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| Endemic Regions of Dengue Fever Image courtesy of the CDC |
Dengue fever infects approximately 400 million people
annually and is a leading cause of illness and death in the tropics and subtropics. It was first documented in
the 1950s in
the Philippines and Thailand and remained there until 1981, when
large numbers of Dengue Hemorrhagic Fever were reported in the Caribbean and
Latin America, including Puerto Rico, the U.S. Virgin Islands, U.S.-affiliated
Pacific Islands and the British Virgin Islands. Yet only recently has it begun making headlines, thanks
to the 2014 FIFA World Cup in Brazil.
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| Aedes aegypti mosquito, a dengue virus vector. Image courtesy of the CDC |
Dengue fever has 4 virus types (DENV 1, 2, 3, and 4) and
is spread by the Aedes mosquito in high
population areas when rainfall is optimal for breeding. It is a bloodborne virus, so transmission can
also occur through exposure to infected blood, organs, and tissues, as well as
through vertical transmission (mother-to-neonate). Dengue hemorrhagic fever is a more severe form
of dengue fever, and risk factors include having a previous infection, being
younger than 12, female, or Caucasian.
Dengue fever may cause high fever, severe headache, eye
pain, joint pain, muscle and/or bone pain, rash, mild bleeding in the nose or
gums, petechiae, easy bruising and/or a low white blood cell count. Warning signs to watch for 3-7 days after fever
temperature declines include severe abdominal pain or persistent vomiting, red
spots or patches on the skin, bleeding from the nose or gums, vomiting blood,
black stools, drowsiness or irritability, pale, cold, clammy skin, or
difficulty breathing. The signs and symptoms
of DHF are consistent with dengue fever, including the fever decline. In DHF, this decline marks the beginning of a
24-48 hour period where capillaries become excessively permeable, causing
ascites and pleural effusions. Without
prompt, appropriate treatment, symptoms can progress to circulatory system
failure and shock, and possibly death.
Currently, there is no vaccination or specific medication
for treatment of dengue fever or dengue hemorrhagic fever. Symptoms are manageable with analgesic pain
relievers (ex. acetaminophen and paracetamol), rest, plenty of fluids to
prevent dehydration, and consulting a physician. DHF can be effectively treated with fluid
replacement therapy with an early clinical diagnosis (this generally requires
hospitalization).
There is good news on the horizon. Sanofi Pasteur, a multinational pharmaceutical company, is
in Phase 3 clinical trials
of the CYD dengue vaccine. The purpose
of the study is to assess the efficacy of the CYD dengue vaccine after 3 vaccinations at 0, 6, and 12 months in preventing symptomatic virologically-confirmed dnegue cases, regardless of the severity, due to any of the four virus types in children aged 2 to 14 years. It is difficult to determine at this time when this vaccine would be available to the public. For more information, please visit www.clinicaltrials.gov
Prevention
To prevent dengue fever when present in endemic regions, eliminate containers that hold water in and around the home to prevent breeding. Wear mosquito repellent indoors and outside (the higher the DEET content, the better) at all times and long sleeves and pants. Windows and door screens should be secure and without holes, and use air conditioning where possible.
For a more technical review: Dengue Detection
Prevention
To prevent dengue fever when present in endemic regions, eliminate containers that hold water in and around the home to prevent breeding. Wear mosquito repellent indoors and outside (the higher the DEET content, the better) at all times and long sleeves and pants. Windows and door screens should be secure and without holes, and use air conditioning where possible.
For a more technical review: Dengue Detection
Thank you for this blog post, Emily. I found it to be an interesting overview of a virus I didn’t know much about. It sparked my interest to read further about Dengue Fever and Dengue Hemorrhagic Fever. One of the most interesting facts I learned is that infection with one strain of the Dengue virus provides immunity to that strain, but actually increases your risk of developing the more severe Dengue Hemorrhagic Fever if infected again by a different strain. According to an article by Maria Guzman, this is because the cross-reactive antibodies from the primary infection binds with the secondary virus to form immune complexes that are still actively infectious and increase the number of infected cells and the viral output of these cells. This combined with other immune responses can lead to shock and death, as you mentioned in your post. So if acquiring the virus the first time is not scary enough, you now have to worry about an even more dangerous secondary infection. Fun facts.
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