Suchergebnisse

We evaluated the prevalence of brucellosis in cattle and humans on properties characterized as family farms in the municipality of Uruará, state of Pará, located on the border of the Trans-Amazon Highway, in a serological study. We randomly sampled cattle and humans from 67 family farms. Cattle sera were tested with buffered acidified antigen and human samples were tested using the slow tube agglutination test (titration of 80 as a cutoff point). The prevalence of bovine brucellosis was 52% [90% CI: 42; 63]. The prevalence of households with at least one brucellosis positive individual was 21% [13; 31]. In households with at least one positive test, 23% of subjects were positive (range 8% and 50%). Five percent (21/422) of all human samples tested were positive. This high exposure rate in humans is a result of high cattle infection rates. We expect that in regions of Brazilian with a high prevalence of bovine brucellosis, there is also a high rate human exposure; however, few human cases have been reported. This is likely because of the largely non-specific symptoms of human Brucella abortus infections. Hopefully this study will bring about new information to public and animal health authorities involved in formulating policies aimed at decreasing disease prevalence.

The isolation of Mycobacterium bovis is critical to a surveillance system for bovine tuberculosis based on detection of lesions in abattoirs. Thus, four solid culture media and three incubation conditions were investigated to elucidate which combination overcomes the others by assessing growth, time to the first appearance of colonies and their number. Ninety-seven samples of granulomatous lesions were submitted to the decontamination procedure by 1-hexadecylpyridinium chloride at 0.75% w/v, and inoculated on two egg-based media, Stonebrink's (ST) and Löwenstein-Jensen's with sodium pyruvate (LJp), and two agar-based media, tuberculosis blood agar (B83) and Middlebrook 7H11 medium (7H11). Each medium was incubated at 37°C for 90 days in three incubation conditions: in air, in air containing 10% carbon dioxide (CO2), and in air in slopes closed with burned hydrophobic cotton and subsequently plugged with a cork to create a microaerophilic atmosphere. The colonies appeared faster and in higher number when incubated in air containing 10% CO2 (p < 0.01), independent of media. B83 showed a faster growth and detected more isolates at 30 days of incubation, when compared to ST (0.0178), LJp (p < 0.0001) and 7H11 (p < 0.0001), though there was no difference between B83, ST and LJp at 60 and 90 days of incubation. 7H11 presented the lowest number of isolates (p < 0.0001) and a longer period for the appearance of the first colony (p < 0.001). According to our findings, the concomitant use of ST and B83 media incubated in air containing 10% CO2 increases the isolation of M. bovis in a shorter period of time, which improves bovine tuberculosis diagnosis.

Preservation of specimens during transportation between abattoirs and diagnostic laboratories defines a critical stage in the definitive diagnosis of bovine tuberculosis by the isolation of Mycobacterium bovis. A 2-step study was designed to verify the maximum time that tissue samples can be stored in saturated sodium borate solution (SSB) with the highest detection of M. bovis isolates. Ninety hamsters were inoculated intraperitoneally with a suspension of M. bovis strain AN5 and were humanely euthanized after 40 days. Their spleens were collected and stored in SSB during four distinct periods (30, 60, 90 and 120 days) with incubation at two temperatures (27°C and 37°C). The control group was cultured on the day of euthanasia. Sixty-nine suspected tuberculous lesions samples were collected in the abattoir and were stored in SSB for three periods (30, 60 and 90 days) at 27°C in the laboratory. The bovine control group was cultured on the day of entry in the laboratory. Both experiments were analyzed separately based on the growth proportion of isolates and the number of colonies. SSB was able to maintain the viability of most M. bovis at high temperatures for up to 30 days. A progressive decline was observed with other storage periods at 27°C, and no growth was obtained after 60-day storage at 37°C. Despite the loss in viability of M. bovis, SSB is the most favorable choice to preserve specimens during transportation across a large country with high variation in environmental temperature. The sensitivity of M. bovis detection by bacteriological examination is inversely proportional to storage time. Therefore, the storage of tuberculous lesion specimens in SSB is recommended to not exceed 30 days at 27°C before cultivation.

