Dengue Fever may sound like some awful fictional disease dreamt up from the progeny of Laurie Garret and Stephen King, but it is real and has spread rapidly over the past few decades. This steady climb in incidence can be seen in the graph to the right, while the post-1960 ubiquity can be seen in the map below. The disease is everywhere, with reported cases even in Florida in 2012. It affects millions of people a year, with a mortality rate of 2.5%.
The Aedes aegypti mosquito transmits the virus which causes the disease and, as per the map, disproportionally affects people in the tropical and sub-tropical regions of the world. Once infected, many people get symptoms which we in the US might consider 'flu-like' - fevers, muscle pain, joint aches and so forth. Specific to Dengue fever, however, is pain behind the eyes (retro-orbital) and a rash.
In many people, the symptoms self-resolve, but in some people, it advances to cause severe hemorrhage and shock, which is called Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS). Once this happens, the victim suffers from catastrophic bleeding and liver failure and without appropriate supportive care, can die rapidly.
We don't yet have a vaccine to prevent Dengue Fever and our best method to reduce incidence resides in vector control (i.e. kill the mosquitoes!). And sadly, we don't have a cure - so unlike, say Influenza, where we can use medicines like Tamiflu if diagnosed early enough, once we diagnose Dengue fever, the best we can do is to ensure that with proper hydration and blood product replacement, a patient won't die.
But given that at the least we can prevent some deaths, surely we would like to make a clinical diagnosis of Dengue fever in a patient as quickly as possible. Unfortunately, clinicians don't have much in their field laboratory arsenal to make the diagnosis. They are forced to use clinical signs and symptoms, including one ridiculous antiquated modality, the tourniquet test, which is actually incorporated into the WHO diagnostic guidelines. It consists of inflating a blood pressure cuff for 5 minutes and then counting the number of red spots on the arm (petechiae). WTF? It doesn't work! A disease that affects millions of people worldwide in 2013 and this is one of the ways the WHO recommends for us to diagnose the disease in the field? It would be hard to find a better example of the failure of the larger US medical community to respond globally rather than parochially.