Detection and characterization of Brucella spp. in bovine milk in small-scale urban and peri-urban farming in Tajikistan

Long ignored but making a comeback: a worldwide epidemiological evolution of human brucellosis

Brucellosis is a commonly neglected zoonosis that remains a serious global public health concern. The epidemiological evolution of human brucellosis has considerably changed over the past few decades, and epidemic geography is continuously expanding. Human brucellosis is emerging and re-emerging, and is imported from areas where it is endemic due to travel, immigration, and international trade. The disease continues to be prevalent in Asia and Africa, including West Asia, Central Asia, North Africa, and East Africa, with the highest incidence in Syria, Kyrgyzstan, Mongolia, Iran, Algeria, and Kenya. Re-emerging cases are frequently recorded in places where brucellosis has been controlled, such as Bosnia, Herzegovina, Azerbaijan, and the USA. In countries with a high disease burden, disease control and eradication have been extremely difficult because of livestock farming being the only source of livelihood, unique religious beliefs regarding animals, nomadic lifestyle, and low socioeconomic levels. Interventions focused on protecting livestock keepers are needed, particularly for those assisting with goat and sheep births and the consumption of raw dairy products. Notably, in most countries with a high disease burden, each period of several years with a low incidence rate was followed by a subsequent increase in cases, highlighting the necessity of continuous investment and surveillance. In addition, advocacy for the inclusion of brucellosis as a globally mandated reported disease, strict restrictions on animal movement, mandated consumption of pasteurized milk, and health education are needed. This study will help form an evidence-based strategy for international organizations to curb the future spread of brucellosis.

Brucellae as resilient intracellular pathogens: epidemiology, host-pathogen interaction, recent genomics and proteomics approaches, and future perspectives

Brucellosis is considered one of the most hazardous zoonotic diseases all over the world. It causes formidable economic losses in developed and developing countries. Despite the significant attempts to get rid of Brucella pathogens in many parts of the world, the disease continues to spread widely. Recently, many attempts proved to be effective for the prevention and control of highly contagious bovine brucellosis, which could be followed by others to achieve a prosperous future without rampant Brucella pathogens. In this study, the updated view for worldwide Brucella distribution, possible predisposing factors for emerging Brucella pathogens, immune response and different types of Brucella vaccines, genomics and proteomics approaches incorporated recently in the field of brucellosis, and future perspectives for prevention and control of bovine brucellosis have been discussed comprehensively. So, the current study will be used as a guide for researchers in planning their future work, which will pave the way for a new world without these highly contagious pathogens that have been infecting and threatening the health of humans and terrestrial animals.

Immunoassay-based evaluation of rOmp28 protein as a candidate for the identification of Brucella species

Introduction. Brucellosis is an important bacterial zoonosis, re-emerging as a serious public health concern in developing countries. Two major species, Brucella melitensis and Brucella abortus, cause recurrent facile infection in human. Therefore, rapid and accurate diagnosis for early disease control and prevention is needed in areas with low disease burden.Hypothesis. This study evaluated the sandwich enzyme-linked immunosorbent assay (ELISA) (S-ELISA) immunoassay for potential use of whole-cell (WC) and recombinant outer-membrane protein (rOmp28)-derived IgG polyclonals in sensitive detection of Brucella.Aim. Immunoassay-based WC detection of Brucella species in important sub-clinical matrices at lower limits of detection.Methodology. We purified recombinant rOmp28 with Ni-NTA gel affinity chromatography and produced IgG polyclonal antibodies (pAbs) using BALB/c mice and New Zealand white female rabbits against different antigens (Ags) of Brucella. Checkerboard sandwich ELISA and P/N ratio (optical density of 'P' positive test sample to 'N' negative control) were used for evaluation and optimization of the study. The pAbs were characterized using Western blot analysis and different matrices were spiked with WC Ag of Brucella.Results. Double-antibody S-ELISA was developed using WC Ag-derived rabbit IgG (capture antibody at 10 µg ml^-1) and rOmp28-derived mice IgG (detection antibody at 100 µg ml^-1) with a detection range of 10² to 10⁸ cells ml^-1 and a limit of detection at 10² cells ml^-1. A P/N ratio of 1.1 was obtained with WC pAbs as compared to 0.6 and 0.9 ratios with rOmp28-derived pAbs for detecting B. melitensis 16M and B. abortus S99, respectively. An increased P/N ratio of 4.4 was obtained with WC Ag-derived rabbit IgG as compared to 4.2>4.1>2.4 ratios obtained with rabbit IgGs derived against cell envelope (CE), rOmp28 and sonicated antigen (SA) of Brucella with high affinity for rOmp28 Ag analysed on immunoblots. The rOmp28-derived mice IgG revealed two Brucella species at P/N ratios of 11.8 and 6.3, respectively. Upon validation, S-ELISA detected Brucella WCs in human whole blood and sera samples with no cross-reactivity to other related bacteria.Conclusion. The developed S-ELISA is specific and sensitive in early detection of Brucella from different matrices of clinical and non-clinical disease presentation.

