Thursday, March 26, 2015

Studying the ecology of disease and primates

We often think of habitat loss, hunting, and perhaps even the pet trade as serious threats to primate conservation. Disease, on the other hand, is commonly forgotten. Yet, increasingly fragmented forests create more opportunities for humans and wildlife to come into contact and potentially transfer and spread disease. Our close genetic relationship with non-human primates further increases the likelihood of spreading illness through contact, making this a topic worth paying attention to.

Cryptosporidium parvum
A study came out recently in the journal PLOS Neglected Tropical Diseases that should remind all of us not to exclude disease as a potential threat to non-human primate conservation. Parsons et al., 2015 studied chimpanzees (Pan troglodytes) and baboons (Papio anubis) in Gombe National Park (where Jane Goodall studied chimps) and found that they are exposed to a parasite called Cryptosporidium. Cryptosporidium is transmitted through food, water, and zoonotic means (from animals to humans).

Death from infectious disease is the leading cause of mortality for the three chimpanzee communities inhabiting Gombe (Lonsdorf et al., 2006; Williams et al., 2008), thus studying disease ecology should allow us to better conserve the Gombe population. While Papio anubis is not endangered, Pan troglodytes is.

Of the 131 non-human primates tested, 16% were positive for Cryptosporidium compared to 9.6% of livestock and just 4.3% of the 185 humans tested. Baboons and chimpanzees were infected at a similar rate. Three species of Cryptosporidium were detected: C. hominis, C. suis, and C. xiaoi.
Bush pig, Photo credit: Derek Keats
Half of the Cryptosporidium documented in the Kasekela community of chimpanzees are of a Cryptosporidium species (C. suis) typically associated with pigs. Surprisingly, C. suis was not detected in any of the humans, baboons, or livestock tested. The authors suggest that the transmission cycle may involve bush pigs, Potaochoerus larvatus, because domesticated pigs are not present in this area due to a mainly Muslim population. The bush pigs are found in the forest the Kasekela chimps inhabit and may serve as a reservoir for the parasite. It seems there are more details to be teased out when understanding the connection between C. suis and humans. Another species of the Cryptosporidium parasite found in this study, C. hominis, is one of two species most commonly found in humans (Chalmers and Katzer, 2013; Insulander et al., 2013). Yet C. hominis was also found in baboons and one of the chimpanzee communities, raising a red flag.

Cryptosporidium has been found in other primate species as well, including mountain gorillas, which were found to have the same species of Cryptosporidium, C. parvum, as found in nearby human populations (Nizeyi et al., 1999; Graczyk et al., 2001). Cryptosporidium has also been reported in red colobus and black and white colobus monkeys (Sayler et al., 2012). The Parsons study thus contributes to a growing body of literature on the prevalence of zoonotic diseases and their transmission. The authors stress the need to further understand the complex connections between primates, their ecology, their contact with humans, and the spread of disease so that we can better understand this relatively unexplored area of primate conservation.

This is an interesting article because Parsons and colleagues tackled a question that is poorly studied. The ecology of how diseases like Cryptosporidium spread and affect our primate relatives is not well understood, but zoonotic diseases make up the majority (60.3%) of emerging diseases worldwide (Jones et al., 2008). This is a timely and interesting paper that is worth reading or at least skimming. You can find the article posted online here. It's free and worth a look!

Links of interest:
Non-human primate biosafety from the University of Minnesota
Studying disease emergence in primates may help us understand emergence in humans
ScienceDaily article on paper

