Seroprevalence of brucellosis and molecular characterization of Brucella spp. from slaughtered cattle in Rwanda

DATA AVAILABILITY STATEMENT : All relevant data are within the paper and its Supporting Information files.SUPPORTING INFORMATION : DATA S1. Raw data in excel format and original gel images.Bovine brucellosis is endemic in Rwanda, although, there is a paucity of documented evidence about the disease in slaughtered cattle. A cross-sectional study was conducted in slaughtered cattle (n = 300) to determine the seroprevalence of anti-Brucella antibodies using the Rose Bengal Test (RBT), and indirect enzyme-linked immunosorbent assay (i-ELISA). Corresponding tissues were cultured onto a modified Centro de Investigación y Tecnología Agroalimentaria (CITA) selective medium and analysed for Brucella spp. using the 16S-23S ribosomal interspacer region (ITS), AMOS, and Bruce-ladder PCR assays. The seroprevalence was 20.7% (62/300) with RBT, 2.9% (8/300) with i-ELISA, and 2.9% (8/300) using both tests in series. Brucella-specific 16S-23S ribosomal DNA interspace region (ITS) PCR detected Brucella DNA in 5.6% (17/300; Brucella culture prevalence). AMOS-PCR assay identified mixed B. abortus and B. melitensis (n = 3), B. abortus (n = 3) and B. melitensis (n = 5) while Bruce-ladder PCR also identified B. abortus (n = 5) and B. melitensis (n = 6). The gold standard culture method combined with PCR confirmation identified 5.6% Brucella cultures and this culture prevalence is higher than the more sensitive seroprevalence of 2.9%. This emphasizes the need to validate the serological tests in Rwanda. The mixed infection caused by B. abortus and B. melitensis in slaughtered cattle indicates cross-infection and poses a risk of exposure potential to abattoir workers. It is essential to urgently strengthen a coordinated national bovine brucellosis vaccination and initiate a test-and-slaughter program that is not presently applicable in Rwanda.The Belgian Directorate-General for Development Cooperation, through its Framework Agreement with the Institute of Tropical Medicine.http://www.plosone.orgam2023Veterinary Tropical Disease

Characterization of Brucella spp. and other abortigenic pathogens from aborted tissues of cattle and goats in Rwanda

BACKGROUND : Abortions cause tremendous economic losses in food-producing animals and may lead to food insecurity. OBJECTIVES : This study aimed to characterize Brucella spp. and other abortigenic pathogens from aborted tissues of cattle. METHODS : For cattle, aborted tissues (n = 19) were cultured, and Brucella spp. were detected using the genus-specific 16S-23S ribosomal DNA interspacer region (ITS) assay and speciated using Brucella abortus, Brucella melitensis, Brucella ovis, and Brucella suis (AMOS) and Bruce-ladder PCR assays. Brucella negative samples were screened using the eight abortigenic pathogens PCR panel. Samples from an abortion outbreak that occurred within a goat tribe were included in this investigation. Sera of females (n = 8) and males (n = 2) were analyzed using the Rose Bengal Test (RBT) and indirect enzyme-linked immunosorbent assay (i-ELISA), while vaginal swabs (n = 3) and aborted tissues (n = 1) were cultured and characterized. RESULTS : The ITS-PCR detected Brucella DNA in cultures from two aborted tissues of cattle (10.5%, [2/19]), which were identified as B. melitensis (n = 1), and B. abortus (n = 1) using AMOS and Bruce-ladder PCR assays. Campylobacter fetus (n = 7) and Leptospira spp. (n = 4) including co-infections (n = 2) of C. fetus and Leptospira spp. were identified from the Brucella negative samples of cattle. Goats (100.0%, 10/10) were brucellosis seropositive on RBT and i-ELISA. Mixed infections caused by B. melitensis and B. abortus were isolated from the vaginal swabs (n = 3) and aborted tissues (n = 1). DISCUSSION AND CONCLUSIONS : This is the first identification of abortion-associated pathogens in aborted cattle indicating the enormous financial losses and a threat to public health. It is therefore essential to include these identified pathogens in the surveillance scheme of veterinary and human services.The Institute of Tropical Medicine, Belgium, and the Department of Veterinary Tropical Disease, South Africa.https://wileyonlinelibrary.com/journal/vms3hj2022Accountin

Prevalence of bovine tuberculosis and characterization of the members of the Mycobacterium tuberculosis complex from slaughtered cattle in Rwanda

