wildlife disease laboratories


Pathologist’s Report on Gao Gao’s Tumor

On the left is the paraffin wax block containing the processed tumor tissue, which is then cut into thin slices (about the width of a human hair) by our histotechnologist. These thin sections are then stained by several different methods to allow microscopic evaluation of the cells in the tumor.

On the left is the wax block with the processed tumor tissue, which is then cut into thin slices (about the width of a human hair). These thin sections are then stained by different methods to allow microscopic evaluation of the cells in the tumor.

As most of you know, giant panda Gao Gao had surgery May 6, 2014, to remove his right testicle after a tumor was discovered by our veterinary staff (see Surgery for Gao Gao). Since that time, we have received a lot of questions about how Gao Gao’s diagnosis was made and what the findings mean for his long-term prognosis. In this blog I’ll tell you about our analysis of the tumor in the Wildlife Disease Laboratories of the San Diego Zoo Institute for Conservation Research and what we know about the tumor in giant pandas and other animals.

After we received Gao Gao’s testicle in the laboratory, parts of the tumor were processed and stained for examination under a microscope. From this, the veterinary pathologists gathered clues from the arrangement and distribution of tumor cells, features of individual tumor cells, and the frequency of tumor cell division and invasion into adjacent normal tissues.

This photomicrograph (taken through a microscope) shows the tumor on the right-hand side compressing the normal testicular tissue on the left.

This photomicrograph (taken through a microscope) shows the tumor on the right-hand side compressing the normal testicular tissue on the left.

We also used a specialized technique, immunohistochemistry, to determine if the tumor was making substances characteristic of one particular cell type or another. All of this information was synthesized to determine the tumor cell type and if the tumor was completely removed.

In Gao Gao’s case, the evidence supports a diagnosis of seminoma, which is a tumor arising from the germ or sperm-producing cells. In addition, there was no evidence in the surgically removed tissues of tumor spread beyond the testicle. In domestic animals, seminomas are common in older dogs, and they are usually completely cured by surgery. However, in other species such as humans, a higher percentage of seminomas will metastasize (spread) to other organs without additional treatment such as chemotherapy.

This high magnification photomicrograph shows a single tumor cell undergoing mitosis (cell division), a characteristic that indicates tumor growth. The dark purple material at the center of the cell is the nucleus beginning to divide.

This high magnification photomicrograph shows a single tumor cell undergoing mitosis (cell division), a characteristic that indicates tumor growth. The dark purple material at the center of the cell is the nucleus beginning to divide.

So what does this mean for Gao Gao? The answer is that we can’t tell for certain if his tumor has been cured by surgery or if there is a small chance that it could reoccur at a later time. This is a common problem for pathologists who work with endangered animals, because very few tumors will ever be observed in these species, whereas it is easy to gather information on tumor behavior in dogs and humans where thousands of cases can be studied over time.

Despite this uncertainty, we are very hopeful that Gao Gao’s tumor will behave more like a seminoma in dogs. In 1997, a seminoma was found in 26-year-old giant panda Hsing Hsing, from the National Zoo, and treated by surgical removal. Hsing Hsing died two years later from kidney disease, and there was no evidence of any remaining tumor at his necropsy. We have had an opportunity to compare the microscopic sections of Hsing Hsing’s tumor with the samples from Gao Gao, and they are very similar.

Allan Pessier, D.V.M., Diplomate, A.C.V.P., is a senior scientist (veterinary pathologist) for the San Diego Zoo Institute for Conservation Research. Read his previous post, The Last Ones?

Update May 23, 2014: Gao Gao seems to be enjoying his keepers’ attention in his bedroom suite as he continues his recovery. He has even been soliciting neck scratches from them.


Beware of Crunchy Figs!

Here's a Moreton Bay fig fruit sliced in half.

The fruit of a Ficus sansibarica provides a cozy home for fig wasps.

Recently, the Wildlife Disease Laboratories received an interesting request from Seth Menser, a senior horticulturist at the San Diego Zoo, asking if we could take pictures of plant parts under the microscope. “I would really like to do a couple of shots of a fig cut in half with the fig wasps still inside. I have the figs needed for the shots. And, if you have never seen inside a fig, with the fig wasps, it is a very incredible thing to look at!” We were curious, so agreed to help.

