A gorilla doctor working to prevent the next pandemic

UC Berkeley: Can you describe your research?

Tierra Smiley Evans: I study human and wildlife interaction at forest edges around the world where we think important pathogens are most likely to emerge. I do a lot of work in East Africa — Uganda, Rwanda, and the Democratic Republic of the Congo. I also work in Southeast Asia, particularly Myanmar. I’ve done some work in Peru and the Amazon Basin.

I typically focus on the whole landscape picture. We typically survey people coming to rural hospitals who have acute febrile illness and try to understand what’s going on. We set up centers across pristine forest areas and more urban settings, and we sample people, wildlife, and mosquitoes. We look at how the viruses differ. Are they more prevalent in one area or the other? Are they evolving quicker in one area or the other? We’re basically trying to understand what environmental pressures may make it more likely that viruses emerge and spread around the world.

I also wear another hat: I’m the chief scientist for a nonprofit called Gorilla Doctors. We provide veterinary care for the world’s eastern mountain and Grauer’s gorillas. Mountain gorillas and humans are great apes, so we’re almost genetically identical. Because of that, we share all the same pathogens. Everything that could be scary for a person is scary for a gorilla as well, so I study pathogens that could decimate mountain gorilla populations and be equally as important for humans.

What do public health measures look like for gorillas?

The Ebola virus is one of our major concerns. In western lowland gorillas, when Ebola outbreaks have occurred, it has completely wiped out populations. We’ve done some mathematical modeling exercises with the mountain gorilla population if a case was introduced in one side of the park or in a lone silverback or in a big family. Pretty much universally, if there’s a case and it’s allowed to spread naturally the way we suspect it would, it would be an extinction-level event for the entire species. They would be gone.

So we spend a lot of time thinking about what our contingency plan would be. We’ve shown that if we can vaccinate 50 percent of the population in six weeks, we could save enough individuals to save the species.

We’ve spent a lot of time sharing this knowledge and talking with partners because we’re just one small group in a whole group of conservation organizations that work with mountain gorillas, and it’s even more complicated because they cross between Rwanda, Uganda, and the Democratic Republic of the Congo. Three governments have to make decisions. We all have to be on the same page for this to work. If we ever were to get a call that there’s a case in a gorilla, we have zero time to waste. We need to be getting vets into the forest that day. So we’ve spent a lot of time making sure we have a stockpile of vaccines, generously provided by Merck.

Do you feel those three governments are supportive of the tactics you're developing?

Yes, I think they are on board with the importance of saving the gorillas.

For human populations, there can be a lot of vaccine hesitancy, misunderstanding, and fear — particularly with the Ebola vaccine, because you get really sick. We make sure all of our veterinarians are vaccinated, and people are out of commission for a couple days. The other problem is the vaccines don’t last very long. You need to get reboosted every three to four years, and for rural populations, that’s a hard sell when you remember how terrible you felt.

Have you experienced any impacts from the recent changes in federal research grants?

Yes, it’s been huge for me. I was a multiple principal investigator on one of the National Institutes of Health’s Centers for Research in Emerging Infectious Diseases Network’s programs. It was an innovative program based on One Health and zoonoses. It was the first time they’d made an investment at that level and scale. The first five years were about developing the infrastructure, network, and collaborations. We were starting to get some interesting, combined papers and were about to hit the ground running, and they canceled the whole thing. That was very frustrating.

I had a rather large contract through USAID Rwanda that was going to expand our regional diagnostics laboratory for Gorilla Doctors. This had been in the works for about five years. A lot of effort’s been put into human reference laboratories in East Africa, but we really need a high-level wildlife diagnostics laboratory, because the big, scary outbreaks are in these areas. Ebola, Marburg, and Mpox all come from animals, so when you’re just covering humans and not testing wildlife during an outbreak, you’re missing a whole piece of the puzzle. We had signed the contract, and before we even got a single payment, the USAID no longer exists, and the whole thing went away. That was a big hit.

I have another project in Uganda working on mobile health. It was trying to create an early warning system for Ebola virus and other high consequence pathogens that may spread between people and wildlife around the windy, impenetrable forests where gorillas live. They said we could keep the award, but we couldn’t send any money to Uganda. We’re still strategizing what we do with that.

The problem is that no one knows how to interpret the rules. I’ve been told a hundred different things on how we can proceed. All the researchers are talking with each other — ‘What did you hear? What was your conversation?’ — and everyone is getting a different story. I don’t even know what to believe.

I heard you worked in Myanmar, which is the subject of new travel restrictions. Has your research been impacted there?

I did my postdoc research there on virus emergence in the forest edge. They have the largest swath of intact natural forest left in Asia, and they don’t use traditional logging equipment: they have this network of government-owned elephant camps. You have all these people moving to undisturbed forests. Our project was to look at what viruses were circulating in humans and the wildlife they were eating. We had some side projects doing healthcare for the elephants.

We were working very close to the border with Yunnan Province, China. I’d been collecting blood samples for five years, and then COVID hit.

All of a sudden, that particular part of the world got really interesting — particularly, big sample sets from people before the pandemic. Sarbecovirus is a subgenus of coronavirus, and there are lots that come from bats. So we started screening people for different sarbecoviruses, and we found a very high seroprevalence.

I got an NIH grant to go back and study this population of people. One of the theories about how we protect against the next COVID is that we need a different boosting system. Did people who had exposure to bat sarbecoviruses have broad-spectrum antibody protection? If so, it kind of proves that’s where we should be going in vaccine research.

Around the time the NIH cuts were happening, we had planned to go for another grant, and we were basically told that this entire inquiry of science is dead. So…that was that, at least for now.

I read in The Scientist that your team is comparing serum from wildlife collected decades ago to animals in the same region today to see how virus profiles have shifted. Has that research been published yet?

It has not. It’s tied to a new project funded by the Wellcome Trust that’s looking at Zika and dengue virus in Africa compared to Latin America. Thank goodness for UK funding. We’re creating this big vacuum. Other countries are recognizing the importance of this work.

One theory is that the reason the virus has behaved so incredibly differently in the two continents is because, in Africa, there’s consistent seeding of new variants from sylvatic cycles into human populations.

That is going to require a lot of freezer diving, going back 20 years, and looking at how much Zika and other arboviruses were circulating at that time, what’s the profile now, and how have things changed. I suspect they will be very different with climate change. That’s what we’re going to be looking at for the next five years.