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The Dengue Threat Abroad and At Home
Posted on Apr 03, 2013 by Ailee Slater (G+)
Thanks to modern advances in health care and disease control, traveling abroad is not nearly as dangerous as it once was: yellow fever can be prevented with a vaccination, Imodium will slow a gurgling gut, and bottled water can ward off everything from E. coli to cholera. However, there is one tropical disease that is not only increasing in prevalence, but also cannot be immunized against: dengue fever.
Dengue fever is spread by mosquitoes. Once bitten, a person will experience flu-like symptoms including nausea, vomiting, rash, headache and muscle pain. These symptoms will also be accompanied by a high fever, usually 40 °C/104 °F. The effects of the dengue virus usually manifest four to ten days after receiving a bite from an infected insect, and last up to ten days.
At the moment, there is no dengue vaccination, so whereas travelers can be immunized to prevent yellow fever and hepatitis, there is no fully preventative measure to be taken against dengue fever. As would be expected, without any form of immunization, dengue is widely contracted - The World Health Organization estimates that there are between 50 to 100 million cases of dengue infection every year. It is considered endemic in more than 100 countries, including frequent tropical travel spots such as Brazil, Indonesia, and other Southeast Asian destinations.
This year, dengue fever warnings have in particular been directed toward visitors planning to travel to Bali. The National Arbovirus and Malaria Advisory Committee of Australia headed a report last month detailing the rise of dengue fever amongst travelers to Bali - according to researchers, rates of dengue fever acquired overseas and brought back to Australia in 2010 were 298 percent higher than would have been expected when looking at a five year mean. Similarly, dengue cases in 2011 were 155 percent higher than this mean rate of infection. Importantly, the report notes that more than half of the dengue fever cases found during this study were acquired in Indonesia, and of those infections, 80 percent came from Bali.
Bali has for some years been a top travel destination for Australians and others looking for tropical beaches and intriguing historical artifacts. Although more and more Australians are traveling to Bali each year, this increase in tourism does not fully explain the huge surge in dengue fever cases originating from Bali. The Australian report calls for more research into why so many more people are becoming infected with dengue after visiting Bali - have travelers become more relaxed and so are taking fewer precautions to avoid the disease? Or, have there been changes in the type and pattern of the dengue virus amongst Balinese mosquitoes? With studies such as this one expressing the fear that Western Australia may soon see epidemic proportions of dengue fever, researchers will no doubt attempt to answer these questions in the very near future.
The Australian report ends with recommendations for travelers, which echo the advice of the World Health Organization on how to prevent dengue fever. The most important step is to avoid mosquito bites - insect repellent, long sleeved and light colored clothing, and window screens can all help to keep bugs away.
Luckily, dengue fever is rarely lethal: the World Health Organization reports that just 2.5 percent of dengue fever cases will result in death. However, if the fever and loss of fluid and plasma accompanying dengue fever are not treated, the likelihood of developing complications rises greatly. And although it is unlikely to cause death, dengue fever should be prevented simply to stop the spread of the disease - although dengue is the result of a mosquito bite, humans are actually the number one carriers and multipliers of the virus. Once bitten, a person can pass along the disease to more mosquitoes, thus spreading dengue fever at a faster rate than mosquitoes could do by themselves. When a traveler goes abroad, gets bitten by a bug and then returns home, the mosquitoes of their native country can now pick up the virus and spread it to more people, leading to further outbreaks around the world.
Brazil is another tropical travel destination currently struggling with dengue fever. An epidemic was reported earlier this year in the centrally located city of Campo Grande, where an average 600 people were reporting symptoms every day. This outbreak was most likely due to heavy rains in January, and the resulting presence of standing water which then became popular urban breeding grounds for mosquitoes. Other Brazilian cities saw large scale dengue infections as well, and the BBC reported that during the first seven weeks of 2013, 200,000 infections occurred throughout the country. This number is especially shocking considering that during those same seven weeks in 2012, just 70,000 cases were recorded.
Luckily, this year's dengue outbreaks in Brazil saw fewer deaths than in 2012, possibly due to better training for health care workers. With the tourism opportunities of the World Cup and Olympics not far off, health officials in Brazil are understandably eager to improve treatment and awareness of dengue fever.
Another country popular with adventurous travelers, and also experiencing issues with the dengue virus, is India. India was criticized at the end of last year for purportedly not responding to or even acknowledging dengue outbreaks across the country, according to the New York Times. One tropical disease expert quoted by the Times was quoted as estimating that 37 million cases of dengue fever plague the country every year, and yet these outbreaks are not adequately recorded or surveyed; a practice that hinders global efforts to monitor and better understand the disease.
For travelers to Bali, Brazil, India and other destinations prone to dengue fever, it is a comfort to know that once infected with one type of dengue, the body is forever immune to that particular strain of the disease. However, there are four serotypes of dengue, so getting infected once is not a protection against future incidents of the disease. In the end, with no way to immunize against dengue fever, simple methods of prevention such as insect repellent are absolutely key to stopping the spread of the virus.