How urbanization affects the epidemiology of emerging infectious diseases

Neiderud, Carl-Johan

Another vector which has adapted to urban surroundings is the mosquito Aedes aegypti, which is a key component for dengue transmission. Dengue is on WHO's list of neglected tropical diseases, and is on the rise worldwide. The number of infections has drastically increased in the tropical regions of the world in the last 40 years. Recent studies have estimated 390 million cases each year, and the burden is the highest in India with onethird of all the new infections (37) . Several factors have played a big role in the escalation, such as urbanization, globalization, and lack of mosquito control. Aedes aegypti lay their eggs in artificial water containers made by humans, which is a key component in the urban transmission cycle. The adaption of dengue through its vector has made dengue an infectious disease on the clear rise (38) . Thailand is a country with all four serotypes of dengue virus, and the epidemics of dengue haemorrhagic fever have shown a possible correlation to originate from the urban capital of Bangkok and then spread geographically in an outward manner to more rural settlements and provinces. A model to understand this mechanism could lead to more effective use of the health systems in the affected areas (39) . Dengue has become a global problem and is no longer restricted to the developing world. Despite better knowledge, it seems tough to control the vector, which has adapted to the urban environment and living close to people. An efficient vaccine is not yet commercially available, but could be a powerful factor in the fight against the global dengue epidemic.