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William T. Talman, MD

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The Benefits of Studying Chimpanzees

Posted: 08/08/2012 4:56 pm

Samiha cleared the ruffled hair from her baby Mwaka's face as she quietly gazed down at him despite the imminent threat. Mwaka's dad had died several weeks ago. It was quite possible that either she or Mwaka would succumb to the same disease before Mwaka reached adulthood. In a neighboring village, Tabitha and her husband Jean Paul had both died recently, so the threat was everywhere and it was real.

Mwaka's father died after becoming infected with Ebola, a viral disease for which there is no cure and for which the only hope is prevention. The disease is one that we often consider in rather remote terms in that it is rarely seen in the United States but occurs most often in equatorial Africa. A recent outbreak in Uganda has already claimed 16 lives.

Ebola's mortality rate, upwards of 90 percent, makes it a death sentence for most who contract it. The disease affects both humans and great apes. In fact, it is arguably even more of a threat in great apes, with estimates that Ebola has killed one third of the world's gorillas as well as many chimpanzees. Humans with the disease are subjected to fevers, chills, pain nearly everywhere, vomiting, loss of appetite, trouble breathing, severe headaches, confusion, seizures, coma, bleeding, and, terminally, failure of multiple organ systems. Modern medical scientists hope to find a way of preventing this dreadful condition.

Indeed, by studying captive chimpanzees scientists are making progress towards an Ebola vaccine that they hope to test in wild apes and ultimately use to protect apes and humans from this disease. To do that, however, research chimpanzees must first receive injections of the vaccine and withdrawals of blood to test their immune response and ensure that the vaccine is safe. But therein lies the rub. Animal rights advocates have petitioned Congress repeatedly over the years to outlaw studying great apes, which include chimpanzees, gorillas, bonobos, and orangutans, in any such experiments even if the apes themselves might benefit from the study. Recently, the Senate Environment and Public Works Committee passed the Great Ape Protection and Cost Savings Act (GAPCSA), which would prohibit invasive research on great apes. The bill defines "invasive research" so broadly as to ban the collection of a blood sample or the performance of non-invasive imaging studies such as magnetic resonance imaging (MRI) or positron emission tomography (PET), procedures performed daily in humans.

Very few studies involving chimpanzees are actually carried out in the United States. When there are alternatives to chimpanzee research -- or any research using animal models, existing laws and regulations already require that scientists use them. Nonetheless, scientists believe chimpanzee studies aimed at improving human and animal health should be permitted in situations where other animal models or other means of testing are inadequate. The results of medical research on animals are most likely to be applicable to humans if the most appropriate animal model is chosen for the studies. For some diseases, that model is the chimpanzee, which shares many physiological features with humans. For example, the chimpanzee, unlike other animals, shares specific immune proteins with humans that make it uniquely suited for studies designed to develop monoclonal antibodies used to treat cancer and autoimmune diseases. And, while scientists themselves have reduced the number of great apes involved in studies, they worry that removing the possibility of studying any given animal model will weaken their fight against diseases that afflict humans and other species.

Because of the continued debate over the scientific use of chimpanzees, the eminent Institute of Medicine (IOM) in the United States recently assessed the necessity of studying chimpanzees in biomedical research. The IOM committee concluded that chimpanzees have made significant contributions to public health and may still be necessary to combat diseases that are far more common than Ebola. One such disease is hepatitis C, a chronic illness that may lie silently in as many as 30 percent of Baby Boomers for whom the ravages of liver failure and even cancer await. Much has already been learned about hepatitis C studies in chimpanzees, and these animals could help further in the continued quest for a vaccine against the disease -- just as they have for hepatitis A and hepatitis B.

Perhaps most importantly, the IOM indicated that research chimpanzees should be available in the event of a new, emerging, or re-emerging disease. With the outbreak of HIV/AIDS in the mid-1980s, chimpanzees played an important role in helping scientists understand transmission of and immune response to the virus. As new contagions evolve and spread, scientists may once again have to turn to animals like chimpanzees to understand the disease and develop and test therapeutics.

But proponents of GAPCSA, largely ignoring the IOM report and responding to well-financed lobbying efforts by animal rights groups, continue to advocate the passage of the bill by Congress. Although the bill contains a contingency clause that could allow great apes to be used in the event of a disease outbreak, the proposed solution is impractical. If the legislation is passed, it could be months before scientists gain access to the animals necessary to develop a vaccine or treatment if faced with a new disease. Given that the stated goal of prominent animal rights groups is to completely eliminate the use of any animals in research, there will be those fighting access to great apes for such studies even in the face of a worldwide epidemic. While scientists wait for approval, human lives could be lost.

So, while Samiha tends to Mwaka not knowing what awaits them both, our legislature moves inexorably toward a law that would limit options for developing therapeutics and vaccines -- vaccines that could protect apes like Samiha and Mwaka and their human cousins Tabitha and Jean Paul.

 
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