Human echinococcosis in Bulgaria: a comparative epidemiological analysis

Abstract

The present article describes the importance of human echinococcosis as a public health problem in Bulgaria, outlines the control measures carried out and evaluates comparatively the situation over three periods spanning 46 years (1950-1995). During the first period (1950-62), a total of 6469 new surgically confirmed cases of hydatid disease were recorded in Bulgaria, with an annual incidence of 6.5 per 100,000 population, and the infestation rate in domestic animals and dogs was high. Echinococcosis was endemic throughout the country. The organization of a control campaign, initiated in 1960, led to a considerable improvement in the situation during the second period (1971-82). Morbidity among humans gradually decreased, with an average incidence of 2.0 per 100,000, and the proportion of infected animals also fell. The distribution of echinococcosis was characterized as sporadic or of low endemicity. During the third period (1983-95), owing to administrative irregularities and economic changes, funds for supporting the campaign were reduced and control structures were dismantled. As a result, the incidence rose to 3.3 per 100,000. Echinococcosis again became endemic, in some regions hyperendemic. The findings provide convincing evidence that cessation of control measures or reduction of campaign activity can lead to intensification in the transmission of Echinococcus granulosus and to a resurgence in echinococcosis to previous levels.

PIP: Prevalent throughout the country, human cystic echinococcosis is a major health and economic problem in Bulgaria. The importance of this disease as a public health problem in Bulgaria is described, followed by a description of control measures conducted and a review of the situation over 3 periods spanning 1950-95. During 1950-62, 6469 new surgically confirmed cases of hydatid disease were recorded in the country, for an annual incidence of 6.5 cases per 100,000 population, and the infestation rate in domestic animals and dogs was high. While echinococcosis was endemic throughout the country during this period, the organization of a control campaign, initiated in 1960, led to a considerable improvement in the situation during 1971-82. Morbidity among humans gradually decreased, with an average incidence of 2.0/100,000, and the proportion of infected animals also fell. The distribution of echinococcosis at that time was characterized as sporadic or of low endemicity. However, during 1983-95, the reduction of program funds and the subsequent dismantling of control structures prompted the incidence of echinococcosis to rise to 3.3/100,000. The disease therefore again became endemic, and even hyperendemic in some regions.