Jun
29
2009

Diagnosing Malaria

I've recently heard about someone living in MN who went to back to Africa to visit family and he came back with a case of malaria. This is exactly the situation advisors to the exhibition Disease Detectives highlighted as a growing problem. Did you know that if you've developed immunity to malaria you lose that immunity when you move away from a region where malaria is endemic?

Exciting news on the diagnostic front comes from Glasgow University where scientists have developed a new test to quickly diagnose malaria. Currently to diagnose malaria researchers look at a patients sample of blood under a microscope and look for signs of the parasite. You need to be highly trained to be good at diagnosing this way. The new procedure is not only faster and more accurate but it can tell if the parasite is resistant to the first line of drug treatment. Go to this link for an article from the university and this link for a BBC video about the new diagnostic technique. In Disease Detectives we highlighted another new diagnostic technique which can easily be used away from expensive labs called a rapid diagnostic test which uses a "dipstick" method to indicate if certain proteins from the parasite is in a patient's blood. We've highlighted two professionals working on the test on the Disease Detective's website. Find out information about Norman Moore and Sara Hallowell who both work on this rapid diagnostic test.

I wonder what is the best way to get these tests to the people who most need them?

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Your Comments, Thoughts, Questions, Ideas

Ravi Katkar's picture
Ravi Katkar says:

How does one lose immunity to malaria by moving "away from a region where malaria is endemic?" Also, do multiple strains of malaria exist?
Thank you.

posted on Thu, 07/02/2009 - 1:13pm
Laurie's picture
Laurie says:

Ravi,

There are 4 different strains of malaria. From the CDC:

"Four species of malaria parasites can infect humans under natural conditions: Plasmodium falciparum, P. vivax, P. ovale and P. malariae. The first two species cause the most infections worldwide. Plasmodium falciparum is the agent of severe, potentially fatal malaria, causing an estimated 700,000 - 2.7 million deaths annually, most of them in young children in Africa. Plasmodium vivax and P. ovale have dormant liver stage parasites ("hypnozoites") which can reactivate ("relapse") and cause malaria several months or years after the infecting mosquito bite. Plasmodium malariae produces long-lasting infections and if left untreated can persist asymptomatically in the human host for years, even a lifetime."

You lose your immunity by not having the continual exposure to the parasite. Also from the CDC:

"Two other characteristics of the immunity acquired against malaria is that the maintenance of this non-sterile state of immune protection requires continued exposure to malaria infection and a functioning spleen. ... ... Likewise, when immune individuals leave a malaria endemic area and reside for several years in a malaria-free area often become susceptible to infection and clinical symptoms if they return to a malarious area."

posted on Tue, 07/28/2009 - 1:41pm
Anonymous's picture
Anonymous says:

If you have immunity genetically then you cant lose it but if it is artificial it wont matter if you move away there is usually an expiration date when after a certain period of time the medicine loses effect. and yes thee are multiple strains i just dont know how many.

posted on Thu, 07/02/2009 - 2:19pm
Laurie's picture
Laurie says:

Actually you become immune to an infectious disease when your immune system is exposed to the pathogen causing the disease. Sometimes the pathogen changes (like seasonal flu or the common cold) so you either need a new vaccine (seasonal flu) or you keep getting new strains (common cold). Other times once you get a disease you won't get it again because your immune system is primed and ready to fight that particular pathogen (chicken pox). In the case of malaria you lose the immunity you acquired after you are no longer exposed to the parasite.

From KidsHealth:

"The immune system, which is made up of special cells, proteins, tissues, and organs, defends people against germs and microorganisms every day. In most cases, the immune system does a great job of keeping people healthy and preventing infections. But sometimes problems with the immune system can lead to illness and infection."

posted on Tue, 07/28/2009 - 1:51pm
Robin S's picture
Robin S says:

Most likely it is because you are no longer exposed to the disease on a daily basis. In the U.S., malaria is virtually non existent. My guess is is that your body doesn't really make antibodies to Plasmodium the way it does to other microbes such as bacteria and viruses. Therefore your B cells cannot mature to plasma cells and you are not conferred lifelong immunity.

posted on Thu, 07/02/2009 - 2:31pm
Robin S's picture
Robin S says:

I could not find an explanation for WHY immunity is lost but this website was quite helpful. http://www.cdc.gov/malaria/biology/humanhost/

My antibody guess was wrong, though.

posted on Thu, 07/02/2009 - 3:18pm
Anonymous's picture
Anonymous says:

There are three Plasmodium parasites that can cause malaria. Only P. falciparum can be completely eradicated from your blood.

posted on Thu, 07/02/2009 - 3:20pm

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