The last few decades have seen dengue, a mosquito-borne viral infection, becoming one of the major public health concerns in the tropical and sub-tropical countries. So much so that over 40 per cent of the world’s population (2.5 billion) is at risk from dengue. According to the World Health Organisation, 50-100 million infections occur every year across the globe.
From less than 10 in the 1970s, the number of countries endemic for the disease has shot up to nearly 100. The major regions where dengue epidemic is seen are in southeast Asia, western Pacific, Africa, Americas and eastern Mediterranean.
Fortunately, of the millions who get infected, the majority do not even exhibit symptoms. Though self-limiting in many cases, a sizeable population suffers from dengue fever. The fever is also usually self-limiting and death is uncommon. But depending on several factors, including age, dengue fever can progress to severe forms. Nearly half-a-million suffer from dengue haemorrhagic fever (DHF), a severe form of the infection. Mortality is quite high in the case of dengue haemorrhagic fever. The extreme form is dengue shock syndrome, and the proportion of patients who die is indeed high.