Outbreak of Foot and Mouth Disease in black bears (Ursus thibetanus) and a sun bear (Helarctos malayanus) at a bear rescue facility in Vietnam

Foot and mouth disease (FMD) is an acute febrile viral disease typically affecting cloven hoofed animals. FMD has a wide host range, high excretion levels, rapid replication rate, and multiple transmission modes, making it one of the most highly contagious and financially important diseases. FMD is endemic in Vietnam and outbreaks regularly occur in livestock. This paper describes an FMD outbreak in 2011 in a group of bears housed at a rescue facility in northern Vietnam. To our knowledge, this is the first confirmed FMD case in a bear species, and the first report of clinical signs of FMD in a sun bear. Sixteen Asiatic black bears (ABB) and one sun bear were housed in the affected bear house. All had been transferred to the facility from private owners, or illegal bear bileextraction facilities. On August 28, 2011, an adult male ABB was reluctant to walk or eat, and developed largeblisters on the foot pads. Over the following 15 days, 14/17 bears developed similar signs; the remaining 3 cohoused bears and an additional 57 bears resident at the facility, in separate enclosures, did not. On day 6, the house was placed under strict quarantine. All affected bears developed vesicles on all foot pads, more severe in the younger bears. Crusty scabbing of the nares was noticed in 6, and very subtle oral mucosal lesions were noted in 3 cases.Bears were lethargic for 24-48 h, apart from the two youngest cubs. Within 1 month the pads of all bears looked normal. RT-PCR was performed on samples from 3 bears using FMDV specific primer sets. All bears were positiveand all positive samples were serotype O. Vesicle fluid from one bear was tested and was positive for FMDVantibodies by ELISA. Sequence alignment of 3 virus bear isolates with 3 Vietnamese porcine isolates revealed several nucleotide differences. Phylogenetic analysis demonstrated clustering of one of 3 bear FMDV isolates with a Vietnamese porcine FMDV isolate, in a branch in close proximity but distinct from the two other bear isolates. This outbreak likely occurred due to the high density of the bears in captivity, and possible indirect contact they had with livestock. The findings are significant for captive bear facilities worldwide; they showed that bears are capable of contracting FMD virus and showing clinical disease, and that the virus spreads easily between bears in close contact and between bears of two different species.