Dengue, Zika, Chikungunya, & Yellow Fever

This is public enemy #1!
Aedes aegypti. Know it and squish it!

There are over 3,000 species of mosquitoes. A fact I think proves there’s no benevolent deity.

This post is a run down of the basic info on the common mosquito born diseases in Brazil: dengue, zika, chikungunya, and yellow fever. It’s essential information if you’re visiting.

Because the mosquitoes are winning.

Last year in the wake of zika and the microcephaly epidemic in Brazil, the federal government mobilized troops to patrol for standing water basically declaring war against mosquitoes. The yellow fever outbreak this year is evidence of how well that went in the long term.

So here’s everything you didn’t want to need to know about mosquito born illnesses in Brazil.

DENGUE: Let’s start with dengue because it kills the most people every year. I know zika is the Kim Kardashian of the bunch, hogging all the media attention, but dengue is most likely to put you in the hospital. There were roughly 1.5 million registered cases of dengue in Brazil last year and of those 629 died. The severity depends on which of the four strains of the virus you get. The worst causes hemorrhaging, but most people just get incapacitating joint pain and high fever.

Dengue is usually transmitted through the bite of an infected mosquito, but it can be passed from mother to fetus. The disease is asymptomatic in 40-80% of cases. The incubation ranges from 3 to 14 days.


  • Sudden high fever
  • Severe headache
  • Severe joint pain
  • Moderate joint pain
  • Severe pain behind the eyes (basically your body will hurt a lot)
  • A skin rash that appears post fever
  • Fatigue
  • Nausea
  • Itching

The Severe Case Symptoms (everything above plus…)

  • Bleeding from the nose and gums
  • Abdominal pain
  • Vomiting
  • Hypotension
  • Dizziness
  • Breathing difficulty

In rare cases, sometimes after a second infection, a person can develop dengue hemorrhagic fever which leads to shock and death in 24 hours. Yeah, dengue totally sucks.

There’s no vaccine. There’s no drug treatment. The only thing to do with dengue is treat the symptoms and be sure not use any aspirin because it increases the risk of hemorrhaging.

Yeah, they’re all cute and cuddly until one drops dead of yellow fever.

ZIKA: If you’ve been to Brazil in the last year and sneezed, you might have had zika. Or maybe you didn’t sneeze. You still might have had zika. Most cases are asymptomatic, about 80%.

Of the most common mosquito borne diseases, zika results in the fewest hospital cases. In 2016 there were 214,193 cases of Zika in Brazil and 3 deaths. The global panic over zika is because of it’s link to microcephaly, a condition that babies develop in utero which prevents the brain and skull from developing normally.

And let’s be clear. There IS scientific consensus that the zika virus is one of the causes of microcephaly. I believe in the CDC, WHO, and peer reviewed scientific journals. Conspiracy theorists can save themselves time and not bother commenting about genetically altered mosquitos. I will just delete them.

The fact the disease is asymptomatic in the majority of cases makes it particularly scary for women who are or may become pregnant. It’s possible to have zika and never know until the baby develops complications. Even if you develop symptoms, they’re usually mild.


  • low grade fever
  • headache
  • skin rash starting on the face and spreading over the body
  • red eyes
  • itching
  • fatigue
  • sore joints

Less Common Symptoms

  • Muscle pain
  • Swelling
  • Sore throat
  • Vomiting or diarrhea
  • Swelling

So now pregnant women all over Brazil can worry that their swollen legs and exhaustion is actually zika. Because there wasn’t enough for expectant parents to worry about. Fucking mosquitos.

There’s no vaccine.

CHIKUNGUNYA: Unlike zika and dengue, if you get chikungunya, you’ll know. 70% of cases develop symptoms. At least you don’t have to wonder whether or not you need a doctor.

Last year there were 265,554 cases of chikungunya resulting in 159 deaths, so worse than zika but not as prevalent as dengue.


  • Sudden onset of high fever
  • Severe joint pain mostly in feet, ankles, hands, wrists

About the joint pain, almost every case has it and in rare cases it becomes chronic.

Less Common Symptoms

  • Intense back pain
  • Headache
  • Muscle pain
  • Vomiting
  • Conjunctivitis
  • Fatigue
  • Photophobia
  • Sore throat

Basically everything hurts like hell.

Like the others, there’s no vaccine for chikungunya and no treatment beyond treating the symptoms.

CDC’s risk area for yellow fever in South America

YELLOW FEVER: The CDC’s website has a map of areas where yellow fever vaccines are recommended. The risk area for Brazil extends just up to the border of our state. So far this year 31 people have died from yellow fever in Esparto Santo. Dear CDC, you need to update your map.

Yellow fever is typically passed via an infected monkey to mosquito to human, so areas without dense forests were considered safe. The incubation period is 3 to 6 days but most cases are asymptomatic.


  • Sudden high fever
  • Severe headache
  • Back pain
  • Muscle pain
  • Nausea & vomiting
  • Fatigue
  • Weakness

After a brief remission, 15% of cases will develop a severe form of the disease.

Symptoms of Severe Form

  • High fever
  • Jaundice (hence the name)
  • Bleeding
  • Shock
  • Organ Failure

Of cases that turn severe 20-50% die.

We got our yellow fever vaccines!

But good news! There’s a vaccine! Two doses taken ten years apart provide lifetime immunity. Yay science! If you’re thinking about visiting Brazil this year, double check to see if your hotel is located within one of the new expanded risk area. Be sure to use a Brazilian site. Remember, the CDC’s map is out of date.

Vaccines are being developed for the other three. Several companies will have zika vaccines ready for clinical trials by the end of the year. Late stage clinical trials of dengue vaccines are already underway, and researchers have reported success with initial clinical trials for chikungunya vaccines. Unfortunately, we’re still years away from these vaccines being available to the public.

In the meantime, don’t cancel your vacation. Just be prepared. Get a yellow fever vaccine. Pack repellent. Sleep with your windows closed and fan on. And for god’s sake, if you see a mosquito, kill it!

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