Dengue fever is caused by a virus that is carried by an infected female Aedes mosquito (called a vector) that injects the virus into a human while she is drawing her blood meal, a meal that she needs in order to reproduce. Over 50 million people, in over 100 countries, are infected every year with dengue. Until a report last week, there was still no way to control the disease. More on the study later.
The symptoms of Dengue Fever appear from a few days to two weeks after being bitten by an infected mosquito. The symptoms may be a sudden onset of high fever, nausea, vomiting, severe headache, muscle and joint pain, and pain behind the eyes, which worsens with eye movements.
The Response of the Immune System to Dengue
There are four genetically similar types of Dengue viruses (subtypes). When a person is exposed to the virus, specialized immune cells produce large proteins called antibodies, also known as immunoglobulins (Igs), that attach to the virus particles and mark them for destruction by incoming inflammatory immune cells.
Unfortunately, exposure to one of the four subtypes does not confer immunity against the other three types. Even more troublesome, because of the peculiarities of the immune response, if one has been previously exposed to one type of Dengue virus, exposure to another subtype may result in Dengue Hemorrhagic Fever. In this stage of the disease, there is a significant amount of bleeding and a person may go into shock. Unfortunately, this disease is frequently fatal especially in children or the elderly.
As in all immune responses, a controlled, well-modulated response is needed by the body when it is exposed to a pathogen like Dengue. When the immune system has a balanced inflammatory response to disease, when it is in immune homeostasis, a person is more likely to successfully fight infection and survive. The key is that the body has to generate enough of an inflammatory immune response to destroy the pathogen, but not so much inflammation that nearby healthy tissue is damaged.
Inflammatory Cytokine Storm
Too vigorous, inflammatory response to infection, for example to the Dengue virus during Dengue Hemorrhagic Fever, may result in destruction of the walls of blood vessels, bleeding, abnormal clotting, and loss of fluids (which can lead to severe dehydration).
This sort of extreme immune response is also reminiscent of what is seen in diseases such as SARS (Severe Acute Respiratory Syndrome), in which the body has an inflammatory or cytokine storm directed initially against the lungs, and goes on to destroy many different organs, resulting in death. [Cytokines are small immune molecules that trigger immune responses].
Decrease Mosquito Breeding Opportunities
Prevention- It Only Takes 15 Minutes:
There is no treatment for Dengue Fever, nor has vaccine development been successful. For now, the best way to avoid infection is to lower the risk of being bitten by an infected mosquito. Unfortunately, since the Aedes mosquito is active during daytime hours, nets around the bed are not an adequate solution.
However, all mosquitoes need water to complete their life cycle, so it is prudent to eliminate any standing water around the home. Think like a mosquito that is looking to lay eggs—it can be in any container imaginable, or a puddle that will not dry out within a few days.
Keep plant saucers, tarps, coolers, tanks, barrels, drums, bottles, tins, coconut shells, tires, buckets, and trenches, free of water.
Empty, cover them, or turn containers over when not in use, so water does not accumulate.
Keep containers of stored water covered at all times.
Empty refrigerator drip pans at least every other day.
Mr. Minchington Israel, Environmental Health Officer of the Government of the British Virgin Islands mantra is: “It only takes 15 minutes to go around the yard, … in search of stagnant bodies of water and do[ing] something about it.”
Mr. Israel also points out that since so many people have moved out of the countryside and crowded into urban areas, family and community-wide efforts are needed to slow mosquito population growth. In addition to the suggestions above, Mr. Israel strongly advocates:
- Maintaining properties free of rubbish, junk, and overgrown vegetation.
- Managing empty lots and abandoned properties.
- Becoming knowledgeable as to where mosquitoes breed and eliminate these breeding areas.
Promising New Approach:
Last week the prestigious journal Nature, published results from an Australian research group reporting that they were able to stop the transmission of Dengue virus (ǂ). Researchers infected the Aedes mosquito with bacteria that “completely blocks the ability of the virus to grow in mosquitoes” (◊). The bacteria do not kill the mosquito, so the mosquito can continue to reproduce itself, and pass the bacteria to other mosquitoes. The infection is highly contagious so it spreads rapidly throughout the mosquito population. Successful testing in the wild supports its promise as a way to control vector populations. According to Flaminia Catteruccia, who works with malaria-carrying mosquitoes in London, “It’s an environmentally friendly approach that does not affect the mosquitoes, just the [growth of the] virus”(◊).
If this concept works, it will take time for further studies to be completed and vector control to occur, so for now, taking personal responsibility is necessary. So in addition to the recommendations above:
- Dengue carrying mosquitoes are active during the day, so netting around beds is not as helpful as in other mosquito-borne diseases.
- Use mosquito repellents on your clothing and person.
- Screen windows and doors against mosquitoes and use bed nets around ill, bed-ridden individuals.
- Wear light-colored long-sleeves and slacks with thick socks.
- A body in immune homeostasis, in immune balance, is better prepared to defend itself against infection.
To optimize one’s immune system: walk or be physically active in other ways for at least 150 minutes a week; eat in a nutritious manner; control your weight; eat darkly-pigmented fruits and vegetables on a daily basis; and consume fish or omega-3 supplements 2-3 times/week.
In addition, it is important to help the body achieve immune homeostasis, immune balance so that the body can battle illness and yet, control unchecked inflammation.
Hyperimmune egg contains a cocktail of antibodies and other active immune factors that help the body balance immune function. Consuming two or more servings/day of hyperimmune egg makes a major difference in your body’s ability to support immune health and heal itself.