Medical Fun Facts Episode 77: Dengue virus

It’s Monday 31 July 2017.

Thanks for subscribing and listening to Medical Fun Facts.

Show notes for every episode are available at

Last week I did Cryptococcus. Tonight, as we progress again through the alphabet I thought about Dengue fever and Dengue virus.

Some browsers do not render the embedded YouTube video. Here is the link

The Dengue virus is in the genus Flavivirus which also includes Zika virus and Yellow fever virus. The Dengue virus is a single-stranded RNA virus transmitted to humans by mosquitoes. Dengue virus is also known as an arbovirus or arthropod-borne virus.

Unlike some other Flavivirus infections, human infection with Dengue virus, Yellow fever virus and Zika virus are not incidental because when infected, our cells produce enough replicated virus for a mosquito to carry it to other humans without the need for other animals to be involved.

Within the species Dengue virus, five serotypes exist.

Until a few hundred years ago, the Dengue virus was transmitted within nonhuman primates and Ædes mosquitoes, with humans as a dead-end host. Now, the transmission cycle is exclusively between these mosquitoes and humans.

Dengue fever is the disease caused by Dengue virus. The disease occurs after a mosquito carrying Dengue virus bites a human and infects the human through the bite site. Symptoms begin to appear between three and fourteen days after infection. The usual symptoms include fever, headache, vomiting, muscle and joint pain, along with a skin rash. It usually takes a week before a patient begins to feel better. In a small number of patients, the disease progresses to Dengue hæmorrhagic fever. Dengue hæmorrhagic fever is characterised by bleeding, an abnormally low platelet count, and blood plasma leakage. When the patient’s blood loss is extreme and their blood pressure falls dramatically, the patient is said to be in Dengue shock.

While infection with one of the five serotypes typically confers life-long immunity to that type and partial immunity to the other types, when infection occurs with another serotype, the complex immunological reactions are thought to give rise to Dengue hæmorrhagic fever as a complication of the less severe Dengue fever.

Several methods have been devised to reduce infection. These include simple measures to avoid mosquitoes plus some vaccines which are currently being investigated. In Australia, work is being done on biological control measures including the use of the bacterium Wolbachia. The notion being that Wolbachia infected mosquitoes are resistant to infection with Dengue virus.

Diagnosis is often made clinically in the tropics and subequatorial areas where Dengue fever and the mosquitoes that carry Dengue virus are endemic.

Patients often have nausea and vomiting plus a low white cell count, and clinical evidence of a low platelet count like petechial hæmorrhages. The earliest changes in laboratory test parameters include a low white blood cell count.

Specific diagnostic tests include direct detection of the NS1 protein or Dengue virus antibodies. PCR tests are also available.

There is no specific treatment for Dengue fever. It’s important not to use drugs that inhibit platelet aggregation like aspirin and nonsteroidal antiinflammatory drugs.

I’ve seen two patients die while infected with Dengue virus. Unfortunately, one patient was given a nonsteroidal antiinflammatory drug which lowered his platelet count to 8 and he bled out. In my mind that was an avoidable death.


And so, ends another episode of Medical Fun Facts.

If you have suggestions or requests for future shows please let me know.

You can find the show notes for every episode at my blog

You can find updates in the Facebook page.

Medical Fun Facts is available in the iTunes podcast store. 

If you think more people would enjoy this show, please head over to iTunes and give Medical Fun Facts a five-star rating and please leave a comment. By doing so iTunes will rank the show higher and make it easier to find.

Medical Fun Facts is also on Stitcher so if you use an Android device, you can download the Stitcher app and listen to the show in Stitcher. Android users should be able to find the Stitcher app in the Google Play store.

The Stitcher link is

Like iTunes, if you visit the show on the Stitcher website and leave a review, the Stitcher algorithms will improve the show’s ranking and more people will be able to find it. Feel free to share the link via Facebook, Twitter, Google+ and any other social media platform.

If you disagree with anything in these podcasts or if you would like to voice a different view, please feel free to write a comment. If I have said something incorrect I welcome correction. Please also feel free to share your comments on social media.

Just remember, for shows with video I go off script for good portions so please listen or watch to catch everything not written in the blog post.

The video can be found at

Tweet me at

Send me a comment on Facebook at

E-mail me at