Genomic insights into anthropozoonotic tuberculosis in captive sun bears (Helarctos malayanus) and an Asiatic black bear (Ursus thibetanus) in Cambodia.

Contact between humans and wildlife presents a risk for both zoonotic and anthropozoonotic disease transmission. In this study we report the detection of human strains of Mycobacterium tuberculosis in sun bears and an Asiatic black bear in a wildlife rescue centre in Cambodia, confirming for the first time the susceptibility of these bear species to tuberculosis when in close contact with humans. After genotyping revealed two different strains of M. tuberculosis from cases occurring between 2009 and 2019, 100 isolates from 30 sun bear cases, a single Asiatic black bear case, and a human case were subjected to whole genome sequencing. We combined single nucleotide polymorphism analysis and exploration of mixed base calls with epidemiological data to indicate the evolution of each outbreak. Our results confirmed two concurrent yet separate tuberculosis outbreaks and established a likely transmission route in one outbreak where the human case acted as an intermediatory between bear cases. In both outbreaks, we observed high rates of transmission and progression to active disease, suggesting that sun bears are highly susceptible to tuberculosis if exposed under these conditions. Overall, our findings highlight the risk of bi-directional transmission of tuberculosis between humans and captive bears in high human tuberculosis burden regions, with implied considerations for veterinary and public health. We also demonstrate the use of standard genomic approaches to better understand disease outbreaks in captive wildlife settings and to inform control and prevention measures.

Epidemiology and pathological progression of erythematous lip lesions in captive sun bears (Helarctos malayanus).

This study investigates the occurrence of erythematous lip lesions in a captive sun bear population in Cambodia, including the progression of cheilitis to squamous cell carcinoma, and the presence of Ursid gammaherpesvirus 1. Visual assessment conducted in 2015 and 2016 recorded the prevalence and severity of lesions. Opportunistic sampling for disease testing was conducted on a subset of 39 sun bears, with histopathological examination of lip and tongue biopsies and PCR testing of oral swabs and tissue biopsies collected during health examinations. Lip lesions were similarly prevalent in 2015 (66.0%) and 2016 (68.3%). Degradation of lip lesion severity was seen between 2015 and 2016, and the odds of having lip lesions, having more severe lip lesions, and having lip lesion degradation over time, all increased with age. Cheilitis was found in all lip lesion biopsies, with histological confirmation of squamous cell carcinoma in 64.5% of cases. Single biopsies frequently showed progression from dysplasia to neoplasia. Eighteen of 31 sun bears (58.1%) had at least one sample positive for Ursid gammaherpesvirus 1. The virus was detected in sun bears with and without lip lesions, however due to case selection being strongly biased towards those showing lip lesions it was not possible to test for association between Ursid gammaherpesvirus 1 and lip squamous cell carcinoma. Given gammaherpesviruses can play a role in cancer development under certain conditions in other species, we believe further investigation into Ursid gammaherpesvirus 1 as one of a number of possible co-factors in the progression of lip lesions to squamous cell carcinoma is warranted. This study highlights the progressively neoplastic nature of this lip lesion syndrome in sun bears which has consequences for captive and re-release management. Similarly, the detection of Ursid gammaherpesvirus 1 should be considered in pre-release risk analyses, at least until data is available on the prevalence of the virus in wild sun bears.

LAPAROSCOPIC-ASSISTED INSERTION OF A VENTRICULOPERITONEAL SHUNT IN A RESCUED ASIATIC BLACK BEAR (URSUS THIBETANUS) IN LAOS.

A 3-yr-old Asiatic black bear (Ursus thibetanus), weighing 68 kg, underwent a laparoscopic-assisted placement of a ventriculoperitoneal shunt for hydrocephalus in the Lao People's Democratic Republic. Rescued as a young cub with a notably domed head, the bear's condition had deteriorated with age, but euthanasia was not a viable option because of cultural issues. Surgery was attempted as a palliative measure. The bear had ventrally orientated crossed eyes (abducens nerve palsy and dorsal midbrain syndrome), papilledema, severe rhinorrhea, depressed mentation, lethargy, a very poor appetite, and was stunted. Hydrocephalus was confirmed via intraoperative 2.0-5.0 MHz head ultrasound, as no magnetic resonance imaging was available in the country. Surgery was planned via 3D modeling of museum skulls and brain cavity, and ultrasound examination of formalin-preserved brains of other carnivores with hydrocephalus. The bear demonstrated a notable improvement in mentation, appetite, and behavior, maintained for 4 yr following surgery.