Zanzibar's impressive attack on malaria

Achuyt Bhattarai, Anders Björkman and colleagues from Tanzania, Sweden, Italy, USA and UK have published their results in the latest issue of PLoS Medicine, where they show that the achievement follows the introduction of improved treatment. Malaria control was then further enhanced by the implementation of widescale use of insecticide-treated mosquito nets (ITNs).

Malaria kills about one million people every year. Most are young children living in Africa. The parasite responsible is transmitted to people when they are bitten (usually at night) by an infected mosquito. The World Health Organization and experts now recommend a new form of treatment known as artemisinin-based combination therapies (ACTs), which include the drug artemisinin – obtained from the sweet wormwood plant. ITNs are also strongly promoted.

People with malaria have had free access to ACT in Zanzibar since late 2003; children under five years old and pregnant women have been given free ITNs (long-lasting insecticidal nets) since early 2006.

The researchers counted the parasites in the blood of a group of children under 14 years in one district of Zanzibar in May (the seasonal peak for malaria) in 2003, 2005, and 2006. They also looked in local health records for malaria-related outpatient visits and admissions between 2000 and 2005 and analysed the overall death records for the region over the same period. Between 2003 (before the introduction of ACT) and 2005, the proportion of children under five with malaria parasites in their blood halved. It decreased another 10-fold between 2005 and 2006, after the distribution of ITNs to this age group. Deaths from all causes in children under five years old halved between 2002 and 2005, and malaria-related admissions and deaths attributed to malaria in 2005 in these children were a quarter of those recorded in 2002. The climate in Zanzibar remained favorable for malaria transmission throughout this period.

The results only cover a relatively short period since the introduction of the two malaria control strategies and will need to be confirmed in longer studies conducted in other countries with a malaria problem. Nevertheless, the Zanzibar research strongly suggests that ACTs together with the widespread use of ITNs could help achieve the goal of eliminating malaria as a public-health problem in sub-Saharan Africa, provided the poor countries in this region can sustain these control strategies over the long term.