The following is a transcript of this audio story.
DANIEL: There’s no denying that COVID-19 has fundamentally changed how we operate as a society.
Because of this disease, we’ve seen entire economies screech to a halt, and a soaring demand for ventilators, disinfectant and, oddly, toilet paper, all in a matter of months.
The scariest part about all of this is, though, is that diseases like this one have come to our doorstep before. You may have become aware of them from the SARs outbreak in 2004, or maybe Ebola in the 1980s and again in 2014; maybe with Cholera, anthrax, cat scratch fever, yellow fever, swine flu–– the list is staggering. The coronavirus is just one member of this enormous family we call “zoonotic diseases.” These are viruses that spread from one species of animal to another. And like its cousins, this strain relied on us to perfect its craft, this time at a wet market in Wuhan, China, where dozens of exotic species were held close together in a way that they would not have otherwise been in the wild.
And so, while many yearn for a vaccine to end the global quarantine, some ask, when did we miss our chance to prevent this from happening altogether? And what does that chance look like?
In Panama, one study shows us an opportunity, a chance to stop a whole class of such diseases before they get to pandemic proportions. And it has to do with deforestation.
*Panama Rainforest Ambi*
MARK: It started as what looked like a little bug bite––eventually started turning into this more crater looking thing, this volcanic eruption essentially coming out of my ankle.
DANIEL: I’m talking with Mark Knetsch, one of the CEOs and nature guides for an environmental non-profit in Panama called Geoversity. Mark helps manage a vital corridor of rainforest known as the Mamoní Valley Preserve, a few hours drive east of Panama City. It’s there that he and I met under a bamboo pavilion overlooking dense rainforest. Why I’m talking to him has to do with the first time he contracted a debilitating disease.
MARK: As the weeks went on, it started getting bigger and bigger. And I started putting my traditional aloe vera on it, see how that works and it was still getting gnarlier and just not doing any progress in terms of curing itself. So, I started getting concerned.
DANIEL: Knetsch has American leishmania, a disfiguring infection of the skin. Hearing him talk about it, you might think of it as this sort of gangrenous thing, maybe caused by a snake bite. But this all started from the prick of a thirsty sandfly no bigger than the head of a push pin.
MARK: Once I noticed that it became the size of about a dime, I realized when I popped the scab off of it, it was actually this crater… a hole.
DANIEL: Left untreated, the disease can result in ulcers that spread across the body. Thankfully, Knetsch was lucky enough to receive swift treatment––now he just boasts a small scar on his leg. But that’s not the case for most people in Panama and across Central America.
Leishmania and another disease called Chagas are, like COVID-19, zoonotic illnesses that spread from animals to humans.
But in Panama, the two may be on the rise due to deforestation, an outcome scientists are saying we have a chance to change.
NICOLE: A lot of models that we’ve worked on tend to hypothesize that there could be––kind of at these intermediate levels of deforestation––an increase in transmission.
DANIEL: That’s Dr. Nicole Gottdenker, a veterinary pathologist at the Center for Ecology and Infectious Disease at the University of Georgia. It’s been her job to study the relationship between deforestation and the spread of these illnesses in Panama.
NICOLE: Often at edges, you can get a change in the local ecology of the composition of plants and animals as well as the climate that exists at an edge between two different types of habitats.
DANIEL: In the last decade, Panama has lost close to 17 percent of its forest cover, mainly due to increases in cattle farming, logging, and mining for gold and copper.
As forest cover shrinks, so does what’s on the blood menu for parasites. Suddenly humans are more appetizing.
The preserve where Knetsch and I spoke is the perfect example of what Gottdenker is talking about. Mamoní Valley has been mostly reforested in the last 20 years, but it’s still flanked by cattle pastures and fragmented jungle––the “edges” that Gottdenker mentioned.
NICOLE: We get an increase in both the abundance of the vectors as well as an increase in the infection rates of the vectors, when we compare that to some areas in, say, more intact forest.
DANIEL: Vectors are the things that carry the disease––ticks, for example, are vectors for lyme disease up here in the Northeast. You may remember that leishmania is carried by a tiny fly. In the case of Chagas the vector is another small insect with a seemingly unassuming name—-the kissing bug.
At first glance, this bug looks like the tip of a pruney finger after staying too long in the pool… but with wings, and an odd checkered pattern outlining its body.
NICOLE: You can have many different sizes of the bug that can range in size from a sesame seed to the size of a small cockroach.
DANIEL: This is the kiss before bed that you definitely don’t want. The way that these bugs spread the disease is by flying into the unguarded home usually in rural areas. And like mosquitos biting the unsuspecting human while they’re asleep. While they’re busy drinking blood, they’re pooping (gross, I know).
And in that feces is the parasite that we know causes Chagas.
NICOLE: Trypanosoma cruzi, which causes this disease, is a really true generalist that any mammal can be infected with the parasite.
DANIEL: Symptoms from the virus can range from some mild swelling to an intense fever, though most people experience the long-term deleterious effects, including congestive heart failure.
NICOLE: It can exist in many different ecosystem types, from dry forests in the Choco, in Argentina, Bolivia, Paraguay and Brazil. It’s endemic in all seven Central American countries.
DANIEL: And according to Gottdenker, they love getting into homes with thatched roofs, dirt floors and windowless kitchens… The kind of homes found just an hour outside of Panama City… the kind of homes found in rural communities, closer to logging sites.
NICOLE: In those houses, that are permissive to the entry of the bug, bugs can then bite and when people are sleeping they can become infected.
