After spending most of her public health career living out of a suitcase, Louisa Messenger has settled down to bring her expertise in infectious diseases and insects to Las Vegas.

Louisa Messenger, a professor in the UNLV School of Public Health, focuses on combatting diseases spread by insects. (Becca Schwartz/UNLV)

What kind of career can a childhood fascination with dinosaurs, bugs, and the natural world lead to? For new UNLV School of Public Health professor Louisa Messenger, this resulted in a journey around the world as a scientist. For the last decade, she has played a key role in finding ways to prevent deadly, vector-borne diseases like malaria, which kills over 700,000 people globally each year.

I develop and evaluate new tools and strategies to interrupt the transmission of vector-borne diseases. These are infectious diseases that are spread by insects. Let's face it, we all hate being bitten by mosquitoes and other bugs, but it's a lot more egregious if that insect then transmits a disease that can potentially kill you.

These vector-borne diseases are a major global health problem. They account for more than 17 percent of all infectious diseases worldwide, and cause the deaths of more than 700,000 people each year all across the world. 

As a kid, I think a lot of us went through that phase where we're obsessed with dinosaurs; we're obsessed with bugs; we're obsessed with the natural world. I just never really grew out of it! I always knew that I wanted to be a scientist, and when I was studying for my undergraduate degree, I was fascinated with the interaction between infectious diseases and the natural world. It really doesn't get more intricate or complicated than how parasitic diseases and insect vectors have co-evolved their mutual symbiotic relationships over many millennia. And now these pathogens are able to cause such a considerable burden of global disease. 

It was really just my fascination with the subject in general that led me to this route.

When I started my career in public health, I was working in Latin America trying to improve the control of a parasite there called American Trypanosomiasis, or Chagas disease. It's a really horrible, neglected tropical disease, which is transmitted by a type of insect called a triatomine bug. They are these really large beetle-like insects, and at night while you're asleep, they come out the holes in house walls and bite you. And while they're biting you and sucking your blood, they defecate on you. There’s a parasite in the feces of that bug that enters your body through the bite wound or your eyes, nose or mouth, which you contaminate while you’re sleeping, by subconsciously touching your face.  

So it's a pretty nasty disease in the first place, but it causes really devastating pathologies. It often goes undiagnosed and becomes a chronic infection. It's really difficult to treat if you are not diagnosed early, and it's actually the leading cause of infectious heart disease in the world. So years after you become infected, you begin to develop irreversible, potentially fatal, heart disease as a result of this. And in endemic communities in South America, more than 97% of individuals over the age of 30 are infected, with 30% of these people progressing to end-stage heart failure, decades after contracting the disease.

I spent about six years of my early career working on this disease all across Latin America, but as with all neglected tropical diseases, obtaining long term sustainable funding for it is really difficult. So in 2015, I moved to sub-Saharan Africa, to Tanzania and I've been mainly working in malaria control ever since.

Malaria, despite being entirely preventable with the deployment and the use of the right health interventions, is still one of the top three communicable diseases worldwide alongside HIV and tuberculosis. It’s also still the leading cause of mortality in children under the age of five in low income countries. 

The main way that we control malaria is by distributing insecticide-treated bed nets. So if you are asleep in your bed, completely covered by your insecticidal net, it physically stops mosquitoes from being able to bite you. The insecticide in the net can then also kill the mosquito when it contacts the net while trying to bite you.

The other thing that we can do is spray long-lasting insecticide on inner house walls. What mosquitos tend to do is, once they've taken a blood meal from you while you're sleeping, they go rest on the walls of the house while they digest their meal. And if that wall is already covered in insecticide, this in theory should also kill them. 

These are the two things that we can do that are very effective to prevent malaria. But if it was really that simple, then I wouldn't have a job! Almost all of the natural mosquito populations across Africa that spread malaria are now highly resistant to all the insecticides that we're able to use in these interventions. 

In a recent data report, there were more than 241 million new cases in 2020 and more than 600,000 deaths. This level of global morbidity and mortality of malaria is quite simply unacceptable, and there are a number of key barriers currently affecting malaria control. One of the most significant ones is, how do we counter insecticide resistance? Basically, how can we get better at killing mosquitoes before they can transmit malaria to humans? What new insecticide, what new tools, what social and behavioral changes can we enact to protect these populations? So, my research focuses on the development of new insecticides and novel tools to control insecticide-resistant malaria-transmitting mosquitoes.

As part of my research the last four years, I’ve been working on two large clinical trials. There are a series of new insecticide-treated bed nets that contain not just one insecticide that mosquitoes can easily evolve resistance to or may already be resistant to, but these bed nets have two different insecticides to slow that evolution and selection for resistance.

My colleagues and I all work under the auspices of the World Health Organization (WHO). For the WHO to be able to approve a new policy recommendation – in our case, to approve a new vector control tool for malaria – the prerequisites include two clinical trials in two different locations in Sub-Saharan Africa. These trials need to monitor malaria infection in those communities for two years to see if those tools protect the population or are they no better than the current gold standard that we use. 