Fig wasp

This amazing view of a fig wasp was taken in our Wildlife Disease Laboratories.

Seth brought up several figs from a Ficus macrophylla, commonly known as a Moreton Bay fig. These trees originate in the subtropical rain forest of eastern Australia but do well in frost-free climates such as ours. These majestic trees can reach up to 200 feet (60 meters) with long, aerial roots providing the tree with additional support to hold up the immense canopy. Seth brought several figs ranging from green and firm to dark maroon with spots on the outside. He explained the life cycle of the fig and the fig wasp as he cut them in half, and we set up the cameras.

Here's one

This female fig wasp has her wings. Is she ready to fly to a new fig?

Ficus trees are unique because the flowering parts of the plants are inside the fruiting parts (figs), making it difficult for insects to pollinate the trees. Thus begins the cooperative relationship with the fig wasp. The fig provides refuge and a food source for the wasps, and, in turn, the wasps pollinate the tree.

To begin the cycle, a tiny female fig wasp enters into a narrow opening (ostiloe) at one end of the fig. While wiggling into this small hole, she often looses a wing or antenna. Safely inside, she lays her eggs. As she is wandering through the fig, she spreads pollen from the fig she hatched in, thus helping the fig tree produce viable seeds. The cycle of the female wasp is complete, and she dies. Her eggs hatch, and the young wasps grow, finding food and refuge in the fig. Interestingly, only female wasps grow wings and leave the fig. The males live their entire life in the fig. Their function is to mate with the females and chew small openings through the fig’s wall for the females to escape, and the cycle begins again.

How many fig wasps can you find in this fig?

How many fig wasps can you find in this fig?

We were totally fascinated by the story. Using a dissecting scope with a camera attachment and a macro lens on a photo stand, we were able to capture the intertwined life cycles of the fig and the wasp. We photographed the narrow ostiole of the immature smooth fig where the female enters. Mature figs looked completely different on the inside. They were soft and fleshy, with delicate flower structures and seeds lightly attached to the inner walls. Each mature fig contained several wingless male wasps, and Seth was lucky enough to find one female flighted wasp.

At first glance, theses tiny wasps are difficult to see. The magnification helps, but a keen eye is needed to see them. How many can you find?

April Gorow is a senior pathology technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, We Never Stop Learning.


We Never Stop Learning

Did you know that hedgehogs evolved 50 million years ago in San Diego County?

Did you know that hedgehogs evolved 50 million years ago in San Diego County?

Dioramas, specimen jars, and stacks of books are all images that come to mind when you think of natural history museums. Museums are not just filled with primary school students on field trips but with invaluable collections. Museum curators are not just librarians cataloging their specimens but scientists and researchers helping to save species. With the number of endangered species increasing, museums have evolved into a major resource for biologists and other researchers who study genetics, taxonomy, comparative anatomy, and even behavior.

Field biologists need to understand the animals they study. They need to understand each animal’s living requirements (food, water, space, territory, and reproductive strategies), but also anatomy and physiology. It is important to understand what makes an animal jump, fly, and live without water for long periods of time. So off to the museum they go.

We have established how important museums are, but where does the museum get their specimens? One place is from us. San Diego Zoo Global has an immense and diverse collection exceeding 7,500 animals. Many of these animals are not displayed anywhere else in the US, which makes the collection unique not only to visitors but to museums and researchers. After an extensive necropsy and investigation of an animal’s death, the body may be saved for a museum.

One of the museums we work with is our neighbor, the San Diego Natural History Museum. Phillip Unitt, the museum’s curator of birds and mammals, boasts that “donations from the San Diego Zoo’s Wildlife Disease Labs have given our collection a worldwide dimension it would otherwise not have.”
Phil likes to share the story of hedgehogs during museum collection tours. Hedgehogs were evolving 50 million years ago in San Diego County. Though now extinct in North America, paleontologists at the museum are able to compare the local fossilized remains to the African hedgehog carcasses received from the San Diego Zoo.

Animals are amazing in their diversity, anatomy, physiology, and adaptability. We continue to learn about them even after death. Archiving and sharing tissue samples from them provide rare and extremely valuable resources for current disease investigations and future research.

