Infant mountain gorilla.

Infant mountain gorilla.


March 29, 2011

Human Virus Linked to Deaths of Endangered Mountain Gorillas

Musanze, Rwanda – For the first time, a virus that causes respiratory disease in humans has been linked to the deaths of wild mountain gorillas, says a team of researchers in a new study published online today in the CDC journal Emerging Infectious Diseases.

Their study, which reports the 2009 deaths of two mountain gorillas that were infected with a human virus, confirms that serious diseases can pass from people to these endangered animals.

The study authors include researchers from the nonprofit Mountain Gorilla Veterinary Project (MGVP); the Wildlife Health Center at the University of California, Davis; the Center for Infection and Immunity at Columbia University; and the Rwanda Development Board.

The sharp divide between gorilla habitat and farmland visible on the slopes of Mt. Muhabura in Rwanda.

The sharp divide between gorilla habitat and farmland visible on the slopes of Mt. Muhabura in Rwanda.

“Because there are fewer than 800 living mountain gorillas, each individual is critically important to the survival of the species,” said Dr. Mike Cranfield, Executive Director of MGVP and a UC Davis Wildlife Veterinarian. “This discovery makes it clear that living in protected national parks is not a barrier to human disease.”

Humans and gorillas share approximately 98 percent of their DNA. This close genetic relatedness has led to concerns that gorillas may be susceptible to many of the infectious diseases that affect people.

The potential for disease transmission between humans and mountain gorillas (Gorilla beringei beringei) is of particular concern because over the past 100 years, mountain gorillas have come into increasing contact with humans. In fact, the national parks where the gorillas are protected in Rwanda, Uganda and the Democratic Republic of Congo are surrounded by the densest human populations in continental Africa.

Silverback gorilla Kwitonda and farmers outside of Volcanoes National Park in Rwanda

Silverback gorilla Kwitonda and farmers outside of Volcanoes National Park in Rwanda

Also, gorilla tourism–while helping the gorillas survive by funding the national parks that shelter them–brings thousands of people from local communities and around the world into contact with mountain gorillas annually.

The MGVP veterinarians, who monitor the health of the gorillas and treat individuals suffering from life-threatening trauma and disease, have observed an increase in the frequency and severity of respiratory disease outbreaks in the mountain gorilla population in recent years.

Gorilla infant with a runny nose.

Gorilla infant with a runny nose.

Infectious disease is the second most common cause of death in mountain gorillas (traumatic injury is the first). “The type of infection we see most frequently is respiratory, which can range from mild colds to severe pneumonia,” said co-author Dr. Linda Lowenstine, a UC Davis Veterinary Pathologist who has studied gorilla diseases for more than 25 years.

Gorilla Doctors Jan Ramer and Eddy Syaluha prepare an antibiotic dart for an infant gorilla sick with respiratory disease.

Gorilla Doctors Jan Ramer and Eddy Syaluha prepare an antibiotic dart for an infant gorilla sick with respiratory disease.

The two gorillas described in the new study were members of the Hirwa group living in Rwanda. In 2008 and 2009, this group experienced outbreaks of respiratory disease, presenting symptoms such as coughing, eye and nose discharge, and lethargy. In the 2009, Hirwa group consisted of 12 animals: one adult male, six adult females, three juveniles and two infants. All but one became ill and an adult female and a newborn infant died.

Tissue analyses showed the biochemical signature of an RNA virus called human metapneumovirus (HMPV) infecting both animals that died. While the adult female gorilla ultimately died as a result of a secondary bacterial pneumonia infection, the HMPV infection likely predisposed her to pneumonia. HMPV was also found in the infant gorilla, which was born to a female gorilla that showed symptoms of respiratory disease.

The study’s UC Davis authors are Drs. Cranfield, Lowenstine and Kirsten Gilardi, Co-Director of the UC Davis Wildlife Health Center’s Mountain Gorilla One Health Program. The lead author is Dr. Gustavo Palacios, a virologist at the Center for Infection and Immunity at Columbia University in New York. Other authors are from the Mountain Gorilla Veterinary Project, Columbia University and the Rwanda Development Board.

