My friend suffers malaria due to plasmodium falsciparum at least every two weeks. It has been treated with coartem, artequine, artesunate+fansida, quinine/quinimax since 2004 without any relief at all. It returns a week or two later and lab tests attest to same. What else should be done?
It is rare for someone living in an endemic area to suffer so regularly from malaria—usually after repeated exposure the body builds up a certain level of immunity which prevents mild attacks developing into serious illness. Also, P. falciparum is not resistant to Coartem, so something else is probably going on.
The first thing to make sure is that your friend complies fully with the medication they are given, and completes the full course of drugs. If they stop taking the pills before the full course is completed, the malaria parasite might be reduced enough for symptoms to subside and for the parasite to be undetectable in blood tests, but is still there in low numbers and so can bounce back after your friend stops taking the pills, resulting in a new bout of disease. This process is called recrudescence, and can be prevented by ensuring that the full course of medication is taken, so that ALL the malaria parasites in the blood are killed.
Otherwise, it is clear that your friend needs to take more preventative measures against contracting malaria. These include sleeping under a long-lasting insecticide-treated bednet, spraying the inside of the house with insecticides to prevent malaria mosquitoes from persisting inside and wearing long-sleeved clothing and insect repellent in the evenings and at night, when mosquitoes are biting most actively.
Your friend may also want to look into taking malaria prophylaxis (preventative medication) at times of the year when they are most at risk from infection, or if they know they will be undertaking activities that leave them vulnerable to mosquito bites (i.e. working outdoors at night for a period of time). Some anti-malarial prophylactic drugs, such as doxycycline, are readily available in most malarial countries at a very good price. However, they cannot be taken indefinitely, so for people living in endemic areas, other preventative measures should be considered first.