World Malaria Day: five challenges in the fight against the disease
Although the number of cases of and deaths related to malaria has been declining steadily for 15 years, the disease continues to cause more than 400,000 deaths annually, primarily in Africa (90% of deaths) and among children (70% of deaths) [source: WHO, World Malaria Report, 2015].
To improve prevention, diagnosis and treatment, limit the spread of the parasite, and address the many challenges that the disease poses requires a combination of multiple strategies.
1. The impact of climate change
In 2012, 2014, and 2015, the MSF teams observed significant malaria spikes in several sub-Saharan African countries, including the Democratic Republic of the Congo (DRC), the Central African Republic (CAR), Uganda, and Mali. In Yida, South Sudan, for example, the number of malaria cases treated at MSF clinics nearly tripled between 2014 and 2015 (from 7,500 to approximately 20,000).
While the reasons for this increase are complex and, sometimes, specific, El Niño, a climate event responsible for rising temperatures and increased rainfall, seems to play a major role. These climate anomalies have also increased the number of malaria cases in regions that had previously been spared.
2. Resistance to insecticides
Vector control efforts, a key component of malaria control strategies, seek to reduce human exposure to mosquito bites through activities such as the use of insecticide-treated mosquito nets, insecticide spraying in and around homes, and elimination of mosquito larvae.
According to the World Health Organization (WHO), more than half of Africa’s population had access to a mosquito net in 2014, compared to 2% in 2000. However, mosquito resistance to pyrethroids, the main insecticides used to treat the nets, is rising. Although documentation on this development remains limited, several countries where MSF works have reported reduced insecticide efficacy. Despite this observation, nets treated with products of limited efficacy continue to be ordered in several countries where the disease is rife.
3. Prevention: Effective, but not lasting, strategies
In 2012, MSF organized one of the first seasonal malaria chemoprevention campaigns (SMC) on a large scale, in Mali and Chad. Since then, the strategy has been incorporated into the national policies of 13 countries in the Sahel and more than 15 million children are expected to benefit from it in 2016.
SMC is based on the preventive distribution of anti-malaria treatments during the high transmission months (seasonal “spikes”) and has shown very promising results: Up to 80% fewer cases of simple malaria and up to 70% fewer severe cases. In addition, combining SMC with other medical activities (malnutrition screening and treatment and vaccination) takes advantage of this contact with large numbers of children to combat multiple causes of infant mortality simultaneously.
However, this strategy is not intended to become a permanent tool in the effort to combat the disease. The impact of these distributions remains of limited duration and ceases several weeks after they end.
4. The parasites' resistance to anti-malarials
Since 2001, the WHO has recommended using artemisinin-based combination therapies (ACT, which uses a drug from Chinese traditional medicine) to treat malaria. ACTs replace earlier drugs, such as chloroquine and sulphadoxine-pyrimethamine, which have become ineffective because the plasmodium parasite, which causes malaria, has become increasingly resistant to them.
The use of these new treatments contributed significantly to the remarkable reduction in the number of malaria-related deaths in the last 15 years. However, since the 2000s, parasite resistance to artemisinin has been documented, particularly in Southeast Asia and also in Latin America. The use of monotherapies (artemisinin alone, not in combination with other drugs), counterfeit and poor-quality drugs, and treatment interruptions once symptoms have disappeared have accelerated this resistance. And as no replacement treatment for artemisinin will be available for several years, the spread of resistance poses a major threat to public health.
5. The search for an effective vaccine
After decades of fruitless research, RTS,S (Mosquirix©) is the first malaria vaccine to have completed clinical development. However, its efficacy is limited, particularly against the severe forms of the disease, and it is complicated to use -- involving four doses and a required 18-month waiting period between the administration of the third and fourth doses.
In October 2015, WHO’s Strategic Advisory Group of Experts on Immunization (SAGE) recommended small-scale pilot projects involving this vaccine to study its conditions of use. MSF has not wanted to participate in this research, believing that it would be too difficult to introduce the vaccine in poor countries, particularly given the low level of protection anticipated and the limited information available regarding its safety.
MSF continues to call for on-going research to develop a safe, efficacious, inexpensive vaccine that is easy to use in developing countries.
In 2015, MSF treated approximately 2 million cases of malaria around the world. More than 750,000 children also benefited from the distribution of preventive treatments (SMC) in Niger, Mali, and Chad.