While You're Away: Dengue and Chikungunya Virus
It is becoming evident that many diseases are emerging, and some are re-emerging. This may be because of climate change, the persistence of poverty in much of the world, the globalization of trade, drug and insect resistance, and the incessant movement of people – for pleasure, business, or out of necessity. All of these help to account for the increase in dengue fever around the world in recent years. Dengue, along with Chikungunya virus, are often referred to as Monsoon Fever, as that is the time of year they are most prevalent.
Dengue, which rhymes with shmengee, is a viral infection which has been with us for at least two hundred years. It has a worldwide distribution throughout the tropics. Recently, it has been making headlines, and causing anxiety amongst travellers, because of a resurgence in Central America, Mexico and the Caribbean. There is concern about the possibility of cases in the southern United States. Could cottage country be next?
Dengue is contracted via the bite of the Aedes aegypti mosquito. This species of mosquito differs from the Anopheles mosquito which transmits malaria in two ways. Firstly, it likes to breed in close proximity to humans, in water containers such as discarded tires, barrels, flower vases and buckets. Therefore it is a risk to travellers who spend time in urban areas. Secondly, it is a day biter, preferring its meals at daybreak and the late afternoon.
This infection is not one you would wish on your worst enemy. It begins abruptly with a high fever, severe headache and tremendous pains in the muscles and bones. The name actually means "breakbone fever". A rash sometimes follows on the fourth or fifth day of the illness. Symptoms usually subside within a week, though the victim may be left with prolonged fatigue, aches and pains and depression. There is no vaccine against dengue, and no specific treatment other than symptomatic care.
A more severe form of the infection, dengue hemorrhagic fever, occasionally occurs and may prove fatal. This, however, is much more likely to happen in children, particularly if they have been exposed to the virus before. It is rare in tourists.
Insect avoidance is the main means of preventing dengue. Protective clothing and staying indoors are not always practical. Electric buzzers, garlic and vitamin B are of questionable efficacy. Use insect repellent containing DEET during daytime hours. There is some controversy regarding the safety of DEET. Current Canadian guidelines suggest the use of 30% DEET in adults, and less than 10% in children. If you are living abroad, try to keep your home and immediate surroundings free of potential breeding sites for the mosquitoes – that is, clean up! Other alternative insect repellents can be found on the malaria page.
Chikungunya certainly wins the award for the disease with the most colourful name! It is also passed by the daytime biting Aedes mosquito, and it can resemble dengue fever, with fever, headache, joint and muscle pains and a rash. Treatment is supportive. Chikungunya occurs in Africa, Asia and the Indian subcontinent, and more recently, has also occurred in Western Europe.
As with other tropical diseases, the risk of dengue and Chikungunya to the average tourist is quite low. With the proper precautions, it is even lower. So cover up, grease up.... and enjoy.