We ran these trials in Tanzania and Benin, so in East and West Africa, in areas that have very different mosquito species, very different communities, very different disease burdens, malaria transmission dynamics and levels of insecticide resistance. We just submitted those results to the WHO to be able to make this new policy recommendation. We're going to have a brand new type of insecticide-treated net that we can better control malaria, transmitted by insecticide-resistant mosquitoes, and it's really important to have this policy recommendation because it enables all of the international donors, stakeholders, and the national malaria control programs across Sub-Saharan Africa to procure those nets. 

We are producing good, epidemiologically robust evidence that these new tools are highly efficacious against malaria. This is really huge, and we're so excited. It's taken a number of years and so much developmental work to get to this stage. It’s a great achievement, but the problem is, it's just like antibacterial resistance – we are constantly playing catch up. We’re not out ahead of the problem at all. We need to develop new tools and need to be able to do this a lot faster if we're ever going to get anywhere near eliminating or even eradicating malaria worldwide.

The hands-on-the-ground work is all out there in the field, but you also don't need to necessarily even leave your home to make a significant difference in public health. 

During the COVID-19 pandemic while all of us were locked down, our team was commissioned by the World Health Organization to perform a large-scale evidence review. We realized we couldn't go out to the field. We couldn't travel. We had to stay at home and stay safe. So, how can a scientist best use our time?

Up to that point, the WHO had been unable to give an official policy recommendation about what malaria control tools to use during humanitarian emergencies, and that's a huge problem for international donors and stakeholders. They need guidance as to what they can procure with their limited resources when they respond to an emergency situation. Those are things like war, social and political conflict, famine, droughts and other natural disasters. All of these increase your risk of malaria, because it essentially displaces people from one area into a new area; and if there is malaria in that new area, and the displaced population has no pre-existing acquired immunity to the disease, it can cause severe malaria epidemics. 

So, our team sat in our respective bedrooms during the pandemic, and we performed this large, systematic review and meta analysis, which enabled the WHO, for the first time, to give recommendations in 2022 for the deployment of insecticide-treated nets during emergencies, as well as a conditional recommendation for spraying insecticides in houses if populations are displaced into an area that has structures that can be appropriately treated.

That's a difficult question. When people ask me, what's your greatest achievement in global health, I think everyone's always expecting you to talk about a particular project or paper or new scientific discovery.

I think the greatest achievement is actually the number of people you can train and mentor and inspire, because our careers are not that long lived and there are so many different public health problems that need to be addressed worldwide. I've mentored and directly supervised more than 20, close to 30 students and young researchers in more than 15 different countries all over the world. I've tried to build capacity at the laboratory level, in the field and at the academic level.

For me, that's what I see my legacy as being – the next generation of people who can continue all of this work after I'm hopefully happily retired somewhere. That's what I would like to be able to leave behind.

That's a great question, and that's exactly the question I had when I was a young student when people suggested, “Oh why don't you go into public health?” I was like, “Is that medicine? Is that nursing? I don't quite get it.”

I think what people don't realize is just how absolutely multidisciplinary and varied public health is and how almost everybody can play a really valuable role from basically anywhere in the world. I feel like we all watch a lot of movies and TV shows, and when they show public health scientists, they really only ever show epidemiologists and medical doctors. Obviously those are incredibly vital roles that you can play in public health, but if you're not a big fan of statistics or you're not pursuing medical school, then maybe it’s not always apparent how public health can be accessible to you.

For example, my principal training is in molecular biology. So we're the ones out there designing new diagnostic tools and new methods of tracking how diseases spread all over the world. I work with a team of mathematical modelers. They're mathematicians by trade and they use our field data to predict future trends for targeted deployment of health interventions. We have an economist on our team, and she calculates how much each new type of a disease prevention strategy costs, and how much disease it would need to prevent to be considered cost effective or worthy of investments from international donors. We also have medical entomologists who collect our mosquitoes in the field. They look at some of our control tools to see if they are killing mosquitoes or changing their behavior. We work with social scientists who spend their time in our communities talking to our study participants, asking them what they do and don’t like about specific health interventions, how they can be improved, and what more we can do to help their health outcomes.

I would tell students not to be afraid to explore your options in public health. There is so much you can do with public health. There's a niche for everybody, and there’s such a wide variety of avenues to explore. You never know what might ignite that fire in you.You shouldn't be afraid to take risks.

I took a risk; my bachelor's was in natural sciences, so it was very, very broad. Absolutely no public health content, and I don’t think I even knew what public health was at the time. But I knew I liked parasites; I knew I liked insects. So I took another risk and did my master’s in medical parasitology at the London School of Hygiene and Tropical Medicine.