An Epidemiological Study of Brucellosis in Different Animal Species from the Al-Qassim Region, Saudi Arabia

Brucellosis is a zoonotic bacterial illness that affects humans and a variety of domestic animals, especially ruminants. It is mostly transmitted through the consumption of contaminated drinks, foods, undercooked meat, or unpasteurized milk or contact with infected animals. Therefore, the present study aimed to investigate the seroprevalence of brucellosis in camels, sheep, and goat herds in the Qassim region, Saudi Arabia, using commonly used diagnostic serological procedures such as the Rose Bengal test (RBT), complement fixation test (CFT), and enzyme-linked immunosorbent assay (ELISA). The seroprevalence of brucellosis in camels, sheep, and goats was determined in the selected areas using a cross-sectional study design and a total of 690 farm animals of both sexes of different ages from the three animal species (274 camels, 227 sheep, and 189 goats). According to RBT results, 65 sera were positive for brucellosis, including 15 (5.47%) for camels, 32 (14.09%) for sheep, and 18 (9.50%) for goats. CFT and c-ELISA were performed as confirmatory tests on positive samples resulting from RBT. With c-ELISA, 60 serum samples were confirmed positive, in 14 (5.10%), 30 (13.21%), and 16 (8.46%) camels, sheep, and goats, respectively. There were 59 serum samples confirmed as positive for CFT, including 14 (5.11%), 29 (12.77%), and 16 (8.46%) for camels, sheep, and goats, respectively. Overall, the highest seroprevalence of brucellosis was found in sheep while the least was found in camels from the three tests (RBT, c-ELISA, and CFT). The highest seroprevalence of brucellosis was found in sheep while the least seroprevalence was found in camels. There was also a higher seroprevalence of brucellosis among female animals than males as well as among old animals than young animals. The study, thus, demonstrates brucellosis seroprevalence among farm animals (camels, sheep, and goats) and the significance of intervention measures against brucellosis incidence in both humans and animals through the creation of public awareness and other relevant policy measures such as livestock vaccination, effective hygiene management, and adequate quarantine or serological analysis for newly introduced animals.

Seroprevalence, associated risk factors, and molecular detection of bovine brucellosis in rural areas of Egypt

