Brucellosis Surveillance and Control: A One Health Case Study

Abstract

Brucellosis is one of the world’s major zoonoses ( Dean et al ., 2012a ). Human infection results mainly from direct contact with infected animals (often occupational exposure) or from the consumption of contaminated raw milk or dairy products (consumer exposure). Human brucellosis exposure can ultimately only be prevented by its elimination in animals. Control and elimination in the animal host are most effectively achieved by mass vaccination and, if possible, subsequent test-and-slaughter programmes ( Zinsstag et al ., 2011 ). Economic studies show that it is highly profitable for pastoral societies to eliminate brucellosis. The societal benefits are three times higher than the investment in the mass vaccination of livestock ( Roth et al ., 2003 ). Hence, brucellosis control is a landmark example of the benefits of a One Health approach to zoonoses control, when compared to focusing solely on public health. The most important causative agents are Brucella melitensis (sheep and goats), Brucella abortus (cattle), B. suis (pigs) and B. canis (dogs). Brucella are gram-negative coccobacillary bacteria with an intracellular predilection in the host. The main clinical feature in livestock is late-stage abortion (Figure 1 ), at which time bacteria are excreted in high numbers. Brucella may be shed during prolonged periods in milk after the cessation of clinical signs. Brucellosis causes mainly a loss of fertility and a reduction of milk production in sheep, goats and cattle. Symptoms of the disease in people are highly variable. In general, B. melitensis causes a more severe illness, with less severe forms caused by B. suis and B. abortus . The main symptoms are fever, sweats, malaise, anorexia, headache, arthralgia, myalgia, backache and weight loss ( Dean et al ., 2012b ). The bacteria can localize anywhere in the body. Two-thirds of the cases become chronic and the illness can continue for years if patients do not receive appropriate treatment ( Roth et al ., 2003 ). There is no or very rare human-to-human transmission of brucellosis. Acute human brucellosis without complications should be treated with a combination therapy of doxycycline-streptomycin or doxycycline-gentamicin. Focal forms often require prolonged treatment. Swiss TPH logo This case study is extracted from Chapter 14 of Zinsstag et al. 2015 (OH Book) and the Policy brief on the elimination of brucellosis in Central Asia. © The Authors 2023