THE BURDEN OF ECHINOCOCCOSIS

Abstract

The echinococcoses, cystic (CE) and alveolar (AE), caused by the larval stages of Echinococcus granulosus and Echinococcus multilocularis, respectively, are well-known by the medical community because of their often dramatic clinical presentation and complexities of diagnosis and clinical management. Surgical removal, percutaneous drainage, and extended chemotherapy are current methods of treatment of these infections that remain prevalent throughout vast areas of the world. Where adequate care is available, the cost of treatment of individual cases can cost thousands of dollars. The impact of these diseases on patients/persons diagnosed with the disease is appreciated by the medical community, but the broader impact of these infections on individuals and the affected communities has been largely unknown or ignored. These infections negatively impact the health and productivity of both humans and lower animals. Assessing the economic impact is especially difficult because it comprises human and animal health as well as agriculture, trade, and market factors. One limited but calculable measure of the economic impact of echinococcosis is the monetary costs incurred by the patients or their families associated with diagnosis, treatment, and permanent disability or deaths due to the disease in humans. This requires that the disease be “reportable” and that information on costs be available. A decision tree analysis was used to estimate the monetary impact of CE in Tunisia where the annual incidence of surgical CE was 15 per 100,000 per year. In Jordan, the total annual human health costs due to CE (both direct and indirect) were estimated at US$79,000 to US$500,000. Indirect costs of human echinococcosis include the long-term ill health of an individual who has either been treated for echinococcosis or is unwittingly affected by undiagnosed disease. In Kyrgyrstan, subjects presenting for treatment with echinococcosis had double the unemployment rate of the general population. These costs associated with diagnosis and medical care can be combined with the concomitant animal health losses to estimate the total economic losses to society. In communities were livestock husbandry is an important economic activity, CE in domestic animals can result in significant production losses including reduction in live weight gain, reduced yield of milk, reduction in fertility rates, and reductions in the value of wool and decreased edible offal. The animal production deficits that result from CE in livestock have been estimated by Monte Carlo sampling techniques. In Jordan, these costs were estimated at between US$2.3 million and US$6.3 million per year. Recent investigations in China have demonstrated that, in addition to direct medical costs, the long-term quality of life in patients treated for CE and AE was permanently affected, indicating that morbidity is more subtle and considerably greater than previously appreciated. Budke and others determined that individuals who were previously unaware they had the disease, but diagnosed with CE or AE in a random cross-sectional study using abdominal ultrasound, experienced a significant decrease in the quality of life. Their investigation determined that the DALYs (disability adjusted life years) lost due to these infections in terms of medical treatment costs, lost income, and physical and social suffering were substantial. Such decreases in the quality of life presumably have significant economic effects including impairment in the workplace and thus having less highly paid work than would otherwise have been the case, having greater levels of absenteeism from work, or possibly requiring greater levels of longterm nursing care. In this issue of the Journal, these authors extend their evaluation of the economic effects of echinococcosis on the Tibetan Plateau and calculate the cost-effectiveness of intervention combining anthelmintic prophylaxis of dogs with vaccination of sheep and goats in terms of DALYs saved. Their models suggest that 65% to 95% of annual losses due to CE can be prevented with the proposed intervention as well as up to 50% of the losses caused by AE in humans. The estimated annual cost of the program would be a small fraction of the estimated livestock and human financial losses caused by these diseases. The authors suggest that the cost-effectiveness of the proposed intervention ranks high according to the World Health Organization’s rating of cost-effectiveness per DALY averted. They predict even further feasibility of the intervention if cost sharing was implemented between the public health and agricultural sectors based on proportional benefits from the control program. These predictions provide optimism for the potential effectiveness and resultant benefits of intervention in the most highly affected areas of endemicity of both cystic and alveolar forms of echinococcosis yet identified.