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BACKGROUND: Rabies has one of the highest case fatality rates among infectious diseases and is prevented through administration of post-exposure prophylaxis (PEP). While human cases in the United States are rare, rabies is enzootic within certain wildlife populations, including bats and raccoons. Almost all cases of human rabies in the U.S. are caused by bat-variant viruses and result from animal exposures. In February 2013, a Maryland resident died of confirmed rabies virus infection, but no animal exposures were identified. Infection was found to have occurred via organ transplantation that occurred 17 months prior to symptom onset. Rabies virus was detected in archived brain tissue from the donor, collected at his time of death in September 2011. Rabies virus from both donor and recipient were identical and typed as raccoon rabies virus variant, phylogenetically related to raccoon rabies viruses circulating in North Carolina, the donor’s home state. Three additional recipients also received organs from the donor.
METHODS: To determine the source of infection in the donor and to identify and assess individuals exposed to infectious materials from donor and recipient, four investigations were launched: 1) Organ Donor Exposure Investigation, 2) Organ Donor Contact Investigation, 3) Maryland Organ Recipient Contact Investigation, and 4) Living Organ Recipient Contact Investigation.
RESULTS: Over 100 people from more than 20 agencies spent over 2,700 hours conducting contact investigation activities that occurred in healthcare, military and community settings. More than 88% of 306 contacts of the deceased organ recipient were assessed within 6 days; 88% of the 190 organ donor contacts were assessed within 10 days. The 564 persons assessed included 417 healthcare workers with 5.8% recommended PEP, 96 community contacts with 15.6% recommended PEP and 30 autopsy personnel with 50% recommended PEP. Donor related contacts represented 188 assessed with 20.2% recommended PEP, compared to 5.6% of 306 deceased recipient contacts. The 3 living organ recipients received PEP and are currently healthy.
CONCLUSIONS: We report the second and third cases of human raccoon rabies in the U.S. Although rare, clinicians should consider rabies in cases of encephalitis of unclear etiology, particularly for cases involving potential organ donors. The 18 month delay due to the long incubation period in the recipient and the donor’s delayed diagnosis of rabies resulted in recall bias and a potential increase in recommendations for PEP. When a human rabies case is identified, it is essential to rapidly initiate a shared public health response.