The research was supported by; the U.S. National Institutes of Health; the Emerging Pandemic Threats PREDICT program of the U.S. Agency for International Development; and a grant from the David and Lucile Packard Foundation.

Watch a video showing the Gorilla Doctors performing an intervention on Noel, a young male gorilla in Rugendo group in Virunga National Park, DRC. This January, the gorilla had been sick with respiratory disease for several days with symptoms worsening so MGVP veterinarians darted him with antibiotics. He made a quick recovery:

About Mountain Gorillas
With only about 786 individuals left in the world, mountain gorillas are a critically endangered species. Mountain gorillas live in central Africa, with about 480 animals living in the 173 sq mile Virunga Volcanoes Massif, which combines Volcanoes National Park in Rwanda, Virunga National Park in the Democratic Republic of Congo, and Mgahinga National Park in Uganda. The remaining population lives within the boundaries of the 128 sq mile Bwindi Impenetrable National Park in Uganda.

About the Mountain Gorilla Veterinary Project (MGVP)
MGVP, a U.S.-based nonprofit organization, is dedicated to saving mountain gorilla lives. With so few animals left in the world today we believe it is critical to ensure the health and well being of every individual possible. Our international team of veterinarians, the Gorilla Doctors, is the only group providing wild mountain gorillas with direct, hands-on care. MGVP partners with the UC Davis Wildlife Health Center to advance One Health strategies for mountain gorilla conservation.

About the UC Davis Wildlife Health Center
The UC Davis Wildlife Health Center, home of the Mountain Gorilla One Health Program, is a multidisciplinary program within the School of Veterinary Medicine at UC Davis that focuses on the health of free-ranging and captive terrestrial and aquatic wild animals. It is the umbrella organization under which faculty, staff, students, and other partners come together to address the complex issues surrounding conservation in a changing world. The Center draws upon faculty expertise spanning a wide range of wildlife species and scientific disciplines and attracts students from around the world to participate in its research and educational programs. In 2009 the One Health Institute was launched to address complex health problems on a platform that recognizes that the health of domestic animals, wildlife, and people are inextricably linked with each other and the environment.


Media Contacts

Molly Feltner, Communications Officer
Mountain Gorilla Veterinary Project

Please consider supporting the Gorilla Doctors by making a secure online donation. Every dollar you give goes to directly supporting our gorilla health programs and One Health initiative. Thank you for your generosity.

For the most up-to-date information about the Gorilla Doctors, “like” our Facebook page. You’ll find gorilla health reports, news items, photos, videos, and links to related content.


  1. Kurt says:

    This is very important for the debate on ecotourism. Rich tourists should now never be allowed to come close to these apes.

  2. Pascale Schampaert says:

    @ Kurt,

    I saved up money especially to go and see those fascinating, gentle creatures in the wild. No, I'm not rich – I chose to work for it and put money aside for this trip. To me, I thought – and still think – that this kind of money is better spent on 'nature' and hopefully helping nature, than rather buy some fancy car which pollutes our environment big times (to name only one example out of trillions)! So, you immediately draw your conclusion that it's because of "rich" people that those precious animals are getting sick. What about the local people living in the immediate proximity of the mountain gorillas'natural habitat? Does this make them materialistically rich aswell in your eyes? They live in (very) poor circumstances and unfortunately don't always get medical treatment.
    When visiting the Mountain Gorillas there are a lot of precautions that are taken: as a tourist, if you're ill, suffering from a fever or even a cold, you will not be allowed to visit them! At Virunga N.P., Congo you even have to wear a mouth mask when visiting them. I find this a very sensible thing to do.
    As far as we can think back in time, animals and people have always tried to live together, even in an ambiguous way. That people should still have loads more respect for animals? Absolutely YES!
    We should be very, very grateful that there are people out there who are literally willing to give their lives in order to protect our Gentle Giants.

    Having visited them myself in Bwindi, Uganda, I feel very "enriched" and consider myself very lucky as it broadend my mental horizon. And thát knowledge to me is farrrrr more important than any kind of money in the world!

