Different rabies outbreaks on two beef cattle farms in the same province of China: Diagnosis, virus characterization and epidemiological analysis

Abstract

Eliminating rabies is challenging in many developing countries, especially in rural areas. In contrast to the annual decline of human cases in China in last decade, the incidence of rabies in livestock has been increasingly reported. This paper reports the rabies outbreaks in beef cattle (Angus) in Shaanxi Province, China, which caused 31 and 5 deaths at an attack rate of 19.4% (95% CI: 13.6%-26.4%) and 0.25% (95% CI: 0.1%-0.6%) in a satellite cow farm (farm A) and a core intensive farm (farm B), respectively. The rabies infection was confirmed by several laboratory tests, and rabies virus (RABV) strains SXBJ15 and SXYL15 were isolated and characterized from farm A and B, respectively. The two strains were found to have a high genomic sequence similarity to the dog-associated China clade I strains previously identified in the neighbouring area. SXBJ15 was shown to have a higher mouse pathogenicity (1.07) than SXYL15 (0.45). RABV was also detected in the saliva and salivary glands from the affected cattle. The potential causes were investigated on the farm, and the biosecurity scores were 20 and 64 (a full score of 82) for farms A and B, respectively.The rabies infection is likely to result from rabid free-roaming dogs (FRDs). On farm A with more cow deaths, the rabies transmission between animals can be attributed to the improper disposal of aborted foetuses and placental materials as a food source for rabid FRDs, high stocking density and drinking water sharing. Additionally, vaccinating cattle with a canine vaccine was shown to help stop the spread of rabies in herds. These results indicate that the occurrence of RABV on cattle farms can be prevented by improving biosecurity measures to control the entry of rural FRDs on the farm and immunizing farm cattle against rabies.

A case of rabies outbreak in a bull-calf from Nigeria

“…In this case, the calf was bitten by FRD in mid-July, and rabies clinical signs appeared in the middle of August, implying a nearly month-long incubation period. Similarly, this supports previous findings of a 15 to 30 day incubation period in cattle exposed to RABV after being bitten by stray dogs (Jemberu et al, 2013;Chao et al, 2021).…”

“…The high incidence of infection in rabies-endemic regions is primarily due to free-roaming dogs (FRDs) in human settlements (Tiwari et al, 2018). Rabid animals, such as cattle, can also be a potential source of rabies in- fection to humans, in addition to canines and wildlife reservoirs (Chao et al, 2021). Veterinary staff had been reported to contract RABV through damaged skin after inserting bare hands into a rabid cow's mouth for routine examination in observed clinical signs of excessive salivation and difficulty swallowing misdiagnosed as choked throat (Wen et al, 2006;Simani et al, 2012).…”

“…This case is no exception, as the affected calf had rabies due to a stray dog bite. Meanwhile, due to varying incubation periods influenced by wound location or depth, the infected cattle developed clinical signs of rabies at different points in time (Chao et al, 2021). It has been found that the affected cattle mostly had dog attacks around head and neck regions (47.8%) at the proximity of the CNS, followed by fore and hindquarters (30.4%), and lastly, the truck region (Dar et al, 2014).…”

Viral sequencing to inform the global elimination of dog-mediated rabies - a systematic review

“…Although dogs were identified as the primary host responsible for most transmission in regions with endemic dog-mediated rabies which were the focus of this study, RABVs broad host range means it is capable of transmission among multiple species. This versatility creates potential for new reservoirs, raising concerns about the effectiveness of control measures, and about these reservoirs being a source of reemergence [160] . In areas where dog-mediated rabies has largely been eliminated, there were several examples of transmission cycles in wildlife, some of which resulted from spillover from dogs.…”

“…These studies recommended mass vaccination of dogs, as well as oral vaccination in specific wildlife populations where variants had emerged [156,157] . Other recommendations included dog population management [76,113,158,159] , monitoring the health of animals for trade and consumption [75,80,97,129] , and raising awareness, particularly in communities identified as "high-risk" [155,158,160,161] . Only 33 publications provided targeted recommendations grounded in genetic evidence.…”