The study was carried out on six villages in northern Egypt to evaluate the epidemiological situation of bovine brucellosis among 989 unvaccinated household cattle by Rose Bengal Plate Test (RBPT) and indirect ELISA (iELISA) and to investigate the existence of Brucella DNA using real-time PCR in 100 milk and 100 sera from seropositive cattle and 50 sera from seronegative cattle. The overall seroprevalence was 20.7% and 23.7% by RBPT and iELISA, respectively. Based on the iELISA results, the seroprevalence was significantly (P < 0.05) higher in the village II (34.7%) and cattle > 7 years (30.1%). More males than females were non-significant seropositive (P = 0.6). There was 95% agreement between RBPT and iELISA, although iELISA showed a higher positivity rate (23.7%, 95% CI: 0.21-0.26) than RBPT (20.7%, 95% CI: 0.18-0.24). DNA of Brucella was confirmed in 16 milk samples by IS711 qPCR from seropositive cattle, however, no Brucella DNA was detected in serum samples tested positive and negative. Brucella abortus was the only species detected based on the alkB gene. Prevalence is highly related to the sampling site and the age of the animals. In conclusion, although qPCR is more accurate and commonly used in the diagnosis of most infectious diseases but in this situation iELISA is preferred and recommended for continuous screening and animal movement restriction and vaccination protocols, especially in high-risk areas.

First record of the human infection of Brucella melitensis in Kyrgyzstan: evidence from whole-genome sequencing-based analysis

BACKGROUND

Brucellosis, a zoonosis mainly transmitted by consumption of unpasteurized dairy products as well as direct contact with infected animals, is endemic in Kyrgyzstan. However, Brucella species in humans have not been investigated and the origin of the disease remains poorly known in wide parts of Сentral Asia. Thus, molecular characterization of the circulating strains is a critical first step in understanding Brucella diversity in the country.

METHODS

In this study, isolates were collected from patients with suspected brucellosis from different regions in Kyrgyzstan between 2019 and 2020. The detection and identification of Brucella was carried out by Bruce-ladder PCR. Next generation sequencing was used to sequence the 89 Brucella isolates, which were genotyped by cgSNP and cgMLST to identify epidemiological connection between Brucella isolates as well as placing them in the context of the global Brucella phylogeny.

RESULTS

The Brucella strains isolated from all regions of Kyrgyzstan were identified as B. melitensis. Based on cgSNP analysis, 18 sequence types were differentiated. The highest numbers of different sequence types were found in Batken (n = 8), Osh (n = 8) and Jalal-Abad (n = 6) oblasts. According to cgSNP and cgMLST analyses, different B. melitensis lineages circulate in Kyrgyzstan, all of them belonging to the Eastern Mediterranean group of the global Brucella phylogeny with the highest similarity to strains from Turkmenistan, Iran and Turkey.

CONCLUSION

In the present study, B. melitensis was identified as a causative agent of human brucellosis in Kyrgyzstan and different lineages could be identified. Since this study focused on isolates of human origin, the identity of Brucella species and lineages circulating among animal populations remains elusive. Implementing culture techniques and use of most recent molecular, bioinformatic and epidemiological tools are needed to set up a One Health approach to combat brucellosis in Kyrgyzstan. Further, other Сentral Asian countries need to take part in this effort as brucellosis is a transboundary disease in these regions.

Brucella spp. Contamination in Artisanal Unpasteurized Dairy Products: An Emerging Foodborne Threat in Tunisia

Brucellosis is a worldwide zoonotic disease transmitted to humans, predominantly by the consumption of contaminated raw milk and dairy products. This study aimed to investigate the occurrence of Brucella spp. in 200 raw milk, ricotta, and artisan fresh cheese samples, collected from individual marketing points in four districts in Tunisia. Samples were analyzed for the presence of Brucella spp. by IS711-based real-time PCR assay. Positive samples were further analyzed by qPCR for B. melitensis and B. abortus species differentiation. The DNA of Brucella spp. was detected in 75% of the samples, B. abortus was detected in 31.3%, and B. melitensis was detected in 5.3% of positive samples. A percentage of 49.3% of samples co-harbored both species, while 14% of the Brucella spp. positive samples were not identified either as B. abortus or B. melitensis. High contamination rates were found in ricotta (86.2%), cheese (69.6%), and raw milk (72.5%) samples. The study is the first in Tunisia to assess the occurrence of Brucella spp. contamination in artisanal unpasteurized dairy products and showed high contamination rates. The detection of both B. abortus and B. melitensis highlights that zoonotic high-pathogen agent control remains a challenge for food safety and consumer health protection and could represent a serious emerging foodborne disease in Tunisia.