    It has nothing to do with paper money but all with a person's attitude : I also say NO to "tourist attractions" such as doing elephant tours (Thailand) because I believe that as long as tourists keep paying for it, those elephants will continue a life in chains … So I radically refuse doing such things.

    Hope my reaction enriched you somehow.

    And many thanks again to all Gorilla Doctors, safe keepers, etc. for looking so well after the very last few.

    Kindest regards,

  3. Gorillagal says:

    Kurt that is a simplistic response. The genie is out of the bottle on this.There is a lot of money being made out of these gorillas for one thing and, like it or not, thats essentially what's keeping them alive.The people living in thIs densely populated area have to have practical reasons for valuing these animals. If the tourists evaporate eventually so will the gorillas. In light of these findings, more care should be taken such as wearing of masks , enforcing distance rules and helping the people around the park with their health etc

  4. Kurt says:

    I will respond to each of you individually, as your comments carry unique, yet correlating assumptions and fallacies.

    @ Pascal – you devote most of your time speaking about money. When I say "rich" I meant relatively – in the WORLD, just because you have "save" money to travel around the world as an eco-tourist – doesn't exclude you from the world's rich, but I would argue having the money to travel to see the world vanishing species, adds you like many before – to treat the worlds exotic animals as an exclusive club (although past generations would want to shoot them with a gun instead of camera).

    Your argument that it is "better for the environment" than buying a car – well i know this isn't really needed to go there, but the amount of fossil fuels needed for inter-continental travel is pretty high – check those stats out yourself and be aware.

    Now about the actual gorillas – you say that it is safe, because tourists wear masks and if they actually tell the tour organisers that they have a sickness (which many wont because it would obviously exclude them from seeing the animal they came half way around the world to see) – any doctor can tell you that these may be precautions but they alone do not eliminate the risk of transfer of disease. Also – disease that are foreign (being from another part of the world) can effect the populations more as there is no natural resistance built up towards it (as opposed to those carried by local people) – You can see colonial history for examples of this effects of foreign diseases on populations.

    Be aware of the SECONDARY consequences of your actions – they are alot tougher to come to grips with than if you went to a circus, or “bad quality” zoo – yet in the end, just as potentially damaging to the welling of individual animals.

    @gorrilagal – Ah I love this typical anthropocentric argument that you have regurgitated. To say that the health and welling of the species is dependant on the ever perpetual expansion and improvement of the economic (albeit you would consider them dire) conditions of the locals. The way you approach the problem of GORILLA extinction is by centring the humans as the solution. Sigh,.. you say that tourists are the only thing keeping the gorillas alive. but you fail to see that THAT is the problem. The dualistic logic you employ is similar to those who argue that if we stop buying products made in china for slave labour than those poor workers will be out of the job – similar arguments I sure could or similar arguments could be used for sex tourism as well.

    The bottom line is that while these situations may be different – the logic behind how the cause and solution of the problem is conceptualised is the same. The problem is the solution and vise-versa – therefore you are able to legitimise supporting the cause of the problem in the name of “practicality” or “need” to work within the system – not against it. How are things to get better if we aren't even asking the right question? There are ways – as I detail below.

    Now if I can address both you, many other eco-tourists:

    There are more important things in the world than arguing for your "right" to intrude on the daily lives of these INDIVIDUALS of vanishing species. – regardless of how you justify it. I would argue that the suffering of the individual gorilla, and the health of the population comes before our desire to purchase or consume an eco-trip to take picture and tell our friends how wonderful it was to be with such "majestic" creatures.

    This recent finding adds to the fact that there is a clear casual link between ecotourism and detrimental impacts to the physical, mental, or social well being of individuals and groups of these animals – due to the intrusion of foreign bodies (social, biological ansd otherwise). That being said, if we ask ourselves – why do we still go to see these animals if there is EVEN A CHANCE of causing some kind of primary or secondary harm to them or their group, the answer is clear – we do it because it is not about them, but about us (humans). They have simply become objects from which our desires are fulfilled.

