Dengue Fever

Introduction

Dengue Fever (DF) is a viral disease which is transmitted to humans by the (Aedes) mosquito. There are four closely-related virus strains (DEN1-4) that can cause DF and they belong to the family of flaviviruses which are also responsible for West Nile Virus, Yellow Fever and Japanese Encephalitis. Degue Fever is now endemic in over 100 countries throughout Africa, the Eastern Mediterranean, Southeast Asia, the Western Pacific and the North, Central and South Americas. Southeast Asia and the Western Pacific see the highest incidences of infections. Currently, the risk to travelers visiting these areas is still considered to be quite low.

Dengue Hemorrhagic Fever / Dengue Shock Syndrome

Individuals who become infected with any of the four strains of the DF virus will usually recover and develop a lifetime immunity to that one particular strain. This initial infection will only create a partial and short-lived immunity to the three remaining strains. Substantial evidence has shown that an individual who is infected a second time, by any of the remaining three strains, has a greater risk of developing the more lethal complication of Dengue Hemorrhagic Fever (DHF) - also known as Dengue Shock Syndrome (DSS). In endemic areas, DHF is most often seen in children under 15 years of age, rather than in adults, and is attributed to the initial infections taking place during infancy. In non-endemic areas the DHF complication affects adolescents and adults due to their initial exposure later in life. ^[1][2]

Prevention

• When outdoors, use insect repellent containing 35% DEET for adults and 10% DEET for children. Follow the directions on the package.
• Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
• Avoid wearing dark coloured clothing.
• Avoid wearing perfume/cologne and scented cosmetics.

Pre-Exposure Vaccines

NO pre or post-exposure vaccines are available.

Symptoms and Treatment

Symptoms

Dengue Fever
The incubation period for Dengue Fever is 3-14 days with symptom onset usually seen between 4-8 days. The clinical manifestations of the disease also vary with patient age. Infants and very young children most commonly develop a mild, low-grade fever accompanied by a skin rash, then recover completely within a few days. Older children and adults may present similarly to infants or present with the more classic symptoms which include abrupt onset, high fever, severe headache, muscle/joint pain and skin rash. Again, patients make a full recovery within a few days. ^[1][2][3]

Dengue Hemorrhagic Fever
Dengue Hemorrhagic Fever (also called Dengue Shock Syndrome) is a complication associated with Dengue Fever rather than a separate disease. This potentially lethal complication affects approximately 1% of the individuals with DF. Patients will commonly present with the classic symptoms (listed above) and a fever reaching 105 °F (40-41 °C). Due to the level of the fever, patients may experience confusion, altered mental state, lethargy and vomiting. As the fever subsides the capillaries within the body may begin to "leak" blood and/or serum into the chest and body cavities. Unexplained bruising or blood spots may appear on the skin. Enlargment of the liver, causing severe abdominal pain, is also common. In severe cases of DHF, an individual may experience a rapid drop in temperature followed by rapid deterioration, collapse of the circulatory system, a critical state of shock and death within 12-24 hours.* ^[1][2][3]

Treatment

At this time there are no specific treatments for DF or DHF. Those requiring medical attention will be treated symptomatically. Acetaminophen (Tylenol™/Panadol™) is the only recommended product for the reduction of the fever. Aspirin and all other non-steroidal anti-inflammatory drugs (N-SAIDs) possess anti-coagulation properties which can further increase blood loss associated with DHF. Commonly used N-SAIDS include ibuprofen (Motrin™) and naproxen (Naprosyn™, Aleve™). Medical personnel should be alerted immediately if the patient is taking any N-SAIDS regularly for any reason, including Cox-1 or Cox-2 inhibitors for rheumatoid arthritis.^[1][2][4]
*Patients experiencing circulatory system collapse can quickly recover if appropriate volume replacement (IV infusion of fluids) is administerd in a timely manner.^[1]