Dengue (pronounced DENG-gey) fever is a painful disease has been around for centuries but began a dramatic upswing in the 1980s. The incidence of dengue has grown dramatically around the world in recent decades. Over 2.5 billion people – over 40% of the world's population – are now at risk from dengue. Here are highlights of what we know about dengue fever.

What is it? Dengue is a flu-like disease caused by any one of four closely related types of dengue viruses carried primarily by female Aedes aegypti mosquitoes, usually found in the tropics and subtropics. The yellow fever mosquito, Aedes aegypti is a mosquito that can spread the dengue fever, chikungunya and yellow fever viruses, and other diseases. The mosquito can be recognized by white markings on legs and a marking in the form of a lyre on the thorax. The mosquito originated in Africa but is now found in tropical and subtropical regions throughout the world.

In the more northern regions, the disease is transmitted by the Asian tiger mosquito, the Aedes albopictus, which can withstand cooler temperatures. It is characterized by its black and white striped legs, and small black and white striped body. It was originally native to the tropical and subtropical areas of Southeast Asia; however, in the past couple of decades this species has invaded many countries throughout the world through the transport of goods and increasing international travel. This mosquito has become a significant pest in many communities because it closely associates with humans (rather than living in wetlands), and typically flies and feeds in the daytime in addition to at dusk and dawn. The insect is called a tiger mosquito because its striped appearance is similar to that of a tiger. Humans can't infect each other — but they can infect mosquitoes, which pass the virus on both to their female offspring and to human bite victims.

Where is it? The infection is most prevalent in South and Central America, where the tropical weather is perfect for mosquitoes, and is a problem as well in Southeast Asia, Africa and the Western Pacific. Cases have also been reported in parts of Europe, Russia and even the U.S., in Florida and near the Mexican border.

What are the symptoms? About half of people infected are asymptomatic (without symptoms) according to the Centres for Disease Control and Prevention, USA. The other half aren't so lucky. Dengue fever is a severe, flu-like illness that affects infants, young children and adults.

Dengue should be suspected when a high fever (40°C/ 104°F) is accompanied by two of the following symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands or rash. It can feel as though your bones are breaking, hence Dengue's alternative name, "Breakbone fever." Symptoms usually last for 2–7 days, after an incubation period of 4 to 10 days after the bite from an infected mosquito.

Severe Dengue is potentially deadly complication due to plasma leaking, fluid accumulation, respiratory distress, severe bleeding, or organ impairment. Warning signs occur 3–7 days after the first symptoms in conjunction with a decrease in temperature (below 38°C/ 100°F) and include: severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness, blood in vomit. The next 24–48 hours of the critical stage can be lethal; proper medical care is needed to avoid complications and risk of death.

How serious is it? Half a million patients are hospitalized each year, but most people recover after two to seven days. Some develop dengue hemorrhagic fever after the initial fever declines — a more severe form of the illness that can cause organ damage, severe bleeding, dehydration and even death. But with early treatment, the mortality rate for all dengue fever is currently less than 1 of 100 people.

Treatment and cure? Patients are given medication for their symptoms and told to drink lots of water. No cure yet, but researchers are testing vaccines. (Vibrionics practitioners, consult your reference books for the appropriate remedy combo for Dengue fever.)

Can you get it more than once? Once you survive your first dengue infection, you're immune to that particular type of virus — but not to the other three types. Many countries are home to all four types, and someone who is re-infected is more likely to develop extreme symptoms. To make matters worse, mosquitoes that carry dengue can also carry yellow fever and the chikungunya virus; one bite could pass on multiple infections.

What are the current numbers? The World Health Organization estimates 50 million to 100 million infections a year (although a 2013 study suggests the number may be as high as 400 million). In the Americas alone, the annual number of cases has boomed from 520,000 in 2003 to 2.3 million in 2013. Before the World Cup in mid-June 2014, host country Brazil frantically battled the mosquitoes that carry dengue.

Why so high? Blame it, in part, on globalization. Mosquitoes can hide and breed in goods that are traded. An infected traveller can also spread the disease to mosquitoes in a new region. In cities where construction and the lack of piped water leads to standing pools of water, mosquitoes thrive.

How do we stop it? Efforts focus on spraying streets and neighbourhoods with pesticides, genetically modifying mosquitoes and encouraging people to ward off mosquito bites with bug spray, nets and long- sleeved shirts and long pants.

Sources:
www.WBUR.org
http://www.ask.com/wiki/Aedes_aegypti?o=2801&qsrc=999
http://www.ask.com/wiki/Aedes_albopictus?o=2801&qsrc=999
http://www.who.int/mediacentre/factsheets/fs117/en/