Research, development of new biotechnological methods, diagnostic tests, confirmation of results, and reinvestigations are possible because of the availability of well-preserved living organisms maintained without any changes. Cryopreservation is a simpler, more reliable and long-term stable method for culture maintenance. Storage temperature and composition of the suspending vehicle are factors that affect the viability of mycobacterial strains. Three vehicles and three storage temperatures were evaluated to define a suitable cryoprotective medium for the preservation of Mycobacterium bovis strains. Colonies of sixteen M. bovis isolates were used to prepare the suspensions, which were then added to three vehicles: sterile 0.85% saline solution (SS), Middlebrook 7H9 broth (7H9), and Middlebrook 7H9 broth with sodium pyruvate (7H9p) replacing glycerol. Aliquots of these suspensions were frozen by three different methods, directly in the -20°C freezer, directly in the -80°C freezer, and at -196°C by immersion in liquid nitrogen (LN). The frozen aliquots were thawed at room temperature after 45, 90 and 120 days. Mycobacterial viability was assessed by counting the living cells on plates of Stonebrink medium before and after the freezing procedure. Storage at -20°C exhibited a lower recovery of M. bovis compared to storage at -80°C (Dunn's test, p=0.0018) and LN (Dunn's test, p=0.0352). There was no statistically significant difference between storage at -80°C and in LN (Dunn's test, p=0.1403), yet -80°C showed better results than LN. All three suspending vehicles showed no statistically significant difference in terms of viability (Friedman's test, p=0.7765). Given the low loss proportion of 5% during storage at -20°C and the high cost equipment required for storage at -80°C and LN, we recommend storage at -20°C or -80°C, when this is available, for preservation of M. bovis field strains.

To assist decision making regarding the National Equine Health Program in the state of Paraná, a study was conducted to estimate the prevalence of infected farms and seropositive animals for Equine Infectious Anemia (EIA) and also identify possible risk factors for the disease. The state was divided into three regions, within which about 300 farms were randomly selected. On the selected farms, a minimum number of animals aged 6 months or older were examined to characterize them as infected or free of EIA. In the sampled farms, an epidemiological questionnaire was applied to investigate possible associations between the disease and its characteristics, including sanitary practices and livestock management. The test used was the Agar Gel Immunodiffusion Test. A total of 2818 equids from 889 farms were tested. In the state, the prevalence of infected farms was 1.55% [0.92; 3.00] and the prevalence of seropositive animals was 0.55% [0.27; 1.00]. Introduction of equids showed an association with EIA (OR=5.5 [1.9; 15.9]). Paraná equine owners should be alerted to the need to observe health precautions regarding EIA when introducing animals to their herd. In 2018, the sensitivity of the Surveillance System for EIA in Paraná was only 1.36%, probably insufficient to change the endemic balance of the disease, therefore, needs to be re-evaluated involving in the process all public and private agents interested in the subject.

The Brazilian Ministry of Agriculture, Livestock and Food Supply established the National Program for Control and Eradication of Brucellosis and Tuberculosis (PNCEBT) in 2001. One of the main strategies adopted by the program is the mandatory vaccination of heifers between three and eight months of age with the B19 strain. In 2007, Brazil allowed the use of RB51 vaccine in bovine females over 8 months of age as an option for the producer, but kept the B19 strain as a mandatory vaccine. This decision is based on the assumption that combining the two vaccines allows to achieve significant vaccination coverage sooner and, consequently, accelerates the fall speed of prevalence. Thus, this study aimed to measure the impact of the combined use of these two vaccines in reducing the prevalence, using as a tool the mathematical modeling. It was concluded that vaccination by RB51, if adopted as a complement to vaccination by B19, mean decrease in the prevalence of bovine brucellosis in less time.

A cross sectional study was performed between June 2009 and March 2010 to determine the situation of bovine tuberculosis (bTB) in Rondônia. The state was divided into three regions and, in each of them, 300 farms with reproductive activity were randomly chosen and considered as primary sample units. In the selected farms, an epidemiologic questionnaire was applied. A fixed number of bovine females older than two years of age was randomly selected and tested through comparative cervical tuberculin test. Considering the State of Rondônia, the apparent prevalence of bTB positive farms was 2.3% (95% CI = 1.5–3.5%). The prevalence in the regions varied from 1.7% (95% CI = 0.7 – 4%) to 3% (95% CI = 1.6–5.7%). The apparent prevalence of bTB positive animals in the State of Rondônia was 0.12% (95% CI = 0.06–0.25%) and varied from 0.08% (95% CI = 0.04–0.18%) to 0.15% (95% CI = 0.07–0.33%) in the regions. The risk factor associated to tuberculosis in the State of Rondônia was the acquisition of animals (OR = 7.1; 95% CI = 1.6–31.1). The State of Rondônia should implement a surveillance system to detect bTB-infected herds to certify them as bTB-free. Moreover, an efficient health education program to inform farmers to test replacement animals for bTB prior to introduction in their herds should also be implemented.

