Why dengue cases are on the rise

Why dengue cases are on the rise

Sub : Science and tech

Sec: Health

Context: In the past few weeks, cases of dengue have been rising in some parts of the country. Karnataka, in particular, has been experiencing a rapid surge in cases in the last few days, while the cases have been climbing up in Kerala and Tamil Nadu as well.

What is dengue?

• Dengue (break-bone fever) is a viral infection that spreads from mosquitoes to people. It is more common in tropical and subtropical climates.
• Most people who get dengue will not have symptoms. But for those who do, the most common symptoms are high fever, headache, body aches, nausea, and rash. Most will get better in 1–2 weeks. Some people develop severe dengue and need care in a hospital.
• In severe cases, dengue can be fatal.
• You can lower your risk of dengue by avoiding mosquito bites especially during the day.
• Dengue is treated with pain medicine as there is no specific treatment currently.

What is the global situation of dengue?

• According to the World Health Organization (WHO), as of April 30, over 7.6 million cases of dengue were reported in 2024. This included 3.4 million confirmed cases, over 16,000 severe cases and over 3,000 deaths.
• In an update on the global scenario dated May 30, it said that 90 countries have known active dengue transmission, adding that “not all of which have been captured in formal reporting”. WHO pinpointed that the actual burden of dengue is underestimated as many endemic countries did not have strong detection and reporting mechanisms.
• The WHO noted that at least five countries, including India, were grappling with the onset of monsoon season, which created suitable conditions for the breeding and survival of Aedes mosquito. Urbanisation and population movements have also played a pivotal role in the increasing burden in the region.
• WHO observed that the incidence of dengue has grown dramatically around the world in recent decades. “About half of the world’s population is now at risk of dengue with an estimated 100-400 million infections occurring each year. Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas,” it pointed out.
• Dengue is endemic in more than 100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and Western Pacific. The Americas, South-East Asia and Western Pacific regions were the most seriously affected, with Asia accounting for around 70% of the global disease burden. However, it also went on to note that dengue is spreading to new areas in Europe, the Eastern Mediterranean and South America.

How does dengue spread and how is it treated?

Dengue virus is transmitted to humans through the bite of infected mosquitoes, with the primary vector that transmits the disease being Aedes aegypti. While cases are mostly asymptomatic or mild, some may develop severe dengue that could include shock, severe bleeding or organ impairment.

According to the National Guidelines for Clinical Management of Dengue Fever, an acute febrile illness of two to seven days duration with two or more of the following manifestations – headache, retro-orbital pain, myalgia, arthralgia, rash and haemorrhagic manifestations – were the clinical features of dengue fever.

What are the emerging patterns in dengue?

• Among the several factors associated with an increasing risk of dengue epidemics were changing distribution of Aedes aegypti vector, urbanisation and human activities fostering conducive environments for vector-host interaction and climate change-induced shifts in weather patterns, according to WHO.
• Public health officials said that the first epidemic of clinical dengue-like illness was recorded in erstwhile Madras in 1780. Dengue virus was isolated in India during 1945 for the first time. The first evidence of the occurrence of dengue fever in the country was reported in 1956 from Vellore district in the State, they said.
• Noting that dengue was once considered to be an arboviral disease of the urban environment infecting populations in municipalities, corporations and cities, they said the infection has spread to all geographic regions including rural and urban due to rapid increase in urbanisation, expanding travel patterns and climatic changes.