Chalmers, Rachel M., and Frank Katzer. "Looking for Cryptosporidium: the application of advances in detection and diagnosis." Trends in parasitology 29.5 (2013): 237-251.
Insulander, M., et al. "Molecular epidemiology and clinical manifestations of human cryptosporidiosis in Sweden." Epidemiology and infection 141.05 (2013): 1009-1020.
Jones KE, Patel NG, Levy MA, Storeygard A, Balk D, et al. (2008) Global trends in emerging infectious diseases. Nature 451: 990–993 doi: 10.1038/nature06536
Graczyk TK, DaSilva AJ, Cranfield MR, Nizeyi JB, Kalema G, et al. (2001) Cryptosporidium parvum Genotype 2 infections in free-ranging mountain gorillas (Gorilla gorilla beringei) of the Bwindi Impenetrable National Park, Uganda. Parasitology Research 87: 368–370. pmid:11403378 doi: 10.1007/s004360000337 
Lonsdorf EV, Travis D, Pusey AE, Goodall J (2006) Using retrospective health data from the Gombe chimpanzee study to inform future monitoring efforts. American Journal of Primatology 68: 897–908 
Parsons, M. B., et al. "Epidemiology and Molecular Characterization of Cryptosporidium spp." Humans, Wild Primates, and Domesticated Animals in the Greater Gombe Ecosystem, Tanzania. PLoS Negl Trop Dis 9.2 (2015): e0003529.
Nizeyi JB, Mwebe R, Nanteza A, Cranfield MR, Kalema G, et al. (1999) Cryptosporidium sp and Giardia sp infections in mountain gorillas (Gorilla gorilla beringei) of the Bwindi Impenetrable National Park, Uganda. Journal of Parasitology 85: 1084–1088. pmid:10647041 doi: 10.2307/3285672 
Salyer SJ, Gillespie TR, Rwego IB, Chapman CA, Goldberg TL (2012) Epidemiology and Molecular Relationships of Cryptosporidium spp. in People, Primates, and Livestock from Western Uganda. Plos Neglected Tropical Diseases 6.(4):e1597. doi: 10.1371/journal.pntd.0001597. pmid:22506085
Williams JM, Lonsdorf EV, Wilson ML, Schumacher-Stankey J, Goodall J, et al. (2008) Causes of death in the Kasekela chimpanzees of Gombe National Park, Tanzania. American Journal of Primatology 70: 766–777 doi: 10.1002/ajp.20573

Friday, March 6, 2015

Viewing a primate in a human setting linked to desiring one as a pet

Scenarios like this scare me Photo from Flickr user sofubared
A study was published last week by Leighty et al., 2015 in the journal PLOS ONE that caught my attention for some unfortunate reasons. (PLOS ONE is an open-access journal, if you weren't aware, meaning you can freely access the articles published in it.) Leighty et al., 2015 report that humans are more likely to want a monkey or a lemur as a pet if they see one in a human setting, which makes me want to pull my hair out. 1144 adults at the Lincoln Park Zoo were shown an image that had a primate (capuchin, squirrel monkey, or ring-tailed lemur) in it and was either in a natural or a human setting and included either a human touching the primate or no human at all. Head to ScienceDaily to see some of the images used in this study. The participants were then asked, “Would you consider getting this animal as a pet?” and, “Is this species endangered in the wild?” Now, these are people who willingly chose to visit the zoo, which seems to indicate they have at least some interest in animals. The results, which I summarize below, could potentially be even more disappointing if this were done with a wider population of adults.

If the primate was in contact with a human and in the non-natural setting, an office, respondents were more likely to state primates are desirable as pets (heck no primates aren't good pets, but more on that later). Almost one out of five people questioned would consider having the primate in the photo as a pet. Those wanting the primate as a pet were significantly more likely to believe the animal was not endangered.

Most people thought the primates in the photos looked "nervous" and more people felt the animal looked "happy" when not in the presence of humans. The animal looked "scared" significantly more frequently when there was a human in the photo. In what is the most confusing result reported from where I sit, the primate was most likely to be seen as "dangerous" in a natural setting with no human present. Perhaps people automatically assumed the primates in the office setting were tamed or domesticated? Or that those primates in photos with humans must be well behaved if they're so close to a person and thus, those primates are not dangerous?

Figure 1. The proportion of respondents who described the primate using the trait when presented with a photo of the primate with or without a human present, averaged across the natural and office settings. From Leighty et al., 2015.

Why is this study so important? Well, there is no federal law preventing US residents from keeping primates as pets. The laws vary by state and there are an estimated 15,000 pet primates according to the Humane Society. Clearly it isn't obvious to everyone that keeping a primate like you would a dog or a cat is a horrible idea. You may have watched a video on YouTube of a slow loris being tickled. This video has close to six million views. Six million! That's a lot of people watching the video and thinking how adorable the loris is. I bet some of them are thinking, "Why, what a cute animal. I want one! They're so tiny! How hard could they be to take care of?" (Well, they're venomous for starters...) An ABC news story also posted on YouTube described how slow lorises are endangered because they're so cute and it falls short of having a quarter of a million views. I'm guessing you can see the problem. People love primates, which is great, but loving them and thinking they'd make a good pet is a real issue. Loving them and assuming that because a primate is on YouTube or in a commercial means that species isn't at risk is another issue.

This study also has implications because primates are also used in the entertainment industry. Capuchin monkeys were used in the photos for this study, and you may remember that Ross on the TV show Friends had a capuchin monkey. Capuchins have also been in movies such as The Hangover II and Night at the Museum. Yet, if most people are rating primates in human settings with humans as "nervous," maybe we shouldn't be using them in movies and advertisements? Never mind that it's not humane to take a very intelligent animal away from it's social group (capuchin monkeys live in groups of roughly twenty individuals), but apparently we are made uncomfortable seeing primates outside of their native habitat and interacting with humans.

