Malaria: Radical Change Of Strategy Offers Hope For Eradication Of Disease

Despite numerous attempts to eliminate malaria, the disease remains one of the most common infections in the tropical regions. More than half a million people die from this disease every year in Latin America, Africa and Asia. Staggering 220 million cases of malaria were reported in the year 2010 alone.

Malaria became resistant to most available drugs

Pharmaceutical approaches to tackling the malaria problem had limited success. Although multiple drugs were introduced to treat infection, the disease has eventually developed resistance to almost all of them. Artemisinin is the newest and reportedly the most efficient drug in the currently available arsenal of anti-malarial tools, but the first cases of resistance to this drug were recently reported from Cambodia.

Neglected tropical diseases like malaria receive very little attention from pharmaceutical industry

Unfortunately, malaria is one of those unprofitable tropical diseases that attract very little attention of pharmaceutical industry. Since malaria mostly affects the population of poor countries, the chances of getting decent profits from selling any newly developed drugs and thus recovering the development costs are not high. This further slows down any progress in funding the solution for the problem of malaria.

Complex life cycle of parasite complicates the task of malaria’s eradication

The complexity of the parasite’s life cycle is yet another contributing factor to this lack of success. Plasmodium falciparum, the parasite causing infection resides in the wild population of several mosquito species. People get infected through the bites of these insects. Multiple drugs and their combinations can treat the affected individuals, with varying degree of success. These treatments, however, do nothing to eliminate the natural pool of disease in the wild. Like many other parasites, Plasmodium eventually develops resistance to the commonly used drugs, making them inefficient in treating the infected people.

Any radical strategy of fighting malaria should not only aim at finding new drugs but also at addressing the problem of the disease pool in nature which is the endless source of new and drug resistant strains of pathogen. 

It is also not an ideal solution: many insecticides are toxic and dangerous for the environment. They tend to kill not only mosquitoes but many other insects as well. This has a potential to affect the balance of natural ecosystems and eventually impact the welfare of local human population.

New Approach Aims To Eradicate Malaria In The Wild Mosquito Population

Radically new idea was proposed by scientists from John Hopkins and Michigan State Universities. In their article recently published in Science, researchers suggest to develop resistance to the malaria-causing parasite in the wild population of mosquitoes. In their approach, malaria-spreading Anopheles mosquitoes were infected with a specific species of bacteria called Wolbachia which makes mosquitoes immune to Plasmodium falciparum infection. Resistance to malaria among mosquitoes would break the parasites lifecycle and prevent human infection. Researchers have shown that Wolbachia-infected mosquitoes are not only resistant to malaria, but also can transfer this resistance to the offspring. In the laboratory experiments, 34 generations of mosquitoes remain immune to malaria after initial infection of their ancestors with Wolbachia. Thus, the seeding of mosquitoes with bacteria in the wild can infect the population of malaria-spreading mosquitoes and prevent human infection.

Approach is dramatically different from everything what we have seen so far. Instead of curing people or eliminating the disease carriers, new method suggests to eliminate the disease among the wild mosquitoes. Essentially, healthy wild mosquitoes mean healthy people in the affected areas.

New method will face potential problems                                                  

New approach proposed by the American scientists is not without its potential problems. Mosquitoes infected with Wolbachia tend to lay smaller number of eggs which means that they are reproducing slower than unaffected insects. This means that the establishing of bacterial infection in the wild population can be rather slow. In addition, the approach in its current form was developed for just one species of malaria-spreading mosquitoes, Anopheles stephensi. In those regions of the world where other species of mosquitoes are predominant the method will not work. It can be adapted for other species, of course, but this required additional research to establish the way of doing this.

On top of this, Plasmodium falciparum is not the only pathogenic species that can cause malaria.Plasmodium vivax is another parasite leading to the same condition. Two more species, P. ovale, and P. malariae can cause a milder former of the disease. It remains to be seen if Wolbachia infection can make mosquitoes immune to these pathogens.  

Eradication of malaria is likely to be achieved through the combination of several strategies

In the current situation when most drugs against malaria are not effective anymore, the biological approach to controlling the wild population of disease-causing pathogen represents an important and promising step in the right direction.

Taking into account the previous failures in the fight with malaria, it is hard to expect that the new approach alone would lead to the disease eradication. But it has a good potential to reduce the number of parasites in the wild and thus make the development of drug resistance to malaria less likely. Combination of several strategies may help at least in reducing the disease’s burden if not in its complete eradication.