London: The global burden of dengue infection is more than triple the current estimates from the World Health Organization, a multinational study including an Indian origin scientist has revealed.
The research has created the first detailed and up-to-date map of dengue distribution worldwide, enabling researchers to estimate the total numbers of people affected by the virus globally, regionally and nationally.
The findings will help to guide efforts in vaccine, drug and vector control strategies.
The study was led by Professor Simon Hay, a Wellcome Trust Senior Research Fellow at the University of Oxford, as part of the International Research Consortium on Dengue Risk Assessment, Management and Surveillance.
Dengue, also known as ` breakbone fever`, is a viral infection that is transmitted between humans by mosquitoes. In some people, it causes life-threatening illness.
There are currently no licensed vaccines or specific treatments for dengue, and substantial efforts to control the mosquitoes that transmit the disease have not stopped its rapid emergence and global spread. Until now, little was known about the current distribution of the risk of dengue virus infection and its public health burden around the world.
"Our aim was to take all of the evidence that is currently available on the distribution of dengue worldwide and combine it with the latest in mapping and mathematical modelling to produce the most refined risk maps and burden estimates. We then hope to use this knowledge to help predict the future burden of the disease," said Dr Samir Bhatt, who led the modelling for the study.
The findings reveal that dengue is ubiquitous throughout the tropics, with local spatial variations in risk influenced strongly by rainfall, temperature and urbanisation. The team estimate that there are 390 million dengue infections across the globe each year, of which 96 million reach any level of clinical or subclinical severity. This is more than triple the WHO`s most recent estimates of 50-100 million infections per year.
Professor Simon Hay explained: "We found that climate and population spread were important factors for predicting the current risk of dengue around the world. With globalisation and the constant march of urbanisation, we anticipate that there could be dramatic shifts in the distribution of the disease in the future: the virus may be introduced to areas that previously were not at risk, and those that are currently affected may experience increases in the number of infections.
"We hope that the research will initiate a wider discussion about the significant global impact of this disease," he said.
Of the 96 million apparent infections, Asia bore 70 per cent of the burden. India alone accounted for around one-third of all infections.
The results indicate that with 16 million infections, Africa`s burden is almost equivalent to that of the Americas and is significantly larger than previously appreciated.
The authors suggested that the hidden African dengue burden could be a result of the disease being masked by symptomatically similar illnesses, under-reporting and highly variable treatment-seeking behaviour.
The study was published in the journal ` Nature .`