The Valuation of Social and Economic Costs of Mosquito-Transmitted Ross River Virus

Abstract

Insect pests (such as mosquitoes) and their associated impacts have become important social, economic and environmental health issues. Mosquitoes transmit diseases, are widely perceived as a nuisance and are becoming a serious health concern for the public. The incidence of contracting mosquito-transmitted diseases has markedly increased in recent decades in Australia (Russell 1994). Currently, Ross River virus is the most prevalent mosquito-transmitted viral disease in Australia with up to 8,000 cases reported annually (Curran et al. 1996). The absence of documented evidence about the full social costs of mosquito-transmitted diseases is a critical issue as there is currently no economic rationale underlying existing resource allocation for intervention programs. This study of the full social costs of Ross River virus was conducted between April and July 2002. Demographic, health-state and disease-related data were collected using survey questionnaires for 201 notified Ross River virus victims from across Queensland. Two self-administered surveys were conducted at the time approximately onset and six months from onset while a phone survey was conducted at 12 months after onset. Direct impacts such as the costs of health care (medical consultations, pathology services and medicines), non health care resources (treatment-related transport) and indirect impacts such as the opportunity cost of lost productivity (due to disability and treatment-related waiting times) of the viral illness were recorded in the questionnaires and were valued using market prices. A non-market valuation method (willingness-to-pay), in conjunction with a self-assessed standard health measure (Short Form 36) were used to quantify more intangible health-related quality of life effects such as change in physical, mental and social functioning. Estimated full social costs of the disease were analysed across age and gender groups. Based on the mean cost estimates for the study sample, the total disease costs have been extrapolated by local government areas as the appropriate administrative areas. A wide range of social and economic costs of the virus has been addressed in this thesis. However, the derived costs cannot be summed into a total estimate as several of these values overlap in terms of coverage. Therefore, only the major cost components, with a minimum of overlap, have been used to estimate the aggregate social cost of the disease. Given the methodological and empirical limitations of the study, the most accurate estimate of the average per capita full costs of Ross River virus in Queensland is estimated at $AUD (2002) 1,070 per case. The estimate of the full social cost of Ross River virus disease can be a vital input for many relevant policy applications. For example, disease costs together with resource costs of current interventions, are essential inputs for ongoing economic evaluations of mosquito control programs at local level. In this thesis, the cost minimisation approach has been presented to evaluate mosquito control programs at the local level where the policy analyst’s task is to minimise the overall social costs (that is, disease costs plus control costs). These economic evaluations have substantial potential benefits to society in terms of the efficient allocation of scarce resources. In addition, estimated disease cost is a significant input for economic impact assessment of regional disease outbreaks. It also can be used to highlight disease impact upon the economy and community and hence draw attention to the scale and scope of such problems to policy makers at all levels so that they can respond appropriately to the mosquito problem, and mosquito-transmitted diseases, as priority issues in the political agenda.