The Importance of Complementary PCR Analysis in Addition to Serological Testing for the Detection of Transmission Sources of Brucella spp. in Greek Ruminants

The early and accurate diagnosis of brucellosis, a ubiquitous zoonotic infection, is significant in preventing disease transmission. This study aimed to assess the infection rate of Brucella spp. in ruminants and to evaluate the agreement between a serological test and a molecular method for the detection of infected cases. Blood and milk samples of 136 ruminants were analyzed using two laboratory methods: the Rose Bengal plate (RBP) test to detect B. abortus and B. melitensis antibodies and the molecular polymerase chain reaction (PCR) method for the presence of bacterial DNA. The agreement between the methods was assessed using the kappa statistic. Based on the RBP test, there were 12 (8.8%) seropositive animals (10 sheep and 2 cows), while 2 (1.4%) samples were positive on PCR analysis. The positive PCR samples were from seronegative cow samples on RBP testing. There was slight agreement (k = −0.02) between the two methods, which was not statistically significant. Our results indicate that complementary molecular methods are useful to detect the bacteria in infected animals that are seronegative due to an early stage of infection. Therefore, a combination of molecular methods and serological tests can be applied to detect brucellosis in ruminants efficiently.

Studies on intra-ocular vaccination of adult cattle with reduced dose Brucella abortus strain-19 vaccine

Brucella abortus vaccines play a central role in bovine brucellosis control with tremendous success worldwide for decades. The study was aimed to evaluate the efficacy of reduced dose (5.0 × 10 9 cfu) of S19 vaccine in adult cattle and its shedding in the milk of vaccinated cattle using molecular techniques. The OIE recommended tests (RBPT, SAT, and iELISA) for brucellosis screening in cattle were used. Seronegative cattle (n = 90) of different age groups (young, old heifers & milking cows, n = 30 each) were selected for the vaccine trials. Antibody titers were recorded at 7th, 21st, 30th, 60th, 90th and 120th days post-vaccination (DPV) to monitor the immune responses following vaccination and at 150th, 180th, 210th and 240th DPB following booster-dose to an intraocular group. The humoral immune responses observed by RBPT and ELISA, proved that antibody titers persisted in s/c group compared to the i/o group in all categories. The IFN-γ stimulation (CMI) due to reduced dose vaccination was noticed early as 30th in all groups and declined after 90th DPV, with higher IFN-γ stimulation among the s/c group. The Bcsp31 and IS711 targeted PCR detected the presence of Brucella DNA in milk samples (n = 120) from the vaccinated cows (n = 30) and confirmed by qPCR (TaqMan assay) at 30th, 60th, 90th and 120th DPV. A Significant number, 70% (7/10) was detected in s/c by qPCR. BCSP31 sequence was deposited at NCBI GenBank (accession no. MK881173-6). PCR and qPCR techniques could provide a reliable diagnosis of brucellosis from milk. The intraocular route remains the safer route for vaccinating adult cattle than subcutaneous.

Importance of brucellosis control programs of livestock on the improvement of one health

Brucellosis not only represents an important health restraint on livestock but also causes high economic losses in many developing countries worldwide. Despite considerable efforts made for the control of brucellosis, the disease is still spreading in many regions (such as the Middle East) where it represents one of the most important health hazards impacting both animals and humans. The present review aims to investigate the efficacy of veterinary control programs regarding brucellosis, with a special focus on current prevention, control, and eradication approaches. The reasons for unsuccessful control programs such as the absence of highly effective vaccines and non-certified bulls are also debated, to understand why the prevalence of brucellosis in livestock is not decreasing in many areas despite considerable efforts taken to date. The importance of governmental and regional investment in brucellosis control remains one of the main limiting factors owing to the limited budget allocated to tackle this disease. In this context, one health concept has generated novel comprehensive approaches with multiple economic implications across the livestock industry and public health. However, the implementation of such global preventive strategies appears to be a key issue for many endemic and low-income countries. According to the collected data, epidemiological contexts including management and trade systems along with well-defined agro-ecological zones should be evaluated in brucellosis endemic countries to improve milk production and to enhance the sustainability of the livestock sector at both national and regional levels.

