Encephalomyocarditis Virus Infection in Raccoons (Procyon lotor)

• Published in: Journal of zoo and wildlife medicine 1994-06, Vol.25 (2), p.233-239
• Main Authors: Zimmerman, Jeff J., Hill, Richard E., Smith, Kirk E., Kneeland, Brad L., Platt, Kenneth B., Hill, Howard T., Beran, George W., Clark, William R., Miller, Lyle D.
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Blood; Encephalomyocarditis virus; Epidemiology; Infections; Mice; Neutralizing antibodies; Viruses; Zoos
• ISSN: 1042-7260; 1937-2825

To determine the susceptibility of raccoons (Procyon lotor) to infection with encephalomyocarditis virus (EMCV), 1-yr-old raccoons were exposed intramuscularly (n = 1) or orally (n = 6). Serum samples were collected at 3-7-day intervals beginning 14 days prior to exposure and continuing to postexposure day (PED) 107. EMCV-specific antibody titers were measured by a serum virus neutralization (SN) test. In the intramuscularly (i.m.) exposed animal, elevated and stable SN antibody titers (1:64 to 1:128) were present from PED 11 through 107. Among orally exposed raccoons, antibody titers were detected in one of six animals. In contrast to the i.m.-exposed animal, antibodies in this individual were low (≤1:16) and transient, falling to undetectable levels by PED 64. Fecal samples for virus isolation were collected four times before exposure, for 10 days after EMCV exposure, and at biweekly or weekly intervals for an additional 82 days. Whole blood for virus isolation was collected in sodium citrate on PED 3, 6, 8, and 11. No virus was detected in fecal samples or whole blood by mouse inoculation assay from any of the raccoons. No overt signs of disease were observed in raccoons over the course of the experiment following exposure by either route. No gross lesions or histopathologic changes attributed to EMCV infection were detected. Serum samples (n = 380) from a free-ranging population of raccoons trapped in Guthrie County, Iowa over a 5-yr period (1984-1988) were tested for neutralizing antibodies against EMCV. The population cross section included adults and juveniles of both sexes. Antibody titers were ≤1:4 in all samples by the SN test. The absence of elevated neutralizing antibody titers suggested that EMCV was not circulating in the wild population. Although raccoons were shown to be susceptible to infection with EMCV, the cumulative results of the experimental and field studies suggest that raccoons are a dead-end host for EMCV and do not participate in the epidemiology of the disease.