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Dengue Fever, an increasingly imminent problem as global warming pursues

Posted Feb 02 2012 4:40pm

One thing that is important to keep in mind: as the issue of global warming (whether you believe it is happening or not) arises, the temperatures of more northern temperate areas are getting warmer, which brings about an important health consideration: tropical diseases are moving more and more north. The problem with this is, as we have never had many of these diseases, and we are not as prepared to handle the consequences of patients coming to us with signs and symptoms of Malaria, Dengue fever, Chagas disease, or Yellow Fever, to name a few.

Also, with the advent of travel, many diseases are not limited to the area in which it is endemic. Patients and individuals that are traveling for business, pleasure, or anything in between, may be hosting certain disease and bringing them back to the United States, or to other areas of the world where it was not previously. The reason I bring up this topic is because yesterday, as a student clinician, I saw a patient who had a history of Dengue fever while traveling in Vietnam. This is not an uncommon story, so I would like to educate both of us on the importance of Dengue Fever in the United States (as well as those of us who will be practicing international medicine in other areas of the world).

Dengue fever is also known as “breakbone fever“, or “O’nyong-nyong fever“. I would assume to say that it is called “breakbone fever” due to the severe muscle and joint pain experienced during the infective state feels as if their bones are breaking from the lifecycle of the dengue virus within the body. The disease is primarily passed by Aedes aegypti mosquito vectors, carrying high titers of dengue viral loads. This same mosquito can be associated with carrying malaria in other parts of the world, as well. Within the past decade, the GeoSentinel Network of Travel Medicine have indicated that dengue has become more frequently diagnosed than malaria in travelers returning from tropical areas, excluding Africa.

About 2/5ths of the world’s population (about 2.5 billion people) are now at risk for dengue fever, due to global warming and ease of travel. The World Health Organization (WHO) states that “In 2007 alone, there were more than 890 000 reported cases of dengue in the Americas, of which 26 000 cases were DHF” [WHO, 2011].

In 1950, it was recognized that there is a more potent, more dangerous, form of this disease known as Dengue Hemorrhagic Fever (DHF), which some experts consider to me a completely separate disease process, while other experts attribute DHF to a complicated dengue fever case (with increasing chance of developing this disease from prior exposure to one of the four dengue viruses). DHF is also caused by the same viruses that can cause dengue fever, but typically result in hemorrhage and even shock (from the gastrointestinal tract or from orifices in the skin) if medical treatment is not sought out by the patient. The mortality rate of DHF is about 10% in those patients who have contracted the disease, mostly of which are children.

Areas of the world that this is a prevalent problem > Tropical and Subtropical areas
> Indonesia and Southeast Asian countries
> Northern Australia
> Central America
> South America
> Eastern Mediterranean Areas
> Africa
(Mostly found in urban and sub-urban areas, where population control and overcrowding may be a prevalent issue)

Signs and symptoms of Dengue Fever (for both children and adults) > Flu-like symptoms
> SEVERE muscle and bone pain
> Sudden onset of high fever 104-105
> Enlarged lymph nodes
> Maculopapular rash may appear 2-5 days after the onset of the high fever; may also be associated with sensitivity of the skin
> Leukopenia (low WBC count)
> Headache
> Eye pain
> Fatigue and nausea
> Usually self limiting
> If complications arise, can result in DHF (liver enlargement, hemorrhage, shock and circulatory collapse)

Tests used for diagnosis of Dengue Fever > Complete blood cell count (CBC)
> Serology testing to look for IgG and IgM antibodies to the dengue virus (diagnostic criteria)
The Vicious Lifecycle of the Dengue Virus When considering the lifecycle of the virus, it is easy to think of it as two cycles touching at one point: one cycle belonging to the virus within the mosquito and incubation times associated, and the other cycle belonging to the virus within the human, serving as a host reservoir.
(1) A mosquito bites an infected person
> Within the mosquito, the virus incubates for about 8-10 days, after which it is capable of transmitting the virus to another human host with just one bite
> It is possible that female mosquitos carrying eggs can transmit the virus to her offspring before birth (transovarial = via the eggs), greatly increasing the chance of spreading the virus to a large number of people
(2) Within the human, the virus circulates in the patient’s bloodstream for about 2-7 days, correlating with the time that the high fever is present
> The mosquitos that bite the humans then are able to pick up the virus from the blood and complete their own lifecycle, only to transmit it to other individuals
Some studies indicate that monkeys may also be a host reservoir for dengue fever

Role of a naturopathic during a Dengue Fever Outbreak > Supportive – replenish water (single most important treatment), electrolytes, and food during the outbreak
> Education – educate patients on how to recognize signs and symptoms, the importance of rehydration and rest.
> Prevention – using mosquito netting, insect repellant, and caution when traveling and working in endemic areas to Dengue Fever; removing standing water from tires, buckets, and other areas to destroy mosquito breeding grounds; Proper waste disposal; Insecticides
> Avoid taking aspirin during dengue fever (Tylenol is fine to bring down a high fever); An alternative therapy to anti-inflammatory OTC’s is cold towel to the forehead and back of the neck to try to bring the body temperature back to normal. Remove and replace with a fresh new cold towel whenever towel warms. Or, place patient in an cold bath to bring down body temperature.
> Currently there is no vaccine for dengue fever; Since dengue is caused by 4 different viruses, creation of a vaccination is challenging
> Interestingly enough, dengue is considered to be a disease that requires reporting to the CDC within 3 days of diagnosis, compared to other diseases, like Cholera and Brucellosis, which require immediate reports


Class notes, Infectious Diseases, Dr. Spicer, Spring 2011, Bastyr University

H., Mark, Merck Research, and Robert S. The Merck manual of diagnosis and therapy. Merck, 2006. Print.

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