See this fine girl for my party, she wear YELLOW - Yellow fever.

Just to reassure any Rema listeners out there, he certainly was NOT speaking about Yellow Fever. Forget Rema though, ever heard of these 2 new rappers, Aedes and Ago? Yeah they've just been signed to a record label called YFV.

Okay, I lied. Kind of.. YFV actually stands for Yellow Fever Virus, a mosquito-born viral illness. Aedes and Ago are actually the causative vectors of YFV. Aedes Spp. and Haemagogus Spp. YFV actually resides in both human and non-human primates and is primarily (90% of cases) in Africa.

Y'all know the drill! We are visiting this case through the lens of a fictional character - Michael.

Michael is part of the American diaspora. He is originally Cameroonian (Sub-Saharan Africa) although he was born and raised in the United states. Michael never got the chance to go back to Cameroon, he was always caught up in school work and well, just life.

As the new year rolled around, Michael decided that things would change. He would visit Cameroon and not just that, make it a solo trip and also go to Central and South America (places with high risk of contracting YFV as well) as he believed that this would finally be his chance to 'discover himself'... now thinking back, Mike was definitely going through a mid-life crisis, yikes!

On the very first day of January 2016, Mike landed in Yaoundé Nsimalen airport. Filled with nothing but excitement and joy as he hailed a taxi to take him to his hotel. This hotel, although beautiful at the scenes, was in the middle of fresh/brackish water. This meant that there would be loads of mosquitoes around, as mosquitoes need a blood meal to reproduce.

Mike wasn't stressed out though, because he was prepared! or so he thought.. he brought some corner store 'triple action mosquito repellent' and thought he had solved that issue. He in fact, did not.

After 4 fantastic days in his hotel, Mike had nothing but good things to report to his family regarding his trip. That evening though, he noticed a couple things. First, that he shivered at night and had a fever, which he thought could be because of the cold air-conditioning in the hotel. Second, he noticed some back pain, which he thought was because of the tough mattress he had been on the past couple days.

The next morning, things got worse. Mike felt weak, his muscles ached, he had a headache, everything made him nauseas and he could not stop throwing up. He went to the hotel's small medical team and explained his symptoms, to which they had told him he probably had yellow fever and suggested he take a rest for 4-5 days, as the symptoms usually resolve within that time frame.

Now, that's accurate for most patients but about 15% of symptomatic patients like Mike, eventually progress to a more toxic version of the virus. This is actually where the 'yellow' comes from, because the most striking symptom of toxic yellow fever is jaundice - yellowness of the eyes, due to liver failure.

Toxic patients, Mike included, also experience melena - dark 'tar' blood in the stool indicating internal bleeding, hematemesis - blood in vomit suggesting bleeding in upper GI tract, delirium, renal failure, mucosal bleeding - blood loss from mucus membranes, shock and a recurrence of the fever and chills.

Dang! everybody say 'poor Mike!'.

Okay, to help Mike, as always we'd have to investigate to make sure we've got the correct illness. Now, for YFV, travel history as well as signs and symptoms are important to ask the patients.

Lab tests will reveal thrombocytopenia - low blood platelet count, prolonged PT and PTT - delayed blood clotting, increased direct bilirubin with a relatively normal alkaline phosphatase. There are also YFV specific IgM and IgG levels which can help confirm the diagnosis but there may be some cross-reactivity with other viruses. Viremia - the entrance of viruses to the bloodstream, only lasts about 3 days, so, Polymerase Chain Reaction (PCR) tests have limited value unless done earlier on in the illness.

In terms of treatment, its very much supportive. Acetaminophen aka paracetamol is also used as pain-reliever (analgesic) and fever reducer (antipyretic) specifically in this case because it is NOT and NSAID (non-steroidal anti-inflammatory drug) which means it does not have risks of causing bleeding, particularly in the GI tract due to induced impaired platelet function like NSAIDs do. Which we obviously do not want in YFV patients as they already struggle with GI tract bleeding and low platelet count (thrombocytopenia) in most cases.

The only good news for our friend Mike here, other than not being part of the 20-50% mortality rate of the toxic version of this illness, is that surviving the illness = LIFETIME immunity!!

Okay my loves, the take away message is to AVOID MOSQUITOES and any area where they would typically reside if you can and ALWAYS request an SQ (single subcutaneous) dose of live-attenuated yellow fever vaccine before travelling anywhere that its required, considered risky for possibly contracting YFV or living in at-risk areas!

Xoxo,

Tehilla.