QUESTION:
My son is studying in Tanzania and was diagnosed June 28, 2011 with malaria while taking Malarone. He took Duo-Cotecxin as prescribed for treatment and was feeling much better. He was given a “clear” blood test result. He started taking Malarone July 16, 2011 and on June 18, 2011 was ill again and diagnosed with malaria a second time in less than 6 weeks. Can malaria occur in this way or is there a possibility that the first case of malaria was controlled but not cured with Dus-Cotecxin and then esculated when he started taking Malarone again?
ANSWER:
There are two possibilities in this case; first of all, your son could have had what is called a recrudescence. This is where levels of the parasite in the blood drop to below detectable limits, and the immune system is able to keep the infection at bay. It can occur due to a failure to complete the course of antimalarial drugs, or indeed also due to treatment failure of the medication itself. Although Duo-Cotecxin is one of the recommended artemisinin-based combination therapies (ACTs) on the market for treatment of uncomplicated Plasmodium falciparum malaria, its cure rate is still at 98.7%, meaning that there is still a possibility of the drug not being completely effective in every instance. Moreover, there is a worrying indication that some strains of malaria are actually managing to become resistant even to ACTs.
The other possibility is that your son became re-infected, and it was a separate case of malaria; he was just very unlucky! This is highly unusual while taking Malarone as a prophylaxis, but it is possible. Determining which of these two scenarios occurred is difficult, but some information may be had from the type of blood test he had; clinics in Tanzania regularly use either blood film microscopy or rapid diagnostic tests (RDTs). Microscopy is notoriously insensitive as a diagnostic, and cannot reliably detect malaria parasites below a certain threshold, which depends on the skill and experience of the technician reading the blood slide. Therefore, if your son was declared negative for malaria based on this diagnostic, after the initial treatment, I think there is a good chance he was suffering from a recrudescence or treatment failure. However, if he was diagnosed by RDT, which is very sensitive to even low levels of malaria parasite in the blood, then I would think it might have been re-infection. However, I have concerns about the accuracy of RDTs so soon after infections have been cleared; the tests usually work by binding to malaria antibodies in the blood, which can sometimes persist even after the parasites have all been cleared. As such, you should also check what the diagnostic was the third time he was tested, and if this differed from the other two times; another possibility is that his infection really was cleared through treatment, and then got sick with something other than malaria; if they used an RDT on him at this point to diagnose malaria, they might have got a positive result confounded by his earlier infection. In these cases, you must ensure that the clinician takes a full history and so knows that the patient recently suffered from malaria; it may not be appropriate to use an RDT in this instance.
If your son is still in Tanzania and would like more information on malaria, he can contact us. I am currently also working in Tanzania and so can perhaps help more if I know the details of his case (where he is based, etc). I would be happy to answer any questions he has.