Epidemiological Characteristics and Clinical Manifestations of Brucellosis and Q Fever Among Humans from Northeastern Inner Mongolia.

Objective: To investigate the distribution, epidemiology, and clinical symptoms of brucellosis and Q fever in northeastern Inner Mongolia. Methods: In this study, 64 townships of Bairin left flag and Alukerqin flag, Jarud flag and Horqin right front flag in four counties with frequent brucellosis and Q fever were selected. Epidemiological characteristics, clinical features, and exposure to risk factors were identified and descriptively analyzed in patients from these areas. Results: There were 367 brucellosis cases in the four regions and 78 positive cases of Q-fever infection. In addition, 24 cases of brucellosis and Q-fever co-infection were identified, with a co-infection rate of 1.13%. Brucellosis and Q fever were mainly concentrated in the 30-65 and 40-55 age groups. For brucellosis, the difference between age groups was statistically significant (χ2 = 29.121, P < 0.05). The sex distribution for brucellosis was 225 men (61.31%) and 142 women (38.69%), and 45 men (57.69%) and 33 women (42.31%) had Q fever. Those with brucellosis and Q fever were mainly farmers, accounting for 79.19% and 78.38% of the total number, respectively. Of the 367 cases of brucellosis infection, the main symptoms were joint pain (52.59%), fatigue (47.14%), lower back pain (38.96%), fever (33.24%), hyperhidrosis (28.88%), and muscle pain (20.44%). Of the 78 cases of Q-fever infection, the main symptoms were joint pain (35.90%), fatigue (30.77%), lower back pain (26.92%), fever (21.79%), and hyperhidrosis (17.95%). Muscle pain also accounted for 12.82%. Conclusion: Occupational distribution suggests that we should strengthen the protection measures against diseases infected through animal husbandry. Among the clinical symptoms, fever, hyperhidrosis and fatigue were associated with brucellosis, while fever, headache, and fatigue were significantly associated with Q fever.

MLVA genotyping of Chinese human Brucella melitensis biovar 1, 2 and 3 isolates.

BACKGROUND: Since 1950, Brucella melitensis has been the predominant strain associated with human brucellosis in China. In this study we investigated the genotypic characteristics of B. melitensis isolates from China using a multiple-locus variable-number tandem-repeat analysis (MLVA) and evaluated the utility of MLVA with regards to epidemiological trace-back investigation. RESULTS: A total of 105 B. melitensis strains isolated from throughout China were divided into 69 MLVA types using MLVA-16. Nei's genetic diversity indices for the various loci ranged between 0.00 - 0.84. 12 out 16 loci were the low diversity with values < 0.2 and the most discriminatory markers were bruce16 and bruce30 with a diversity index of > 0.75 and containing 8 and 7 alleles, respectively. Many isolates were single-locus or double-locus variants of closely related B. melitensis isolates from different regions, including the north and south of China. Using panel 1, the majority of strains (84/105) were genotype 42 clustering to the 'East Mediterranean' B. melitensis group. Chinese B. melitensis are classified in limited number of closely related genotypes showing variation mainly at the panel 2B loci. CONCLUSION: The MLVA-16 assay can be useful to reveal the predominant genotypes and strain relatedness in endemic or non-endemic regions of brucellosis. However it is not suitable for biovar differentiation of B. melitensis. Genotype 42 is widely distributed throughout China during a long time. Bruce 16 and bruce 30 in panel 2B markers are most useful for typing Chinese isolates.

Seroprevalence of human brucellosis and molecular characteristics of Brucella strains in Inner Mongolia Autonomous region of China, from 2012 to 2016.

In the present study, a total of 1102304 serum samples were collected to detected human brucellosis between the years 2012 and 2016 in Inner Mongolia. Overall, an average of 3.79% anti-Brucella positive in Inner Mongolia was presented but the range of positive rates were among 0.90 to 7.07% in 12 regions. Seroprevalence of human brucellosis increased gradually from 2012 to 2016. However, the incidence rate of human brucellosis showed a declining trend. One hundred and seven Brucella strains were isolated and identified as B. melitensis species, and B. melitensis biovar 3 was the predominant biovar. MLVA-11 genotypes 116 was predominant and had crucial epidemiology to the human population. All 107 strains tested were sorted into 75 MLVA-16 genotypes, with 54 single genotypes representing unique isolates. This result revealed that these Brucellosis cases had epidemiologically unrelated and sporadic characteristics. The remaining 21 shared genotypes among two to four strains, confirming the occurrence of cross-infection and multiple outbreaks. Extensive genotype-events were observed between strains from this study and Kazakhstan, Mongolia, and Turkey, these countries were key members of the grassland silk road. Long-time trade in small ruminants (sheep) in these countries has possibly promoted the spread of Brucella spp. in these regions.

MLVA genotyping of Brucella melitensis and Brucella abortus isolates from different animal species and humans and identification of Brucella suis vaccine strain S2 from cattle in China.

In China, brucellosis is an endemic disease and the main sources of brucellosis in animals and humans are infected sheep, cattle and swine. Brucella melitensis (biovars 1 and 3) is the predominant species, associated with sporadic cases and outbreak in humans. Isolates of B. abortus, primarily biovars 1 and 3, and B. suis biovars 1 and 3 are also associated with sporadic human brucellosis. In this study, the genetic profiles of B. melitensis and B. abortus isolates from humans and animals were analyzed and compared by multi-locus variable-number tandem-repeat analysis (MLVA). Among the B. melitensis isolates, the majority (74/82) belonged to MLVA8 genotype 42, clustering in the 'East Mediterranean' group. Two B. melitensis biovar 1 genotype 47 isolates, belonging to the 'Americas' group, were recovered; both were from the Himalayan blue sheep (Pseudois nayaur, a wild animal). The majority of B. abortus isolates (51/70) were biovar 3, genotype 36. Ten B. suis biovar 1 field isolates, including seven outbreak isolates recovered from a cattle farm in Inner Mongolia, were genetically indistinguishable from the vaccine strain S2, based on MLVA cluster analysis. MLVA analysis provided important information for epidemiological trace-back. To the best of our knowledge, this is the first report to associate Brucella cross-infection with the vaccine strain S2 based on molecular comparison of recovered isolates to the vaccine strain. MLVA typing could be an essential assay to improve brucellosis surveillance and control programs.