Herd-level contamination of Neospora caninum, Toxoplasma gondii and Brucella in milk of Iranian dairy farms

The bulk milk examination is a reliable screening tool for monitoring the quality of milk in the farms. The infection to Neospora caninum, Toxoplasma gondii and Brucella sp. Was evaluated in bulk milk samples of dairy farms in Hamedan province, West part of Iran. All the dairy farms (n = 149) were examined for N. caninum, T. gondii and Brucella infections using milk ring test (MRT), microbiology, serology (Enzyme-linked Immunosorbent Assay), and molecular techniques. Based on molecular methods, Brucella-infection was negative in all farms; while, 55 %, 5.4 % and 2.7 % of samples were positive for N. caninum, T. gondii and mix infection, respectively. The highest Neospora-infection was detected in the farms with history of abortion in fall and winter. There was significant association between Neospora-infection and the presence of dogs and rodents in the farms, herd size, and age of the animals. Also, a significant association was seen between Toxoplasma-infection and the presence of cats and rodents in the farms, as well as age of the animals. Average total bacterial count (TBC) was calculated 1.14 × 10⁶±1.1 × 10⁶. The highest TBC was in the farms from Central locations of studied area (5.7 × 10⁶±2.24 × 10⁶), farms with more than 120 animals (7.9 × 10⁶±2.8 × 10⁶), and farms with ≥50-months age (1.74 × 10⁶±6.3 × 10⁵) in spring and summer (6.9 × 10⁶±3.7 × 10⁶). The number of somatic cells was estimated between 1 × 10⁴ and 2 × 10⁶ (Average = 4.2 × 10⁵±3.39 × 10⁵). The current study was a comprehensive evaluation of Neospora, Toxoplasma and Brucella infections in milk samples of Iranian dairy farms for the first time. Neospora-infection is responsible for economic losses in the region. Health education and milk pasteurization are so helpful for inhibiting the milk borne diseases. To reduce the risk factors, predict and design the appropriate schemes like redundant of heterogeneous animals are recommended.

Bovine brucellosis - a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.

Seroprevalence of Brucellosis in Buffalo Worldwide and Associated Risk Factors: A Systematic Review and Meta-Analysis

Background: Brucellosis is an important zoonotic disease caused by Brucella spp. Brucellosis is widely distributed in more than 160 or 170 countries around the world, where it poses a huge threat to animal husbandry and human health. About 150 million head of water buffalo, distributed across more than 40 countries worldwide, are kept for the purposes of service, milk, and meat. High incidence of Brucella spp. in buffalo has negatively affected dairy products and meat products.

Results: We searched all research related to seroprevalence of brucellosis in water buffalo anywhere in the world in PubMed, Science Direct, SpringerLink, China National Knowledge Infrastructure, Wanfang Database, and VIP Chinese Journal Databases. A total of 26 articles published from 1985 to 2020 met the final selection criteria. The overall seroprevalence of buffalo brucellosis worldwide was 9.7%. The seroprevalence before 2010 (20.8%) (95% CI: 5.6–42.2) was much higher than the seroprevalence rate from 2010 to 2020 (4.2%) (95% CI: 1.8–7.5). Subgroup analysis by feeding mode found that the point estimate of seroprevalence in stock buffalo (11.5%) (95% CI: 3.6–23.0) was higher than that in captive buffalo (10.6%) (95% CI: 4.9–18.1). Subgroup analysis by farming mode found that the seroprevalence was higher in captive-bred buffalo (10.7%) (95% CI: 6.6–15.7) than in intensively farmed buffalo (8.5) (95% CI: 0.9–22.2). The seroprevalence in buffalo living in dry lands (6.4%) (95% CI: 2.0–12.9) is greater than that in buffalo living in wetlands (5.1%) (95% CI: 1.8–10.4) (P < 0.05). The seroprevalence in female buffalo (10.1%) (95% CI: 3.4–19.7) was higher than that in male buffalo (4.4%) (95% CI: 2.0–7.4). The seroprevalence in lactating buffalo was higher than that in buffalo of other ages (26.9%) (95% CI: 1.8–66.5). Subgroup analysis by detection method found that the seroprevalence detected by the complement fixation test (27.3%) (95% CI: 0.7–70.8) was much higher than that detected by other methods.

