ENCEPHALOMYOCARDITIS VIRUS-INFECTION IN RACCOONS (PROCYON-LOTOR)

To determine the susceptibility of raccoons (Procyon lotor) to infecti on with encephalomyocarditis virus (EMCV), 1-vr-old raccoons were expo sed intramuscularly (n = 1) or orally (n = 6). Serum samples were coll ected at 3-7-day intervals beginning 14 days prior to exposure and con tinuing to postexposure day (PED) 107. EMCV-specific antibody titers w ere measured by a serum virus neutralization (SN) test. In the intramu scularly (i.m.) exposed animal, elevated and stable SN antibody titers (1:64 to 1:128) were present from PED 11 through 107. Among orally ex posed raccoons, antibody titers were detected in one of six animals. I n contrast to the i.m.-exposed animal, antibodies in this individual w ere low (less-than-or-equal-to 1:16) and transient, falling to undetec table levels by PED 64. Fecal samples for virus isolation were collect ed four times before exposure, for 10 days after EMCV exposure, and at biweekly or weekly intervals for an additional 82 days. Whole blood f or 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 in oculation assay from any of the raccoons. No overt signs of disease we re observed in raccoons over the course of the experiment following ex posure by either route. No gross lesions or histopathologic changes at tributed 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 antibodie s against EMCV. The population cross section included adults and juven iles of both sexes. Antibody titers were less-than-or-equal-to 1:4 in all samples by the SN test. The absence of elevated neutralizing antib ody titers suggested that EMCV was not circulating in the wild populat ion. Although raccoons were shown to be susceptible to infection with EMCV, the cumulative results of the experimental and field studies sug gest that raccoons are a dead-end host for EMCV and do not participate in the epidemiology of the disease.