The HSUS has compiled this concise yet informative summary of various aspects of primate research in the United States, including the species and number of non-human primates (NHPs) used, types of research, housing, and government support for primate research.
Species Used
The term "nonhuman primate" includes monkeys, apes and prosimians, but certain species are more commonly used in research while some are not used in research at all in the U.S. An analysis of federal NHP research grants* for 2000 through mid-2002, conducted by The HSUS, revealed that macaques (primarily the rhesus macaque) are the most commonly used monkeys; this category also includes crab-eating macaques, pig-tailed macaques and others. Additional species used are marmosets, squirrel monkeys and tamarins. The chimpanzee is the only great ape species used in research, and it is estimated that there are more than 1,000 remaining in research laboratories in the United States. Although wild chimpanzees are listed as endangered under the Endangered Species Act, they have been "split-listed" so that captive individuals are listed as threatened and therefore continue to be used in research. The chimpanzee is the only species with such a split-listed status.
Number of NHPs Used in Research
According to statistics provided by the U.S. Department of Agriculture, 69,990 NHPs were used in research in the US during 2007; an increase of 11 percent since 2006 and the highest number of NHPs used since the USDA started tracking statistics in 1973. Furthermore, this number represents only those NHPs used for research and does not include NHPs used for breeding purposes or those simply being held for research. If one uses the most recent information available, the total number of primates in laboratories in the United States, including those used for breeding or being held, is approximately 112,000. A number of institutions have expanded their primate facilities in the last decade. Recent events and publications indicate that the increase in the use of NHPs for research is expected to continue. Finally, China is greatly increasing primate use and export and is establishing itself as a global force in the NHP research industry. The low cost of conducting research in China is one aspect that is appealing to countries such as the United States.
Research and Procedures
Nonhuman primates are used extensively in various areas of research including, but not limited to, human pathologies and diseases (such as AIDS, Parkinson's disease and hepatitis), psychological disorders (such as depression and anxiety), toxicology, transplantation, nutrition (including infant nutrition), dentistry, biological warfare and biodefense, drug abuse, vaccine and other drug testing, and cloning. During infectious disease research, monkeys are infected and the resulting disease is allowed to progress, which can result in symptoms such as severe diarrhea, dehydration, wasting and anorexia, In some cases, the primates receive no intervention and ultimately die from the disease being studied.
Nonhuman primates are also subjected to a wide array of invasive procedures, some of which cause severe pain and distress. These procedures include long-term restraint (as long as several days), multiple surgeries, food and water deprivation, lethal dosing, irradiation, blood and tissue sampling, and much more. Some procedures involve handling by humans in which leather gloves are used to wrestle the animals out of their cages
Overall, the majority of research conducted on nonhuman primates is invasive[1]. For example, an analysis of monkey research revealed that 77 percent of the grant projects for the years 2000-mid 2002 were invasive, 12 percent were minimally invasive, 8 percent were noninvasive, and 3 percent could not be categorized.
Housing
Nonhuman primates are social animals and whether or not they are housed with other animals is crucial to their well-being. The HSUS has tried to determine from grants and publications how NHPs are housed, but this information is often not readily available. Animal Welfare Act standards require "provisions to address the social needs of nonhuman primates of species known to exist in social groups in nature" (section 3.81 (a)). Macaques, great apes, marmosets, and almost all other species of NHP used in research live in social groups in the wild. The committee at each institution that oversees animal research (known as the Institutional Animal Care and Use Committee—or IACUC) can provide an exemption for "scientific reasons"—we believe that such exemptions are used without adequate justification.
According to the APHIS [Animal & Plant Health Inspection Service] Animal Care Report of Winter 2001, "65 percent of primates in research are pair/group housed, with only 13 percent having no contact with other primates." But these numbers are misleading because the survey included breeders, so the percentages do not convey the housing conditions of the NHPs actively used in research.
Due to the type of research being conducted—particularly infectious disease research—monkeys used in active protocols are often housed in isolation (single housing). Baker (2007) conducted a survey of 22 primate institutions housing approximately 36,000 primates and compared social housing of all primates with those used in research protocols. It was found that while 73 percent of the NHPs were socially housed, only 46 percent of those used for research purposes were. Single housing has been shown to lead to depression, withdrawal, frustration, self-biting, hair pulling, rocking and other psychotic behaviors (Bayne et al, 1992; Bayne et al, 1995; Bellanca, R & Crockett, C, 2002; Jorgensen et al, 1996; Lutz et al, 2003; National Research Council, 1998; Rommeck et al, 2009).