Conclusion: The results of this meta-analysis showed that buffalo brucellosis infection is very common in buffalo herds around the world. Although the seroprevalence of brucellosis in buffalo and humans is relatively low, serious effects upon animal husbandry and public health make it necessary to take effective control and preventive measures to control the spread of this disease.

Serological and Molecular Phylogenetic Detection of Coxiella burnetii in Lactating Cows, Iraq

This study is carried out to investigate the prevalence of Coxiella burnetii (C. burnetii) infections in cattle using an enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) assay targeting IS1111A transposase gene. A total of 130 lactating cows were randomly selected from different areas in Wasit province, Iraq and subjected to blood and milk sampling during the period extended between November 2018 and May 2019. ELISA and PCR tests revealed that 16.15% and 10% of the animals studied were respectively positive. Significant correlations (P<0.05) were detected between the positive results and clinical data. Two positive PCR products were analyzed phylogenetically, named as C. burnetii IQ-No.5 and C. burnetii IQ-No.6; and then recorded in the National Center for Biotechnology Information (NCBI) under an accession numbers of MN473204.1 and MN473205.1. Comparative identity of the local strains with NCBI-BLAST strains/isolates revealed 97% similarity and 0.1-0.6% of total genetic mutations/changes. NCBI-BLAST Homology Sequence reported high significant identity (P<0.05) between the local, C. burnetii IQ-No.5 and C. burnetii IQ-No.6; strains and C. burnetii 3345937 (CP014354.1) Netherlands isolate at 99.10% and 99.06%, respectively. The current study concluded that the percentage of infected cows with coxiellosis is relatively high, and Coxiella should be listed as abortive pathogen. Therefore, additional studies should be performed including different animals, samples, and regions.

Evaluating the efficiency of TaqMan real-time PCR and serological methods in the detection of Brucella spp. in clinical specimens collected from suspected patients in Ardabil, Iran

BACKGROUND

This study aims to evaluate the efficiency of the TaqMan real-time PCR and serological methods in detecting Brucella spp. in clinical specimens that have been collected from suspected patients in Ardabil, Iran.

METHODS

In this cross-sectional study, a total of 113 consecutive patients suspected of brucellosis who were referred to the three hospitals in Ardabil province were selected. In the first step, the diagnosis of brucellosis was performed by serological methods including the Rose Bengal slide agglutination test, Wright test, 2-ME test, and BrucellaCapt test. In the next step, TaqMan real-time PCR with primer and probe targeting the bcsp31 gene was used for the detection of Brucella spp. Specificity, sensitivity, and positive and negative predictive values of the TaqMan real-time PCR assay were calculated.

RESULTS

Among 113 suspected patients with different clinical manifestations, the Rose Bengal slide agglutination test, Wright test, and 2-ME test were positive in 60 cases; however, the BrucellaCapt test titer was 1:160 for one patient. Six patients had high initial serum antibody titers; 2-ME titers of ≥1:640; STA titers of ≥1:1280; BrucellaCapt titers of ≥ 1:2560. Among positive cases, no correlation was observed among gender, age, and life (residence) in urban or rural areas. The TaqMan real-time PCR was positive in 35% of all 60 positive cases. The comparison of the results of the BrucellaCapt and TaqMan real-time PCR methods revealed that 19 out of 54 (35.2%) and 2 out of 6 (33.4%) BrucellaCapt positive cases with titers of >1:320 and ≤ 1:320 were positive, respectively. The sensitivities and specificities of the TaqMan real-time PCR assay were 49.1% and 100% respectively.