    I think if you both of you think about the underlying logic and attempts to legitimise you POTENTIALLY endangering even an individual, you will see that you see these gorillas as not dynamic, living individuals, but static objects – sort of like a those, stuffed in a museum. If you thought of them as individuals, living breathing, not “majestic beings” but individuals – you would have a difficult time shrugging your shoulders and paying into the larger systemic problem ( gorrillagal – human development of the region/ pascal- green washing capitalism) that the demise of these individuals (let alone the lot of them) is linked to.

    If you want to help them – stay home and donate your money to these doctors who try to limit the suffering, and increase the health of individuals. To help save the species – donate money to reduce corruption in the local governments (i can give you some organisations) and other broader ways to addressing the root of the problem. Stop lying to yourselves. By buying the tourist tour , you endanger the welling of the individual and species, AS WELL AS support and justify the fact that the existence of these gorillas hinges on the tourist industry. – don't just shrug your shoulders and pretend that you have to work within the system we have now just because it justifies your ability to go see a living museum, of the most exclusive sort. Be active, if not with your pocketbooks, then with your minds.

  5. gorillagal says:

    Kurt. Oh dear; where to start…what assumptions you make..
    I do donate money to a number of conservation organisations(G.doctors included) and don't trip profanely around world. I haven't seen the gorillas and am unlikely to do so for a variety of reasons. I do have some ambivalence about eco-tourism. I would just love it if people could leave animals alone to get on with their have spaces to exist for their own value and merit."as living, breathing beings" as you put it …Fact is: it isn't happening and it is highly unlikely to happen. You are living in la la land. To consider animals without the context of and intersecting issues of African people is arrogant . It doesn't work. ( As much as I admire Dian Fossey, it may have been that type of thinking that contributed to her isolation and demise) The people who live there mightn't have the sort of middle-class Western educated notions you espouse …most of them are barely surviving and rich Western people moralising about an individual animal's intrinsic worth could mean little , be puzzling or just plain insulting . They have to have their own reasons to value these animals and the ecosystem in which they live .It's their country….maybe it's tourism, maybe it's something else (like valuing the mountains/forest for the water it brings to their crops). Self interest is a great it or not. Bagging me out about also caring for the people living around the park sounds pretty bizzare with a strong whiff of the misanthropic about it… Here's a "broader way" ( to use your jargon ) for you that involves caring about (oh no!!) people AND the gorillas: the best way to get population numbers under control is to raise the status of women, educate them and enable some basic healthcare …which was what I was on about. The virus that infected the gorillas could just as likely come from the people around and working in the the park as much as the tourists. Your comment of "the ever perpetual expansion and improvement of the economic conditions of the locals" is puzzling .It sounds like an ideological rant, is full of false assumptions about what I think and wasn't even mentioned by me…..

    To some extent I empathise withsome of your your notions but there isn't any area on earth now where wildlife is left to itself…we have interfered with every nook and crany of the planet and the population growth of humans is just getting biggger .These gorillas already live in what is essentially a zoo/park type set up…rather large to be sure, but they will always have to be managed. The pressing tide of humanity all around them will see to that …in practical terms that is probably the best that can be hoped for …in fact, that is probably what most of the world's last remaining bits of wild places will be like in the coming years.Maybe humans will self destruct and the planet will go on best as it can species, new climate..who knows? I'm afraid I just don't see us living in some idealistic eden where animals are left alone in huge areas and valued for their intrinsic worth..humans have always interfered and, most, if not all socieities have had some sort of collapse eventually .. most species become extinct too..99% over the history of life on earth..gorillas and humans will most probably be part of that cycle..still : I'll do what I can for both…and ,in that vein, if you care to list links to the organisations that help reduce corruption, I would consider that to be something constructive.

  6. Its ironic that the very people who pay 500 dollars to visit the gorillas and also contribute to the conservation efforts are the very same people who are passing this virus to the endangered gorillas. One wonders whether we should stop gorilla tourism completely!!! this is confusing.

  7. Great posting! Such news are rarely known to the many but everyone should be aware that our wildlife number is decreasing and we need to do something for it.

  8. Judith Avery says:

    Another bunch of I-know-better- than you do palaver! Long-winded,pompous individuals who love to see their thoughts in print ! Spare us !