April Gorow is a research coordinator for the Wildlife Disease Laboratories, San Diego Zoo Institute for Conservation Research. Read her previous post, Victor Lives On.


Desert Tortoises: Healthy Expressions

This desert tortoise is on the thin side.

This desert tortoise is on the thin side.

Compared to the numerous mammalian species you normally encounter, such as dogs and cats, desert tortoises have relatively limited means of expression. To make matters worse, they hide out in their burrows for extended periods of time and are mostly quiet. Furthermore, they can pull their legs and head back into their shell as a safety precaution when startled, so all that remains visible are their shell and the armor-like aspects of their front and hind limb scales. So, how we can tell if a tortoise is sick?

When your physician does an exam, simply asking you questions makes the task much more straightforward. Wildlife veterinarians, on the other hand, have to be much more clever and creative in using indirect measures of health. Some steps included in a routine desert tortoise health check are:

1) Activity
Is the tortoise behaving as expected? Is it alert to its surroundings? A tortoise that is letting its head hang and does not react to the examiner may be suffering from general debilitation

2) Measurements
The tortoise’s size is determined based on its shell length, using calipers. The size is an indicator of the age group of a tortoise. All desert tortoises over 20 centimeters (about 7.9 inches) are categorized as adults. It is difficult to determine the actual age of a tortoise unless you know the hatch date. The rings on the scutes of the shell are a poor indicator of age. A regular-size adult desert tortoise weighs about 5.5 to 8.8 pounds (2.5 to 4 kilograms).

3) Body condition score
This is an indicator to determine the muscle and fat mass of a tortoise. A desert tortoise with a prominent bony ridge on the top of its head is severely under condition, whereas one that cannot retract its head and limbs into its shell due to abundant subcutaneous fat stores is well over condition.

4) Shell
The shell of a tortoise is a specialized modification of skin. It contains nerves, blood vessels, and bone and is sensitive to trauma as well as metabolic derangements. The latter can be caused by an unbalanced diet and/or lack of natural sunlight or imitations thereof leading to soft and/or malformed shells.

5) Nares
The nares are inspected for exudate (runny nose) and erosions. Depending on the type and severity of the exudate, the tortoise may be suffering from an upper respiratory tract disease. Erosion around the nares indicates a more chronic disease process

6) Oral cavity
The mucous membranes of the oral cavity are examined for a healthy pink color, and the tongue is examined for presence of erosions and/or plaques. Tortoises with yellow, casseous plaques on their tongue may be suffering from a viral or bacterial infection.

7) Coelomic cavity palpation
By carefully pressing fingers into the soft skin area near the hind legs and into the shell cavity, an experienced examiner can determine whether there are masses in the coelomic cavity. Masses may include eggs or urinary bladder stones.

Why don’t we take their temperature? Tortoises, as other reptiles, are ectotherms: they do not control their body temperature as consistently as mammals but rely on environmental sources to regulate internal heating and cooling.

Identifying unhealthy tortoises is an important task at the San Diego Zoo’s Desert Tortoise Conservation Center in Las Vegas for individual animal and population health. The Center temporarily houses almost 2,000 tortoises, and each individual has to have a health check at least once a year. The goal is to release the tortoises into their native habitat, the Mojave Desert, to increase the wild population numbers. However, only healthy animals can be released to increase their chance of survival and minimize the risk of spreading disease. Unhealthy individuals are treated by San Diego Zoo Global veterinary medical staff.

Josephine Braun, D.V.M., is a scientist in San Diego Zoo Global’s Wildlife Disease Laboratories.


The Social Network…of Birds

Two bee-eaters appear to be sharing a meal in their aviary.

These two bee-eaters sharing a meal in their aviary are part of the same social network.

The age of social networking has the world communicating through cyberspace on just about anything. We are now connected to a network of people on Facebook and Twitter with whom we tune in daily to see what our friends are up to. In the past hour, my friends on Facebook looked at the nutrition facts on a candy bar (Is that really a good idea?), posted a CUTE photo of a clouded leopard (thanks to my “friend,” San Diego Zoo Global), and humorously referenced her boss mistaking a Kanye West song for the ‘80s hit single “Ghostbusters.” This is my social network.

