TORONTO – The UN University’s Institute for Water, Environment and Health (INWEH) has released the first-ever maps of global vulnerability to dengue and has warned that climate change could cause the disease to spread to Europe and the mountainous regions of South America.
The study published Tuesday by INWEH, based in the Canadian city of Hamilton, shows the expansion and contraction of areas vulnerable to dengue during the year, while stressing that it is an endemic disease in over 100 countries and is rapidly spreading.
Around 400 million people are currently infected by the dengue virus, which causes between 250,000 and 500,000 serious infections every year and accounts for about 20,000 deaths, besides immense economic costs.
Only in Southeast Asia it is calculated that dengue accounts for healthcare costs of $950 million a year.
The UN also estimates that 2.5 billion people are at risk of contracting the disease, but in 70 years the figure would rise to between five and six billion.
According to the authors of the study, based on Water-Associated Disease Index, the highest levels of vulnerability to dengue are found in South Asia and countries situated near the equator, such as Colombia, Sierra Leone, Nigeria and Indonesia.
The maps show a seasonal variation in levels of vulnerability to dengue in all continents, mainly due to the annual fluctuations in temperature and precipitation which are contributing factors, according to the authors of the study.
The areas exposed to dengue are more vulnerable in the months of January, April, July and October.
However, the authors warn that climate change could cause the disease to spread to areas where it does not exist today, including parts of Europe and South America.
An increase in 2 to 4 degrees centigrade in the minimum temperatures could lead to favorable conditions for the survival of the Aedes mosquito, which spreads dengue, in the mountainous regions of South America and wide parts of Europe.
At the same time, the increase in maximum temperatures could reduce the areas where the Aedes mosquito can survive.
“The purpose of this project is to help in decision-making and distribution of resources in the long term regarding diseases related to water,” INWEH researcher Corinne Schuster-Wallace told Efe.
“It is not a tool for predicting outbreaks, but a tool against dengue and other diseases related to water,” she added.
“We have developed this tool not only to study the physical factors, such as temperature or rainfall, but also factors like social development and vulnerability of communities,” she further said.
The study, which analyzes the dengue situation in the Brazilian state of Pernambuco from 2000 to 2010, said that change in land use pattern and increase in population in semi-arid areas increased vulnerability.
Another researcher, Sarah Dickin, added that Brazil’s case shows the importance of considering long term changes as development of water resources and pattern of urbanization process could be used in checking the disease.