Primatology.net

In the past, we have covered how pathogens like Ebola virus and Anthrax bacteria are causing thousands of deaths among great ape populations in Africa. In this post I will introduce another pathogen, one that causes Yaws disease, that is having severe affect on the reproductive success of gorillas, as reported by Florence Levréro et al. in the American Journal of Physical Anthropology. The paper is titled, “Yaws disease in a wild gorilla population and its impact on the reproductive status of males.”

A brief side-note, Florence was a co-author on the gorilla susceptibility to Ebola paper I reported on last July… so to say she knows a thing or two about wild gorilla populations and current pathogens affecting them is an understatement. And, before I get into the details of the paper, let me preface with some information on Yaws. Yaws is a tropical infection of the skin, bones and joints caused by the spirochete bacterium Treponema pertenue. This disease is similar to sphyllis. Symptoms of Yaws include:

• The disease is transmitted by skin contact with infected individuals or eye gnats, the spirochete entering through an existing cut or similar damage.
• Within ninety days (but usually less than a month) of infection a painless but distinctive ‘mother yaw’ ulcer appears.
• These tracts heal with keloid formation which can cause deformities, disabilities and limb contractures.
• The bone lesions caused are periostitis, osteitis, and osteomyelitis, damage to the tibia can lead to a condition known as sabre shins.
• In a very few cases a condition known as goundou is caused where growths on the nasal maxillae can result in extensive and severe damage to the nose and palate.
• Examination of ancient remains has led to the suggestion that yaws has affected hominids for the last 1.5 million years.

In the 1950s, Yaws was the center of attention of worldwide treatment program which sought to eradicate the disease. The program was successful among humans. So successful that the program managed to reduced the an estimated 50 million Yaws patients to nearly zero. But the disease is on the rebound as reported by the World Health Organization, just last month. According to Wikipedia, where I paraphrased all this information from, “Yaws is on the rise again, with roughly a half a million sufferers, mostly in poor, rural areas.”

Yaws’ growth among human populations, in Africa, is being transmitted to great ape populations, like the gorillas studied here, through flies. Flies are often found in places were there is overpopulation, caused by human development and deforrestation. Ultimately, as both Florence and I argued before, Yaws, Ebola, and Anthrax are products of human encroachment on gorilla territories. The acquired immune systems of these great apes did not have previous exposure to these pathogens, and made them ultimately more susceptible to these introduced communicable diseases.

Okay that being said, the authors studied how Yaws is affecting gorillas in the wild, specifically among a gorilla population in the Republic of Congo. The scope of the paper was limited to studying the reproductive success of gorillas with Yaws, and any conclusions drawn from that could indicate whether gorillas decided on mating or not mating with an individual infected with Yaws.

From what I can tell, and I am not completely sure about this, Yaws isn’t fatal… so they didn’t study the mortality. The bacteria seems to just manifest itself as lesions and causes deformities… but I don’t know if those lesions can get infected and compromise the immune system of the individual with Yaws.

Of the 377 gorillas, in population that was studied, about 64 of them had Yaws. That’s over 17%! As reported in the abstract of the paper, the trends in sex and age of the gorillas are as follows:

“Lesions were more prevalent among males than females above 8 years old. This sex-bias prevalence could result from the behavioral characteristics of males through a greater exposure to wounds. Lesions were also more prevalent in unmated adult males (either solitaries or those living in nonbreeding groups) than in males leading breeding groups.”

Here is an image, from the paper, of three infected gorillas with Yaws. Click the image for a higher resolution photo. In my opinion, this disease renders gorillas to look like ghastly gouls.

As I skimmed the paper, before I read it all, I wondered if there outward appearance affected their sociability?

In my mind the authors answered that question. They provided several examples that sealed the deal for me, but they decided on reporting their observations and conclusions modestly,

“Proportionally more unmated adult males presented lesions than did males leading breeding groups. In addition, breeding groups included no silverbacks at an advanced stage of the disease. This suggests that yaws is related to the competitiveness and vigor of males. Two complementary hypotheses can be formulated. Either affected males exclude themselves from reproduction because they do not have enough strength to compete with other males to gain and/or retain females, or they are not or are less chosen by females. Sexual selection by females could influence their decision to leave a group and their choice of group to integrate…

Since breeding groups led by affected and nonaffected silverbacks had similar numbers of immatures under 6 years old, these results suggest that the disease could have an impact on the reproductive success of males only at advanced stages….

