The reach of Dengue has grown

She was enjoying the tropical clime, visiting with friends. She started having fevers. The malaria test was negative. Her head ached. The pain behind her eyes felt like she'd been staring at a computer screen too long. Her joints ached. She vomited and didn't want to eat or drink anything her friends tried to feed her. A rash appeared : red dots coalescing, not raised. She started to itch, even on her palms. The rash began to peel. 

A few days later her friend got sick and then another and then another. Pretty soon everyone had the same headache and eye pain, fevers. Some had rashes; some didn't. They all got better.

They had Dengue.

Painful Dengue (pronounced "DEN-gay") is sometimes known as Breakbone Fever.

There are over 100 million cases of this Flavivirus each year worldwide. Travel and transport have spread it globally, along with each of its 4 serotypes (DENV1-4) spreading new strains into new areas. One of its vectors, the Tiger Mosquito (Aedes Albopictus), has spread in the US even as north as Chicago and New York City.

What are the Symptoms?

About half of cases have no noted symptoms. Others have fevers alone or mild symptoms. Symptomatic diseases can be Dengue Fever or the more dangerous forms: Dengue Hemorrhagic Fever or Dengue Shock Syndrome.


  • Sudden high fever (sometimes preceded by facial flushing)
  • Severe Eye pain ("eye strain")
  • Headache
  • Joint, muscle pain
  • Nausea, vomiting, loss of appetite
  • Possibly swollen lymph nodes or a sore throat.
  • Lab values: platelets and white counts may be low.
  • Heart rates may be lower than expected during fever.

After a few days (2-5)

  • Possible rash (flat red spots coalescing). Can itch and peel, including palms.
  • Rash can also occur initially with fever.
  • These symptoms usually last between 3-7 days.

After initial symptoms. some develop Dengue Hemorrhagic Fever (DHF)

  • As the fever drops, warning signs may develop and blood vessels may become “leaky”.
  • Bleeding - from nose, mouth, gums
  • Vomiting blood or heavy vaginal bleeding
  • Black tarry stools (gastrointestinal bleeding)
  • Unexplained skin bruising
  • Pinpoint red dots called petechiae

Others develop even further symptoms and have Dengue Shock Syndrome (DSS)

  • Shock (low blood pressure, confusion, minimal urination)
  • Low Blood Pressure

Symptoms of bleeding and shock require IMMEDIATE medical attention.

What is the treatment?

Most people are able to rest, keep hydrated, and possibly take limited doses of acetaminophen (Tylenol, paracetamol) for fever, under the advice of a doctor. Patients should not take aspirin, naproxen (Aleve), or ibuprofen (Advil) as they can increase bleeding.

Hospitalization is needed for severe cases of dengue with bleeding (Dengue Hemorrhagic Fever) or shock (Dengue Shock Syndrome), or other signs or symptoms of severe illness (especially in dengue reinfection).

There is no specific drug or treatment for dengue besides supportive care (intravenous fluids, blood products, electrolytes, oxygen). With access to good medical care, fatality is less than 1% for dengue.

There are steady steps being made towards a dengue vaccine (successful Phase III trial).

Dengue can be diagnosed by blood tests (PCR and serology).

How is it transmitted?

Fevers usually begin 4-7 days (but can be 3-14 days) after a bite by an infected female mosquito (Aedes aegypti and Aedes albopictus). Fevers beginning 2 weeks after exposure are likely not dengue.  Mosquitoes can bite indoors, feed during the day, and reproduce in standing water (tires, barrels, vases). Use insect repellant (DEET), cover up to avoid bites, and avoid areas with Dengue.

It is not transmitted person-to-person. 

It can be spread by the same mosquito as Zika.

Where is it?

Dengue is found in tropical and sub-tropical areas, often in cities - from the Caribbean, Central and South America to Africa to Asia and into northern Australia. Most infections in the US are imported. Outbreaks have occurred in Florida  (Key West; Marin County 2013), southern Texas, and Hawaii. Any temperature rise can increase spread. Mosquito-borne illnesses are increasingly becoming a problem where they we thought to not be an issue.

Can I get Dengue again?

Yes. In fact, each subsequent infection is more dangerous. Infection with 1 serotype leads to immunity to that serotype but only transient immunity to the other 3 serotypes. Infection with an additional strain can result in an overly exuberant immune response, creating the dangerous DHF and DSS.

What else might it be?

Malaria, often found in the same locations, can initially resemble dengue and can be deadly if treatment is delayed. Likewise, severe illness attributed to dengue may be from untreated Leptospirosis (which also rises after flooding). Chikungunya is spread by the same mosquitoes and is mistaken for dengue (but has no further treatment).

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