While malaria has the lion’s share of public fear because of its deadliness, dengue fever--another mosquito-borne illness--is not a tropical disease to take lightly.
Changing climate, industrialization, and population growth accompanied by urban crowding have all contributed to the widening endemic zones for dengue virus. Before the 1970s, dengue virus was only endemic in 9 countries. Now, we see dengue propagation in over 100 countries around the world in the Americas, Africa, and southeast Asia, putting 40 percent of the world’s population in a risk zone. Annually, 400 million people are infected with dengue, though thankfully due to the disease’s generally mild symptoms, of those infected only about 22,000 die. This positions dengue far behind malaria in terms of its propensity as a global killer.
Uncomplicated dengue fever lasts between 2 and 7 days, with symptoms including nausea and vomiting, skin rashes, general aches and pains, and localized pain behind the eyes, in muscles and joints, and even in the bones. Only 1 in 4 people infected with dengue virus will actually show symptoms, but these symptoms are generally mild enough that they do not require hospitalization, only rest and plenty of water. Unfortunately, there are four separate strains of dengue fever, and coming down with one of them does not confer any immunological resistance to the other three. That means that someone can potentially contract dengue fever four separate times in their life.
Concerning, however, is that dengue fever may morph into dengue hemorrhagic fever, a more severe form of the disease that is immediately a health risk. This is only known to happen in 1 out of every 20 symptomatic cases, but the infection to occurrence proportional rate has been climbing in recent years. As the endemic zones creep larger and larger for this virus, healthcare professionals are seeing more and more instances of dengue infections transmogrifying into the much more worrying dengue hemorrhagic fever.
Should dengue fever symptoms present more severely, immediate medical help is advised as it is likely that the disease has progressed to dengue hemorrhagic fever. Symptoms of dengue hemorrhagic fever include severe stomach pain and tenderness, vomiting more than 3 times in a 24-hour period, bleeding from the nose or gums, and extreme restlessness. Untreated, dengue hemorrhagic fever can progress into dengue shock syndrome and result in encephalitis, internal bleeding, neurological symptoms, jaundice, complete system shut down, and death. Pregnant women and those who have contracted the disease one or more times before are both more likely to have their dengue infection manifest as dengue hemorrhagic fever.
So what can be done to lower the numbers of those infected with the dengue virus annually?
It’s a complicated convergence of issues, as it turns out. Because mosquitoes are the carriers of dengue fever, it makes sense to try and eliminate the presence of them around populated areas in high-risk regions. Thus far, however, insecticide use has not been particularly helpful in curbing mosquito populations. Employing bed netting, air conditioning, and tight window screening might help to keep mosquitoes out of domestic areas, but the trouble comes down to the cost. Many regions most hard-hit by dengue fever are also impoverished and cannot afford these protective implementations. The next step might be to vaccinate people and inoculate local populations against dengue virus before it can infect them. While there is a vaccine available in some countries, it is not accessible universally and can only really provide limited protection. As we discussed earlier, dengue virus has four viable strains, so producing an all-encompassing vaccine for every strain has proven to be a challenge.
Even though dengue fever isn’t especially deadly, it would appear that effective options for combatting it are pretty limited. Historically, dengue fever was seen as a childhood disease, but since the proliferation of heavily urban, industrial, and unsanitary living environments, dengue now affects everyone across the age spectrum. Changing global climate now favors extremely warm and humid conditions across the tropics and subtropics and has also contributed significantly to the rise in viral prominence.
In order to prevent further expansion of the disease, change realistically starts in the public sector. Strong local government leadership aimed at reducing breeding sites for mosquitoes near residential areas will certainly go a long way towards pushing back dengue infections. Community education on preventative measures and radio and television PSA broadcasts can work in tandem with local governments to disseminate good hygiene and proper drinking water storage information. Encouraging healthcare-seeking behavior and providing accessible clinics will also reduce the chance that dengue fever patients will have life-threatening complications.
As a disease that affects people globally and contributes to millions of dollars lost in economic damages, stopping dengue fever in its tracks will have to be a concerted global effort. But it’s certainly not impossible! Just as polio and smallpox have been eradicated in many areas, so too can we eliminate these tropical vector-borne diseases.
Dengue/Dengue Hemorrhagic Fever: The Emergence of a Global Health Problem: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626838/pdf/8903160.pdf
Dengue fever: new paradigms for a changing epidemiology: https://link.springer.com/article/10.1186/1742-7622-2-1
A model of dengue fever: https://biomedical-engineering-online.biomedcentral.com/articles/10.1186/1475-925X-2-4
Clinical profile and outcome of dengue fever: https://bit.ly/32O7T0O
CDC - Dengue: https://www.cdc.gov/dengue/index.html
MedlinePlus - Dengue: https://medlineplus.gov/dengue.html