1,720,964 research outputs found
Zoonotic diseases in high-risk populations in the Free State province, South Africa
No full textZoonotic diseases are infectious diseases transmitted from vertebrate animals to humans and are accountable for more than 60% of all recognized human diseases and 75% of all new or emerging infectious diseases (EID). In South Africa (SA), endemic zoonoses include Mycobacterium bovis (M. bovis), Brucella sp., and Leptospira sp. The prevalence and burden of other pathogens, such as hantaviruses, are unknown. Therefore, identifying high-risk occupations and other risk factors are important for control and preventative measures to decrease the disease burden of these zoonoses. Thus, this study aimed to investigate the incidence rate of M. bovis and Brucella sp. in cattle and farm workers in two different farming communities (communal and commercial), as well as their associated risk factors. This study aimed to document occupational exposure to Brucella sp., Leptospira sp. and hantaviruses across the Free State province, South Africa. Four commercial farms and a rural cattle farming community within the Moqhaka and Ngwathe municipal regions were selected for the purpose of this study. From these farms, sputum and blood specimens were collected from 13 commercial farm workers and 13 communal farm workers. Sputum samples were screened for M. bovis through Mycobacteria Growth Indicator Tube (MGIT) culture. Blood specimens from these 26 farm workers, in addition to 301 archived sera, were screened for Brucella sp., hantaviruses, and Leptospira sp. antibodies using commercially available enzyme-linked immunosorbent assays (ELISA). From the 26 farm workers, no M. bovis was isolated. Out of the 327 sera screened, 35/327 (10.7%) were Brucella sp. IgG positive, 17/327 (5.2%) Leptospira sp. IgM positive, and 38/327 (11.6%) hantavirus IgG positive. A combined total of 321 cattle were screened for M. bovis through tuberculin skin testing (TST); 71 cattle were from communal farms and 250 from commercial farms. Additionally, blood samples collected from 69 and 1793 cattle within the communal and commercial farms, respectively, were screened for Brucella sp. using a Rose Bengal test (RBT) and complement fixation test (CFT). A total of 8/321 (2.5%) cattle reacted positive to the TST, and two were positive using the interferon-gamma release assay. Initial RBT screening resulted in 52/1859 (2.8%) positive results, further testing using a CFT identified 19/1859 (1%) brucellosis-positive cattle. A higher percentage of brucellosis-positive animals were from communal cattle (6/69; 8.7%) compared to commercial cattle (13/1859; 1.1%). Statistical analysis and probability values were calculated using a chi-squared or Fisher's exact test in the case of sparse data. Analysis identified higher Brucella sp. occupational exposure in veterinarians (p-value = 0.0006) and laboratory workers (p-value = 0.031). Further analysis showed a statistically significant correlation between people who reported illness post-exposure to animal blood/tissue (p-value = 0.029); and older age (p-value = 0.0008) with Brucella sp. seropositivity. Working at the abattoir (p-value = 0.024) was identified as a high-risk occupation for contracting Leptospira sp. In conclusion, the low incidence rate of M. bovis in cattle suggests limited contact with known reservoirs (i.e. buffalo or other wildlife). However, the higher incidence rate of brucellosis in communal cattle highlights the importance of implementing mass herd vaccination campaigns, particularly in communal settings. This report documents the seroprevalence of Leptospira sp., Brucella sp. and hantaviruses in various high-risk occupations in the Free State province and can be used as a basis for the development and establishment of adequate preventive or control measures
The epidemiology of tuberculosis in cattle and humans living in the wildlife-livestock-human interface in the rural Mnisi community Mpumalanga province South Africa
