So Tiny, Yet so Lethal

Photo: Parasitology Lab of Manhiça Health Research Centre (CISM), Mozambique.

The findings by Ross, Patrick, and many others marked an era that many would describe as crucial to humankind, as mosquitoes were then officially described as “human foe”

Mosquitoes may have lived in existence with humankind for many years, but only about 120 years ago they were first incriminated as dangerous organisms responsible for transmitting malaria, one of humanity’s most dangerous disease.

This breakthrough finding was as a result of remarkable research by a British man of many talents, Ronald Ross. His curiosity to find the culprit insect, that transmitted malaria back then was intensively driven by another physician, Patrick Manson’s hypothesis that mosquitoes could have been the main suspects. Ten years earlier, in 1878, Manson had discovered that certain mosquitoes may have been acting as a link of human filarial worms, and could do so for malaria parasites too.

The findings by Ross, Patrick, and many others marked an era that many would describe as crucial to humankind, as mosquitoes were then officially described as “human foe” rather than just a mere co-existing group of insects occupying space on the planet.

To date, with rigorous research and expansion of knowledge on these insects over time, several mosquito species have now been incriminated as carriers of several pathogens, making mosquitoes the most studied, the most famous, and the most dangerous organism on the planet.

New ways to kill mosquitoes, apart from the already existing ones, are now urgently needed, due to resistance and changes in mosquito behaviour

Today, even though the biology, ecology and behaviour of this insect are now better understood than in the last century, we still lose many lives —nearly 1 million— as a result of the diseases it transmits. In addition, nearly half of the world’s population live in geographical areas coinciding with the presence of these species. The most affected and most vulnerable populations are those living in poor environmental (poor drainage systems suitable for the sustenance of these organisms) and poor housing conditions, with poor wages, poor health system and poor road infrastructures, just to mention a few. This group is often described as “impoverished”.

Discussing the protection gaps of primary vector control tools with a community member in Matutuine, southern Mozambique. (Photo: Mercy Opiyo)

There is no doubt that the fight against mosquitoes has significantly reduced the burden of the diseases they transmit, and the great outcomes achieved today are worth acknowledging and applauding. This success, of course, has been largely achieved through killing mosquitoes with anti-mosquito tools —‘often described as vector-control tools’—, thanks to scientists, innovators, industries and donors. New ways to kill mosquitoes, apart from the already existing ones, are now urgently needed, due to resistance and changes in mosquito behaviour, amongst other reasons. Consequently, vector biologists (or ‘entomologists’) are continuously searching for better tools with the hope that someday they will find that silver or, even better, golden bullet.

Designing interventions or tools of any kind will require early-stage involvement of target communities to improve the designs of tools and methodologies

It is worth mentioning that we cannot ignore the role that “impoverished” societies have played and will continue to play themselves in the fight against vector-borne diseases. Acceptability, adherence and usage are some of the keywords that will determine if our tools will have an impact. As the burden reduces and/or because the tools we use in our daily lives become monotonous (used year in, year out), these key indicators may decrease, and vector control tools could consequently protect fewer people than anticipated.

As such, designing interventions or tools of any kind will require early-stage involvement of target communities to improve the designs of tools and methodologies. As scientists, philanthropists, artists, funders, industries, politicians and many others continue to fight this vector-borne disease war, I am convinced that we will win one day and that the “impoverished” communities will one day be defined as “thriving”. But only if we act according to one of the Ross’ advice: “an acute instinct for the right direction”.