I wonder what would happen if the same questions from the Lincoln Park Zoo study were asked to people after viewing the slow loris being tickled on YouTube. Are people even thinking about what the primate feels in the video or are they just watching it for the cute factor? Asking people to assign the traits in the figure above might make them think about the larger picture.

The bottom line is we need studies like this so that we can better understand why people believe keeping a primate as a pet is a good idea. The better we understand the psychology, the better able we are to combat these desires and educate people.

Just in case you had any doubts: primates shouldn't be pets. The The International Primatological Society, the American Society of Primatologists, the Humane Society, the American Veterinary Medical Association, and the Jane Goodall Institute all speak out against having primates as pets. Keeping a primate as a pet is selfish. It does nothing to conserve or protect them and in fact causes harm. The primate pet trade can mean these animals are taken from the wild, making them a valuable commodity to be sold rather than an animal to be protected. By keeping them as pets, we do a disservice to these wild animals, removing them from their natural environments to serve no better purpose than a domesticated animal would. The problem is they're not domesticated animals. Keeping primates as pets is anthropocentric, meaning that humans are put first because we are the most important species, and counter intuitive to conservation. Pet owners often claim that their animal lovers but anyone who is keeping a wild animal as a pet is not.

Pet in Slovakia Photo credit: Kurt Bauschardt
Human houses aren't a suitable environment for primates. Thirty percent of privately owned primates in Mexico City suffer injuries caused by falls, burns, and even electrocution (Duarte-Quiroga and Estrada, 2003). They can choke themselves on leashes like the one in the left-hand photo. And you thought leaving your dog home unattended was a bad idea? Our homes are a poor replication of their environment.

Primates are complex socially and quite intelligent. Their needs cannot be met by private owners. Those captured abroad and imported illegally have usually been removed from their mothers at a young age (Duarte-Quiroga and Estrada, 2003; Jones-Engel et al., 2004; Wright, 2005) and suffer emotional consequences. Pet primates often have behavioral problems that arise because they are housed in inadequate social environments (Johnson-Delaney, 1991).

Primates are also dangerous to humans. Some diseases can easily be transferred from primates to humans. Heard of herpes B? It's easily transferred from macaques to humans and isn't detectable through a simple blood test because it travels through the nerves. Symptoms include fever, fatigue, skin lesions and even severe brain damage and death. Monkeys also bite and scratch to the point where some owners resort to removing nails or teeth in an effort to control behavior. Not to mention that if you somehow decide a larger animal such as a chimpanzee would make a lovely companion, you're looking at an animal that is much stronger than you and can rip your face off. Remember Charla Nash?

True animal lovers wouldn't keep a primate as a pet if they were educated on the intelligence, behavior, and ecology of the animal. It does a disservice to primate conservation, makes for an unhappy primate, and often results in a less than satisfied owner. If I haven't convinced you, take a look at the links below. No primate should be forced into being someone's pet.

Links of interest:
Clever Monkeys series on YouTube showing how intelligent primates are
Lincoln Park Zoo's page on why primates make poor pets
National Geographic News on the perils of keeping primates as pets
Jungle Friends Primate Sanctuary message to those who think they want a pet monkey-lots of links within this resource


Katherine A. Leighty, Annie J. Valuska, Alison P. Grand, Tamara L. Bettinger, Jill D. Mellen, Stephen R. Ross, Paul Boyle, Jacqueline J. Ogden. Impact of Visual Context on Public Perceptions of Non-Human Primate Performers. PLOS ONE, 2015; 10 (2): e0118487 DOI: 10.1371/journal.pone.0118487

Duarte-Quiroga, A. and Estrada, A. 2003. Primates as pets in Mexico City: An assessment of the species involved, source of origin, and general aspects of treatment.. American Journal of Primatology, 61: 53–60. 

Johnson-Delaney, C. A. 1991. The pet monkey: Health care and husbandry guidelines.. Journal of Small Exotic Animal Medicine, 1: 32–37. 

Jones-Engel, L., Engel, G. A., Schillaci, M. A., Kyes, K., Froehlich, J.Paputungan, U. 2004. Prevalence of enteric parasites in pet macaques in Sulawesi, Indonesia. American Journal of Primatology, 62: 71–82.

Wright, J. 2005. The primate trade in Indonesia: a rural perspective Manchester, UK: University of Manchester. Unpublished BSc thesis