Get PDFThesis (PhD)--University of Pretoria, 2016.The aim of this study was to investigate the prevalence and epidemiological significance of tuberculosis (TB) in bovine and humans living at a wildlife/livestock/human interface, as well as the risk factors associated with TB transmission at that interface. The Mnisi community was chosen as it is located at the western border of the Kruger National park (KNP) and enables research at the wildlife/livestock/human interface. The first objective of the study entailed investigating the presence of bovine tuberculosis (BTB) in 10% of Mnisi?s livestock, using the comparative intradermal skin test. A low individual prevalence of 0.33 % (95% CI.0.14 ? -0.79) was detected. Further investigations into the causative agent in livestock, using genotyping techniques identified the KNP parental strain, M. bovis KNP VNTR -1 strain.1 Supporting records from the provisional Mpumalanga Veterinary Services and the physical location of dip-tanks where BTB was detected, it was established the infection was a result of spillback infection from wildlife in the neighbouring KNP. The epidemiological significance of BTB in human TB was investigated through the isolation and genetic characterisation of the Mycobacterium tuberculosis complex (MTBC) strain population in the Mnisi community. Mycobacterium bovis was not detected in the human population. However, a high genetic diversity of M. tuberculosis was observed among the 13 isolates obtained.The M. tuberculosis isolates were identified as the following eight families: T; Beijing; LAM 11_ZWE; EAI5; MANU1; X1; X2; and S families. The predominant lineage was as T family, sub-lineage ST53. Based on the high diversity (8 clusters/13isolates) and the predominance of the T family, it was concluded that the TB population structure within the Mnisi community was largely impacted by human migration from urban towns and neighbouring Mozambique. A questionnaire was administered to investigate BTB transmission risk factors at the livestock/human interface. It was established that there were low risk levels of BTB transmission at the human/livestock interface mainly based on the fact that the majority of the households in the community obtained pasteurised milk commercially, and although undercooked/raw meat and organs were preferred, the majority of respondents reported that they discarded the meat if changes in meat quality were observed.tm2016Veterinary Tropical DiseasesPh
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Pilot investigation of selected milk-borne pathogens in communal cattle in the uMkhanyakude district of KwaZulu-Natal, South Africa
Get PDFDissertation (MSc)--University of Pretoria, 2017.This study was a pilot investigation of selected milk-borne pathogens in communal cattle in the UMkhanyakude district of KwaZulu-Natal, South Africa. Fifty seven milk samples were collected from 12 bovine tuberculosis (BTB) positive cattle herds. Udder hygiene assessment was also carried out during sample collection. Convenience sampling of milk samples was done during a BTB diagnostic pilot project involving selected BTB positive herds at the Nibela diptank in the uMkhanyakude district. The milk samples were tested for the presence of the following milk borne pathogens: Mycobacterium bovis (M. bovis), Brucella abortus (B. abortus) and Staphylococcus aureus (S. aureus). In addition, the microbiological quality of milk in the study population was assessed by means of total bacterial counts, total coliforms counts and total E. coli counts. A questionnaire survey to determine the level of knowledge, milking hygiene and milk consumption behaviour of 12 households that participated in the BTB pilot study was administered.
A total of 21 cattle representing 6 cattle herds, tested positive for B. abortus antibody on Brucella Milk Ring (BMRT) test. The detection of S. aureus in the milk samples was done by bacterial culture, catalase tests, oxidase tests and staphylase tests. The prevalence of S. aureus was found to be 49%. The isolation of B. abortus and M. bovis was attempted but compromised by constraints that were beyond the investigator?s control (drought related decrease in milk production and inadequate laboratory facilities). The constraints included inability to collect adequate quantities of milk as required for tests due to a sharp decrease in milk production of cows during the severe prevailing drought. Lack of adequate laboratory facilities for B. abortus and M. bovis culture in the study area and the resulting long time lag between collection of milk samples and identification of B. abortus and isolation of M. bovis at the designated bacteriology laboratory of DVTD further decreased the probability of successful culture. The seroprevalence of B. abortus in milk was determined by Brucella Milk Ring test and was found to be 38%. The presence of M. bovis was confirmed by PCR in one pooled milk sample from 5 cows. On quantification of total coliforms, 21% of the milk samples had more than 20 cfu/ml and 59% of milk samples contained E. coli. It was found that 59% of the milk samples yielded 100 cfu/ml and 26% of milk samples had results recorded as ?too numerous to count? and 15 % milk samples had total bacterial count of less than 100 CFU/ml.
