A significant proportion of malaria patients in high risk African countries such as Kenya are likely to receive doses of malaria medicine that are too low to offer effective treatment.
New research presented at the 7th Multilateral Initiative on Malaria (MIM) Pan African Malaria Conference in Dakar last week revealed that about 21 million people in the region (24 per cent of confirmed malaria cases) were at risk of being prescribed inadequate doses of artemisinin-based combination therapy (ACTs).
This is the frontline drug for treating malaria. The study, which was conducted by the Worldwide Antimalarial Resistance Network (WWARN) found that patient groups at risk of sub-optimal dosing included malnourished children under five years of age, overweight and obese adults, pregnant women, patients with high levels of malaria parasites in their blood as well as those using poor quality medicines.
“Antimalarial drugs remain a key tool for the control and elimination of malaria. These findings are worrying given that sub-optimal dosing among vulnerable populations not only leads to poorer treatment outcomes for patients, but can also fuel the emergence and spread of anti-malarial drug resistance,” said Kasia Stepniewska, Head of Statistics at WWARN and lead author of the study.
The researchers warned that if treatment is not strong enough to eliminate all malaria parasites in a patient’s blood, the remaining parasites that withstood the low dose could evolve to become more resistant to future treatment.
“There is an urgent need to tailor treatment approaches for populations at risk in order to protect the efficacy of drugs and prevent the development of drug resistance,” said Dr Stepniewska.
Simon Kariuki, head of the malaria programme at the Kenya Medical Research Institute, noted that to solve the sub-optimal dosing challenge among high risk groups, health practitioners could determine malaria drug doses given to patients based on the amount of parasites in their blood as opposed to their weight as is the practise currently.
“We could also use drugs with a longer half-life that will remain for a longer time in the blood until all malaria parasites have been cleared,” said Dr Kariuki.
Resistance to antimalarial medicines has long been recognised as a serious threat to global efforts to control and eliminate the disease.
Protecting the efficacy of malaria treatments is thus a top priority globally.
To date, the epicentre of ACT drug resistance is in Southeast Asia (Cambodia, Myanmar, Thailand, Vietnam and the Lao People’s Democratic Republic).
By using collaborative approaches to analyse data across many countries, researchers hope to develop strategies that will prevent or at least delay the spread of drug resistance in Africa.
“While artemisinin resistance has not yet been confirmed in Africa, we can do a lot more to improve how we use antimalarials and hence reduce the risk of drug resistance becoming established here,” said Karen Barnes, professor of clinical pharmacology at the University of Cape Town, South Africa, and head of pharmacology at WWARN.