MALARIA costs Africa big – its estimated “penalty” on African economies annually ranges from $50m for Uganda to $1.2bn for Chad.

But the good news is that it is on the decline- considerably so.

According to the recently released Global Burden of Disease report, several countries in sub-Saharan Africa have had very large gains in life expectancy since 1990, largely attributable to the decrease in mortality rates due to HIV/AIDS, malaria and perhaps a decline in civil conflict.

As of 2015, nine out of 10 malaria victims globally were in Africa. However, as a world region the continent has also achieved the most progress in combating the disease according to a recent study.

Researchers working on the Malaria Atlas Project (MAP) at Oxford University’s Zoology department found that the number of Plasmodium falciparum incidences on the continent reduced from their peak in 2003, when reported cases were 222 million, to about 187 million reported cases in 2015. Plasmodium falciparum is the parasite that causes the deadliest form of malaria.

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The results of the study, published in the journal Nature, also showed that overall malaria infection prevalence on the continent has halved since the year 2000.

DECLINE

The decline in prevalence was largely followed by patterns of increasing use of insecticide treated nets (ITNs). 68% of the decline in the Plasmodium falciparum prevalence rate as of 2015 is thanks to the use of mosquito nets, while Artemisinin-based combination therapy (ACT) and indoor residual spraying contributed 19 and 13% respectively.

Combined, these three interventions averted 663 million clinical cases of malaria since 2000, according to the study.

In another study, it was found that although there has been a continent-wide decrease in mortality due to malaria since 2000, there is more nuance when the data is looked at in terms of regions.

For example, in east Africa, the decline in deaths began earlier and was more rapid than in other regions. In central and west Africa the decline in death rates was slow until 2005, after which it declined more rapidly than in east Africa.

In 2015, Nigeria reported, at 61 million incidences, the highest number of cases of Pf malaria followed by the DRC and Uganda at 18 million and 8 million cases respectively.

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Nigeria also leads the rest of the continent in malaria fatalities. Last year, 31% of all estimated malaria deaths were from Nigeria while the DR Congo was second with 12%.

The good news, however, is that the two countries also showed larger declines in death rates from malaria between 2000 and 2015.

Malaria deaths in both Nigeria and the DR Congo declined from 23.6 to 10.5 and 24.8 to 10.3 deaths per 10,000 people per year. In the same period Uganda and Burundi (at 25.6 to 4.1, and 29.6 to 4.7 deaths per 10,000) saw some of the steepest declines.

WORLD’S MOST MALARIAL TOWN

The northern Uganda district of Apac was in 2010 declared the world’s “most malarial town” by Time magazine. The average resident in Apac is bitten 4 to 5 times every night by malaria parasite carrying mosquitoes – which adds up to 1,600 bites on average annually!

This high entomological inoculation rate (EIR) – the number of infective mosquito bites received by an individual during a season – is possibly due to the district’s proximity to Lake Kwania, a swampy extension of the bigger Lake Kyoga. In these shallow swampy waters mosquitoes seem to find safe haven for laying their eggs.

For now, the continent seems to be winning the war against one of its greatest killers. Malaria control funding alone saw a 20-fold increase in funding between 2000 and 2015, funding which enabled interventions like distribution of insecticide treated nets, artemisinin-based combination therapies and indoor residual spray programmes.

If we were to gaze into the future and foretell how this fight will go – it doesn’t look good for malaria! With new technological tools, such as those deployed by MAP, and the continued improvement in accuracy of their findings, faster and more effective interventions are possible.

However, we shouldn’t be quick to celebrate as historical trends have shown. The gains made so far can all be reversed if malaria parasites acquire resistance against artemisinin (as was the case with chloroquine in the 1990s). The same is possible with mosquito resistance to pyrethroids (active ingredients in the insecticide used for indoor residual spraying).