Evaluating the role of surgical sterilisation in canine rabies control: A systematic review of impact and outcomes

Current recommendations for the elimination of canine-mediated human rabies focus on mass dog vaccination as the most feasible and cost-effective strategy. However, attempts to control rabies are often combined with canine surgical sterilisation programmes. The added value of sterilisation is widely debated. A systematic review was undertaken to compare the outcomes and impact of vaccination and sterilisation programmes with vaccination only programmes. A systematic search of three electronic databases (CAB Abstracts, Medline and Global Health) and grey literature was performed. From 8696 abstracts found, 5554 unique studies were identified, and 16 studies met the inclusion criteria. Eight described vaccination only programmes and eight described vaccination and sterilisation programmes. Indicators of impact measured were dog bites and/or doses of post-exposure prophylaxis administered; numbers of dog and/or human rabies cases; dog population demographic changes; changes in health and welfare of dogs, and indicators related to human behaviour change. The studies were contextually very diverse, programmes being implemented were complex, and there was variation in measurement and reporting of key indicators. Therefore, it was difficult to compare the two types of intervention, and impossible to make an evaluation of the role of sterilisation, using this evidence. Given the large number of vaccination and sterilisation programmes conducted globally, the lack of studies available for review highlights a gap in data collection or reporting, essential for impact assessment. There are several knowledge gaps concerning the impact of the sterilisation component alone, as well as subsequent effects on rabies transmission and control. Prospective studies comparing the outcomes and impact of the two interventions would be required in order to establish any additional contribution of sterilisation, as well as the underlying mechanisms driving any changes. In the absence of such evidence, the priority for rabies control objectives should be implementation of mass vaccination, as currently recommended by the World Health Organisation.Author summary: Rabies is an important viral zoonosis that causes approximately 59,000 human deaths every year. The vast majority of cases result from a bite from an infected dog. Annual vaccination of at least 70% of the dog population is recommended for elimination of canine rabies. Canine surgical sterilisation programmes are sometimes conducted alongside rabies vaccination. However the contribution of sterilisation to rabies control, above that of the vaccination alone, is controversial. This systematic review compared the outcomes and impacts of vaccination and sterilisation programmes with vaccination only programmes. Sixteen studies met the study’s formal inclusion criteria, however we were unable to answer the question using this evidence and the role of sterilisation remains unclear. We identify gaps in knowledge regarding the implementation and impact of the sterilisation component as well as any resulting effects on rabies transmission and control. Prospective studies evaluating the two types of intervention would provide comparative evidence, which is needed to enable informed decisions to be made regarding whether sterilisation should be conducted for the purposes of canine rabies control.