According to the UN, malaria infects more than two million and kills nearly one million people around the world each year. This mosquito-transmitted disease is present in tropical and humid zones and is caused by a parasite carried by Anopheles mosquitoes.
However, of the almost 500 different Anopheles species, only a few dozen are capable of carrying the parasite and only a handful are responsible for the vast majority of transmissions. Therefore, understanding the key differences between the deadly parasite-transmitting species and their harmless, but still annoying, cousins is a critical step towards being able to develop targeted solutions in the global fight against malaria.
Variation in the ability of different Anopheles species to transmit malaria is determined by many factors, including feeding and breeding preferences, as well as their own immune responses to parasite infections. The effectiveness of programmes to control or eliminate these mosquitoes is impacted by their variable resistance to insecticides as well as other features such as how they detect and follow the smell of humans.
To study such variations, Dr Robert Waterhouse, a Marie Curie International Outgoing Fellow at the Massachusetts Institute of Technology, along with an international team of scientists, sequenced and compared the genomes of sixteen Anopheles species from around the globe. “We used similarities to genes from Anophelesgambiae and other well-studied organisms such as the fruit fly to learn about the possible functions of the thousands of new genes found in each of the Anopheles genomes,” explained Dr Waterhouse.
Limiting the damaging effects of insects on human health and agriculture has traditionally involved pesticide-based controls, sometimes indiscriminately killing many beneficial insects, and these days often with variable and declining success. For example, some mosquitoes are becoming resistant to insecticides commonly used on protective bed nets, while others are changing their behaviours to avoid the insecticide-treated nets by biting earlier in the evening when people are still outdoors.
“Thus,” said Dr Waterhouse, “novel approaches require a detailed biological understanding of each species in order to be able to develop interventions that focus on the malaria-carrying mosquitoes and minimise ecologically harmful effects.”
This research was published in two articles in 'Science'.
More information on Dr Waterhouse’s MSCA project.