At the time, my parents and friends said, “Medical parasitology. What on earth are you going to do with that? What kind of job needs a master’s like that? Are you sure you don't want to do something more mainstream?” But no, that's exactly what led me down the route that I took. I wrote my thesis paper on American Trypanosomiasis, loved every second of it, stayed for my PhD in the same lab, and I haven't looked back ever since.

It was a bit of a long time coming I think. I started working all around the world in 2012, living out of a suitcase the entire time. In 2019, I finally decided that I should settle down and unpack the suitcase, maybe even buy some furniture. And so I moved back to London, then subsequently spent most of my time out in Africa for all of 2019. And then COVID hit.

That completely changed everything about the world, but it particularly changed academia in the UK. The problem with COVID-19, as it was with most countries, is that our UK economy was decimated by it. I realized that my career wasn't going to be very sustainable there post-COVID, so I started to look elsewhere. I'm a dual UK-U.S. citizen. My mother was from California – I just don't sound remotely American since I grew up in London.

I have lived and worked in the States before. I’ve worked in Baltimore with Hopkins, I've worked at CDC in Atlanta for two years. I knew I liked the States. I have visited Las Vegas many times before on holiday, and I love this part of the world: the outdoors, the national parks, the weather, the climate. I said, “Okay if I could go and live anywhere in the U.S, where would I want to go?” and, importantly, I knew there was a public health school in Vegas. Thankfully, there was an assistant professor job in the department of environmental and occupational health at UNLV. The posting had the words “infectious” and “diseases,” and I thought, “I fit that. Let's apply.” I interviewed, was offered the job, and that made the decision very easy for me. So that's how I'm here.

Well, I'd say that Vegas is by far not the weirdest place that I've ever lived in, by a long stretch. I think I knew what I was getting myself into and was just really excited by the opportunity to come and live here.

But for friends and colleagues, particularly those from Europe and from Africa who have maybe never been to the U.S. before, all they have seen is Vegas on TV or in movies. They go, “so you're moving to like, The Hangover place, or Fear and Loathing in Las Vegas?” I have to say, “No, no, no, no, no – it's not quite like that.” Life in Henderson where I live and at the UNLV School of Public Health is very nice, enjoyable, and peaceful. It's very different from what's portrayed in the movies. I think that's the only misconception I have to explain to people. So, I'm really happy to be here.

This won't be surprising in the slightest, but my greatest passion is traveling and seeing the world. I think that's probably why I was so drawn to global public health as opposed to regional public health, because my favorite thing to do is to get on a plane, go somewhere remote and exciting, experience new cultures, meet new people, eat new food, and see some of the most amazing, natural and man-built sites in the world.

There is so much out there to see, and I just want to have as many new and exciting experiences as possible. That's what I spend most of my time doing when I'm not working. The best part about global health is you get to do both. If you go on a work trip, you get to do your exciting science and research, but then you also get to see potentially a really interesting part of the world that lots of people may never get the opportunity to go to.

One of the places I went to recently that I really loved — because I love insects, I love the natural world, I love animals — was Western Papua, which shares a border with Papua New Guinea and is technically part of Indonesia, but it's very, very remote. There live the Birds of Paradise. They are a number of different species of passerine birds on different small islands that each have very distinct behaviors and dances that the males do for courtship of the females. There are a few documentaries such as Attenborough's Paradise Birds and Dancing with the Birds that I would really recommend. They're just such an amazing example of evolution, but you can still go and see them in real life.

It’s really difficult to get to. It takes a few days, a few flights, and a few ferries. Also the birds are not easy to find. You have to wake up at three o'clock in the morning and hike up a mountain with a local guide because they're literally found only in one single bush in this one tiny island in the entire world. It’s a lot of effort to go, but when you see them, it's just an absolute miracle of nature. Things like that are what I really like to try and experience in the world.

College can be really difficult because it's such a transformative time in your life, and there's so much incredible pressure on you to perform academically and in a really short space of time. It often feels like you're simply measured by numbers and metrics like your GPA, and that's tough since you think it's going to essentially determine the rest of your life. But it really doesn't. 

It may seem like it's difficult at the time, but the best thing that you can do is try to enjoy yourself, learn as much as you can, and do what you can do to the best of your ability. If you don't quite make your grade, it doesn't dictate the rest of your life. I honestly don't remember most of my final grades. I haven't seen my original degree certificate in at least 10 years; I misplaced it somewhere in South America.

And if you fail a course and have to take another one, it’s not the end of the world. For example, I didn't pass one of my last lab practicals in my second year of undergrad, which is incredibly ironic considering I am now a principal lab scientist. Because of that, I wasn't able to do a practical thesis and had to do a written thesis, and that's exactly how I got into parasitology. I chose to write my final thesis on parasitic worms and their ability to potentially compromise vaccine efficacy through host immunomodulation.

So that was how I got on my right path, by complete happenstance. I think that's what many people experience. It's hard to say, “Don't worry about it, everything will turn out alright,” but I think it really does for almost everybody. I'm sure if you ask lots of people, they'd say something similar.

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