Silent malaria infection: waiting for the storm

First thing people do when they hear I am voluntarily infected with malaria:

Next, the questions start pooring:
"How are you feeling?"
"How is the malaria?"

"Nope, I'm perfectly healthy!"

Recap

Four days ago I was infected with 1,000 malaria infected red blood cells. This is actually a very low dose. If an infected mosquito delivers only one parasite into my skin and it would find its way to my liver, it would grow there during seven days and eventually lead to a blood stage infection with more than 60,000 circulating infected red blood cells. This is still too low to notice, but since malaria parasites (P. falciparum) multiply 10-fold each 48 hours, you'll start noticing that you're infected about 12 days after that itchy mosquito bite.

Blood samples taken this morning

In my case? Let's do the math:

1,000 parasites (inside a red blood cell) were injected in a volume of 5 liters of blood (me!). Today, four days and two multiplication rounds later, this should amount to a number of 100,000 infected red blood cells, or 20 infected red blood cells per mL or 1 infected red blood cell per 250 million(!) healthy red blood cells.

Still a really low number right? Actually, this is still too low to detect my infection using a microscope... But it should be just near the detection limit of current qPCR techniques.

Quantitative Polymerase Chain Reaction

I'm not going to get too technical, but to explain this technique quickly: it is possible to detect the genetic material of malaria parasites by specifically amplifying a small part of its DNA or RNA (chain reaction) until there is so much of it that you can visualize and quantify it using fluorescent molecules.

That's the technical part, the lab technician analyzing my blood sample should get something like this on her/his screen in a couple of hours:

What's next?

The waiting game.

Each morning and evening a blood sample is taken for analysis (microscopy and qPCR). I expected this to be quite annoying, but until now it went very easy. I'm lucky to be in the caring hands of an expert team of doctors and nurses!

The researchers from Jenner Institute expect us (controls) to start noticing the first malaria symptoms on day 7 to 9. Around that time the number of parasites will be high enough to start seeing them under the microscope. And that will be the (scientific) endpoint of this clinical trial...

For me, it will only be the beginning of the end. From the moment I receive therapy (pictured above), the infected red blood cells will be killed which causes more inflammation and actually a worsening of symptoms. 

For now though.. I am enjoying my time in the beautiful city of Oxford.

Click here for more info on malaria, the parasite causing the infection, vaccine trial in Oxford.

If you would be interested in joining a clinical malaria challenge you can always check these websites:

Radboud University (Nijmegen, Netherlands)
Jenner Institute (Oxford, UK)

Walter Reed Army Institute of Research (Maryland, USA)

Seattle Biomed (Washington, USA)