Prevalence and risk factors of brucellosis among veterinary health care professionals

The study describes prevalence, clinical symptoms and risk factors for brucellosis in personnel engaged in veterinary health care in Karnataka, India. A total of 1050 sera samples were collected from animal handlers, veterinarians, veterinary students, para-veterinarians and persons engaged in artificial insemination of animals. The sera samples were tested for brucellosis by Rose Bengal plate test (RBPT), serum agglutination test (SAT), IgG and IgM indirect ELISA and PCR. Age, sex, clinical symptoms and risk factors were recorded in structured questionnaire. Of the 1050 samples tested, 6.76, 6.38, 3.90, 2.67 and 2.0% were positive by IgG ELISA, RBPT, SAT, IgM ELISA and PCR, respectively and overall prevalence recorded was 7.04%. The prominent clinical symptoms observed were intermittent fever (71.62%) followed by joint pain and body aches. A high degree of suspicion, awareness and multimodal diagnostic approach is suggested for early diagnosis, treatment and disease follow up.

Genotyping of Indian antigenic, vaccine, and field Brucella spp. using multilocus sequence typing

INTRODUCTION

Brucellosis is one of the most important zoonotic diseases that affects multiple livestock species and causes great economic losses. The highly conserved genomes of Brucella, with > 90% homology among species, makes it important to study the genetic diversity circulating in the country.

METHODOLOGY

A total of 26 Brucella spp. (4 reference strains and 22 field isolates) and 1 B. melitensis draft genome sequence from India (B. melitensis Bm IND1) were included for sequence typing. The field isolates were identified by biochemical tests and confirmed by both conventional and quantitative polymerase chain reaction (qPCR) targeting bcsp 31Brucella genus-specific marker. Brucella speciation and biotyping was done by Bruce ladder, probe qPCR, and AMOS PCRs, respectively, and genotyping was done by multilocus sequence typing (MLST).

RESULTS

The MLST typing of 27 Brucella spp. revealed five distinct sequence types (STs); the B. abortus S99 reference strain and 21 B. abortus field isolates belonged to ST1. On the other hand, the vaccine strain B. abortus S19 was genotyped as ST5. Similarly, B. melitensis 16M reference strain and one B. melitensis field isolate were grouped into ST7. Another B. melitensis field isolate belonged to ST8 (draft genome sequence from India), and only B. suis 1330 reference strain was found to be ST14.

CONCLUSION

The sequences revealed genetic similarity of the Indian strains to the global reference and field strains. The study highlights the usefulness of MLST for typing of field isolates and validation of reference strains used for diagnosis and vaccination against brucellosis.