DBobby Reiner, one of the authors of the study and assistant professor at the University of Washington, said the reason for the increase in the disease was due to the widespread shift from rural to urban life. People who live in poor conditions in the "unplanned megacities" of the world are at particular risk.
"Dengue is a mosquito-borne disease. There is a growing population of people living in poorer urban areas where there are no screens on the windows, no air conditioning and plenty of stagnant water. These are ideal conditions for mosquitoes, "he said.
Dr. Reiner said there are few proven interventions to fight the disease – the only Dengue fever vaccine is incomplete and little has been sought on control measures such as insecticides.
"There is no evidence of what to do," he said.
There are four different dengue serotypes – or strains – and one person who has been infected with a serotype is more likely to develop the severe form of the disease if it is re-infected with another.
Dr. Rachel Lowe, assistant professor at the London School of Hygiene and Tropical Medicine, who was not involved in the study, said that people are moving around the world in large numbers, increasing their chances of being exposed to different serotypes.
She added, "More frequent interaction between the different serotypes could lead to more people developing heavy dengue fever, which in some cases can be fatal.
"If you have these vast urban areas where poor sanitation and close contact between the vector and the human being exist, the number of cases will increase."
The dengue mosquito bites throughout the day, so malaria control measures like bed nets do not work, she added.
"It's extremely difficult to control the vector, and once it's fixed, it's very difficult to get rid of it. Things like improved sanitation and infrastructure are important to ensuring that people have enough running water so they do not have to rely on temporary water reservoirs, "said Dr. Lowe.
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