Scientists are developing new methods to understand how people are influenced by their social network. Who we are connected to in the virtual world and in real life influences different aspects of our own lives, such as whether we vote in elections, our happiness, our weight, and whether we catch the flu or acquire other diseases. In collaboration with James Fowler, Ph.D., a professor at the University of California, San Diego, we are also trying to learn how connectedness influences the spread of disease in bird populations.

Avian mycobacteriosis is a bacterial disease of birds caused by Mycobacterium avium and other related species of mycobacteria. This is a challenging disease of birds, because whenever a case arises, we do not know how far an infection has spread through a group of “connected” birds sharing the same aviary. Traditionally, disease acquisition has been attributed entirely to contact with other infected birds; however, recent studies conducted by the Wildlife Disease Laboratories, a division of the San Diego Zoo Institute for Conservation Research, show that the environment may also be playing an important role in the spread of this disease. So, which is more important, the social network or the environment?

A powerful method of untangling this dizzying question is a social network analysis. Years of careful record keeping has created an archive of data documenting each bird’s aviary and enclosure-mates. These data can be used in conjunction with health history to determine whether the occasional cases of avian mycobacteriosis we see are attributed to a bird’s social network or its environment history. What makes the problem interesting is that the network is dynamic. Similar to how I might change my Facebook network by adding or dropping a friend, one of our birds might change social networks when she moves into a new enclosure to be closer to her new boyfriend (i.e., she drops her old bird “friends” and adds a new bird “friend”). Evaluating these dynamics through time is where social network analysis is remarkably powerful. Ultimately, we hope to uncover the relative contribution of mycobacterial infections due to both the social network and the environment.

We are just beginning this fascinating journey into understanding the influence of social networks on disease dynamics in our animals, so you will have to stay tuned to find out the answers. These answers will allow us to develop better disease-management protocols to mitigate risk to birds at the San Diego Zoo and San Diego Zoo Safari Park, as well as in conservation programs around the world.

Carmel Witte is a researcher with the San Diego Zoo Institute for Conservation Research. Read her previous post, Cutting-edge Science in Historical Surroundings.


Blue-chinned Sapphire Mystery

Males have the bright blue plummage, while females are less striking.

Males have the bright blue plumage, while females are a bit less striking. Photo credit: Philipp Lehmann

I love watching hummingbirds in my yard. These tiny nectar-eaters amaze me with their feathers of iridescent hues. The blue-chinned sapphire Chlorostilbon notatus is a species of hummingbird covered in shiny blue feathers—more a trick of the light than an actual feather pigment. Here at the San Diego Zoo, I have been able to take an up-close look at this species, aptly named for its beautiful color. However, I am not a bird keeper, I am a pathology technician. And this bird was not on exhibit—it was in my hand as I conducted an external postmortem (after death) exam. This tiny bird, still sparkling in blue feathers, had passed away and it is my job to help determine why.

Blue-chinned sapphires were added to the Zoo’s collection from the Caribbean last year. Unfortunately, when some of them arrived they did not survive very long. My job as a pathology technician is to look for anything wrong outside and inside these animals. But I could find nothing out of the ordinary—all of its internal organs looked great.

But when our veterinary pathologists looked under the microscope at the tissues from the birds, they made a Eureka! discovery—the birds were deficient in vitamin A. The pathologists let the nutritionists know, and they tested the nectar the sapphires were being fed—it, too, was low in vitamin A! The nectar was changed, and the rest of the birds have thrived.

It might seem a ghoulish job to study animal organs, but the results are worth it. The next time you are visiting the Zoo or Safari Park, remember that, even in death, animals are helping us learn about and conserve species around the world!

Rachael Holland is a research technician at the San Diego Zoo Institute for Conservation Research’s Wildlife Disease Laboratories.


Veterinarians Don’t Just Operate, They Educate!

Yes, veterinarians even examine panda cubs!

Yes, veterinarians even examine panda cubs!

For veterinarians at San Diego Zoo Global, in addition to caring for the animals in our collection, one of the most important things they do is share their vast knowledge and expertise with aspiring veterinary students at the university level. Until one has actually observed or practiced in a zoo veterinary hospital, it is impossible to fully understand the amount of discipline needed and the challenges faced by veterinarians and support staff. The clinical veterinary medicine and veterinary pathology externship programs at the San Diego Zoo, San Diego Zoo Safari Park, and San Diego Zoo Institute for Conservation Research’s Wildlife Disease Laboratories provide just such an opportunity to a select group of students each year.

