Assessing all the impacts of a rabies control intervention

For the first time, a One Health framework has been developed to assess social, animal welfare and ethical impacts together with epidemiological and economic impacts of rabies control measures. Besides the usual measures of how dog rabies cases, dog bite incidents and human rabies cases changed as the intervention was carried out, community based interviews were carried out to measure how attitudes changed towards street dogs, the control programme, and dog related problems.  Assessments of the intervention on animal welfare and ethics were also carried out.

The framework was tested with a case study of rabies control in Colombo City, Sri Lanka, comparing the periods 2002-6 (baseline situation) and 2007-2011 (intervention). In 2006, mass dog culling (by gassing) was banned and replaced with vaccination and sterilization of roaming dogs. Vaccination of owned dogs and PEP provision was unchanged between the two periods, but education on dog bite prevention and the establishment of dog managed zones were also implemented from 2007-2011.

Epidemiologic data suggested that dog rabies cases and dog bites fell significantly; from 172 to 68 total dog cases and from 13,871 to 9,216 for annual dog bites. There were 3 human deaths from rabies in each of the periods, while the total number of people seeking medical attention for dog bites in the City rose from 6,288 (baseline) to 7,680 (intervention), reflecting the increased awareness of the need for treatment (though clearly most people still do not present for treatment), and possibly also improvements to the reporting system. An estimated 9,384 dogs culled in the baseline period fell to 0 for the intervention, whilst 5,323 dogs were sterilized during the intervention period.

Costs for each component were derived, and the total cost of programme was assessed for each period. Around $1.00m more was spent during the intervention period than the previous years, with 80% of this being in the animal health sector, and 20% in the human health sector.

The intervention averted an estimated 738 DALYs (life years spend with disability), attributed to the reduction in psychological distress of dog bite treatment, as deaths were unchanged. Community surveys revealed a better acceptance of the control methods and the roaming dog population, fewer dog related problems and a reduction in the perceived dog population. They also suggested that education had resulted in less fear of roaming dogs and rabies. When asked about dog population management going forwards, no community groups mentioned culling as an appropriate strategy, instead preferring sterilization, vaccination and education.

The animal welfare assessment took into consideration the distress cause by each aspect of the control programmes (culling, vaccination, dog catching nets, sterilization etc), and the number of dogs subjected to each. Overall the intervention was deemed to have a low-intermediate animal welfare impact, compared to the intermediate-high impact of the baseline situation.  A more qualitative ethical assessment considered aspects of rights, fairness and virtue.

Although the reporting of non-monetary outcome makes traditional cost-benefit calculations more difficult, the authors argue that this approach has important implications for rabies control strategies, given that the acceptability of control programmes is critical to community participation and therefore their chances of success.

Summarised by Louise Taylor, based on “A One Health Framework for the Evaluation of Rabies Control Programmes: A Case Study from Colombo City, Sri Lanka” published by Barbara Häsler et al. in October 2014 (PLoS Negl Trop Dis 8(10): e3270. doi:10.1371)