The recent surge in dengue cases globally, including in new regions has been alarming and poses significant global health challenges. The World Health Organisation (WHO) forecasts the possibility of record-level cases this year due to global warming favouring disease-transmitting mosquitoes.
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Dengue fever, caused by the dengue virus (DENV), is a highly prevalent infectious disease estimated to be infecting over 400 million people each year as per the WHO. DENV is an RNA virus of the Flaviviridae family with four serotypes (DENV-1 to 4). Infection with one serotype provides lifelong immunity to that type, but subsequent infections with different serotypes can lead to severe, life-threatening forms of the disease. There is no specific antiviral treatment for dengue, so prevention relies on controlling mosquito populations and raising public awareness. Despite global efforts, dengue cases continue to rise, with millions reported annually worldwide.
Outbreaks in 2023
Since the beginning of 2023, several regions in America have witnessed significant dengue outbreaks, reporting over two million cases till July, with Brazil, Peru, and Bolivia having recorded the highest number of cases this year. Although cases have been reported across all subregions of the Americas, a majority of cases stem from the Southern Cone, encompassing countries such as Argentina, Brazil, Chile, Uruguay, and Paraguay. Several countries in the Americas have reported a co-circulation of all four DENV serotypes, thus presenting several challenges for public health authorities in controlling and managing the outbreaks.
Changing climatic conditions in Europe, such as increased heat waves, floods, and prolonged hot summers, have created favorable environments for dengue-causing mosquito species. The European Centre for Disease Prevention and Control (ECDC) has warned of an increase in DENV infections across the region. In 2022, Europe saw a significant rise in locally acquired dengue cases.
More dengue cases
This month, there was an outbreak of dengue fever reported in Egypt’s Qena province after several positive cases. Prior to this, Sudan recorded its first-ever dengue case in February, even though it is not considered endemic in the Middle East due to unfavorable climate conditions. While the Middle East has experienced some outbreaks, they have been relatively small in scale compared to countries in Asia. Bangladesh, Thailand, Malaysia, Cambodia, and India, in particular, have reported higher case numbers compared to previous years.
Dengue cases have soared in India, mostly due to heavy rains and inadequate control measures, which create the ideal breeding environment for mosquitoes. States like Kerala, Odisha, Assam, Tamil Nadu, Maharashtra, West Bengal, and Karnataka are reporting large numbers of dengue cases.
The recent surge in dengue cases worldwide including India thus demands immediate attention and action. While public health measures are being implemented to control the spread of the disease, individual awareness and responsibility play a crucial role in curbing dengue transmission. Recently, Takeda released the first vaccine for the disease, which has been approved in a few countries. The vaccine has modest efficacy in preventing severe disease but still has much ground to cover in terms of preventing infection, providing uniform protection against all serotypes, and ensuring long-term immunity.
Continued research and collaboration, including genomic surveillance of the virus, are essential to understanding the evolution and adaptation of the virus, developing effective strategies to combat dengue and other mosquito-borne diseases and safeguarding global health and well-being.
(Bani Jolly and Vinod Scaria are researchers at CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi)
