Dr. Johnson Kyeba Swai is still getting used to his new title since earning his PhD. But after his research contributed to two groundbreaking vector control tools earning the World Health Organization’s stamp of approval, he’s already left an indelible mark in his field. Ahead of International Youth Day, we spoke to the Senior Research Scientist at Ifakara Health Institute about his research and advice for aspiring young scientists.  

What sparked your interest in malaria that led to your career in this field?

As a young person, I really wanted to become a medical doctor and go into neurosurgery. Along the way, I realized I didn’t enjoy physics — which in Tanzania was a requirement for medical school. But I did enjoy chemistry, biology, and geography so I decided to do my bachelor’s in molecular biology and biotechnology. I took courses in zoology, parasitology, and entomology and that was when I started learning about parasites that are transmitted by vectors.

After finishing my bachelor’s, I was lucky enough to be referred for a research position at Ifakara Health Institute. At the time I didn’t have much experience, but I was willing to learn. Soon after I started, I got sick with malaria. For two or three days my colleague had to take care of me — it was that bad.  

That experience really solidified my interest in malaria research. I enjoyed the process of going to the field. I enjoyed the process of collecting and sorting mosquitoes and testing different interventions. But once I had the disease as an adult and saw how life-threatening it is, it was settled. I wanted to play a part in making the world a better place. I think from then on, I just fell in love with entomology research around malaria specifically.

Tell us about your research interests and your work on spatial repellents. 

My first research project was on spatial emanators. I worked on hessian treated strips before eventually moving to the team that generated data for the efficacy dossier for SC Johnson’s Mosquito Shield™ and Guardian™ products. Both are now prequalified for use by the World Health Organization, which is really exciting. 

Spatial emanators, which are also called spatial repellents, help fill gaps in protection that we see with other vector control tools like insecticide-treated bed nets and indoor residual spraying. Studies have shown that mosquitoes are biting earlier in the evening and later into the morning, when people are less likely to be sleeping under bed nets or inside their homes. Spatial emanators are a special class of tool that can help fill these gaps by preventing mosquitoes from biting individuals, essentially creating a bubble of protection. 

I’ve worked on SC Johnson’s spatial emanators for four years now, throughout my PhD, and have evaluated these products across the full spectrum of test methodologies — from free flight chambers to semi-filled systems to experimental huts and even in a small-scale residential trial. I really understand how they work, and I think they are a really good tool. Moving forward, I think we will see more research into their efficacy for outdoor protection. And this is just my opinion, but I think we will see a WHO recommendation for standalone use in the next five to ten years. 

Why is it so important that we develop new vector control tools? Why can’t we rely on existing tools alone?

In some regions of the world, people rest under semi-open structures that either have thatch or iron sheet roofing and no walls. Take forest workers or migratory rice farmers, for example. They move away from home for economic reasons and live on the fringes of the forest or around rice farms, where you see high rates of malaria transmission. In these scenarios, it’s very hard to deploy a bed net. But if they could hang a spatial repellent where they sit or sleep at night, they could lower their risk of being bitten by an infectious mosquito. Spatial emanators would be a very good tool for these kinds of situations. 

What trends are you seeing in Tanzania and across Africa in terms of mosquito behavior? 

There are definitely changes in mosquito behavior that demonstrate the need for tools beyond core interventions like bed nets or indoor residual spraying. Anopheles mosquitoes, especially, are biting indoors more, and earlier in the evening as well as later into the morning when people are not under nets. And I think this is where, again, spatial emanators have an advantage because they provide around-the-clock protection.

There’s also a need for new tools that goes beyond gaps in protection. We have used the same kind of pyrethroid insecticide in bed nets and indoor residual spraying for so long that we now have resistance. And because the agricultural sector uses the same family of chemicals, mosquito larvae is repeatedly exposed to these pesticides, increasing resistance.

Because of the lessons we have learned with previous interventions, we already need new active ingredients for spatial emanators. Some of my colleagues are already working on this. Associate Professor Ingrid Chen is screening for new actives that would allow us to have non-pyrethroid based spatial emanators. If successful, we could deploy a pyrethroid based spatial emanator today and a non-pyrethroid spatial emanator tomorrow, creating a mosaic that could reduce the pressure for mosquitoes to develop resistance. We do not want to be in a situation where we always need to find new active ingredients and new chemicals.

You are fairly young to be conducting research at this level. What advice do you have for students and aspiring scientists? 

Any early career scientist, or any young person seeking a career in the science world, needs to have mentors. There will be times when you will have writer’s block, or your mind gets foggy, or you just don’t know what comes next. That’s when a mentor comes in. They can help guide you and push you in the right direction. They can tell you where your strengths lie and where you need more training or experience. No matter how innovative or smart you are, you need the right support system. You need people who will support you and pull you up when you feel like you’re going down or when you take a risk and fail, which is part of life. 

And we need more field entomologists! And more parasitologists. Just a few years ago an entirely new Plasmodium species was discovered, Plasmodium knowlesi, and it infects humans. We need more field entomologists out there identifying potential new risks so we can move faster to contain them. I believe we could have blocked the invasive Anopheles stephensi mosquito from traveling to Africa if we were able to better screen and track its spread.

To any aspiring scientist who wants to work in entomology, I will say, please do it with passion. We can learn a lot from history, but we’re also seeing so many technological advancements that there’s so much more we can do and discover. If you really want to choose this career path, my message is simple: do it!