In 2003, our veterinarians and pathologists collaborated to create an externship program, and since then it has grown exponentially. With more than 30 accredited veterinary schools in the United States, we have collectively hosted over 200 students from the US as well as Canada, Mexico, Brazil, Germany, France, Italy, India, Thailand, and China (just to name a few!). Working with such a diverse group of students also helps us, as we gain knowledge of veterinary practices in other countries. Since we often send and receive animals to and from zoos worldwide, this proves very beneficial throughout the animal shipment process.

As with specialties in human medicine such as cardiology or orthopedics, zoo veterinary medicine is a specialty where focused training and education is required. During and even after graduation, volunteering to participate in as many observational opportunities as possible enhances students’ ability to learn the many different aspects of the profession in the clinical setting. Students should strive to observe different practice areas in veterinary medicine such as small animal, large animal, equine, zoo and exotic, pathology, research, or industrial. This demonstrates to selection committees that a student has researched the profession and holds a genuine interest in pursuing a career in the field of zoo and exotic animal medicine.

Once a veterinary student has chosen zoo medicine as a field of interest, applying for and participating in an externship rotation is an important step toward success. Most university career counseling offices have information regarding externships, and there are numerous externship opportunities listed on the American Association of Zoo Veterinarians website as well, including our facilities. Each program listing contains specific information needed for applying to select institutions. Most programs accept applications at least a year in advance, sometimes two, so it is important to begin identifying potential programs as a college freshman or sophomore.

Our veterinary student externs must be in their fourth or senior year during their rotations. This ensures they have enough experience and education to receive the greatest benefit while working in our practice. Once students graduate and obtain their degree in veterinary medicine and a license to practice, many will apply for the University of California, Davis, Residency, which includes one year each at three different zoological institutions: Sacramento Zoo, San Diego Zoo, and San Diego Zoo Safari Park. The residency program also partners with SeaWorld San Diego and offers residents an eight-week opportunity to work in aquatic veterinary medicine.

While it takes a great deal of initiative, discipline, leadership skills, and patience, working as a veterinarian in a zoo setting is also extremely rewarding. For those with sincere passion for conservation and caring for the Earth’s creatures, working as a zoo veterinarian is not just a living but truly a way of life. It brings the staff of our veterinary services and pathology departments and San Diego Zoo Global as a whole great satisfaction knowing that the years of experience we share will be translated through the work of future generations of zoo veterinarians.

For information regarding SDZG veterinary externships

For information regarding the UC Davis Residency program:
And select the following Program Descriptions:
• Zoo and Wildlife Pathology
• Zoological Medicine

Valerie Stoddard is a senior administrative assistant at the San Diego Zoo Safari Park. Read her previous post, Elephant Serenade.


Tortoise in the Glass: Evaluating Health Problems

To you, a typical tortoise might look like this:

desert tortoise adult

But to me, a tortoise may also look like this:

desert tortoise tissue samples

I’m a veterinary pathologist, which means I spend a lot of quality time looking through a microscope at slides with tissues to try to evaluate health problems that show up as changes in those tissues. I can find dying cells, inflammation, various pathogens, scarring, thinning, thickening, bleeding, tumors, strange crystals, and unusual pigments. All of the changes help us understand the health problems affecting an animal.

At the San Diego Zoo Institute for Conservation Research, I work exclusively on tortoises that have died at the Desert Tortoise Conservation Center. Why bother? Well, it turns out that one of the best ways to figure out what health indicators most accurately indicate disease is to compare the information from the live tortoise to the changes we see in the tissues if the animal dies. The more we know about which tools work to predict severity and type of disease, the faster and more precise we are at identifying and helping animals at risk.

To get information from enough tortoises to allow good conclusions to be drawn, I need to look at a lot of slides. Since 2009, over 4,500 slides have been made of desert tortoise tissues, providing an invaluable resource for the understanding of disease in desert tortoises. Since November 2012, I’ve been describing the changes I see so that they can be correlated to what was found in the live animal. Thankfully, I haven’t been working all alone; Dr. Lily Cheng, another veterinary pathologist, volunteered to spend two whole months staring at a mountain of desert tortoise slides. Between the two of us, we’ve done more than 3,000 slides belonging to over 250 tortoises!

