Photos by Lenka Znamenackova & Milehna Guarido

Living in Africa, we often hear and read about malaria and other viruses spread by insects and animals. But how did we get to know so much about these diseases, and who are the scientists behind all the critical research aimed at protecting us from them? We caught up with one of them to find out. Meet Dr. Milehna Guarido, an entomologist specialised in mosquito research.

Please, introduce yourself to our audience - who are you, and what do you do?

I'm Dr. Milehna Guarido, and I'm a medical entomologist, which means I work with insects that can spread diseases to humans. I come from Brazil and for the past nine years, I've been based in South Africa, leading research projects that focus on the surveillance of arboviruses (viruses that can cause serious illnesses in people and animals like Dengue and Yellow fever) and malaria spread by arthropods, like mosquitoes, and their ecology throughout the country.

What brought you to South Africa?

Since I was a child, I dreamed of living in Africa. My dream became a reality when I was offered a scholarship at the University of Pretoria. I didn’t skip a beat and moved to South Africa. I completely fell in love with this beautiful country, with its nature, its people, and, of course, the mosquitoes (someone must love them, right?).

What led you to specialise in Mosquitoes?

I've always been fascinated by animals, diseases, and the link between them, and that curiosity led me to study biology. I dreamed of working with animals, such as bats and primates, all the creatures that play a crucial role in the spread of diseases in nature. Unfortunately, when I applied for an internship hoping to work with these animals, the position wasn't available at that moment.

Instead, I was offered the opportunity to help temporarily with mosquito research for three months, until I could switch to working with primates. But I found these tiny insects so fascinating that I ended up never leaving the research. Instead, I have dived deep into the world of mosquitoes and the diseases they carry. Sometimes, the unexpected turns lead you exactly where you're meant to be.

What is the most rewarding thing about your work?

An essential part of my work involves understanding how viruses spread through mosquitoes, how these insects live and interact with their environment and other animals, and how we can protect communities from the diseases they transmit.

I work with an incredible team of experts, including epidemiologists, veterinarians, and virologists. By combining our knowledge and sharing our data, we're able to gain a better understanding of the disease’s dynamics, how to prevent them, and even how to forecast future scenarios of potential areas affected and what will happen if an invasive mosquito species or a different virus enters the country.

Based on this research, measures are being taken to protect communities living in the areas that are or may be affected. It's science with a real-world impact, and I'm proud to be part of it.

What do you find most challenging?

We work across a mix of environments—wildlife areas, rural villages, and urban neighbourhoods—and some of our field sites can be challenging. There are risks posed by wild animals, exposure to diseases, and even urban violence. You could assume that fieldwork is the hardest part of my job, but for me, the real challenge is something else.

We live in a world that moves fast, where everything is expected to happen quickly. On the contrary, mosquito research doesn’t work that way. It requires a significant amount of time and patience, as hours are spent at the microscope sorting through samples. We collect thousands of mosquitoes, and identifying the species requires slow, detailed laboratory work. However, in the end, when all the results come together and patterns begin to emerge, it’s incredibly rewarding and makes it all worthwhile.

Tell us more about your work in the field. Where do you go and what is your favourite area?

A significant part of my work involves fieldwork, where I essentially go out and hunt mosquitoes. We begin by identifying areas where mosquito-borne diseases have previously occurred or could potentially emerge. We also focus on places where we believe the mosquito species capable of spreading viruses are present. This includes wildlife areas such as national parks and private reserves, rural communities near park borders, and even urban settlements.

Initially, much of our research has focused on the areas along the border with Mozambique. More recently, we’ve expanded into central regions and even places you wouldn’t expect to find large numbers of mosquitoes, like the dry savannas of the Kalahari and Karoo.

It’s hard for me to choose a favourite field site, but I feel especially connected to some of the national parks in KwaZulu-Natal province and Kruger National Park. I had the chance to visit them every month for about four years straight. Spending a significant amount of time in one place helps you understand the rhythms of the environment and its wildlife. And the sunrises and sunsets there are breathtaking.

Hunting mosquitoes sounds intriguing. How do you do that?

There are several methods for collecting mosquitoes, each tailored to specific research goals. I rely on techniques designed to attract and capture adult females who are the ones biting humans in search of a blood meal before laying eggs.

One of the most effective tools we use is CO₂-baited traps, such as the CDC miniature light trap and tent traps, and vegetation aspiration.  Female mosquitoes are attracted to the carbon dioxide we exhale. We use dry ice that releases CO₂ as a bait, which mimics a potential host and lures mosquitoes into the trap. All traps are set at sunset and checked at sunrise when we collect trapped mosquitoes alive.

Some mosquitoes prefer to rest in dense vegetation during the day. To catch those, we use a method called vegetation aspiration, when a mechanical aspirator is used to systematically search and collect resting mosquitoes from plants and shrubs in the early morning.

Mosquitoes are immediately euthanised in the field and transported to laboratory facilities where we morphologically identify and process them for the rest of the research goals.

How does Craghoppers gear work for you? What do you like about the gear?

My field experience has improved significantly since I started wearing Craghoppers.

During the fieldwork, I'm exposed to a very high number of mosquitoes - we are talking about hundreds, even thousands, of mosquitoes at a time. By the time we enter the trap to collect mosquitoes, they are starved and tend to bite us aggressively. In my personal experience, wearing NosiLife significantly reduced the bites and made me feel more protected. Ticks used to be another big problem for me when walking through the bush, but I haven't had any ticks on me since I started wearing Nosilife gear.

We also spend long hours outdoors—driving, walking, and working under the sun—and having clothing that’s comfortable in harsh conditions and offers protection from both insects, ticks, and the sun is absolutely essential.

The NosiLife gear gives me peace of mind when I’m out in the field, and it has become my go-to kit for work and travel.

Disclaimer: I didn't do any control experiment with my NosiLife gear, and this is my personal experience, which may vary from person to person.

Is there any thrilling moment from your fieldwork that you will never forget?

There have been countless unforgettable moments. I’m lucky to travel all over South Africa for work, often to places far off the tourist map where most people wouldn’t think of going to. Those journeys have brought me to incredible wildlife encounters and some of the warmest, kindest people I’ve ever met.

We’ve been chased by elephants more than once, found lions napping in front of our mosquito traps, delaying our work, and even had curious cheetahs check out our setup. The wildlife definitely keeps things interesting!

The most striking, though, is how people react when I explain what I do. No matter where I am, what language is spoken, or who I meet, often, without hesitation, people would invite me into their home to collect mosquitoes. It keeps reminding me of the universal truth: If you ever doubted how powerful something tiny can be, try to sleep with one mosquito in your room.

What advice could you give to young scientists looking to follow in your footsteps?

If you’re a curious person who loves life and the beauty of nature, you already have what it takes to be a scientist like me. I still remember the first time I looked at a grain of beach sand or a drop of river water under a microscope—it blew my mind to see so many tiny forms of life packed into such a small space. The world is incredibly vast and full of surprises!

Being a scientist can be challenging and frustrating at times, but it’s so rewarding when you get to do what you’re genuinely passionate about and get to see how your passion positively changes the world. Share what you learn, teach others, and inspire curiosity. If you do that well, you’ll never really feel like you’re working, because you’ll enjoy every single moment.

Milehna Guarido is a Brazilian scientist specialising in medical entomology, based in South Africa. She completed her PhD studies at the University of Pretoria under the TWAS project and has since worked on many other projects funded by the CDC (Centres for Disease Control and Prevention). She is also a passionate wildlife photographer, often capturing unexpected wildlife encounters during her work in the field. You can connect with her on LinkedIn or Instagram.