The current scenario of international beef trading has increased the pressure for better and faster diagnosis of bovine tuberculosis. Although traditional culture remains the gold standard method to confirm Mycobacterium bovis infection, it is exceedingly time consuming, and demands viable mycobacteria. Molecular methods overcome the flaws of the bacteriological methods with faster detection and identification. However, mycobacterial features like a complex cell wall and pathogen–host interaction make the molecular detection a challenge. Three protocols for DNA extraction (A, B and C) from bovine tissues were tested to verify the most suitable technique for routine diagnostic assessment of their specificity and sensitivity. Thirty culture-positive and thirty culture-negative granulomatous lesions were included in the trial. From each sample, three tissue suspensions at different dilutions (10-1, 10-2 and 10-3) were prepared and submitted to DNA extraction. PCR procedures targeting IS6110 were performed, employing two volumes of DNA: 5 µL of all three dilutions, and 2.5 µL of the 10-1 dilution. Protocol A was able to detect members of the M. tuberculosis complex in most samples. The sensitivity of the test decreased with increase in tissue-suspension dilution. Although Protocol A presented the highest sensitivity followed by C and B, it showed the lowest specificity, which can be due to a failure in primary isolation caused by the lack of viable organisms or incubation time. Regardless classical bacteriological methods are still recommended by OIE, after evaluating the sensitivity of DNA extraction protocols and PCR procedures, we conclude that the best strategy for M. bovis detection is to follow Protocol A on concentrated tissue suspensions.

In order to plan the fight against bovine brucellosis in the state of Alagoas, Brazil, a cross-sectional study was carried out between April and October 2018 to estimate the prevalence of infected herds and animals, as well as the risk factors associated with the disease. Through a two-stage sampling design, blood samples were collected from 3,046 bovine females aged ≥ 24 months from 634 herds, in two different regions of the state. A questionnaire was applied at each farm to assess the association of possible risk factors with the disease. All selected animals were screened by the Rose Bengal test followed by retesting of positives by the Complement Fixation test. For the state, the prevalence of infected herds was estimated at 3.2% [2.1; 4.9] and that of seropositive animals at 0.9% [0.5; 1.4], with no statistical difference between regions. The risk factors identified were pasture rent (OR = 3.11 [1.28; 7.37]) and herd size equal to or greater than 14 females aged ≥ 24 months (OR=4.91 [2.02; 11.66]). It was recommended that the state of Alagoas develop health education action with the beef and dairy cattle production chains, so that producers avoid renting pastures or start practicing it with sanitary care for brucellosis and that they also observe these same concerns when introducing animals in their herds. In addition, the state should consider the convenience of structuring a surveillance system aiming at the eradication of bovine brucellosis, given the low prevalence of infected herds and seropositve animals.

A study was conducted to verify that the State of Santa Catarina has maintained a low prevalence of bovine brucellosis, which would allow the state to move forward with implementing strategies for disease eradication. The state was divided into five regions. In each region, a predetermined number of randomly selected properties was sampled. In each property, blood samples were collected from randomly selected cows with ages equal to or greater than 24 months. Sera from the animals were submitted to a serial testing protocol, with screening by the buffered acidified antigen test and confirmation by the 2-mercaptoethanol test. In each property, a questionnaire was used to identify the risk factors associated with the disease. In the state, the prevalence rate of infected herds was 0.912% [0.297 - 2.11] and infected animals was 1.21% [0.09 - 4.97]. Relative to the earlier study in 2002, there was no difference. The risk factors associated with the condition of a herd infected with brucellosis were as follows: herd size ? 12 cows (OR = 7.47 [2.14 - 34.34]) and the presence of flooded areas (OR = 5.68 [1.62 - 26.13]). In view of the low prevalence, it is recommended that the state proceed with the implementation of eradication strategies that are based on a surveillance system structured to detect and eliminate infected herds, and supported by an effective compensation fund for the replacement of seropositive animals. Additionally, the State should make a significant effort to educate and supervise producers to ensure the testing of breeding animals for brucellosis before introducing them into their properties.