For example, we can report the case of a skeletal adult female with a completely destroyed nose who became solitary after residing in a breeding group for at least one and a half years. During her seven subsequent visits to the clearing before disappearing, solitary males or adolescent males from groups that she approached rejected her and behaved agonistically towards her. Both a solitary life for a female gorilla and the rejection of an adult female by males are very uncommon. Given the cognitive abilities of primates, the question of social discrimination based on how gorillas perceive their partners with skin lesions warrants further investigation in the future. “

This is a double whammy for gorillas, actually make that a quadruple whammy. Not only do we have to worry about the regular three headaches such as deforestation, poaching and fatal pathogens like Ebola; but now conservation efforts are impacted because this new pathogen is affecting reproduction and gorilla social group cohesivity.

Although Yaws can be treated with several doses of antibiotics, how can people deliver that to wild gorillas? Instead, the authors advocate, as was done in the Ebola paper, that the pharmaceutical industry needs to roll up their sleeves and start working on vaccines for these diseases. There’s a lot at stake here.

Again, many thanks to Betsy, who sent me a copy of the Science article over-viewing some of the ethics and current debate topics about the use of chimpanzees in biomedical research in the United States. The topic and scope of this piece is very poignant, it tackles two critical and morally charged topics in our lives: ecology and conservation versus public (human) health and biomedical research. The author successfully outlined many of the pros and cons behind both sides of the debate. I did appreciate what the article addressed, however it was a bit jumpy in organization. I will do my best to organize it in a more clear manner.

As that article points out, currently the United States of America is the only nation that continues to use chimpanzees for biomedical research. The last nation to use chimps, Japan, stopped using them in October of 2006… so it isn’t like the US is the only one that has been doing this for a long time. Over the last 100 years, chimps have proven to be a remarkable model organism to use for this type of research, one such example is the use of chimpanzee were critical in developing a novel vaccine for hepatitis B, a very lethal virus that has infected over 2 billion people. Their continued use in biomedical research has focused on developing a HIV vaccine, an equally devastating disease.

But, the future of HIV research, or other research dependent on chimpanzees as a model system is in jeopardy. The NIH, or National Institutes of Health, is the main supporter of biomedical research with use of chimpanzees. However, it has imposed a moratorium or ban on further breeding of chimps used in federally supported research. This has currently caused a significant drop in the number of chimps available for research, nearly 400 less chimps in the last ten years. A smaller supply of chimps creates a dramatic strain on the success and thoroughness of biomedical research. Furthermore, anyone with any background in genetics, would know a larger and more diverse population of breeding animals creates more healthy offspring. Of the remaining 1,000 chimps only 200 females are capable of breeding. This is the one main issue many proponents of biomedical research are concerned about, with fewer number of chimps available, their current and future research will be severely impacted… ultimately threatening the future of human health.

The NIH has imposed a ban on future breeding of chimps because a subdivision of the institution determined that a smaller population is more fiscally maintainable, and not because of the ethics and morals of using chimpanzees in biomedical research. But that hasn’t hampered the campaigns against this aspect of research. Someone who uses chimps and monkeys in biomedical research, specifically AIDS research, Jonathan Allan, of the Southwest National Primate Research Center in San Antonio, Texas summarizes the ethical catch 22 one must make,

“You shouldn’t be comfortable with [this type of research]. You should have to search your soul as to the balance between the research and the good that comes from it and the bad part, which is what happens to the animals. It’s a difficult place to be. If you’re comfortable with it and you don’t have any problem with it, that’s a problem.”

Norman Letvin, an immunologist at the Beth Israel Deaconess Medical Center has also done AIDS vaccine experiments with chimpanzees and monkeys. He further comments on finding a clearly established set of rules and compromises that appease to ethical concerns as well as accomplishing successful research,

“These kinds of discussions need to be focused on very specific questions about a particular study.” Letvin no longer experiments on chimps and says he can’t see any compelling reason today to use large numbers of them for biomedical research. But he stresses, as do many other investigators, that this animal model has led to “enormously valuable” medical advances in the past and may well in the future.”

The crux of the campaign against using chimpanzees in biomedical research lie on several different foundations. Primarily, there is a large concern that this endangered species is disappearing from its natural ecosystem at an alarming rate. Most people would rather see efforts be made in conserving the species rather than infecting them with lethal pathogens and dosing them on drugs. I side to this issue just as much, if not more, than the use of them in biomedical research. Secondarily, as most of you may know, chimps are our closest living relatives. Genetically they are remarkably similar to us, and behavioral research has also shown that they have complex personalities, incredible intelligence, and a depth of familial relations that rival our own. To subjugate this keen species to invasive research that affects their lives in such deleterious manners is torturous.