Are you curious about what sorts of things we see? Good! We are always on the lookout for bacteria or viruses that cause that most feared of tortoise infections: upper respiratory disease. This is more than just a head cold like people get and is a big factor in tortoise population decline. Some savvy souls may note that no light microscope can show an individual virus particle (you really need an electron microscope for that, since viruses are smaller than the wavelength of visible light). Conveniently, however, some viruses clump together to form rafts of virus particles. These are big enough to see with a microscope, just as you can see a patch of lawn even if you are too far away to pick out a single blade of grass. The virus most common and dangerous in tortoise respiratory disease (herpesvirus) forms these aggregations in the nuclei of cells, and they are called intranuclear inclusions.

Below are some cells from a tortoise that had severe upper respiratory disease. On the left side of the picture, you can see normal nuclei: round or oval purple shapes that look very speckled, like chocolate chip cookies. On the right side of the picture, the nuclei are bigger and have clumps of magenta in the center surrounded by a clear rim. They no longer resemble chocolate chip cookies at all. Those magenta blobs are viral inclusions from herpesvirus!

Herpes inclusions

The work continues at a good pace, and there are only about 1,300 slides left to look at. They weigh almost 7 kilograms (15 pounds) altogether. Wish me luck!

Kali Holder, D.V.M., is a postdoctoral associate in the Wildlife Disease Laboratories for San Diego Zoo Global.


Cutting-edge Science in Historical Surroundings

Looking across St. Michael’s bridge, early morning, in Ghent, Belgium.

I stood on the side of Saint Michael’s bridge staring at the stunning city before me: Ghent, Belgium. For four nights I was privileged to live in the beauty of this Central European city and take in all of her cafes, castles, and (my favorite!) chocolate. More importantly, I was there on official San Diego Zoo Global business to join some of the world’s best minds for a short, intensive workshop on molecular epidemiology and attend an influential conference that is held only once every three years: The International Symposium of Veterinary Epidemiology and Economics (ISVEE; endearingly called “iz-v”). It was an amazing opportunity provided by special funds set aside for employee development to meet with, learn from, and establish collaborations with some of the best in the field.

My journey started with the workshop in molecular epidemiology. The course instructors came from distant corners of the globe, including New Zealand, Scotland, and the U.S. to share their expertise with approximately 30 participants. We gathered for 3 days under the dim lights and a vaulted ceiling of wooden beams on the 4th floor (a.k.a. the attic) of a medieval Dominican monastery, Het Pand. This venue was not exactly the white, sterile laboratory from the movies (or the Zoo’s lab!) in which molecular science is usually performed, but I liked the contrast…cutting-edge science in historical surroundings.

Het Pand is the medieval Dominican Monastery where the molecular epidemiology course was held, Ghent, Belgium.

Molecular epidemiology is a specialized subfield of epidemiology (see Epidemi-what?) that requires unique tools and techniques to uncover patterns of disease transmission at the genetic level. My interest in this topic stems from the Zoo’s Molecular Diagnostic Laboratory. The lab was established in 1999 as part of the Wildlife Disease Laboratories to fulfill a need to develop diagnostic tests suitable for our animals and to improve our ability to identify and control important diseases. As one of the only zoo-based molecular diagnostic labs in the world, it has been instrumental in the development of diagnostic tests and animal disease research. For example, in 2007 a generous grant from the Ellen Browning Scripps Foundation allowed us to carry out a large study to describe herpesviruses in hoofed mammals (antelope, deer, goats, sheep, cows, and similar species). These herpesviruses can cause a fatal disease called malignant catarrhal fever when they are passed from animals that naturally carry the virus to new, susceptible hosts. Molecular methods can be used to look at the genetic similarities between viruses found in different animals to determine who is passing them to whom. This is where the epidemiology comes in.

