Tanzania: Winning the War

THE LAUNCH IN 2003 OF ARtemisinine-based Combination Therapy (ACT) in Zanzibar has dramatically reduced the incidence of malaria, a study has revealed.

Additional distribution of long lasting insecticidal nets (LLINs) in early 2006 resulted in a 10-fold reduction of malaria parasite prevalence, said the study, whose results were published in PLos Medicine, said.

The results indicate that the Millennium Development Goals of reducing mortality in children under five and alleviating the burden of malaria are achievable in tropical Africa with high coverage of combined malaria control interventions.

The study, titled Impact of Artemisinin-Based Combination Therapy and Insecticide-Treated Nets on Malaria Burden in Zanzibar, was conducted by among others, Patrick Kachur of Zanzibar Malaria Control Programme, Achuyt Bhattarai of the Infectious Diseases Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden, and Rashid Khatib of Ifakara Health Research and Development Centre, Dar-es-Salaam, Tanzania.

The study was supported by US Centres for Disease Control and Prevention, the Italian Co-operation and the Global Fund for Aids, Tuberculosis and Malaria. The Roll Back Malaria strategy recommends a combination of interventions for malaria control.

Zanzibar implemented ACT for uncomplicated malaria in late 2003 and long-lasting insecticidal nets from early 2006. ACT is provided free of charge to all malaria patients, while LLINs are distributed free to children under five and pregnant women.

The researchers investigated temporal trends in Plasmodium falciparum prevalence and malaria-related health parameters following the implementation of the control interventions in Zanzibar.

Cross-sectional clinical and parasitological surveys in children under 14 were conducted in North A District in May 2003, 2005, and 2006.

Survey data were analysed in a logistic regression model and adjusted for complex sampling design and potential confounders. Records from all 13 public health facilities in North A District were analysed for malaria-related outpatient visits and admissions.

Mortality and demographic data were obtained from the District Commissioner's Office. Plasmodium falciparum prevalence decreased in children under five between 2003 and 2006.

Between 2002 and 2005 crude under-five, infant (under 1), and children aged 1-4 mortality decreased by 52 per cent, 33 per cent, and 71 per cent, respectively. Similarly, malaria-related admissions, blood transfusions, and malaria-attributed mortality decreased by 77 per cent, 67 per cent and 75 per cent respectively between 2002 and 2005 in children under five.

Climatic conditions favourable for malaria transmission persisted throughout the observational period.

Malaria kills about one million people every year, many of them young children living in sub-Saharan Africa. Plasmodium falciparum is transmitted to people when they are bitten by an infected mosquito.

In the human body, the parasites reproduce in the liver before invading red blood cells. Here, they multiply again before bursting out and infecting more red blood cells as well as causing a high fever and sometimes damaging vital organs.

The transmission circle is completed when a mosquito bites an infected person and ingests parasites with its blood meal.

The World Health Organisation currently recommends the use of ACTs for malaria control.

These contain a natural antimalarial compound from sweet wormwood and a synthetic drug. The use of insecticide-treated nets is also now being strongly promoted.

THE INCREASED MALARIA-related morbidity and mortality, especially in children under five, due to emerging resistance of Plasmodium falciparum to conventional antimalarial drugs, calls for immediate action to roll back malaria in sub-Saharan Africa.

This need has been clearly recognised in the Millennium Development Goals "to halt and begin to reverse malaria incidence" as well as in the Abuja Declaration objective to halve malaria mortality in Africa reduced by 2010 through implementation of combined control strategies.
n 2000, the overall treatment failure of chloroquine was found to be 60 per cent in a 14-day efficacy trial. consequently, the Zanzibar Ministry of Health and Social Welfare decided in November 2001 to change both first- and second-line treatment guidelines for uncomplicated malaria from chloroquine and sulfadoxine-pyrimethamine to artemisinin-based combination therapies.

The ACT policy was implemented in September 2003, when Zanzibar became one of the first regions in sub-Saharan Africa to recommend routine use of ACT. This action was followed by strengthened vector control, culminating in a nation-wide distribution campaign of LLINs from early 2006.

Both ACT and vector control measures have independently proven to be efficacious malaria control strategies. Ecological studies have credited ACT with enhancing treatment efficacy, reducing malaria transmission, and possibly forestalling drug resistance in low-endemicity areas.