Understanding Dengue Fever
If you are planning any long haul trip to the tropics or sub-tropics, the chances are you’ve sensibly done a lot of research into malaria and antimalarials in the region you plan to visit.
But have you thought about Dengue fever? It certainly sounds like an illness but what EXACTLY is it? And more importantly, how can you prevent it?
What is Dengue Fever?
It is a viral infection spread most commonly by the bite of infected A. Aegypti and A. Albopictus mosquitos. It is widespread in hot, humid climates where the mosquito population is high. Outbreaks typically occur in crowded urban areas where there are lots of mosquito breeding sites in the form of stagnant water and lots of people to bite. The illness is present in many of the same regions that malaria is endemic but the two tropical diseases are caused by completely different organisms. This is a virus whereas malaria is caused by a parasite so antimalarials do not protect you from Dengue fever.
There are four strains of the virus and if you are infected with one strain you should have lifelong immunity to that strain. However, you may still be infected with the other strains and you may be at an increased risk of developing severe Dengue fever when you get infected with a second strain.
What are the symptoms?
The symptoms include:
- High fever (true to its name)
- Pain behind the eyes
- Muscle, joint or bone pain
Typically, the fever clears up on its own with plenty of rest, water and paracetamol for any pain. You should always visit a doctor to establish the cause of your symptoms to rule out other conditions and obtain appropriate treatment.
The fever can rarely develop into a more serious illness typically called severe Dengue. Severe Dengue usually develops 2-3 days after the symptoms of Dengue start. If you exhibit the following symptoms then seek immediate emergency medical attention:
- Bleeding gums
- Rapid breathing
- Persistent abdominal pain
- Vomiting and blood in vomit
- Feeling extremely tired
Severe Dengue can progress into shock which can cause a rapid drop in blood pressure, weak rapid pulse, fast breathing, reduced urination and dry mouth. You will need I.V fluids from the hospital to stabilise blood pressure and prevent dehydration. The majority of people make a full recovery but severe Dengue can be fatal in up to 40% of cases.
It is unusual for a traveller to get severe Dengue as it is more common for those who have had Dengue once before to develop severe Dengue.
Where are you at risk?
Dengue is a particular risk in the following regions:
- South and Central America
- South East Asia
- Pacific Islands
- Indian Subcontinent
For the year 2015, Thailand public health officials have estimated a 100% rise in cases of Dengue. From January 2015 to 18/08/2015 there have been 51,500 suspected cases, a 100% rise for the same period in 2014. Thailand is an extremely popular tourist destination and as the risk of malaria is low in many of the tourist hotspots the importance of bite avoidance is often underplayed. You must avoid being bitten by mosquitos to protect yourself from Dengue.
Can you catch it off another person?
Transmission of the illness is a cycle whereby a mosquito bites an infected human which then transmits the virus through biting an uninfected human and so it continues. Dengue cannot be spread by person to person contact; only via mosquito bites.
How can you prevent it?
There is no vaccine and no specific treatment if you contract it and you can’t take tablets as a preventative measure.
The main way to prevent Dengue Fever is to avoid being bitten. The mosquitos which transmit Dengue bite during daylight hours as opposed to the malaria-transmitting mosquitos which tend to bite during the evening. Therefore, it is crucial that you use an effective insect repellent at all times.
Repellents containing 20% or more DEET are the most effective and need to be reapplied regularly to exposed skin over the top of sunscreen. There is a wide selection of insect repellents you can choose from that will keep you protected during your travels.
Loose fitting, long-sleeved clothing is best as mosquitos can bite through tight clothing. There are clothing treatment sprays such as Lifesystems Expedition Ex4 Mosquito Control Fabric Treatment which can be used to reduce the risk further. Socks should be worn to protect the feet.
Finally, try to stay away from crowded areas where there is stagnant water e.g public toilets or ponds as this is where the mosquitos breed and make sure you seek medical attention if you think you may have Dengue.