Looking for patterns within molecular data (i.e., patterns across changes in DNA) requires methods that are new to me as an analytical epidemiologist. Thus, my goal in attending the course was to develop a working knowledge of such techniques to further improve the Wildlife Disease Laboratories’ ability to answer some pressing conservation questions. On the second day I was introduced to a new data analysis technique called Analysis of Molecular Variance (or “AMOVA” for short). Such a technique will allow me to extend our valuable data on herpesviruses and ask new or additional questions like: “Are animals in multispecies exhibits more likely to transmit the virus to each other?” Such an analysis could have a big impact on providing information that helps zoos better manage endangered species in the presence of this known disease.

A view of Maastricht, looking over the Meuse river.

Following the workshop, my travels then took me 90 miles east to the Belgium-Netherlands border where I joined 1,000 conference participants in Maastricht, The Netherlands, for 5 days of everything-animal-related epidemiology. Maastricht is a beautiful, historic-yet-modern city on the banks of the Meuse River that is famous for the birthplace of the European Union and the single European currency, the euro. My days in Maastricht consisted of attending talks on the latest work in the field, while the evenings presented opportunities to meet veterinary epidemiologists from around the world and engage in discussions of their research projects and areas of expertise.

I was honored to be a representative of San Diego Zoo Global at this venue and share some of our notable conservation work in epidemiology. Experiences like these provide me with better capabilities for using science to save species.

Carmel Witte is a senior research coordinator at the San Diego Zoo Institute for Conservation Research. Read her previous post, Investigating Primate Malaria in the Amazon.


Investigating Primate Malaria in the Amazon

A microscope slide shows the malarial parasite in a red blood cell red (see arrow) of a sampled primate.

When I first met Marina Bueno, I was instantly drawn to her excitement and passion for research in conservation medicine, a field that blends aspects of wildlife conservation, wildlife health, and human health. Marina is a veterinarian and doctorate scientist who works with the University of São Paulo’s Laboratory of Wildlife Comparative Pathology in the School of Veterinary Medicine and Animal Sciences. She also works with TRÍADE, a Brazilian organization for conservation medicine research, and Instituto Pri-Matas, a nonprofit organization conducting a project with golden-headed lion tamarins. Last summer, Marina spent extended time training in our Molecular Diagnostics Lab, learning how to improve DNA isolation techniques for some of her work. This is where we first discussed potential opportunities for collaboration on her projects investigating primate malaria in the Amazon.

Brazil’s Amazon region is seeing large-scale, human-induced (often referred to as anthropogenic) environmental changes that affect people and wildlife habitat. In a study conducted by Marina and collaborators, primates were surveyed across two protected field sites in the Amazon that are currently under severe anthropogenic pressure due to large construction projects that include the building of roads and dams. The idea was to sample South American primates in these sites to better understand what diseases they have and how these diseases could impact primate conservation and human health in these areas.

Marina Bueno samples primates in the Amazon for potential diseases.

They found that approximately 20 percent of surveyed primates carried a malaria-causing parasite, Plasmodium brasilianum. While infection with primate malaria generally does not harm the primates, there has been speculation that some of the primate-specific malarial parasites may not be so primate-specific. Some scientists believe that mosquitoes feeding on primates infected with Plasmodium brasilianumcould transmit the malarial parasite to humans when they bite a human host.

Marina’s research documents these malaria infections in primates, providing recommendations to closely monitor the human and primate populations for Plasmodium brasilianum infection in these areas of severe anthropogenic pressure, a situation that has been known to promote human malaria epidemics. The investigation also recommends that primates be tested for the presence of malaria infection before being relocated to other areas of Brazil for conservation or translocation projects so as not to inadvertently introduce malaria into areas where it has been eradicated.

Working collaboratively with scientists from around the world is a role that our Wildlife Disease Laboratories naturally falls into with its multidisciplinary group that includes veterinary pathologists, scientists, a molecular diagnostic laboratory, a histology laboratory, and an epidemiologist. Epidemiology expertise was provided for this particular collaborative project on primate malaria in the Amazon region. The study will be published soon in a peer-reviewed journal.

We are excited about our collaborations with our Brazilian counterparts in their quest to conserve one of the most ecologically diverse areas of the world and their search for harmony between human progress and wildlife conservation.

Carmel Witte is a senior research coordinator at the San Diego Zoo Institute for Conservation Research. Read her previous post, Epidemi-what?

The above photos are printed with permission from Marina Bueno.