The USDA, the agency responsible for implementing and enforcing the AWA, has set standards for cage size requirements. For example, a monkey weighing 3-10 kilograms (6.6-22 pounds) is required to have only 4.3 square feet of floor area, and a height of 30 inches. Infant primates can be housed in isolettes (similar to an incubator), if they are very young. Infant monkeys are used in invasive research just as adults are.
Stainless steel cages built for individual monkeys are similar across laboratories. All cages are built with three major considerations in mind: ease of cleaning, access to the monkey, and the ability to fit more animals into a room. The typical cage is enclosed on three sides and the top, bottom and front are made of bars. Monkeys in individual cages have been known to reach out and hold the hand of a neighbor; this may be the only contact that a monkey will have with another. Some monkeys are aggressive to neighbors and reaching around may result in bitten fingers.
Psychological Well-Being
It is important to note that the Animal Welfare Act calls for a "physical environment adequate to promote the psychological well-being of primates" [section 13(A((2)(b)]. The USDA standards regarding this issue require that research institutions (as well as other entities regulated under the AWA) "develop, document, and follow an appropriate plan for environment enhancement adequate to promote the psychological well-being of nonhuman primates." The plan must address social grouping (discussed above), environmental enrichment and special considerations.
Environmental enrichment refers to enrichment of the physical environment to promote species-typical behavior. Examples include perches, objects that promote feeding/foraging, swings, and other manipulanda. "Special considerations" refers to the needs of infants/juveniles; great apes weighing over 110 pounds; those showing psychological distress; those being used in research that requires restricted activity; and individually housed primates unable to hear or see others.
It has been 23 years since Congress mandated that psychological well-being of nonhuman primates be addressed. The USDA has continually failed to meet this mandate, essentially leaving laboratories, and other entities to self-regulate. The agency did adopt standards in 1991, but five years later the USDA itself determined that these standards needed to be clarified and made enforceable, which led to the issuance of a draft USDA policy in 1999. While the draft policy would have led to improvements, those regulated under the AWA (including the biomedical industry) managed to stop the regulatory process. As a result, there have been no regulatory changes and the legal standards regarding psychological well-being remain weak and difficult to enforce.
In her recent study, Baker (2007) found that changes to enrichment programs were most often prompted by regulatory or accreditation visits. This supports the argument that improved regulations and their enforcement will improve conditions for primates in laboratories, as Congress intended with passage of the 1985 AWA amendments. Clear standards that can be properly enforced will prompt these facilities to provide their primates with improved care or they could face financial consequences.
Government Support for Primate Research
Recent analyses by The HSUS have shown that the federal government spends over a billion dollars per year on primate research. The eight National Primate Research Centers alone received $1.2 billion in 2007. The NPRCs were established by Congress in 1960 to provide an infrastructure and resources to investigators conducting primate research. Supported by the National Institute of Health, the centers, according to their annual reports, have more than 27,500 primates of 20 different species. There are currently eight NPRCs:
- California (Davis, Calif.)
- New England (Southborough, Mass.)
- Oregon (Beaverton, Ore.)
- Southwest (San Antonio, Texas)
- Tulane (Covington, La.)
- Washington (Seattle, Wash.)
- Wisconsin (Madison, Wis.)
- Yerkes (Atlanta, Ga.)
Additional government-funded primate resources include chimpanzee centers at the University of Texas MD Anderson Cancer Center, University of Louisiana at Lafayette New Iberia Research Center, Alamogordo Primate Facility and Primate Foundation of Arizona; the Caribbean Primate Research Center; a squirrel monkey colony at the University of South Alabama; and a baboon research resource at the University of Oklahoma Other resources in the U.S. include private breeding facilities, some of which receive federal funding.
Importation of Primates on the Rise
We have seen a vast increase in the number of primates imported from other countries to facilities in the United States. In 2006, 26,638 primates were imported into the US; a 44 percent increase over 2004 (IPPL, 2007). Three companies were responsible for more than 75 percent of all of these imports: Covance (11,738), Charles River Laboratories, Inc (5,359) and Shin Nippon Biomedical laboratories (SNBL) (3097); all serve as contract testing laboratories. Some companies own, at least in part, facilities in the originating countries as well. These facilities often capture monkeys from the wild and breed them. Cynomolgus macaques made up 92 percent of the primates imported in 2006, followed by rhesus macaques, marmosets, squirrel monkeys, other macaques, and other primates. Half of the imported primates were from China.
