Volume 29-16
15 August 2003

[Table of Contents]

HUMAN RABIES, BRITISH COLUMBIA - JANUARY 2003

On 30 January, 2003, a 52-year-old man from the greater Vancouver region of British Columbia died from undiagnosed rabies encephalitis caused by bat-associated rabies virus. The diagnosis of rabies was not considered until the review of postmortem brain histological sections on 3 March, 2003. This is the first recognized case of human rabies probably acquired in British Columbia and only the second known case of rabies to have died in British Columbia. This report briefly summarizes the initial presentation and public health actions.

Case Presentation

The patient presented to his community hospital on 6 January, 2003, with left upper arm weakness of two days' duration. He was sent home but returned the next day with progression of these same symptoms into both arms and decreased deep tendon reflexes. He had no significant neck pain or pain in any of his limbs, and remained well oriented and afebrile. His medical history was significant for kidney transplantation in September 2000.

The patient's breathing muscles rapidly became affected, and he was heavily sedated and intubated in the emergency department on 8 March, before admission to the intensive care unit (ICU). Over the next 7 days the weakness and hyporeflexia spread to the legs. The working diagnosis was atypical Guillain Barré syndrome, but the patient failed to respond to intravenous immune globulin. He was transferred to a tertiary care hospital ICU on 16 January under the care of the Neuromuscular Disease Unit. The patient underwent a tracheostomy on 18 January. Despite further investigations and treatment, the patient's condition deteriorated over the coming days, ending in brain death. Ventilatory support was removed on 30 January, and the patient died of an undiagnosed neuropathy.

Laboratory Results

On 3 March, brain histopathologic slides first became available for examination by the tertiary hospital's neuropathologists. A likely diagnosis of rabies was made on the basis of extensive leptomeningeal inflammation and prominent intracytoplasmic inclusion bodies (Negri bodies) throughout the brain tissue, affecting a large proportion of the neurons. The BC Centre for Disease Control and local public health authorities were notified the same day. Arrangements were made for overnight shipping of brain tissue samples to the Centre of Expertise for Rabies in Ottawa, Ontario, for confirmatory direct fluorescent antibody (DFA) and reverse transcriptase-polymerase chain reaction (RT-PCR) testing. BC public health officials were notified on 4 March that the rabies DFA test was strongly positive.

A history taken from the patient's wife on 3 March indicated that the deceased had not travelled outside of British Columbia in the previous 12 months and had never left the continent. The couple lived in an urban setting in the greater metropolitan area and had no history of bats in the house. They had one dog and two cats, all of which were well. The patient had been an avid outdoorsman and hiker, often going off-trail through the forest and bush. Although he had not mentioned to family members any bat (or other animal) bite or scratch occurring in the previous year, he had commented to family members that he had been around bats in abandoned cabins in British Columbia during that period.

Subsequent monoclonal antibody and RT-PCR testing identified the virus strain as a variant associated with Myotis bats (most common species is the little brown bat).

Public Health Interventions

Public health preparations began on 3 March for rabies post-exposure prophylaxis (RPEP) of community contacts and potentially exposed health care workers (HCWs) at the two hospitals, and immunization of exposed staff began at both sites on 4 March. Family, friends, staff, and other patients who had had direct contact with the bodily fluids of the patient during his infectious period were identified and offered RPEP after proper informed consent. The infectious period was considered to extend from 1 week before first symptom onset throughout his hospital stay. Initial triage with risk assessment criteria identified people at higher risk of mucous membrane or percutaneous exposure to saliva, such as those involved in intubation or respiratory care. In total, approximately 440 HCWs were given RPEP because of known or possible exposure. Two household contacts (spouse and niece) and 12 community contacts with possible direct saliva contact were given RPEP as well.

Discussion

This patient's atypical presentation with paralytic “dumb” rabies and delayed diagnosis contributed to a large number of health care workers being potentially exposed to infectious body fluids and tissue, as did his long hospital course, intubation, and tracheostomy. The uncertainty relating to how much his immune compromised state may have influenced viral shedding also contributed to a lower threshold for offering RPEP to possible contacts.

In British Columbia, rabies is endemic only in bats. Approximately 10% of tests on bats carried out because of human contact are positive for rabies, and an estimated 1% of all bats are infected. Each year, several hundred people in British Columbia receive RPEP because of possible rabies exposure, in 80% because of contact with bats.

Source: R Parker, MD, D McKay, BScN, C Hawes, BScN, Fraser Health Authority, BC; P Daly, MD, E Bryce, MD, P Doyle, MD, W Moore, MD, I McKenzie, MD, D Roscoe, MD, S Weatherill, BScN, Vancouver Coastal Health Authority; DM Skowronski, MD, M Petric, MD, K Pielak, MHSc, M Naus, MD, BC Centre for Disease Control. 

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