Brucella species circulating in rural and periurban dairy cattle farms: a comparative study in an endemic area

Shedding rate of Brucella spp. in the milk of seropositive and seronegative dairy cattle

Brucellosis in cattle herds has caused severe economic losses in many regions worldwide. A cross-sectional study was performed to investigate the presence of Brucella spp. in industrial dairy cattle farms in Iran. For this purpose, 935 blood and 935 milk samples were randomly collected from industrial dairy cattle farms in Iran's Alborz and Tehran provinces. Blood and milk samples were collected on the same day from each cow. Serological, bacteriological, and molecular characterization of Brucella isolates were performed using standard methods. Our results revealed the seroprevalence of brucellosis in dairy cattle farms in the Alborz and Tehran provinces, reaching 19.8%, 6.7%, 5.1%, 14.1%, and 13.1% using the Rose Bengal plate test (RBPT), serum agglutination test (SAT), 2-mercaptoethanol test (2-ME), indirect enzyme-linked immunosorbent assay (i-ELISA) and milk ring test (MRT), respectively. Furthermore, the results of bacterial culture and PCR analyses showed the presence of Brucella abortus among dairy cattle in the Alborz province and Brucella melitensis and B. abortus among dairy cattle in the Tehran province. Moreover, statistical analysis with Cohen's Kappa has highlighted the near-perfect agreement between RBPT and i-ELISA (k = 0.86). In contrast, substantial agreement was shown between RBPT and SAT performance (k = 0.70) and moderate agreement between RBPT and 2-ME (k = 0.67). The findings of this investigation showed shedding of Brucella in the milk of seropositive cows, which is a serious problem involving the maintenance and further spread of Brucella infection on the farm. Therefore, for brucellosis detection or eradication in dairy cattle farms, bacteriological and serological tests of milk samples should be performed along with blood analysis to inhibit the uncontrolled spread of the disease in animals and humans.

Evaluation of serological diagnostic tests for bovine brucellosis in dairy cattle herds in an endemic area: a multicenter study

Brucellosis is known as one of the most common zoonotic diseases worldwide affecting both livestock and humans. It causes abortions, reduces milk production, and infertility in infected animals. The disease is routinely diagnosed through three serological techniques, such as rose bengal plate test (RBPT), standard agglutination test (SAT), and indirect enzyme-linked immunosorbent assay (I-ELISA). The aim of this study was to identify and compare the brucellosis seroprevalence among dairy cattle farms through these different serological tests. From 2112 sampled dairy cattle in different parts of Iran, RBPT, SAT, and I-ELISA led to 296 (14.02%), 215 (10.18%), and 297 (14.06%) positive results, respectively. Brucella abortus biovar 3 (62 cases) was identified as the most common cause of brucellosis in tested animals. Our results showed that the specificity and sensitivity of I-ELISA were higher than those obtained by RBPT and SAT. In this study, the overall agreement of RBPT and SAT with I-ELISA reached 95.21% and 94.12% in dairy cattle farms, respectively. Furthermore, Cohen's kappa statistical analysis revealed that the best degree of agreement was seen between RBPT and I-ELISA (0.80), followed by RBPT and SAT (0.78) and finally SAT and I-ELISA (0.72), thereby indicating a strong agreement between RBPT and I-ELISA methods and good agreement between SAT and I-ELISA methods. The McNemar analysis also showed that a significant difference exists between positive and negative results determined by SAT and I-ELISA methods (p < 0.0001). However, the positive and negative results determined by I-ELISA and RBPT did not show a significant difference (p = 0.9207). Therefore, I-ELISA was a more specific and sensitive serological test when compared to RBPT and SAT and could remarkably decrease non-specific reaction by improving the serological screening specificity for an accurate brucellosis diagnosis in endemic areas.

Brucellosis in livestock: First study on seroepidemiology, risk factors, and preventive strategies to manage the disease in Famenin, Iran

Background and Aim:

Brucellosis is an infectious disease in humans and livestock. The disease is endemic in many regions of Iran, for example, Hamedan Province. Knowledge of infection rate and associated risk factors is essential to control and prevent the disease. The study aimed to estimate the prevalence of brucellosis and associated risk factors in cattle, sheep, and goats in Famenin, Hamedan Province, West of Iran.

Materials and Methods:

Blood samples of 1758 animals (1470 sheep, 190 goats, and 98 cattle) were obtained in different rural regions of Famenin. The samples were evaluated to detect of Brucella-antibodies using rose Bengal plate test (RBPT), Wright standard tube agglutination test (SAT), and 2-Mercapto-Ethanol (2-ME) techniques. The risk factors associated with brucellosis such as age, gender, history of vaccination against brucellosis, and abortion history in animals were evaluated. In the sampling process, the critical gaps related to the distribution of brucellosis in the herds and regions are identified for designing the strategies to prevent and control the disease.

