Race B et al. 2014, Chronic wasting disease agents in nonhuman primates (Emerg Infect Dis 20(5):833-837)

This short Dispatch from the NIAID Rocky Mountain Laboratories in Hamilton, Montana, reports the long-term follow-up of primates exposed to chronic wasting disease (CWD) prions from deer and elk. Squirrel monkeys were highly susceptible by both injection into the brain and by mouth, while cynomolgus macaques showed no infection after more than ten years. The authors read this as a substantial species barrier and a probably low risk to people, while still advising that exposure to possibly contaminated tissue be minimised. It extends the group's earlier 2009 report in the same journal (Race et al., Susceptibilities of nonhuman primates to CWD), and it is the macaque result that the 2026 Calgary-led study challenges. Information only, not medical advice.

Key facts

  • Citation: Race B, Meade-White KD, Phillips K, Striebel J, Race R, Chesebro B. Emerg Infect Dis 2014;20(5):833-837, DOI 10.3201/eid2005.130778, a Dispatch in the May 2014 issue; all six authors are at NIAID, NIH, Hamilton, Montana.
  • All 13 squirrel monkeys inoculated into the brain developed disease, and 11 of 12 given CWD by mouth (about 92 percent) did too; oral incubation averaged about 68 months, with the last animals euthanised at 80 and 107 months.
  • Disease signs in squirrel monkeys were subtle, mainly gradual weight loss, and the one orally exposed animal that stayed well at 108 months was one of three with a particular PRNP octapeptide-repeat genotype.
  • Brain and lymphoid tissue findings did not differ significantly by route; abnormal prion protein was found in the spleen of 46 percent of intracerebrally and 60 percent of orally exposed monkeys.
  • Cynomolgus macaques (15 animals: 9 oral, 6 intracerebral) showed no prion infection by immunoblot or immunohistochemistry in the 7 that had been tested, and none had developed disease after more than 10 years.
  • A squirrel-monkey-adapted CWD agent passed into two further squirrel monkeys caused disease at 23 to 24 months, over 11 months sooner than in the donor animal, showing the agent was still adapting; macaques given that adapted agent were also disease-free at 72 months.
  • The authors judge the macaque result to show a substantial species barrier, estimate that any macaque incubation would exceed 18 years, and conclude CWD is likely a low risk to humans while advising minimal exposure.
  • Funding came from the NIH/NIAID intramural research program.
  • The 2009 report from the same group had 11 of 13 intracerebrally inoculated squirrel monkeys sick at 33 to 53 months and macaques healthy at about 70 months, so the 2014 paper adds roughly four more years of follow-up.

Timeline

  1. 2009Earlier report from the same group published in Emerg Infect Dis 15(9), with macaques healthy at about 70 months.
  2. 2014Dispatch posted online on the CDC EID site (page date 17 April 2014; no received or accepted dates are given).
  3. 2014Dispatch appears in Emerg Infect Dis volume 20, number 5.

Last checked 1 November 2026

Sources for this page