Risk Factors and Protective Immunity Against Rabies in Unvaccinated Butchers Working at Dog Slaughterhouses in Northern Vietnam.

Vietnam is a rabies-endemic country where eating dog meat is customary. However, the risks of rabies transmission to dog slaughtering and processing workers have not been identified. This study aimed to determine the rabies neutralizing antibody (NTA) and risk factors in dog slaughterers to propose appropriate intervention methods for this occupational group. In 2016, a cross-sectional study on NTA against rabies virus and related factors was conducted among 406 professional dog slaughterers in Vietnam. The participants were interviewed using a structured questionnaire, and their sera were tested for rabies NTA by a rapid focus fluorescence inhibition test. Statistical algorithms were used to analyze the data. The results showed that most of the professional dog butchers (344/406 subjects, 84.7%) had no rabies NTA. Interestingly, 7.8% (29/373) had NTA without a rabies vaccination history. Over 5 years of experience as a dog butcher was positively associated with the presence of NTA in unvaccinated individuals (OR = 6.16, P = 0.001). The NTA in vaccinated butchers was present in higher titer and for longer persistence to those of other previously reported professionals, which is possibly as a result of multiple exposures to low levels of rabies virus antigens during dog slaughtering. Our study demonstrated that professional dog butchers in Vietnam are at a high risk of rabies virus infection, apart from those with common bite experiences. In countries where dog meat consumption is customary, rabies control and prevention activities should focus on safety during dog trading and slaughtering.

Rabies-infected dogs at slaughterhouses: A potential risk of rabies transmission via dog trading and butchering activities in Vietnam.

The study aimed to determine the status of neutralizing antibodies and rabies virus infection in dogs at slaughterhouses in Hanoi city from 2015 to 2017. A total of 2,376 pairs of blood and brain samples were collected from dogs at 92 slaughterhouses (8 large slaughterhouses and 84 small slaughterhouses) in 6 districts in Hanoi. Of the 1,500 dog samples from the large slaughterhouses where imported dogs were slaughtered, no dog brain samples were infected with rabies virus and no blood samples were positive for rabies neutralizing antibodies. Meanwhile, 7/876 (0.8%) of dog brain samples from small slaughterhouses in which slaughtered local dogs were positive for rabies virus and 26.4% had neutralizing antibodies against rabies virus. Analysis of the genetic characteristics of these rabies viruses showed that they all had a common origin with the domestic strains circulating in Northern Vietnam. Research results suggested that there was a potential risk of rabies transmission to humans through dog slaughtering activities in Vietnam. Vaccination for dogs should be strengthened, strictly implemented and frequently monitored to reach the rate of herd vaccination coverage as WHO's recommendation. Dog trading and slaughtering activities should be strictly monitored to minimize the risk of rabies transmission to humans.

Evaluation of Rapid Neutralizing Antibody Detection Test against Rabies Virus in Human Sera.

Rapid and easy determination of protective neutralization antibody (NAb) against rabies in the field is very important for an early and effective response to rabies in both animal and human health sectors. The rapid neutralizing antibody detection test (RAPINA), first developed in 2009 and then improved in 2012, is a quick test allowing detection of 0.5 IU/ml antibodies in human and animal sera or plasma. This study aimed to assess the RAPINA test by comparison with rapid focus fluorescence inhibition test (RFFIT), using 214 sera of vaccinated and unvaccinated professional dog butchers, laboratory workers and rabies patients in Vietnam. The sensitivity, specificity, false negative rate, false positive rate and concordance of the RAPINA test as compared to RFFIT were 100%, 98.34%, 0%, 1.66% and 98.6%, respectively. The positive predictive value and negative predictive value were 91.7% and 100%, respectively when RAPINA test was used. With its remarkable sensitivity, specificity and easy implementation, RAPINA test can be used for rapid determination of NAb in the field.