As a result of a blood test I have just been informed that at some time I have had malaria. Though I have no idea when this was. I once was ill for 4 days with what I thought was flu and that is the only occasion I can remember. Therefore I have never been treated for malaria. Could you please tell me if there is any chance the disease will come back.
That will depend on the type of malaria you had. I presume you found out you were infected through a blood test – it is likely a test that looked for antibodies to malaria in your blood. These tests can sometimes differentiate between the different species of malaria, and so it is definitely worth asking the clinic or doctor that performed the test if they can give you this information. Your location, or places where you have travelled in the last 4 years, may also assist in determining which type of malaria you had. Given that you barely registered being sick, I would suspect that you probably didn’t have Plasmodium falciparum, which is usually the most severe kind; it also cannot survive dormant in your system for long periods of time, so if you happened to have this kind, you wouldn’t need to worry about it coming back (though of course you can still be re-infected by all types of malaria, so prevention is still important!).
However, the other three main types of malaria can linger in a patient’s body. P. malariae is the least acute of all the malaria species, and can survive for a long time in the bloodstream, meaning that some people can have the infection for long periods of time without really feeling sick. If the blood test you took looked directly for parasites in your blood, and you tested positive, it is likely you have this kind. Like all uncomplicated cases of malaria, it is easily treatable, and once cured, you won’t have worry about it coming back (again, you do still need to watch out for being bitten by mosquitoes and getting re-infected though!).
The final two types of malaria are P. vivax and P. ovale. These persist in the body in a slightly different way than P. malariae – these have a special life stage which can lie dormant in the liver. Months or even years later, these dormant stages can re-activate and enter the blood stream, causing the patient to feel symptoms again, such as fever and nausea. Therefore, if you find you tested positive for one of these two forms, it is very important to ask your doctor about receiving medication (called primaquine) that will specifically target the liver stages of the parasites, to ensure you don’t get a recurrence of the infection later on.
As I’ve mentioned a couple of times earlier in this response, a key thing to be aware of is that even if you don’t have a recurring form of malaria, or treat it successfully, you will still be susceptible to re-infection if you are bitten by an infected mosquito. As such, if you live in or travel to a region known to have malaria transmission, it is crucial to take steps to prevent infection. For example, sleeping under a long-lasting insecticide treated bednet greatly reduces your risk of being bitten by the mosquitoes that carry malaria; similarly, wearing long-sleeved clothing and insect repellent, especially at night when malaria mosquitoes are most active, is recommended. Finally, medication is available that can be taken to prevent malaria (these are called prophylactics). As they can be expensive and are not recommended to be taken over long periods of time, these tend to be used primarily by people travelling to malarial areas rather than residents. There are several different forms of these prophylactics available commercially; the one to use will depend on several factors, including where you are travelling to.