Results:

About 6.88% and 89.31% of animals had a history of abortion and vaccination against brucellosis, respectively. Most of the animals were female (92.49%) and in the range of 2–3 age old (39.8%). The antibodies to the Brucella-infection in animals were 2.73% with RBPT and 1.30% with SAT and 2-ME. The prevalence of brucellosis was detected 1.3% among individual animals and 11% among herds. This rate was 1.43% for sheep and 1.05% for goats, with no significant statistical difference. No seropositive case was detected in cattle samples using RBPT, STAT, and 2-ME. The highest rate of brucellosis (6.25%) was detected in Emamzadeh-Pirnahan region (22.2% goats and 5.6% sheep). In sheep, most cases of the disease were in 3–4 age-old group (1.92%), animals without a history of abortion (1.58%), and without a history of vaccination against brucellosis (2.80%). Furthermore, 5.94% of males and 1.11% of females were detected positive for brucellosis (p < 0.001). The chance of brucellosis in rams was 5.6 folds higher than in others (odds ratio = 5.64). Brucellosis in goats was detected 2.94% and 1.89% in the age groups <1 and 2–3 year-old. Furthermore, 1.22% of females and 1.34% of animals without a history of abortion were positive. Brucellosis was found in 0.61% of vaccinated and 3.85% of non-vaccinated goats. Except for gender in sheep, no significant statistical correlation (p > 0.05) was observed between prevalence of brucellosis and risk factors. In farmers, low level of information about the transmission and also control and preventive methods of the disease was dominant. Consumption of traditional and unpasteurized dairy products is also very common in the studied regions.

Conclusion:

This is a comprehensive evaluation of animal brucellosis parallel to humans’ cohort study in the Famenin region for the first time. Although the rate of brucellosis in animals is low in the region, explaining the risk factors to farmers, mass vaccination, regular screening of animals, and culling the positive animals are very important for controlling and reducing the disease in the region.

Animal and human brucellosis in Algeria: a review

Tawla n Malṭa d aṭṭan ittenṭaḍen ɣer umdan i d-xeddment tbaktiriyin n tewsit Brucella spp. D aṭṭan amaḍlan u tella deg tmura n wagrakal am Lezzayer anda mazal txeddem axessar deg lmal. Ad d-nawi dagi tasɣunt tamatut ɣef tawla n Malṭa di Lezzayer, anda i tt-id-ufan yakan ɣer umdan seg 1895 u deg wass-nni mazal-itt d ugur ameqqran i yimeẓla n tdawsa. Tella tezqaft deg tejṛutin n yimdanen deg temnaḍt ɣer tayeḍ, tamnaḍt yennul ugar d tamnaḍt uzawaɣ i yesɛan weḥd-s aktamur alemmas (tajṛut/100 000 imezdaɣ) n 65.87 teḍfer-itt-id s 9.89 deg temnaḍt Agafa-Asamar ɣef wakken i d-iwekked uɣlif n tdawsa. Aktamur n tejṛutin n tawla n Malṭa n yizgaren iɛedda s uḍfar deg 5% ar 0,76% deg tlemmast n yiseggasen n 90 d 2014 s usileɣ imfeccec anda seld ṣa yiseggasen n wahil n takza d usnefren akked ucraḍ s tgezzayt REV-1 i d-ihegga uɣlif n tdawsa mazal yegguma ad isenger aṭṭan-agi. Ilaq daɣen ad negzu dakken anerni n umḍan n tejṛutin timaynutin n yimdanen i ittujerden kifkif-it akked tejṛutin ɣer tɣeṭṭen i yellan d aɛwin n temsalmit meqqren i umdan di Lezzayer.

Brucellosis in Iranian livestock: A meta-epidemiological study

Brucellosis is a widespread zoonotic disease affecting human and livestock health. This meta-epidemiological study is aiming to draw a comprehensive picture of the Brucella prevalence in Iranian livestock, trying to estimate most affected subgroups as well as the most appropriate methods and sampling conditions for brucellosis screening programs. A literature search was performed among data published between 1 January 1970 and July 2020. Different subgroups were compared according to animal species, gender, age, sampling season, sampling locations as well as the diagnostic method used for brucellosis screening. To determine heterogeneity of studies, Chi-squared test was used and a random effect model (REM) estimated the pooled prevalence among subgroups. A total of 45 publications, comprising 240 studies/data-reports, were evaluated. A significant increase in the number of studies was found over time (Coefficient = 0.151, p value < 0.001). The most studied species in Iran was cow (n = 75), followed by sheep (n = 63), goat (n = 45), camel (n = 40) and Buffalo (n = 16). The most identified Brucella species in livestock were Brucella melitensis (n = 50), Brucella abortus (n = 39), mix infection of B. melitensis and B. abortus (n = 11) and vaccine strain of B. melitensis Rev1 (n = 4). PCR-based tests were the most common applied diagnostic method (n = 140), while the highest prevalence rate of positive samples was obtained by indirect ELISA (69%). The prevalence of brucellosis was significantly higher in females (10.91%) compared to males (8.23%). The meta-epidemiological study of brucellosis in Iranian livestock would help to strengthen surveillance, control and prevention approaches to counter the spread of this zoonotic disease.