Human brucellosis: Incidence, prevention and strategies for control

Brucellosis is a highly contagious zoonotic infection caused by Gramnegative, facultative intracellular bacteria belonging to the genus Brucella. The main species with moderate-to-significant human pathogenicity are: Brucella melitensis (from sheep and goats), Brucella suis (from pigs), Brucella abortus (from cattle), and Brucella canis (from dogs). The pathogen is primarily transmitted to humans through direct or indirect contact with infected animals or by consuming contaminated food, such as undercooked meat and untreated milk and dairy products (e.g., cheese, butter or ice cream made from raw milk). The infection causes abortion, sterility, or stillbirth in domestic and wild animals, and decreases milk production, resulting in significant economic losses. In humans, it presents a wide spectrum of symptoms, including undulant fever, general malaise, fatigue, muscle pain, arthralgia, orchitis/epididymitis, endocarditis, and meningitis. Human cases are primarily associated with occupational exposure. Livestock owners, farmers, veterinarians, artificial inseminators, milkers, meat packers or laboratory workers are at higher risk of frequent exposure to the pathogen. The World Health Organization (WHO) identifies brucellosis as one of the most neglected zoonotic diseases. Its incidence is higher in underdeveloped nations (over 170 countries/regions), with the Mediterranean region particularly affected. The disease is also known by various names, including Mediterranean flaccid fever, Malta fever, Crimean fever, or Gibraltar fever. Brucellosis remains a significant public health concern, with approximately half a million new human cases reported annually worldwide. In the European Union (EU), according to Directive 2003/99/EC, brucellosis is subject to mandatory surveillance in 25 Member States. Based on the 2022 report by the European Food Safety Authority (EFSA) and the European Centre for Disease Control and Prevention (ECDC), there were 198 confirmed cases of illness, resulting in 55 hospitalizations, with a notification rate of 0.04 cases per 100,000 population. This represents a slight increase (29.2%, 0.03% per 100,000 population) compared to 2021. Controlling brucellosis mainly involves education and prevention, as well as personal hygiene measures and food safety practices. Surveillance, identification and isolation of infected animals are critical for managing prevention, control, and eradication programs. This chapter examines the recent prevalence of brucellosis, the pathogenicity of the microorganism as well as the clinical manifestations of the infection in humans. It also describes the methods for detecting the pathogen, outlining appropriate measures to prevent the presence of Brucella spp. in food.