Should the moratorium on chimp breeding be lifted, then as the article points out, that puts a burden on Chimp Haven and other non-profit chimpanzee rescue centers to support the ‘used’ chimpanzees. This draws a fine line in over what to do. It seems like both we as humans and they as chimps are screwed either way… Have we become so insensetive that we disregard our distant evolutionary cousins as if they were biological trash? If we do continue to use chimpanzees then how will we support them, and can we find an ethical common ground? UCSD’s Varki, Gagneux, and primatologist James J. Moore offer an interesting suggestion. They advocate in a 2005 commentary in Nature, titled, “The ethics of research on great apes,” “that chimpanzees should be used only in experiments that could also be done ethically in humans. That would rule out vaccine studies that intentionally infect animals with potentially harmful viruses, for instance.”

I would like to see researchers drop relying on chimpanzees for any type of invasive research, be it biomedical or psychological… we should focus our efforts in creating alternatives, such as supporting the Virtual Cell or other situations where the lab animals do not endure suffrage. We do have the technology to simulate diseases, and can focus on developing complex computer models that can figure out all the possibilities. Why don’t we do that? …Something to ponder about.

Some related and useful links on the history and campaign againt chimpanzees in biomedical research:

• NIH Chimpanzee Management Program (ChiMP) for Biomedical Research Chimpanzees
• Testimony on Biomedical Research and Chimpanzees by John Strandberg, D.V.M., Ph.D., National Center for Research Resources National Institutes of Health
• Tell the Government to Stop Funding Biomedical Research & Testing on Chimpanzees

John Cohen has contributed a little news focus in the current issue of Science, that I’d love to get my hands on. Unfortunately, my current university doesn’t have access to the latest issues of Science and from what I can read of Cohen’s news item, it really sparks my interests! It is titled, “The Endangered Lab Chimp” and here’s all you get as a visitor,

“A decline in the number of chimpanzees available for biomedical research in the United States has sparked a growing debate on the opportunities and costs of studies with our closest relatives.”

For me, this is a really heated debate. I personally have seen and read about some critical research done on chimps that have advanced biomedical research and in the long run bettered human lives… but I really am torn on the benefits versus the costs of subjugating chimpanzees to confinement and invasive medical torture.

I’d love to see what Cohen has to summarize about this debate and how the medical and biological communities are siding. Anyone with access to Science care to share it with me? You can email it, or upload it and link it up by commenting to this thread. Thanks!

Photo by Amy Fultz

Despite all residents receiving vasectomies prior to arrival at Chimp Haven, the caregivers stumbled upon a surprise yesterday morning… a healthy baby chimpanzee in the arms of her mother.

Chimp Haven reports that their next step is to determine paternity and address the failed vasectomy.

This is an interesting occurrence given the recent management allegations Chimp Haven has faced (discussed in previous posts/comments from Kambiz and DAB). The chimps (Teresa and the father, unknown at this time), sound like they are doing well at Chimp Haven, as successful breeding has generally been seen as a sign of good behavioral and physical health.

Earlier this week, my coworker, Betsy, who also blogs here at Primatology.org, handed me a short little press release. The press release discussed the role of anthrax in the devastating die-off of great apes in what was once one of the most dense areas of primates in the world. It is titled, “Sudden Great Ape Die-Off in the Periphery of the Dja Biosphere Reserve,”and comes by way of Patrick Guislain and Jef Dupain who later published, in the American Journal of Primatology (AJP), this paper, “Anthrax in Western and Central African great apes.” Here’s the abstract the paper,

“During the period of December 2004 to January 2005, Bacillus anthracis killed three wild chimpanzees (Pan troglodytes troglodytes) and one gorilla (Gorilla gorilla gorilla) in a tropical forest in Cameroon. While this is the second anthrax outbreak in wild chimpanzees, this is the first case of anthrax in gorillas ever reported. The number of great apes in Central Africa is dramatically declining and the populations are seriously threatened by diseases, mainly Ebola. Nevertheless, a considerable number of deaths cannot be attributed to Ebola virus and remained unexplained. Our results show that diseases other than Ebola may also threaten wild great apes, and indicate that the role of anthrax in great ape mortality may have been underestimated. These results suggest that risk identification, assessment, and management for the survival of the last great apes should be performed with an open mind, since various pathogens with distinct characteristics in epidemiology and pathogenicity may impact the populations. An animal mortality monitoring network covering the entire African tropical forest, with the dual aims of preventing both great ape extinction and human disease outbreaks, will create necessary baseline data for such risk assessments and management plans.”

The authors of the AJP paper used PCR, a way of amplifying genes, to screen for the presence of Anthrax genes from the bodies of dead primates. In their paper they tabulate the data from their assays, and show how they can differentiate between other apathogenic variants. They make a very convincing argument on the importance of tracking down the impact of anthrax because of its potential to lie dormant in the ground and infect for hundreds of years. That is crucial considering our best interests are to conserve and preserve these species for as long as we can; we don’t want another factor affecting that main goal.

