Dengue Fever

In 2019 the Marshall Islands has experienced an outbreak of Dengue Fever. Some say it is the worst outbreak in years. As of 12/1/19 there have been 1,395 dengue like illness of which 431 have been lab confirmed. The outbreak started on Ebeye, it later spread to Majuro and there have been a few cases on Utrik and Aur. As of 12/1/19 there has been one death (a 6 year old) and one severe dengue patient evacuated out-of-country. A travel ban to outer atolls has been in effect. This has been helpful to limit the spread of the illness to remote islands that have little capacity to manage serious health problems.

The following is an overview or Dengue fever.

Dengue is a viral infection caused by four types of viruses (DENV-1, DENV-2, DENV-3, DENV-4) belonging to the Flaviviridae family. The viruses are transmitted through the bite of infected Aedes aegypti and Aedes albopictus female mosquitoes that feed both indoors and outdoors during the daytime (from dawn to dusk). These mosquitoes thrive in areas with standing water, including puddles, water tanks, containers and old tires. Lack of reliable sanitation and regular garbage collection also contribute to the spread of the mosquitoes. The Aedes mosquito does not transmit malaria. Malaria is transmitted by the Anopheles genus.

Risks
Dengue occurs in > 100 countries worldwide. The risk of Dengue exists in tropical and subtropical areas of Central America, South America, Africa, Asia, and Oceania. Dengue occurs in urban and suburban settings with higher transmission rates happening during the rainy season. Although the geographic distribution of dengue is similar to that of malaria, dengue is more of a risk in urban and residential areas than is malaria.

Symptoms
An estimated 40%–80% of infections are asymptomatic. Those with symptoms get ill between 4 to 7 days after the bite. Symptomatic infection most commonly presents as a mild to moderate, nonspecific illness characterized by flu-like symptoms which include a sudden high fever coming in separate waves, pain behind the eyes, muscle, joint, and bone pain, severe headache and a skin rash with red spots.

As many as 5% of all dengue patients develop Dengue Hemorrhagic Fever (DHF), a severe, life-threatening disease. Symptoms include severe abdominal pain, vomiting, diarrhea, convulsions, bruising, and uncontrolled bleeding. Complications can lead to circulatory system failure and shock (known as Dengue Shock Syndrome) and can be fatal. For those who develop severe dengue, close observation and frequent monitoring in an intensive care unit (ICU) setting may be required and can reduce risk of death among patients with severe dengue by at least 20-fold to <0.5%. 

Treatment
No specific antiviral agents exist for dengue. Treatment is primarily supportive care of symptoms. Patients should be advised to stay well hydrated and to avoid aspirin (acetylsalicylic acid), aspirin-containing drugs, and other nonsteroidal anti- inflammatory drugs (such as ibuprofen) because they can increase the risk of bleeding. Fever should be controlled with acetaminophen and tepid sponge baths. Febrile patients should avoid mosquito bites to reduce risk of further transmission.

Prevention
The best way to control control Dengue outbreaks is to prevent infection.

  • Take meticulous measures to prevent mosquito bites during the daytime. 
  • Use a repellent containing 20%-30% DEET or 20% Picaridin on exposed skin. Re-apply according to manufacturer’s directions.
  • Wear neutral-colored (beige, light grey) clothing. If possible, wear long-sleeved, breathable garments.
  • If available, pre-soak or spray outer layer clothing and gear with permethrin.
  • Get rid of water containers around dwellings and ensure that door and window screens work properly.

A vaccine to prevent dengue (Dengvaxia) has been licensed in almost 20 countries and approved for commercial use in 11 countries. However, in late 2017, the vaccine manufacturer, Sanofi Pasteur, announced that people who receive the vaccine and have not been previously infected with a dengue virus may be at risk of developing more severe manifestations of dengue.

People infected with the same Dengue virus serotype become immune to future infections of the same serotype. However, if a person is infected subsequently with a different serotype, immunity wanes over time which increases the risk of developing Dengue Hemorrhagic Fever.

Dengue does tend to be cyclical, breaking out once every three to five years. After each outbreak, the good news is that a lot of people have been infected, so you have herd immunity that lasts for awhile, until the next cycle. Dengue is related to Zika Virus, Yellow Fever, West Nile Virus, and Japanese Encephalitis. It can be misdiagnosed for Chikungunya, Zika Virus, or Yellow Fever.

References