CONCLUSION

The sensitivity of the TaqMan real-time PCR assay was low in the diagnosis of brucellosis, while the BrucellaCapt test turned out to be a very valuable, sensitive, and specific test for the diagnosis of brucellosis in suspected patients and, thus, can provide reliable results in medical laboratories.

Use of touch-down polymerase chain reaction to enhance the sensitivity of Brucella melitensis detection in raw milk

Brucellosis is a highly contagious bacterial zoonotic infectious disease severely affecting the public health and economic features of endemic and non-endemic countries. The present study assessed the potentials of using the touch-down polymerase chain reaction (TD-PCR) compared to the conventional PCR and culture methods in order to detect Brucella melitensis in raw milk samples of 55 sheep and 45 goats through deriving the primers from the omp31 element of the Brucella genome. In addition, nine isolates of B. melitensis were identified using the culture method. No positive cases were found in sediment samples, while the fatty tap layer test by conventional PCR and TD-PCR revealed 6 and 16 positive samples, respectively. Based on the survey of the limits of detection by TD-PCR and conventional PCR, TD protocol had a detection threshold of three logs higher than the conventional protocol under the experimental condition. The developed protocol of this study was highly sensitive and extremely fast. Therefore, this TD-PCR protocol could detect even a very low number of bacteria in milk samples. To our best knowledge, this is the first report on the use of the TD-PCR method to identify B. melitensis in milk.

Fluorescence signal amplification assay for the detection of B. melitensis 16M, based on peptide-mediated magnetic separation technology and a AuNP-mediated bio-barcode assembled by quantum dot technology

Members of the Brucella spp. are facultative intracellular bacteria that can cause global brucellosis, a zoonotic disease. Herein, a novel fluorescence signal amplification (FSA) method for the rapid detection of B. melitensis 16M was developed based on peptide-mediated magnetic separation (PMS) technology and Au nanoparticle (AuNP)-mediated bio-barcode assay technology assembled by quantum dots (QDs). The PMS technology was used to specifically capture and isolate B. melitensis 16M from food. The immunomagnetic bead-B. melitensis 16M bioconjugates (IMBs-B. melitensis 16M) were then identified by IgY on the surface of AuNPs and the oligonucleotide chains on the surface of the gold nanoparticles were hybridized with bio-barcodes assembled by quantum dots (QD-probe2). The IMB/B. melitensis 16M/IgY-AuNP-probe1/QD-probe2 bioconjugates were concentrated by magnetic separation. Therefore, as the concentration of B. melitensis 16M in the sample increased, the unbound QD-probe2 in the supernatant reduced, and the B. melitensis 16M in the sample could be indirectly measured by detecting the fluorescence in the supernatant. This FSA method can detect B. melitensis 16M concentration in the range of 10 to 106 cfu ml-1 without pre-enrichment, and the limit of detection (LOD) is as low as 10 cfu ml-1 with high specificity. Furthermore, the proposed method for the detection of B. melitensis 16M has a LOD of 1.07 × 102 cfu ml-1 and a linear range from 102 to 107 cfu ml-1 in milk, and a LOD of 1.72 × 102 cfu ml-1, and a linear range from 102 to 106 cfu ml-1 in lamb leach. In addition, this method takes less than 3 h to perform. Thus, the assay that was developed in this study shows promise for rapid, sensitive, and specific detection of B. melitensis 16M.

