LOCAL TRANSMISSION OF DENGUE FEVER
Down here in South Florida, we get outbreaks of tropical infections even in wintertime. A while ago, I wrote about a mosquito-borne virus that strikes warm weather regions: Dengue Fever.
At that time, I reported that places as far apart from each other as Singapore, Nicaragua, and Bangladesh had reported Dengue outbreaks. Not since the beginning of the year, but on the same day. This distribution meets the WHO definition of pandemic.
(PANDEMIC: According to the World Health Organization, the pandemic phase is characterized by community level outbreaks in different regions.)
This week, the Florida Department of Health in Miami issued an alert after two local residents came down with Dengue symptoms, bringing the total to 14 for 2019. These cases were not thought to be contracted in other countries, but locally in the South Florida area. The implication is that local mosquitoes in the area are a reservoir for the disease.
This differs from, for example, the Ebola virus in 2014. With Ebola, the only U.S. infections occurred from exposure to a Liberian who arrived in the U.S after being infected in West Africa.
What is Dengue Fever?
Dengue fever is an infection caused by a virus transmitted to humans by mosquitoes. If you live between latitude 35 degrees north and 35 degrees south, and lower than 3000 feet elevation, you’re eligible.
An estimated 400 million people get infected with the Dengue virus every year. Luckily for the grand majority, they don’t even know they have it, but 96 million cases result in sickness.
Rates of Dengue infection are thought to have increased greatly since 1960 due to encroaching civilization and population growth in warmer regions. As a resident of South Florida, I believe that the widespread introduction of residential air conditioning around that time may have precipitated the explosion in potential victims.
How You Get Dengue Virus Infections
The mosquito in question is the Aedes Aegypti; other species may also spread it. The mosquito itself doesn’t get sick, but the virus is now in its saliva for life. The mosquito passes Dengue onto other humans through its bite.
How to Recognize Dengue Fever
There are actually four different but related viruses that cause dengue fever, but the symptoms are similar.
If you’re in the unlucky minority that gets sick, you can expect to see signs about four to seven days after the infectious bite. You may experience:
- A high fever (up to 104 degrees Fahrenheit) of sudden onset
- Severe headaches
- Pain behind the eyes
- Severe joint, bone, and muscle pain
- Nausea and vomiting
- Skin rashes (several days into the sickness)
Sometimes, the orthopedic symptoms are so painful that Dengue has been called “Breakbone Fever”. Thankfully, most resolve their symptoms in one to two weeks and are immune to the virus (at least the specific strain they contracted; remember, there are four). If someone with a history of Dengue fever gets sick again, it is likely with a different strain. Second Dengue infections tend to be worse than the first.
Although most recover fully, a small minority will develop a life-threatening version of the disease called “Dengue Hemorrhagic Fever”. Complications such as resistant fevers, bleeding from nose and gums, blood and lymphatic vessel damage, and liver enlargement can occur. The disease may progress to “Dengue Shock Syndrome” where massive bleeding, organ failure, and circulatory collapse occurs. If you had to compare it to another disease, think of end-stage Ebola.
What’s The Cure for Dengue Fever?
There is no cure for Dengue fever. Treatment is symptomatic; that is, you treat symptoms like fever with acetaminophen (Tylenol), give oral hydration, and enforce bedrest. A vaccine was approved by the FDA this year, but only for a certain subgroup of patients and not for the general population.
Dengue Fever Prevention
If you live in an area where Aedes Aegypti makes its home, you can best protect yourself with a few precautions:
- Use DEET or other mosquito repellant regularly (even indoors in some areas)
- When outdoors, wear long-sleeved shirts
- When outdoors, wear long pants and tuck the cuffs into your socks
- Clothing can be sprayed with the insecticide Permethrin 0.5% (but not skin)
- If you have air conditioning, keep the windows and doors shut
- If you don’t have air conditioning, use mosquito netting and door/window screens
Reduce the mosquito population by eliminating standing water wherever possible. Eliminate junk like tin cans, flowerpots, and old tires that could serve as breeding grounds. Bird baths and your pet’s water dish may also continue mosquito larvae.
In olden days, epidemics of tropical disease affected various cities (for example, New Orleans) in the Southern United States. These can become problems again in disaster settings, especially if caused by viruses. Be sure to acquire knowledge about the recognition and treatment of the infectious disease that can affect your region. If you do, you’ll be more likely to succeed, even if everything else fails.
Joe Alton MD
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