Epidemiology of Brucellosis and Genetic Diversity of Brucella abortus in Kazakhstan

Abstract

Brucellosis is a major zoonotic infection in Kazakhstan. However, there is limited data on its incidence in humans and animals, and the genetic diversity of prevalent strains is virtually unstudied. Additionally, there is no detailed overview of Kazakhstan brucellosis control and eradication programs. Here, we analyzed brucellosis epidemiological data, and assessed the effectiveness of eradication strategies employed over the past 70 years to counteract this infection. We also conducted multiple loci variable-number tandem repeat analysis (MLVA) of Brucella abortus strains found in Kazakhstan. We analyzed official data on the incidence of animal brucellosis in Kazakhstan. The records span more than 70 years of anti-brucellosis campaigns, and contain a brief description of the applied control strategies, their effectiveness, and their impact on the incidence in humans. The MLVA-16 method was used to type 94 strains of B. abortus and serial passages of B. abortus 82, a strain used in vaccines. MLVA-8 and MLVA-11 analyses clustered strains into a total of four and seven genotypes, respectively; it is the first time that four of these genotypes have been described. MLVA-16 analysis divided strains into 28 distinct genotypes having genetic similarity coefficient that varies from 60 to100% and a Hunter & Gaston diversity index of 0.871. MST analysis reconstruction revealed clustering into "Kazakhstani-Chinese (Central Asian)", "European" and "American" lines. Detection of multiple genotypes in a single outbreak confirms that poorly controlled trade of livestock plays a crucial role in the spread of infection. Notably, the MLVA-16 profile of the B. abortus 82 strain was unique and did not change during 33 serial passages. MLVA genotyping may thus be useful for epidemiological monitoring of brucellosis, and for tracking the source(s) of infection. We suggest that countrywide application of MLVA genotyping would improve the control of brucellosis in Kazakhstan.

Genome Sequences of Brucella Melitensis Strains QH2019001 and QH2019005 Provides Insight Into Different Evolutionary Origins Within Qinghai Province, China

“…Due to thehigh mutation rate in tandem DNA repeats loci, the MLVAplatform provides the ability to distinguish eld and vaccine strains [22], associate isolates with geographic origins, and discriminate most Brucella species with a high homogeneity discriminatory power [23]. In China, MLVA genotyping provides a basis for reliable disease monitoring when combined with strain phylogeny and regional and time distributions, thus potentially providing valuable insight when examining an epidemiological linkage or trace-back investigation during a brucellosis outbreak [13,24,25].Furthermore, previous studies have shown thatMLVA can be used as an epidemiological tool for strain resolution and to distinguish relapses from reinfections in brucellosis patients [26].…”

Molecular characteristics of Brucella melitensis isolates from humans in Qinghai Province, China

“…Due to the high mutation rate in tandem DNA repeats loci, the MLVA-16 scheme provides the ability to distinguish eld strains [21] and associate isolates with their geographic origins [22]. In China, MLVA genotyping provides valuable insight when examining an epidemiological linkage or trace-back investigation during a brucellosis outbreak [10,23,24].…”

Using combined recombinant protein in the diagnosis of bovine brucellosis

“…The disease causes not only great economic losses in animal husbandry, but also poses a serious threat to public health (2,15). A complicated epizootic and epidemiological situation for brucellosis persists in the Republic of Kazakhstan where the disease remains endemic (21,33). The efficacy of brucellosis control and eradication programs primarily depends on the timely detection of infected animals by serological tests.…”