BACKGROUND : Bovine tuberculosis (bTB) is an endemic disease in Rwanda, but little is known about its prevalence and causative mycobacterial species. The disease causes tremendous losses in livestock and wildlife and remains a significant threat to public health. MATERIALS AND METHODS : A cross-sectional study employing a systematic random sampling of cattle (n = 300) with the collection of retropharyngeal lymph nodes and tonsils (n = 300) irrespective of granulomatous lesions was carried out in six abattoirs to investigate the prevalence and identify mycobacterial species using culture, acid-fast bacteria staining, polymerase chain reaction, and GeneXpert assay. Individual risk factors and the origin of samples were analysed for association with the prevalence. FINDINGS : Of the 300 sample pools, six were collected with visible TB-like lesions. Our findings demonstrated the presence of Mycobacterium tuberculosis complex (MTBC) in 1.7% (5/300) of sampled slaughtered cattle. Mycobacterium bovis was isolated from 1.3% (4/300) animals while one case was caused by a rifampicin-resistant (RR) M. tuberculosis. Non-tuberculous mycobacteria were identified in 12.0% (36/300) of the sampled cattle. There were no significant associations between the prevalence and abattoir category, age, sex, and breeds of slaughtered cattle. CONCLUSIONS : This study is the first in Rwanda to isolate both M. bovis and RR M. tuberculosis in slaughtered cattle indicating that bTB is present in Rwanda with a low prevalence. The isolation of RR M. tuberculosis from cattle indicates possible zooanthroponotic transmission of M. tuberculosis and close human-cattle contact. To protect humans against occupational zoonotic diseases, it is essential to control bTB in cattle and raise the awareness among all occupational groups as well as reinforce biosafety at the farm level and in the abattoirs.The Belgian Directorate-General for Development Cooperation, through its Framework Agreement with the Institute of Tropical Medicine.https://journals.plos.org/plosntdsdm2022Veterinary Tropical Disease

Molecular characterization of Brucella spp. from seropositive herds of cattle farmed at the wildlife-livestock-human interface in Rwanda

DATA AVAILABILITY STATEMENT : The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.Seroprevalence studies showed that brucellosis is prevalent in cattle in Rwanda with no recent study on the characterization of Brucella spp. Therefore, this study aimed to characterize Brucella spp. in seropositive herds of cattle farmed at the wildlife–livestock–human interface. Whole blood samples (n = 118), milk (n = 41), and vaginal swabs (n = 51) were collected from 64 seropositive herds. All samples (n = 210) were inoculated onto modified Centro de Investigacion y Tecnologia Agroalimentaria (CITA) selective medium. Cultures were analyzed to detect Brucella spp. using 16S−23S ribosomal DNA interspacer region (ITS) PCR, the Brucella cultures were speciated using AMOS and Bruce-ladder PCR assays. Brucella spp. were detected in 16.7% (35/210) of the samples established from the samples using ITS-PCR. The AMOS PCR assay identified mixed Brucella abortus and B. melitensis (n = 6), B. abortus (n = 7), and B. melitensis (n = 1) from cultures from blood samples; mixed B. abortus and B. melitensis (n = 1) and B. abortus (n = 4) from cultures from milk samples; mixed B. abortus and B. melitensis (n = 6), B. abortus (n = 8), and B. melitensis (n = 1) from cultures from vaginal swabs. Bruce-ladder PCR assay confirmed B. abortus and B. melitensis cultures. The isolation of Brucella spp. was significantly associated with districts, with the Nyagatare district having more isolates than other districts (p=0.01). This study identified single ormixed B. abortus and B. melitensis infections in cattle samples in Rwanda, which emphasizes the need to improve brucellosis control at the wildlife–livestock– human interface and raise the awareness of cattle keepers, abattoir workers, laboratory personnel, and consumers of cattle products.The Belgian Directorate- General for Development Cooperation, through its Framework Agreement with the Institute of Tropical Medicine.https://www.frontiersin.org/journals/veterinary-scienceam2023Veterinary Tropical Disease

Agarose gel electrophoresis for Bruce–ladder PCR products amplified from cultures of tissues from slaughtered cattle.

Lanes M: Gene Ruler 100 bp (ThermoFischer Scientific, Johannesburg, South Africa); lanes 1–5: B. abortus; lanes 6–8: B. melitensis; lane 9: positive control, B. suis ZW45, lane 10: positive control, B. melitensis rev 1, lane 11: B. abortus (REF 544), lane 12: positive control, B. abortus S 19, lane 13: negative control with sterile water.</p

Raw data in excel format and original gel images.

(XLSX)</p

Univariable associations between animal characteristics and ITS PCR assay of <i>Brucella</i> spp. isolates from cultures of tissues of slaughtered cattle in Rwanda.

Univariable associations between animal characteristics and ITS PCR assay of Brucella spp. isolates from cultures of tissues of slaughtered cattle in Rwanda.</p

Sequences of oligonucleotide primers used for the distinction of <i>Brucella</i> species isolated from slaughtered cattle in Rwanda.

Sequences of oligonucleotide primers used for the distinction of Brucella species isolated from slaughtered cattle in Rwanda.</p

Agarose gel electrophoresis of the 16-23S interspacer region (ITS) PCR products amplified from cultures of tissues from slaughtered cattle.

Lanes M: DNA Gene Ruler 100bp plus (Thermo Fischer Scientific, Johannesburg, South Africa), lanes 1–7: amplification of a 214 bp sequence of the genus Brucella spp., lane 8: negative control containing sterile water, lane 9: positive control with B. abortus RF544.</p

A map of Rwanda with provinces and districts with red stars showing the locations of abattoirs visited in this study [22].

A map of Rwanda with provinces and districts with red stars showing the locations of abattoirs visited in this study [22].</p