Molecular identification of <i>Brucella</i> species and biovars associated with animal and human infection in Iran

Abstract

Brucellosis is a costly contagious disease of human, domestic and wild animals. It is a serious health problem in Iran causing significant economic losses therefore, control approaches to prevent its spread are of great importance. In Iran, the species and biovars of virulent <em>Brucella</em> species are still under-reported due to the inadequate diagnostic protocols and insufficient laboratory facilities. The objective of this study was to characterize <em>Brucella</em> isolates obtained from passive animal and human surveillance in Iran from 2011 to 2018 in order to understand the current epidemiological situation of the disease. A total of 419 samples (milk, blood, cerebrospinal fluid, abomasum content and aborted fetus tissues) were collected from 65 cases/case series (human and animals) and examined bacteriologically. The initially identified <em>Brucella</em> isolates were further characterized using phenotypic and molecular approaches. All recovered isolates were either <em>B. abortus</em> or <em>B. melitensis</em>. The infection in sheep appeared to be exclusively associated with <em>B. melitensis,</em> but both <em>B. abortus</em> and <em>B. melitensis</em> were common in bovine samples. Samples from one sheep and one goat were confirmed to be infected by the <em>B. melitensis</em> vaccine strain Rev1. In spite of <em>B. abortus</em> burden in animals (14 cases in cattle and camel), brucellosis in human was predominantly associated with <em>B. melitensis </em>(15 cases). The results confirmed that <em>B. melitensis</em> biovar 1 and <em>B. abortus</em> biovar 3 remain the most prevalent biovars in Iran. This report builds a picture of the significance of different <em>Brucella </em>species in different hosts in Iran and provides applicable information for the healthcare professionals about the public health risks of brucellosis and relevant preventive strategies.