For Gubler, the disease is an occupational hazard — he has spent his career studying dengue in the field, and now directs the vector-borne diseases division of the US Centers for Disease Control and Prevention, based at the National Center for Infectious Diseases in Fort Collins, Colorado.
Once a sporadic illness, dengue is on the rise. Epidemics are now regular in southeast Asia, India, the western Pacific and much of South America see map. Outbreaks are also getting bigger and more serious, with a higher proportion of DHF cases. The World Health Organization WHO receives reports of about , dengue fever cases each year, but estimates that as many as 50 million people are infected annually. Yet the disease is neglected. Almost entirely absent in the developed world and difficult to study, dengue has received little attention — and a fraction of the research funding devoted to better-known tropical diseases.
Although dengue doesn't rival malaria as a killer, the sheer number of people infected and the fever's debilitating nature mean that it has an enormous economic impact. Measured in units devised by the World Bank called disability-adjusted life years, which quantify disruption to quality of life and economic productivity, dengue's burden on some societies is comparable to that of HIV, tuberculosis or hepatitis.
In South America, its impact rivals that of malaria, and in southeast Asia, it is public-health enemy number one 1. He, Gubler and other experts are now trying to push dengue up the public-health agenda — with some success. In January, WHO's executive board drafted a resolution urging international agencies and national governments to spend more on studying and tackling dengue. This effort to raise dengue's profile is partly due to renewed hope that it will be possible to produce a vaccine, which would bolster efforts in mosquito control and disease surveillance.
But this will only happen, say dengue experts, if scientists rise to the challenge and are supported by adequate funds. How did the situation get so bad? Demographic changes — particularly urbanization — are largely to blame. Massive troop deployments and refugee movements in the Second World War established southeast Asia as the world's dengue hotbed. But in the years after the war, efforts to combat yellow fever and malaria held the disease in check by ridding the region of Ae.
Dengue's comeback was triggered by the arrival in South America of widespread vaccination for yellow fever in the s and the scaling back of a worldwide anti-malaria initiative in the s. Mosquito-control efforts slackened, as urbanization continued to gather pace 3. Over the past five decades, the disease's incidence has grown fold 4. But its tendency to lie dormant in any given region before exploding into a severe outbreak has contributed to dengue's neglect by public-health experts.
Cuba and Brazil have this year been hit by severe epidemics. But in countries experiencing a lull, it is easy for health authorities to give dengue a low priority. Any effort to control dengue will involve spraying with insecticides, and outlawing of open water containers and litter such as discarded tyres — which can collect water and serve as perfect nurseries for aquatic mosquito larvae.
As such, it can be hard to sell to public-health authorities. A vaccine, however, would be a different matter — more likely to gain a high profile and financial backing.
Work began on dengue vaccines in the s, but progress has been slow. Part of the problem is that — unlike yellow fever — dengue is caused not by a single virus but by four distinct viral 'serotypes'.
Each is equally infectious and pathogenic. And the catch is that once a person's immune system has fought off and memorized an infection by one dengue serotype, a secondary infection with a different serotype is thought to be the biggest single risk factor for developing DHF.
The reasons for this are not well understood. Different dengue serotypes are seen as similar by the immune system — when a new serotype infects someone who has had a previous bout of dengue, it is recognized.
But although antibodies bind to the new virus, they do not do so as effectively as they would to the serotype they encountered previously. So when immune cells called macrophages arrive on the scene to ingest the virus—antibody complexes, the virus remains infectious. And unfortunately, macrophages are the very cells that dengue prefers to infect. As a result, exposure to a second dengue serotype can cause higher levels of infection than occurred the first time around 5 , 6.
Researchers led by Francis Ennis, an immunopathologist at the University of Massachusetts Medical School in Boston, have found that this has knock-on effects on another arm of the immune system: the 'killer' T cells that attack virus-infected cells. When exposed to a burgeoning infection with a second dengue serotype, the T cells can overreact. The killer cells start producing excessive quantities of cytokines 7 , molecules that at normal concentrations help to coordinate immune responses.
In excess, they can cause other cells, and capillaries, to leak fluid. This, Ennis suspects, leads to DHF 8. The phenomenon is worst in very young children with naive immune systems. They may receive antibodies against one serotype in their mother's milk and then become infected by a mosquito carrying a different one. So any reliable dengue vaccine must provide complete protection against not just one serotype but all four, and be safe for babies.
Otherwise, vaccination in an endemic area could cause a rise in DHF incidence, even if it reduces the total number of dengue cases. To make matters worse, says Alan Rothman, who works in Ennis's team, there is no good animal model with which to study dengue and DHF. Although monkeys produce antibodies against the virus and sometimes develop a fever, they never get the haemorrhagic form. So research into dengue vaccines involves a largely blind leap from the test tube to clinical trials.
Despite these obstacles, dengue vaccines are now edging towards clinical use. Camping gear : Treat clothes, shoes, and camping gear with permethrin, or purchase clothes that have been pretreated.
Stagnant water : The Aedes mosquito breeds in clean, stagnant water. Checking for and removing stagnant water can help reduce the risk. Thermoregulation is how the body maintains a steady internal temperature, which is essential for keeping it healthy. Learn more here. A febrile seizure can occur in a young child when their body temperature suddenly rises, usually as a result of infection or inflammation.
Learn more…. Several conditions, such as the flu, may cause chills with a fever. Learn more about chills with a fever here. Fever in toddlers normally resolves without treatment. However, some situations warrant medical attention.
Learn more about when to seek help here. Ear thermometers take a person's temperature using an infrared sensor. Learn more about their accuracy, how to use them, and alternative methods here. Everything you need to know about Dengue fever. Medically reviewed by Jill Seladi-Schulman, Ph. Signs and symptoms Pictures Treatment Causes Diagnosis Prevention Dengue fever, also known as breakbone fever, is a mosquito-borne infection that can lead to a severe flu-like illness.
Signs and symptoms. Share on Pinterest Mosquitoes spread dengue fever. Share on Pinterest If you are spending time in a tropical region, use mosquito nets that are treated with insecticide.
Scientists identify new cause of vascular injury in type 2 diabetes. Adolescent depression: Could school screening help? If you think you might have dengue fever, call a doctor right away. You also should call a doctor if you develop symptoms of the infection after going to a region that has dengue fever.
A doctor or nurse practitioner will examine you. He or she will ask you questions about how you're feeling, your medical history, and recent travels. Your doctor might want you to give a blood sample to test for the disease.
If you've been diagnosed with dengue, call your doctor or get to a hospital emergency room right away if your symptoms get worse or if new symptoms appear, especially in the day or two after the fever goes down. For mild cases, doctors usually recommend drinking plenty of fluids to avoid dehydration, getting lots of rest, and taking acetaminophen to relieve the fever and pain.
People with dengue shouldn't take medicines with aspirin or ibuprofen, which can make bleeding more likely. Most cases of dengue fever will go away within a couple of weeks and won't cause any long-term problems. But dengue hemorrhagic fever requires treatment in a hospital with intravenous IV fluids and close monitoring. That's why it's really important to call a doctor or go to the ER if symptoms are severe or get worse in the first day or two after the fever goes away.
That's when dengue hemorrhagic fever is most likely to develop. You can help keep yourself free of dengue fever by avoiding mosquito bites. If you live in or will be visiting an area where there's dengue fever:. There is no vaccine against dengue fever yet. Because the infection is common in tropical and subtropical areas, take precautions when visiting those regions. Reviewed by: Steven Dowshen, MD. Larger text size Large text size Regular text size.
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