Brucellosis: the evolution of the disease in Portugal over two decades

Abstract

Background: Human and animal health are closely linked, with this relationship being a potential source of diseases to humans, with brucellosis being a classic example. Several prevention strategies have been successfully implemented to control brucellosis, but monitoring the disease is an essential instrument for early implementation of prevention measures, in order to mitigate any damage that an increase in cases may have on the human and animal population. Therefore, the aim of this study was to characterize the evolution of notified cases of human brucellosis in Portugal between 1998-2018. Methods: Retrospective observational study that included all reported cases of human brucellosis in Portugal, between 1998 and 2018 (last official public data available). Data was collected from reports made available by the Directorate-General for Health (DGS). Descriptive statistics (frequencies mean, median, proportions) by sex, age and geographic location were performed using Microsoft Excel® software. Results: Between 1998 and 2018, 3752 cases of brucellosis were reported in Portugal, the majority of which were male (n=2298, 61.2%), aged between 15 and 54 years (n=1870; 49.8%). With the exception of 2011, the number of cases reported in males was systematically higher than in females. The regions with the most reported cases are the North (n=1298; 34.6%) and Center (n=1323; 35.3%) of Portugal. The highest number of reported cases were recorded in North region (13 of the 21 years studied). The highest number of reported cases was observed in 1998 (n=817), while the lowest was observed in 2017 (n=16). The number of cases decreased substantially between 1998 and 2004 (variation of -82.6%), with this decline being interrupted by a small increase in cases in 2005. From 2005 onwards, the number of cases resumed its downward trend, although with some fluctuations and in a less pronounced way until 2018. Conclusion: In the last two decades, the number of reported cases of human brucellosis has decreased significantly. The improvement of the notification system, socioeconomic changes and animal brucellosis eradication programs are determining factors for this decrease. However, brucellosis is not eradicated in Portugal; therefore, the surveillance of human cases is essential to develop timely strategies for controlling brucellosis, not only at human level but also at animal and environmental levels.N/