Brucellosis: an emerging disease in Portugal

Abstract

Human brucellosis is one of the most common zoonosis worldwide. In Portugal, brucellosis is a notifiable disease in humans and the casuistic puts it among the three zoonosis with the highest incidence. Despite this, studies on prevalence of brucellosis in Portugal are scarce. The present study intends to evaluate the epidemiological situation of human brucellosis in Portugal and to identify the species associated with human cases. It also intend to investigate the origin of infection in humans using molecular typing studies and whole genome sequencing approaches. In this work, we propose study the genetic polymorphism of several virulence factors in Brucella spp. Our results showed that Brucella melitensis is the main species associated to human brucellosis and that there is a strong epidemiological link between many cases studies, whose originated small clusters and may even correspond to small outbreaks. In this study, it was possible to verify a strong phylogenetic proximity between isolated strains in the Mediterranean area (Spain, Greece and Italy) probably due to geographical, cultural and type of food proximity. In this work, using an advanced approach, new generation sequencing methodologies, we were able to validate the use of MLVA - 16, the gold standard for typing Brucella spp., using in silico extraction. Globally, the findings presented in this PhD thesis contribute for better understanding of the brucellosis situation in Portugal. The results may contribute to the implementation of a new laboratory tool to improve the epidemiological surveillance of brucellosis. Furthermore, is providing more accurate and quick information to the decision makers with responsibilities in the area of the implementation of measures of prevention and control of this disease in our Country, both in human and veterinary health, in line with the One Health approach.