DANIEL: I wanted to learn more from the people catching these bugs, so I met up with her colleagues at the Gorgas Memorial Institute for Health Studies to discuss how these bugs are invading Panama’s villages.
DANIEL: The building is bright white, with old Roman columns that made it stand out from the bustling traffic and modern shopping outlets of Panama City. It’s also worth noting that this building was named after American Army physician, William C. Gorgas, who helped stop the spread of yellow fever during the construction of the canal.
DANIEL: Can I leave my stuff in here?
FRANKLYN: Yeah, yeah, you can put it over here.
DANIEL: I’m brought up to the second floor, where less than a dozen rooms support research of these diseases for the entire country. Everywhere you look, there are stacks of paper and whirring centrifuges. There’s even a life-sized model of a kissing bug on someone’s desk.
FRANKLYN: In this room, we isolate parasites, as T. cruzi and leishmania parasite, Leishmania panamensis mainly.
DANIEL: And that’s all leishmania right there.
FRANKLYN: Yeah, leishmania and, for example, new emerging diseases.
DANIEL: I sat down with Dr. José Calzada and Dr. Azael Saldaña just moments after they returned from checking their bug traps in the field.
Both are veterinary pathologists collaborating with Dr. Gottdenker and her colleagues at the University of Georgia. Together, they have amassed more than 28 years of experience studying these illnesses in Panama. They say, to understand why these diseases are so obscure, you need to understand that they’re not affecting everyone equally.
JOSÉ: These are neglected diseases for neglected populations.
AZAEL: The rural people and the indigenous populations, they are the poorer people here in Panama that are affected by leishmania disease, Chagas disease, and many other parasitic diseases
DANIEL: That’s Dr. Calzada and Dr. Saldaña, respectively.
AZAEL: That is because they are living in an area where the parasite is still there and the vectors are there.
In the case of leishmaniasis disease, we have around 3,000 cases a year here. It’s a disease that is quite prevalent here in Panama.
DANIEL: Calzada and Saldaña both tell me that Leishmania and Chagas are actually very old diseases. Both have cases dating back to the late 1800s according to the World Health Organization. But in that time, treatments haven’t changed much; and that’s because the populations being affected most are on those that are on the fringes of society.
According to Saldaña, each of Panama’s ten provinces still have annual cases for the two diseases.
AZAEL: We are a small country, we need to do something because we are also few people––less than four million people living here.
DANIEL: In a study they conducted in 2015, Saldaña and Calzada assessed the housing quality across the country and then compared it with the prevalence of leishmania disease. What they found was that it wasn’t enough to just be near deforested areas… You also had to be poor.
AZAEL: In the case of Chagas disease, the house condition is quite associated with Chagas disease.
DANIEL: In fact, in the rural villages east of the Panama Canal, some communities are so plagued that people identify where they’re from using the leishmania scars on their face, marks that look similar to third degree burns.
JOSÉ: When we do the studies near Panama City in Panama Oeste, like Chorrera area, we’ve been to primary schools where at least 70 or 80 percent of the children there––l you can see all the leishmania scars.
DANIEL: Why poor people suffer disproportionately has to do with the treatment and where it’s available. Unfortunately, the most affected people have to travel far and frequently for leishmania treatment, a painful series of injections with a mixture that still uses trace amounts of arsenic. Calzada says that’s a hard sell when you’re a farmer.
JOSÉ: There are no roads, they have to go by horse or walking. Just imagine the treatment for leishmania––they have to take a shuttle daily for 20 days. So they have to walk two or three hours from their house to the [medical] center to get one shot. And these shots are really painful and toxic. At the end of the day, they don’t get the complete treatment. They cannot go for 20 days without working. That’s one of the main difficulties with these infections right? The neglected diseases.
DANIEL: In the case of Chagas, diagnosis is even more difficult. After a brief acute phase, the parasite can lay undetected in the heart for decades, most patients often exhibiting zero symptoms until sudden cardiac failure decades after being bitten. Without physical signs of infection, many don’t know to get tested until it’s too late. In the last few years, Saldaña and Calzada have resorted to testing domestic dogs, just to see if their owners might be infected.
JOSÉ: The research to discover a new drug from the beginning to the end is really high high––maybe many millions of dollars just to try one different drug.
We recently tried a new drug, a topical cream––which is a new alternative treatment for leishmaniasis––and the cost of the phase 2 and phase 3 clinical trials was around how much Azael?
AZAEL: Almost thirty.
JOSÉ: Almost $30 million dollars for this topical cream.
DANIEL: Just to try it?
JOSÉ: Just to try it. And to make it commercially available it’s much more money.
DANIEL: And why so expensive?
JOSÉ: That’s the cost of trying new drugs…
DANIEL: Nicole Gottdenker, the researcher earlier in the story, says their work on Chagas and leishmania may become the groundwork for similar diseases that are worsened by deforestation: diseases like malaria in Malaysian borneo, henipavirus in Cameroon, or even ebola in Western Africa.
The goal is to codify these patterns so that we can avoid most of the zoonotic illnesses out there. Probably the worst thing we can do right now is assume these viruses are distant.
Even in the U.S., Chagas may be just starting to gain more attention.
NICOLE: There’s over 300,000 people affected by Chagas in the United States. I mean there’s transmission in wildlife in the U.S. definitely––in Texas it’s in dogs as well. In Louisiana and Texas and other areas, there have been some cases they call autochthonous or local transmission to people.
JOSÉ: Everybody wants to urbanize and that’s in contradiction with diseases.
DANIEL: Music from this audio story was by Podington Bear via the Free Music Archive.
In Panama City, Panama, I’m Daniel Hentz.