QUESTION
I had malaria as child, more than 30 years ago. It was successfully treated with no relapse. I have since travelled to malaria- endemic countries, but the last time was over 3 years ago. No symptoms. I recently donated blood and routine screening has detected malaria antibodies. How long do the antibodies persist?
ANSWER
Based on your experience, I would say at least three years! While I doubt your antibodies would persist since your infection as a child, it is more likely that in your more recent trips to malarial areas you have been re-exposed to the parasite, but for whatever reason, the infection didn’t progress into a full-blown episode of malaria. This could well be due to some residual immunity from childhood, or you just received a light enough infection that your general immune system was able to fight off. Either way, this would have produced new antibodies against malaria, which were picked up by the blood screen.
The length of time antibodies persist is important information in the control of malaria, since serological tests (which detect antibodies) can be used for screening of populations in low-transmission environments, but their efficacy is reduced in locations where people have been treated for malaria but their antibodies persist. Also, understanding how antibodies are created and maintained in the body is necessary for gaining an appreciation of how preventive measures, such as bednets, might potentially leave populations more vulnerable to malaria later on, through lack of acquired immunity.
WHILE IN VIETNAM, I HAD VIVAX AND FACIPRIUM MALARIA.THE OLDER I GET I COME DOWN WITH THE CHILLS,FEVER AND PROFUSE SWEATING.BLOOD TEST NEVER DOES SHOW ANY MALARIA BUT DOES SHOW THE VIVAX ANTIBODIES.DOES THIS MEAN I STILL HAVE MALARIA OR HOW LONG DO THE ANTIBODIES REMAIN IN MY BODY AND WHY NO MALARIA CELLS?
Antibodies can persist for a long time (months or even years) after a patient has had malaria – the presence of antibodies alone does not mean that you are still infected with malaria, or that a recurrence of malaria is causing your recent symptoms. If you did have recurrent malaria, the malaria parasites would be visible in your blood during the periods when you experienced the symptoms. As this does not seem to be the case, it is more likely that your symptoms are being caused by something else. However, if you wanted to be sure, you could discuss with your doctor the possibility of taking a course of primaquine – this drug is able to kill the liver stages of vivax malaria, which cause recurring malaria. Primaquine is not suitable for people with certain types of G6PD deficiency, so you may need to be tested for this before taking the drug.