The Value of Primate Research is Challenged
The value of research on nonhuman primates has been called into question, particularly as the European Union is considering an end to the use of wild-caught primates and great apes. One current debate is in regards to the use of nonhuman primates for HIV research. It has been widely accepted by the scientific community that the chimpanzee model for HIV was a failure because chimpanzees infected with HIV do not progress to AIDS (Bailey, 2008; Nath, Schumann and Boyer, 2000, and others). A former director of Yerkes National Primate Research Center, Thomas Insel, noted in 1999 that 15 years of HIV research on chimpanzees produced little data relevant to humans, adding "I can't tell you what it is that those studies have given us that has really made a difference in the way we approach people with this disease" (Smaglik, 1999).
As scientists steered away from the chimpanzee model for HIV, attention turned to the use of monkeys, such as the rhesus, pigtail and cynomolgus macaques. After years of pursuit and tens of millions of dollars, the failures of the monkey models are becoming increasingly evident, with AIDS patient advocacy groups calling for an end to funding for this type of research and increased funding for prevention and other avenues (Quinn, 2008). As Bailey noted in his review of HIV vaccine research, over 85 vaccines have gone to human clinical trials and all have failed, with some actually causing increased likelihood of HIV infection.
As changes to laws are considered internationally and primate research is more closely scrutinized, the value of nonhuman primate research will be increasingly challenged.
[1] The following practices would be considered as invasive: inoculation with an infectious agent, surgery or biopsy conducted for the sake of research and not for the sake of the nonhuman primate (NHP), and/or drug testing. "Minimally invasive refers to a minor procedure, such as venipuncture,. Finally, "noninvasive" indicates that the animal received no physical or psychological insult.
References
Bailey, J. (2008) An assessment of the role of chimpanzees in AIDS vaccine research. Alternatives to Laboratory Animals, 36(4):
Baker, K. (2007) Enrichment and primate centers: closing the gap between research and practice. Journal of Applied Animal Welfare Science, 10(1): 49-54.
Bayne K, Dexter S, Suomi S. (1992) A preliminary survey of the incidence of abnormal behavior in rhesus monkeys (Macaca mulatta) relative to housing condition. Lab Anim 21:38–46.
Bayne K, Haines M, Dexter S, Woodman D, Evans C. (1995) Nonhuman primate wounding prevalence: a retrospective analysis. Lab Anim 24:40–44.
Bellanca R, Crockett C. 2002. Factors predicting increased incidence of abnormal behavior in male pigtailed macaques. Am J Primatol 58:57–69.
International Primate Protection League (2007, April) U.S. primate imports spike. Retrieved December 9, 2008 from http://www.ippl.org/2007-us-primate-imports.php
Jorgensen, M.J., Novak, M.A., Kinsey, J., Tiefenbacher, S. & Meyer, J.S. (1996) Correlates of self-injurious behavior in monkeys. XVIth Congress of the International Primatological Society/XIXth Conference of the American Society of Primatologists, Abstract No. 767.
Lutz, C., Well, A. and Novak, M. (2003) Stereotypic and Self-Injurious Behavior in Rhesus Macaques: A Survey and Retrospective Analysis of Environment and Early Experience. American J Primatol 60:1-15 .
Nath, B.E., Schumann, K.E., and Boyer, J.D. (2000) The chimpanzee and other non-human primate models in HIV-1 vaccine research. Trends in Microbiology, 8 (9): 426-431.
National Research Council (1998) The Psychological Well-Being of Nonhuman Primates. Washington: National Academy Press.
Quinn, A (2008, March 25) Government sees overhaul of AIDS vaccine effort. National Post, Retrieved December 31, 2008 from http://www.nationalpost.com/life/health/story.html?id=25cf4ab5-b4f1-4dea-9c38-65054b88a180&k=80580
Rommeck, I., Anderson, K., Heagerty, A., Cameron, A., McCowan, B. (2009) Risk factors and remediation of self-injurious and self-abuse behavior in rhesus macaques. J Appl Amin Welf Sci 12(1):61-72.
Smaglik, P. (1999, August 16) AIDS vaccine researchers turn from chimps to monkeys. The Scientist, 13(16). Retrieved December 29, 2008 from http://www.lclark.edu/org/ncal/objects/AIDvaccine.htm
* The HSUS retrieved this information from the National Institutes of Health (NIH) Office of Extramural Research's Computer Retrieval of Information on Scientific Projects (CRISP).
