The World Health Organization estimates that more than 40 percent of the world’s population reside in communities where dengue fever is endemic. About 400 million people are infected by the virus every year, and one-fourth of those cases evolve into dengue fever itself—resulting in fever, headache, rash, vomiting, and other symptoms.
This leads to about 21,000 deaths—all of which ought to be preventable. Unfortunately, there is still no working vaccine that could prevent infection in humans.
That’s why scientists are eager to find ways to cut down on the number of infections—and that starts with the source: mosquitos that carry the virus. In a new study published Thursday in PLOS Neglected Tropical Diseases, a group of Taiwan researchers show the results of an ambitious project to use sewer-dwelling robots to monitor mosquito breeding grounds. The authors say this helps public health experts fight the spread of dengue fever in urban communities.
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Disease-carrying mosquitoes tend to thrive in these areas. After all, sewers and other underground waters can’t be easily monitored and regulated—and thus they can be an easy haven for the bloodsuckers to breed. Many dense cities are also home to aging, labyrinth-like sewer systems that humans cannot safely travel through.
Robots, however, aren’t limited by the same constraints as humans. They have an easier time traversing small, dark environments. They don’t have to fear the hazards that could harm humans like scurrying rats or literal human waste. They can sit still for hours, or even days, to monitor areas with high precision.
That’s why the Taiwan team put together a new platform that combined a real-time monitoring system with a crawling robot, and deployed several of them around sewers in five districts in Kaohsiung City in southern Taiwan. The monitoring systems were outfitted with instruments that could take real-time high-resolution images.
An illustration of the monitoring system.
Liu et al., 2023, PLOS Neglected Tropical DiseasesThe robots crawled to sewer locations suspected to be hotspots for mosquitos; those areas were also set up with mosquito gravitraps, which measure mosquito density as a “gravitrap index” (GI) number, above the sewers to observe how effective the robot monitoring systems were.
In all, the robots were able to find evidence of mosquito habitation in 20.7 percent of the inspected sewers. In those sewers, public health teams applied treatment measures like insecticides or high-temperature water jets to get rid of the mosquitos. The gravitraps confirmed drops in density from 0.62 to 0.19 GI.
Though it’s unclear exactly how well this program helped to decrease dengue fever cases in Kaohsiung, less mosquitos is welcome news for nearly any community. The researchers believe the new study may show the way to eradicate disease-causing mosquitoes that find ways to thrive in especially populous areas.
At the very least, most people would probably be more welcoming of robots buzzing around through the sewers versus on the street.