All throughout last year we posted on how a virus, Ebola, has been decimating primates in the Congo… but we largely were unaware of the impact of other pathogens that are contributing to this die-of. As the authors of this paper advocate there is a necessity to understand other key players that are affecting the conservation of great apes.

The Canadian blood donor form has a new question, “Have you, in your past or present job, taken care of or handled monkeys or their body fluids?” The Canadian Press reports that it’s being used as a precautionary measure to avoid the Simian Foamy Virus (SFV), thought to be contracted through bites and scratches from monkeys, chimpanzees, and baboons (which is interesting since they sum up these primates as “monkeys” in the form’s question).

Doris Kaufmann of the Canadian Blood Services, Calgary Office:

“Simian foamy virus is actually considered a retrovirus. Retroviruses that are known to affect humans do include HIV and others that we routinely test for.”

While there are no known cases of humans becoming sick from SFV, the precaution is taken in the event that the disease has a lengthy incubation period. The new question is estimated to eliminate less than 1,000 potential donors – a lower cost than testing all donated blood for the virus.

In a paper from the November issue of Genome Research, researchers from the Division of Biostatistics and Bioinformatics at the National Health Research Institutes are closely examining the genetic variation between humans and chimpanzees (I don’t have access to it yet – free online access is available to Genome Research articles 6 months after publication, but the article highlighting the paper is available in the China Post). Chimps don’t suffer from some of the debilitating diseases that humans can endure, so looking at our genetic differences may lead to information that might enable scientists to alter gene expression and therefore the environment in which these diseases thrive. More information on gene expression is hoped to play a role in finding cures for Alzheimer’s disease, AIDS, and hepatitis B and C.

(Photo courtesy of Bristol Zoo Gardens)

With a little help from clomifene (a drug that women have been using to aid in ovulation), Salome, a western lowland gorilla, carried a baby to term and gave birth on December 15th. The 30-year-old gorilla from the Bristol Zoo was mating, just not successfully conceiving. Veterinarians reported that she had a diminished ovarian reserve and after gynecological consults, Salome was given a drug to stimulate ovulation. Three months later she became pregnant.

Bristol Zoo deputy director, Dr. Bryan Carroll reported that,

“Female gorillas, like their human counterparts, find conceiving more difficult as they get older, so zoos may now be able to give some of their important breeders a helping hand. Being able to treat female gorillas with human fertility drugs is potentially a very important breakthrough.”

It will be interesting to see where this goes and what debates, if any, it sparks in zoo science over the next few years.

Six out of 21 monkeys in the Shirakami Mountains tested positive for B virus according to the Daily Yomiuri. In a statement issued by Kazutaka Osawa of Nagasaki University, the infected monkeys (between 3 and 13 years old) were captured near residential areas between July and November. The transfer of the disease to humans usually occurs through bites and scratches by monkeys.

Bad news for humans as 80% of those who have contracted the B virus and go untreated die from complications. Since 1932, approximately 40 human deaths have been reported in relation to monkey bites.

About six days ago, I shared with y’all some horrific news that 5,000 or so gorillas have lost their lives to Ebola.

For me it has been a hard number to grasp. But, some bittersweet news is coming out of Rwanda about how mountain gorillas are too isolated to contract the disease… for now. The news article that reported this, “Rwanda: ‘Gorillas Safe From Ebola‘,” writes,

“Mountain gorillas in Virunga Park do not face a threat from Ebola, a senior official with Rwanda Office of Tourism and National Parks (ORTPN), has said. Fidel Ruzigandekwe, the Executive Director of Rwanda Wildlife Authority, a department under ORTPN, said on Monday that the primates are not endangered as those in the Congo basin region…

…The Congo basin which covers DRC, Congo-Brazzaville, Gabon, Equatorial Guinea, Cameroon, and the Central African Republic is located about 2000 kilometres from the Virunga Mist, home to hundreds of the Mountain gorillas.

Ruzigandekwe said there are both regional and international efforts to prevent the deadly disease from spreading to the apes.

He said that one of the existing efforts was that of the Mountain Gorilla Health Contingence Plan (MGHCP), which is shared by the three countries, which checks for possible disease outbreaks in the Virunga Mist.”

This is good news, for now, but we cannot rely on the physical barrier, being the Virunga mountains, as the sole deterent of this highly communicable and virulent disease. Knowing that over 5,000 gorillas lives have been lost, a much more smaller, denser, fragile and immunologically isolated population of Mountain gorillas is more at risk than the populations of Western lowland gorillas that are facing this horrible disease.