In the United States, mosquitoes have long been more of a nuisance than a real health threat. Malaria is mostly unheard of in the United States and even the West Nile Virus appears rarely. A new threat is emerging, however, in the southern United States and especially along the border between Texas and Mexico. That threat comes in the form of the Aedes mosquito and it is dengue fever.
Each year, about 100 cases of dengue are reported in the United States – these are found primarily in people who have recently traveled to tropical areas, where the disease is more prevalent. However, there are probably many more cases that aren’t reported and at least three cases of dengue that were contracted in the United States have been reported.
In the western hemisphere, dengue fever is becoming a major public health concern. In Central America, dengue fever has already reached epidemic levels. Now, the United States is being threatened.
The dengue family of viruses may results in simple dengue, a viral, flu-like disease sometimes called dengue fever. Or, it may results in dengue hemorrhagic fever, a much more serious, often fatal disease which is a complication of dengue infection. The virus is spread when a mosquito bites an infected person, then an uninfected person. When a person has been infected with more than one form of the dengue virus, they have an increased risk of contracting dengue hemorrhagic fever. Because all of the dengue viruses are becoming increasingly prevalent, so too is the risk of developing the more serious dengue hemorrhagic fever.
Dengue is a common illness in the tropics – each year there are tens of millions of reported cases of the common form of the illness, dengue fever. In addition, hundreds of thousands of people suffer each year from the more serious form, dengue hemorrhagic fever. It’s common in Asia, the Pacific, Australia, Africa, the Americas and the Caribbean. As an interesting note, the mosquitoes that transmit dengue, unlike the mosquitoes that cause malaria, prefer to bite during the day rather than at night – perhaps indicating why incidences of the illness are higher in the sunnier regions of the world.
The mosquitoes that transmit dengue fever are common in cities, but rarely found at elevations above 4,000 feet. Like any mosquito, they need water to breed. However, only a small amount of water is needed – as little as a teaspoon of water is enough to sustain thousands of mosquito eggs.
Most countries where dengue fever is a problem have no effective mosquito control programs and their public health systems aren’t adequate to detect and control these types of epidemics. Cities in tropical countries are also growing rapidly, leading to increased opportunities for mosquitoes to emerge in response to substandard sanitation. Air travel is another increasing opportunity for the disease to spread.
At present, there’s no vaccine that can prevent infection with the dengue virus. Treatment for viral illnesses is also typically difficult. The best way to protect yourself against dengue and dengue hemorrhagic fever is to avoid being bitten by mosquitoes in the first place. The same tactics that protect you against mosquitoes in your backyard will also protect you against mosquitoes carrying the dengue virus.