Reoccurring Malaria

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QUESTION

Can malaria reoccur year after year from a single infection? I have been told that it comes back every year by many people. I have had malaria once and it never came back after successful treatment. My thinking is that once the parasite has been eliminated from the system it is gone unless you get bitten again.

ANSWER

There are several different types of malaria that infect humans, and two of these species (Plasmodium ovale and Plasmodium vivax) can recur from year to year after a single infection.

The way it happens is that these types of malaria are able to form dormant life stages which hide in the liver. Most malaria medication only targets the blood stage form of malaria, and so these liver stages escape being killed by the medication, and can survive for long periods of time without the patient knowing about them. Then, at some point later (no one knows exactly what triggers the relapse—there is evidence that infection with other forms of malaria can instigate relapse, or being bitten by mosquitoes, or even just the climate), the liver stages activate again and re-enter the blood stream, which causes a renewal of symptoms.

It is possible to prevent these relapses—there is one type of medication, called primaquine, which is able to kill the dormant liver stages and thus completely clear the patient of malaria. However, it is important to talk to your doctor before taking primaquine, as it is not suitable for some people (especially those with G6DP deficiency).

Apart from these two types of malaria, the other three forms that infect people (P. falciparum, P. malariae and P. knowlesi) cannot reoccur in the same way as described above – if you have been infected with one of these, and then been successfully treated, you cannot get the disease again unless you are bitten by another infected mosquito.

Malaria Re-occurrence

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QUESTION:

I’ve been infected with malaria vivax, for this i’ve taken the treatment for three days, after three days i don’t have any symptoms but after two days again I’m feeling the fever and abdominal pain which i’m having since the diagnosis is still persisting. Why is it happening? Are there any chances even after treatment for re-occurrence? My urine is yellow color but there is no jaundice?

ANSWER:

“Vivax” malaria, caused by the parasite Plasmodium vivax, is known for cyclical fevers every couple of days. As such, it may be that while the medication is working, you are still experiencing some mild symptoms as the infection is not completely cleared. For this reason, it is very important to take the full course of medication prescribed to you by your doctor; DO NOT stop taking it as soon as you feel better, as you might not have killed all of the malaria parasites in your blood, putting yourself at risk for the infection to persist. Alternatively, it might be that the strain of P. vivax you have is not responding to the medication you have been given; in parts of Papua New Guinea and Indonesia, for example, the local strains of P. vivax have been shown to have high levels of chloroquine resistance, which is usually used for treating P. vivax. If you are located in an area of known P. vivax resistance to chloroquine, your doctor should be able to recommend a different regimen of treatment to ensure that the infection is cured thoroughly. You should take a blood test after completing treatment to be sure that the parasite is no longer in your blood stream. In addition, P. vivax can produce dormant liver stages called hypnozoites that can remain within the liver hepatocyte cells and cause relapse or recurrence of the disease many weeks or months after the initial infection. To destroy these liver stages, and thus prevent relapse, you should ask your doctor about taking another drug once you have completed your initial treatment. This second drug is called primaquine, and will kill the P. vivax hepatocytes.