboratory. The observations regarding clinical parameters such as SGOT and SGPT dysregulation are consistent with published scientific literature. A platelet level abnormality of only about 37% indicates that other clinical parameters should also be considered when looking at infection and recovery. “

This study provides a snapshot of the spread of dengue virus across the country at different times of the year. Insights from such studies can highlight changes in transmission patterns and also help with better preparedness to combat the disease in the future.