Improved methods to capture the total societal benefits of zoonotic disease control: Demonstrating the cost-effectiveness of an integrated control programme for Taenia solium, soil transmitted helminths and classical swine fever in northern Lao PDR

Background: Control and elimination of zoonotic diseases requires robust information about their effect on both human and livestock health in order to enable policy formulation and the allocation of resources. This study aimed to evaluate the cost-effectiveness of controlling Taenia solium taeniasis/cysticercosis in both humans and pigs, and soil-transmitted helminths (STH) in humans by integrating their control to on-going human and animal health control programmes in northern Lao People’s Democratic Republic. Method: A cross-sectional study was carried out in 49 households, focusing on the prevalence of T. solium taenias/cysticercosis and soil transmitted helminths before and after a twelve month intervention. The village data was collected using a semi-structured questionnaire through a door-to-door survey. The village data was then projected to the wider northern Lao PDR population using stochastic modelling and cost-effectiveness ratio (after aggregating the net cost to capture both human and animal health parameters) and GDP per capita as a threshold, to determine the cost-effectiveness of the integrated control of T. solium taeniasis/ cysticercosis and STH, assuming linear scaling out of the intervention. The zoonotic DALY (zDALY) approach was also used as an alternative method of estimating the cost-effectiveness ratio of controlling T. solium taeniasis/cysticercosis in humans and pigs. Findings: Using cost-effectiveness analysis after aggregating the net cost and control of T. solium taeniasis/cysticercosis alone as the base case, the study found that simultaneous control of T. solium taeniasis/cysticercosis in humans and pigs, STH in humans and Classical Swine Fever (CSF) in pigs was USD 14 per DALY averted and USD 234 per zDALY averted using zDALY method hence considered highly cost-effective whereas controlling T. solium taeniasis/cysticercosis without incorporating STH and CSF was the least cost-effective (USD 3,672 per DALY averted). Additionally, the cost-effectiveness of controlling T. solium taeniasis/cysticercosis in people and pigs using zDALY as an alternative method was USD 3,662 per zDALY averted which was quite close to our findings using the aggregate net cost method. Conclusion: The study showed that control of T. solium taeniasis/cysticercosis alone in humans and pigs is not cost-effective in northern Lao PDR whereas control of STH is. Consequently, integrating T. solium taeniasis/cysticercosis control with other cost-effective programmes such as STH and CSF markedly improved the cost-effectiveness of the intervention. This is especially important in low resource countries where control of zoonotic neglected tropical diseases could be integrated with the human and animal health sectors to optimize use of the limited resources. Trial registration: Australia New Zealand Clinical Trials Registry (ANZCTR) ACTRN12614001067662. Author summary: A study was conducted in northern Lao PDR to ascertain the cost-effectiveness of controlling Taenia solium (T. solium taeniasis/cysticercosis) using five approaches namely: i) T. solium taeniasis/cysticercosis alone in the human population (the base comparator), ii) T. solium taeniasis/cysticercosis and soil transmitted helminths (STH) in the human population, iii) T. solium taeniasis/cysticercosis alone in the human and pig population, iv) T. solium taeniasis/cysticercosis in the pig population and STH in humans, and v) T. solium taeniasis/cysticercosis, STH and Classical Swine Fever (CSF) in humans and pigs. Using cost-effectiveness ratio (after aggregating the net cost and using zDALY approach as an alternative method), the study found that the simultaneous control of T. solium taeniasis/cysticercosis, STH and CSF in human and pig population was USD 14 per DALY averted and USD 234 per zDALY averted thus considered highly cost-effective whereas control of T. solium taeniasis/cysticercosis alone in the human and pig population was the least cost-effective as it was found to be USD 3,672 per DALY averted using the aggregate net cost method and USD 3,662 using the zDALY approach,. We concluded that inclusion of STH and CSF to T. solium taeniasis/cysticercosis mitigation efforts drastically improved the overall cost-effectiveness of the intervention in northern Laos where all the three diseases are endemic.