Malaria Prevention via Mosquito Elimination
Malaria is a mosquito-borne infectious disease that causes flu-like symptoms that eventually lead to coma and death. An estimated 3.4 billion people in over 97 countries, including some in Asia, Latin America, and Europe, are at risk of contracting the disease. The WHO estimates that anywhere between 473,000 and 789,000 people die each from the disease spread by mosquito bite.
Spread by protozoans of the plasmodium genus in the anopheles gambiae mosquito, malaria is especially prevalent in sub-Saharan Africa, often claiming the lives of young children. Despite malaria mortality rates having fallen by 42 per cent since 2000, the WHO estimates that an African child dies every minute due to the disease.
However, scientists may be even closer than previously thought in eliminating the spread of malaria. Researchers at Imperial College London published a study on June 10, 2014 in the journal Nature Communications that stated that it was possible to breed mosquitoes that eliminate their own species.
“Malaria is debilitating and often fatal and we need to find new ways of tackling it,” said lead researcher Professor Andrea Crisanti in a press release from Imperial College London. “We think our innovative approach is a huge step forward. For the very first time, we have been able to inhibit the production of female offspring in the laboratory and this provides a new means to eliminate the disease.”
By genetically modifying the anopheles mosquitoes, scientists created a fully fertile strain of the mosquito that produced 95 per cent male offspring. Since only female mosquitoes bite, and therefore spread malaria, male mosquitos are harmless.
The modification was accomplished by inserting a DNA cutting enzyme called I-Pol into the anopheles mosquito. I-Pol works by cutting out the X chromosome during sperm production so that males only pass on a Y chromosome to their offspring.
Mosquito chromosomes are similar to human chromosomes in that the X chromosome codes to create male offspring while the Y chromosome codes to create female offspring.
After modifying the mosquitoes, scientists placed the modified insects into five cages with natural wild-types to breed. In four of the five cages, mosquito populations were eliminated after six generations due to the lack of females.
“What is most promising about our results is that they are self-sustaining,” explained Dr. Nikolai Windbichler in the same press release. “Once modified mosquitoes are introduced, males will start to produce mainly sons, and their sons will do the same, so essentially the mosquitoes carry out the work for us.”
Though it took researchers six years to produce the enzyme, research is still in its early testing phase. The next logical step is to introduce the genetically modified mosquitoes into the wild to begin the elimination of the anopheles species.
“The research is still in its early days, but I am really hopeful that this new approach could ultimately lead to a cheap and effective way to eliminate malaria from entire regions,” explained Dr. Roberto Galizi from the Department of Life Sciences at Imperial College London. “Our goal is to enable people to live freely without the threat of this deadly disease.”
Malaria prevention has been threatened by insecticide-resistant mosquitoes and drug-resistant parasites. Though malaria is completely treatable, there has been no effective vaccine produced thus far.
For those in malaria prevalent countries, in addition to researchers hoping to eliminate malaria, the research published by Galizi et al. is especially notable.