Every year on May 16, India observes National Dengue Day. This day raises awareness about the growing threat of dengue fever, especially during the monsoon season. Usually, it is during the monsoon that due to stagnant water, mosquito breeding increases. The government also aims to highlight the importance of prevention, public participation for awareness, as well as timely medical care to control the spread of the disease.National Dengue Day 2025 Theme:Each year, a unique theme is observed in order to raise awareness. This year, the main theme is people-led prevention. The theme is : Act Early, Prevent Dengue: Clean Surroundings, Healthy Living.Origin of National Dengue DayThe Ministry of Health designated May 16 as National Dengue Day in 2010. This was done to intervene when dengue cases increased throughout the pre-monsoon and monsoon seasons.As per the World Health Organization (WHO), "Dengue epidemics tend to have seasonal patterns, with transmission often peaking during and after rainy seasons. There are several factors contributing to this increase, and they include high mosquito population levels, susceptibility to circulating serotypes, favourable air temperatures, precipitation and humidity, all of which affect the reproduction and feeding patterns of mosquito populations, as well as the dengue virus incubation period. Lack of proactive control interventions and staff are some of the other challenges."Dengue And India: SignificanceDue to climate change, monsoon has arrived early, thus the Union Health Ministry has directed all air, sea, and land ports across the country to step up surveillance for vector-borne diseases. Authorities have been asked to strengthen preventive and control measures to curb the spread of infections such as dengue, chikungunya, Zika, and yellow fever. The advisory comes amid concerns over rising cases during the rainy season, a period that typically sees a surge in mosquito breeding and transmission. India continues to report a significant number of cases and deaths linked to vector-borne illnesses each year, making early intervention and preparedness critical.Dengue and India: HistoryAs per a 2012 study published in the Indian Journal of Medical Research, the official journal of the Indian Council of Medical Research, titled Dengue in India, notes that it was in 1780 when the first epidemic of clinical dengue-like illness was recorded in Madras (now Chennai). The first virologically proved epidemic of dengue fever occurred in Calcutta (now Kolkata) and the Eastern Coast of India in 1963-64.However, during the last 50 years, notes the study, a large number of physicians have treated and described dengue diseases in India, but the scientific studies which address problems with regard to the disease may have been limited.What is Dengue?The study notes that Dengue is an acute viral infection with potential fatal complications. It was first referred to as "water poison" associated with flying insects in a Chinese medical encyclopedia in 992 from the Jin Dynasty.The word "dengue" is derived from the Swahili phrase Ka-dinga pepo, which means "cramp-like seizure". The first clinically recognized dengue epidemics occurred simultaneously in Asia, Africa, and North America in the 1780s.As per Global Medicine, the first clinical case report dates from 1789 of 1780 epidemic in Philadelphia is by Benjamin Rush, who coined the term “break bone fever” because of the symptoms of myalgia and arthralgia.How Does Dengue Happen?As per the Centers for Disease Control and Prevention (CDC), dengue viruses usually spread to people through the bites of infected Aedes species mosquitoes. This mosquito bites a person infected with the dengue virus and then becomes infected. The infected mosquito then bites people and infects them with the dengue virus.