Web and Social Media Assistant, Global Health Policy Center
In my last piece about the 2011 Global Malaria Forum that took place in October in Seattle, I outlined several reasons to be optimistic. In this piece, I discuss the obstacles that global malaria control efforts face.
When the Bill & Melinda Gates Foundation announced in 2007 that foundation’s goal was malaria eradication, it created a sensation. Many people felt this lofty ambition not only ignored a history of failed malaria eradication attempts but, quite simply, was unrealistic. While the ultimate goal of global health efforts is to put an end to disease – such as was done in 1980 with smallpox – the call by the Bill & Melinda Gates Foundation in 2007 divided the global public health community.
On one side, the Gates Foundation along with Margaret Chan, the Director-General of the World Health Organization (WHO) and others argue that if we don't make eradication the ultimate goal, we will only keep malaria at bay; the disease will continue to kill innocent people and could resurge at any moment. Others argue that if we raise expectations too high and don't see immediate results, we could lose political will and along with it, financial support. In our current economic environment, calling for eradication – a goal that is estimated to cost $5 billion annually – is unpalatable to many. The most endemic countries, skeptics also argue, are prone to a combination of civil strife and political disunity that makes eradication exceedingly difficult. While the successes of the past few years have certainly narrowed the divide between these two camps, the debate between them still exists.
On scientific grounds, eradicating malaria is complex and difficult. To begin, there are four species of human malaria. The two most common are Plasmodium falciparum (P. falciparum) and Plasmodium vivax (P. vivax). P. falciparum is the most dangerous of the four species, causing the vast majority of malaria deaths, particularly in Sub-Saharan Africa. P. vivax, on the other hand, is seldom fatal but is the most common of the four species. These two species respond differently to medicines, exhibit drug resistance in different ways, and most importantly, make finding a fool-proof vaccine against all malaria nearly impossible.
Another challenge is that malaria is caused by a single-cell parasite which has the ability to evolve in ways that evade the human immune system. Even if someone contracts and recovers from malaria, that does not guarantee him or her protection from malaria infections in the future. This fact makes finding a fool-proof vaccine for malaria unlikely. With a viral disease like measles, for example, injecting a vaccine – which is typically a weakened strain of the measles virus – into the blood stream allows the body to create antibodies and develop immunity to future infection of that virus. With the malaria parasite, however, the body can't develop this same immunity because the malaria parasite continually changes.
The parasite's ability to evolve also enables it, over time, to become resistant to treatment medicines. As stated on the WHO website, “the emergence of parasites resistant to artemisinin [the drug most used to treat malaria] at the Thai-Cambodian border could seriously undermine the success of global malaria control efforts.” Further, it is not only the parasite that has the ability to adapt, but also the mosquito. The Anopheles mosquito, the mosquito responsible for spreading most cases of P. falciparum malaria, can develop resistance to insecticides after prolonged exposure. This reality can severely undermine existing interventions like indoor residual spraying of insecticides and widespread use of insecticide-treated bed nets. For all of these reasons, it is critically important to create new tools that allow scientists to continually stay one step ahead of the parasite and mosquito at all times, a very difficult task.
While the overall situation appears daunting, there are numerous reasons to be optimistic about the future of malaria control efforts. I truly believe that. It is just so important – looking forward – to keep these obstacles in mind and be realistic as to what can be achieved in what time frame. The leaders present at the 2011 Global Malaria Forum did exactly this.