Characterization and evolution of countries affected by bovine brucellosis (1996-2014)

This paper describes the global distribution and temporal evolution of bovine brucellosis due to Brucella abortus during a 19-year period (1996-2014) using the information officially reported to the World Organisation for Animal Health (OIE) by veterinary services of 156 countries. Variables that can influence the health status of bovine brucellosis (i.e., year, per capita Gross Domestic Product (GDP), continent and bovine population) were also analysed. Countries were classified into three categories of health situations: ENZOOTIC: countries infected, which may have been free of brucellosis but for periods of fewer than 3 years; NON-ENZOOTIC: countries where the disease was present but that had at least a 3-year period without the disease; and FREE: countries where the disease remained absent during the whole period. The countries free from bovine brucellosis, or in the process of eradication, were located in Oceania and Europe, while the more affected regions were Central and South America, Africa and parts of Asia. Among the Non-Enzootic countries, the results showed that a very high proportion managed to control the disease during the period of study, with a sharp decline in the percentage of infected countries from 71% in 1996 to 10% in 2014. Among the Enzootic countries, a much smaller proportion managed to control the disease, with a slight drop in the percentage of infected countries from 92% in 1996 to 80% in 2014. A relationship was found between the status of the disease and the availability of economic resources; thus, countries with a high GDP per capita tended to be free from bovine brucellosis. On the other hand, countries with a larger bovine population showed a greater probability to have the disease present. An increase in surveillance programmes and implementation of control policies were observed during the period of study.

Human brucellosis caused by raw dairy products: A review on the occurrence, major risk factors and prevention

Despite considerable efforts made to address the issue of brucellosis worldwide, its prevalence in dairy products remains difficult to estimate and represents an important public health issue in many areas of the globe today. This is partly explained by the increasing tendency for consumption of raw dairy products, making the prevention and control of this zoonosis even more critical. This review summarizes reports published since the early 2000s on human brucellosis caused by contaminated dairy products and the systems of evaluation and assessment which are used to improve the diagnosis, surveillance, control and prevention of the disease. For this purpose, five comprehensive electronic databases were investigated and relevant studies were identified for systematic review. The design and quality of the studies revealed notable variation, especially in the methods used for the detection and characterization of Brucella spp. This report provides helpful information about the health risk associated with the consumption of raw milk and relevant preventive strategies.

Detection of Brucella spp. in milk from seronegative cows by real-time polymerase chain reaction in the region of Batna, Algeria

Aim:

The aim of this study was to detect Brucella spp. DNA in milk samples collected from seronegative cows using the real-time polymerase chain reaction (PCR) assay for diagnosis of brucellosis in seronegative dairy cows to prevent transmission of disease to humans and to reduce economic losses in animal production.

Materials and Methods:

In this study, 65 milk samples were investigated for the detection of Brucella spp. The detection of the IS711 gene in all samples was done by real-time PCR assay by comparative cycle threshold method.

Results:

The results show that of the 65 DNA samples tested, 2 (3.08%) were positive for Brucella infection. The mean cyclic threshold values of IS711 real-time PCR test were 37.97 and 40.48, indicating a positive reaction.

Conclusion:

The results of the present study indicated that the real-time PCR appears to offer several advantages over serological tests. For this reason, the real-time PCR should be validated on representative numbers of Brucella-infected and free samples before being implemented in routine diagnosis in human and animal brucellosis for controlling this disease.

Isolation of Brucella abortus and Brucella melitensis from Seronegative Cows is a Serious Impediment in Brucellosis Control

Brucellosis is a zoonosis occurring worldwide, with economic and public health impacts. Its diagnosis remains a challenge in endemic countries and basically relies on serology. The present study was carried out on two dairy cattle farms allegedly free from brucellosis, but with sporadic cases of abortion. The aim of this study was to investigate the presence of Brucella (B.) spp. in uterine discharge of seronegative cows after abortion. In farm I, B. melitensis biovar (bv) 3 was cultured from two of five cows after abortion, while in farm II, B. abortus bv 1 was cultured from three of eleven cows after abortion. These cows had been intrauterinely infected but remained seronegative until abortion and seroconverted only thereafter. Shedding of brucellae in uterine discharge of culture positive/seronegative aborting cows is a serious problem resulting in maintenance and further spread of infection. Thus, serosurveys in endemic countries have to be accompanied by molecular detection and/or culture of aborted material to close the diagnostic window and to hinder uncontrolled spread.