Dengue fever is one of the most common mosquito-borne viral diseases of human beings. It has become a major reason for public health concern internationally over the recent years because of disease morbidity and mortality. Globally around 2.5 billion people are living in areas where dengue viruses can be transmitted. Spread of mosquito vectors & viruses in geographical distribution are two main reasons of rise in incidence and prevalence of dengue fever & appearance of dengue hemorrhagic cases. Urban areas of the tropics have been identified to be highly endemic. According to estimates made by WHO around 50–100 million infections of dengue are prevalent every year globally. (Deen et al. 2006) In Pakistan first dengue outbreak was reported in Karachi in 1994 as environmental conditions are conducive to Aedes mosquito breeding. Economic and security related migration introduced virus to Lahore as well. According to Punjab Health Department 590339 suspected cases were reported in Lahore & 21685 confirmed by serology. It has been observed that 5-10% of these cases develop DHF.(Mahmood et al. 2013)
Dengue is mainly transmitted by mosquito vector i.e. Aedesaegypti and can also be transmitted by A.albopictus to a lesser extent. Virus that causes dengue has four different types that are closely related to each other.Infected female mosquitoes transmit this virus to human beings through bite.An infected mosquito can transmit this virus to humans for the rest of its life. Symptoms of dengue range from very mild fever to very high fever including intense headache, retro-orbital pain, muscular and joint pain, and rashes. There is no vaccine or any specific medicine to treat dengue. Patients having dengue fever are advised to take rest and drink ample fluids. They are advised to use paracetamol in order to reduce high grade fever or visit the physician if fever persists. Recovery from infection by one provides lifelong immunity against that serotype but confers only partial and transient protection against subsequent infection by the other three. There have been enough proofs showing that subsequent infection increases the risk of severity of disease which can result in DHF (WHO).
Leaking of plasma, fluid accumulation, respiratory distress, and intense bleeding and organ impairment makes severe dengue a fatal complication. Warning signs includes decrease in temperature (below 38°C/ 100°F), severe abdominal pain, rapid breathing, bleeding gums, malaise, and restlessness,continuous vomiting and hematemesis. These can occur three to seven days after first symptom recognition. In order to prevent complications and minimize the risk of death adequate and timely health care is required in next 1-2 critical days.(Halstead 1980)
In 1950s when dengue epidemics occurred in the Philippines and Thailand then Dengue hemorrhagic fever was first identified. Till 1970 nine countries had encountered epidemic DHF and this number has increased more than four times and keeps on rising. Today rising number of DHF cases are causing increased dengue outbreaks in the Americas, and in Asia, where all four dengue viruses are endemic. DHF has turn out to be a prominent reason of hospitalization and demise among kids in several states.In Asia, widespread DHF has enhanced geologically from Southeast Asian regions to west China. Various regional states of the South and Central Pacific have encountered significant or slight DHF outbreaks.In previous twenty years deterrence and management has come to be more immediate with the escalating geographical spreadof dengue and dengue hemorrhagic fever and higher ailment occurrence (Gubler 2002).




In the absence of bleeding or organ manifestation, DHF is medically challenging to diagnose, and the numerous etiologic agents can barely be distinguished by clinical tests. The specified diagnosis of DHF depends mainly on laboratory testing.(Drosten et al., 2002)