One of my favorite authors, Laura Ingalls Wilder, described getting malaria in her book Little House on the Prairie. (They called it fever 'n ague, and though it came from eating watermelons that grew in the night air. Ma and Pa Ingalls had a huge fight over that little bit of false information.)
When I worked at Bellevue, it wasn't uncommon to get a patient who'd been traveling from Africa with the following symptoms:
- shaking chills and fever that cycled every 2-3 days
- headaches and joint pain
- hemolytic anemia (low red blood cell count due to bursting red cells)
- jaundice, or yellowing of the skin or eyes
- enlarged spleen (it's job is to clear out the broken red cell bits)
Malaria, and parasites in general, are fascinating. We've heard of the "eat or be eaten" survivalist mentality in the wild kingdom, but we don't usually consider the microscopic guys that are trying to use (and sometimes eat) us as well.
|The round purple things are red blood cells.|
The purple banana thingies are P. falciparum (source: Wikipedia)
What is malaria caused by?
A microorganism called Plasmodium. Plasmodium falciparum and plasmodium vivax are responsible for most deaths due to malaria in the world.
How does the parasite infect us?
This gal, the female anopheles mosquito. She carries infected blood with the parasites and spreads it around. So generous of her! Not.
|Anopheles mosquito, drinking so much blood that it's coming out the other end. GROSS. |
Also, sorry if this picture just made you itch like mad. (Source: Wikipedia)
Can malaria kill you?
Yes. The infections in sub-saharan Africa are deadliest; malaria from other parts of the world aren't as deadly.
Let's say I'm healthy, and I get bit by that THING. What happens?
The parasites (sporozoite stage) in the mosquito saliva enter your blood. They end up in your liver, where they multiply and turn into the next stage (merozoite stage). Those bust open your liver cells and infect your red blood cells, where more merozoites are made, and some male and female forms (gametocytes). When your red blood cells bust open spilling out more parasites, that's when those shaking chills and fever start to happen. When a mosquito bites the now unhappily-infected-you, the male and female gametocytes get sucked by the mosquito, and they end up making more sporozoites and the whole thing starts over again.
Man, and that's the watered down version!
For a more detailed diagram and about 10 more life cycle terms I sorta skipped over, click here.
How is it diagnosed?
Classically, it's diagnosed by looking at a smear of the patient's blood under a microscope. It looks like that picture up above, or you can see the parasites within the actual red blood cells. There are also Rapid Diagnostic Tests available, but not all hospitals around the world have them as they're expensive.
How do you treat it?
Back in the 17th century (maybe even as early as the 1500s), it was discovered that the bark of the Cinchona tree could cure malaria.
The compound in it responsible for this is called quinine. Quinine is so cool--in fact I did a Medical Mondays on quinine! Nowadays, most types of malaria are resistant to quinine, and synthetic versions of it are used (such as mefloquine).
|Cinchona flowers (Source: Wikipedia)|
Another medication, artemisinin, is also used and was used as far back as 200 BC in China for the treatment of malaria.
Nowadays, several different medications are used to treat malaria, almost always in combinations. It's hard to keep up with. Here is a nice update on treatment.
|See the skinny, sickle-shaped red blood cell in the center?|
One last cool medical factoid:
You might have heard of sickle cell anemia. This is a disease in which blood cells turn into a sickle shape, and it causes all sorts of problems. People who have two sets of sickle genes can be quite sick, but those that only have the trait, or one sickle cell gene, are resistant to getting malaria. Traditionally, most people with sickle cell trait live in places where malaria is endemic. So it's believed that mutation occurred and was kept as an evolutionary advantage for people in these areas. (Parasites are less likely to complete their life cycle, because the abnormal red cells are cleared out of the circulation faster). Cool!
This may be all the malaria you can handle with your monday morning coffee, so I'll stop now. But please stop by the CDC to learn more about prevention, traveling, treatment, and mosquito-y stuff.
HA! And you thought vampires were bad...