Malaria easily made the list we published last year of the ten worst diseases.

It infects more than 250 million people per year and can cause nasty symptoms including fevers, chills.  Of those, roughly 2.5 million die.

What makes it such a dangerous disease?  Why are we unable to fight it like many other diseases?

Malaria is an unusually complex disease.  It goes from humans to mosquitos and then back again.  Malaria is specifically transmitted by the anopheles mosquito which picks it up when it takes a blood meal from a human who has it.

Once inside the mosquito, the malaria has to escape the blood sack, replicate, and then eventually spread to the blood sucking part itself.  There, it waits until the mosquito bites a human, and then infects the person.

Malaria has a complex life cycle in people.  It starts by heading to the liver where it slowly establishes itself and waits for 1-2 weeks.  In this period, there may be limited or no symptoms.

After this period, each of the malaria protozoans that had infected the liver cells can pump out 30-40,000 of another form of the disease.  This form specifically goes to and infects red blood cells themselves.

It doesn’t end there.

After infecting the blood cells, the malaria continues to replicate.  It tends to do so at a cyclical pace, pumping out more copies of itself at a pace that can cause the red blood cells to simply pop.

It is at this point that symptoms are felt, as large amounts of red blood cells are destroyed by this process.

How does the disease avoid the immune system?

Malaria is among the class of more chronic diseases that need to maintain themselves in their host for a longer period of time.  This is due to the need to be present at high levels when bitten by a mosquito to ensure the spread of the disease.

If the mosquito bites someone but the malaria is not present at high enough levels, the disease won’t spread.

As such, it has developed a wide variety of tactics that confuse the body and prevent it from eliminating it.

A key method is the limited amount of exposure.  Malaria infects cells and then hides inside of them.  It is only floating around the bloodstream for a limited period of time, and so limits the time that it is exposed to the full force of the immune system.

Inside cells, it is a lot safer.

Another such method is by the adoption of variant components.  Your immune system develops a response to specific components.  Think of an immune response as making a key to open a lock.  It takes some time and is limited to working on one lock.

Malaria has many different ways to express its components.  Each variation is like switching the lock.  In doing so, it stays one step ahead of the immune system, and presents too varied a front for an effective response to develop.