You are having P. vivax which unfortunately persists in the liver
. It gets reactivated due to any mental or physical stress
which is present even for a short duration, like an exam, a journey, a deadline or project which gives you inadequate rest and improper meal timings. this reduces your immune levels and reactivates this persisting malaria in the liver. Primaquine
sulfate is given after an episode of malaria to eradicate malarial parasites from the liver. This does not mean that you would not suffer from malaria again. You can get infected by an infected mosquito also in spite of primaquine. The only way to ensure that you don't get recurrent malaria is to ensure that you are not exposed to mosquitoes especially from dusk to dawn. Also you can take a prophylaxis of tab. chloroquine sulfate 500 mg once a week as a prophylaxis. Please note that Primaquine can only be taken if your G6PD test is normal. Unfortunately the only way to develop immunity to malaria is to suffer from it.