In Papua New Guinea (PNG), where more than one and a half million malaria cases emerged in 2022 alone, protection from mosquito bites is crucial to safeguarding health and wellbeing. In cooperation with the Australian Institute of Tropical Health and Medicine’s (AITHM) Associate Professor Stephan Karl, PhD candidate Michelle Katusele is working to make life outside the mosquito net safer for people living in the Tropics.
As a researcher from PNG, Ms Katusele knows firsthand how mosquito-borne diseases impact the community. This is why, in her PhD, she’s trialling ‘spatial emanators’, small devices that release insect repellent into the air in selected households in PNG.
“The spatial emanators are made of a plastic frame and have a mesh in them that is treated with insecticide,” Ms Katusele said. “The insecticide is released into the air, creating a nice protective space for people inside a house or in sheltered outdoor structures.”
The chemical in the spatial emanator may deter a mosquito from feeding on a human. Depending on the insecticide used, spatial emanators can also kill or affect the reproductive system of a mosquito.
“With no need for electricity, relying only on air circulation, these devices could redefine how families in remote areas protect themselves. You simply hang it from the ceiling, for example, and forget about it,” Ms Katusele said.
“When we conducted our first trials in October 2023, it was the first ever study on spatial emanators in PNG,” Ms Katusele said.
“We are looking at the effectiveness of two devices. The first one, which we tested in 2023, lasts for up to a month,” she said. “The one we are currently testing is actually a prototype, designed to last for more than a year.”
For the study, two villages on the north coast of PNG near Madang with around 40 houses in total were equipped with spatial emanators. The exact number of devices per house depended on the number of rooms and the size of the rooms.
“In order to calculate how efficient the products are, we count the number of mosquitos that land on our volunteers every hour,” Ms Katusele said. “This method is called the ‘human landing catch’. It is regarded as a gold standard to measure adult mosquito abundance, and in turn, it allows us to measure the efficiency of our devices.”
While final results will come in 2025, early signs are encouraging, and Ms Katusele is optimistic that spatial emanators will make a difference in PNG.
“In our first trial we saw some really promising results, and we had really good protection rates inside buildings,” Ms Katusele said. “The first device reduced the number of mosquitoes from biting people by 50 to 60 per cent. This is very promising, and we are very excited about this.
“In outdoor areas, we also see some potential for using the one-month product in future, but only for shorter periods of time,” Ms Katusele said, adding that she was hoping to see better results for outdoor spaces in the current trial with the longer lasting emanator.
If successful, Ms Katusele’s work could mean that families in PNG, and potentially communities across the Tropics, can enjoy safer spaces outside the mosquito net, decreasing malaria cases and contributing to a better quality of life.
A former Wellcome Trust M.Sc. fellowship recipient, Ms Katusele is one of the first PNG PhD students benefitting from a JCU-UPNG cotutelle agreement allowing her to obtain a PhD from both institutions. She was recently offered a prestigious JCU PhD Scholarship to support her studies.