All 10 respondents who reported consumption of milk from their own cattle confirmed that all household members consumed milk on daily basis. With regards to treatment of milk before consumption, 10 respondents indicated that they either boil or sour the milk before consumption. Consumption of raw milk was reported by 1 respondent and only 1 respondent indicated that they sold excess milk. As treatment of milk reduces the risk of zoonotic pathogens transmission from milk to humans the fact that the majority of respondents applied his intervention before consumption can be seen as risk reduction behaviour for the transmission of zoonotic pathogens from milk to humans.
Although the results on the presence of B. abortus were inconclusive, the overall findings in the study indicated that the raw milk in the study population posed a high risk of transmitting zoonotic diseases to humans. The cows? milk in this study was found to be of poor microbiological quality because of the presence of M. bovis, high prevalence of S. aureus and the counts for coliforms and E. coli that exceeded the limits set by the South African standards under the Foodstuffs, Cosmetics and Disinfectants Act, No. 54 of 1972: Regulations relating to milk and dairy products.Veterinary Tropical DiseasesMScUnrestricte
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Investigation into the diversity of antifungal aerobic endospore-forming bacteria associated with bulk and crop rhizosphere soil.
Get PDFThesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.Members of the genus Bacillus are mainly Gram positive, aerobic rod shaped, endospore-forming bacteria that are increasingly being recognised for their ability to promote plant growth and antagonise fungal pathogens. From a biological control perspective, Bacillus spp. strains that produce antifungal compounds are of particular interest. In this study, aerobic endospore-formers were isolated from an undisturbed indigenous grassland soil and screened for antifungal activity and other plant growth promoting traits. Endospore-formers were also isolated from rhizosphere soil associated with the roots of maize, wheat and kale grown in pots containing soil from the same grassland site. Microbial diversity amongst isolates showing antifungal activity was investigated using different molecular fingerprinting methods, namely, intergenic transcribed spacer–PCR (ITS-PCR), random amplified polymorphic DNA-PCR (RAPD-PCR) and 16S rRNA gene amplification and sequencing. Characterization of the active antimicrobial compound(s) associated with selected isolates was also attempted.
Prior to isolating from bulk and rhizosphere soils, samples were pre-heated to eliminate heat sensitive vegetative cells. Mean endospore counts were; wheat rhizosphere, Log 6.03 c.f.u g-1 soil; maize rhizosphere, Log 5.88 c.f.u g-1 soil; kale rhizosphere Log 5.90 c.f.u g-1 soil; and bulk soil Log 5.67 c.f.u g-1soil. A total of three hundred and eighty-four isolates were screened for antagonism towards Rhizoctonia solani using dual-culture plate bioassays. Thirty four of the isolates (~9%) mostly isolated from the bulk soil inhibited R. solani at varying degrees. Differences in antimicrobial interactions were apparent in in vitro bioassay; supposedly due to different concentrations and/or types of antimicrobial compounds. Biochemical tests for amylase, cellulase, chitinase, and proteinase activity, siderophore production and inorganic phosphate solubilisation were conducted. None of the isolates possessed all of these attributes and only a few showed multiple traits. Ninety-one percent of the isolates exhibited proteinase activity, 76% were able to hydrolyze starch whereas only four displayed cellulase activity. Only four isolates from the bulk-soil were capable of solubilising inorganic phosphate.
ITS-PCR and 16S rRNA gene sequence analysis showed high levels of genetic homology amongst isolates and the majority were closely associated with representatives of the B. cereus group. Isolate C76 was the exception, being closely matched with B. subtilis. ITS-PCR banding
profile was useful for distinguishing between species but did not distinguish within species. RAPD-PCR distinguished finer levels of genetic diversity between and within sample sets, with primer OPG-11 showing the greatest levels of heterogeneity. DNA extraction methods and the influence of template DNA dilution were investigated to determine their influence on RAPD-PCR analysis reproducibility. Prominent bands were comparable for crude template- and kit-extracted DNA but slight changes in band intensity and in some instances, additional faint bands were observed. At the highest DNA concentrations tested (7 μg/ml), further bands with molecular weights above 2.5 kbp were apparent. Strict standardization of PCR conditions greatly reduced variability of the RAPD-PCR analysis.
Isolates from the different sample sets were screened for the presence of genetic markers associated with the biosynthesis of zwittermicin A, an aminopolyol antibiotic produced by some members of the B. cereus group. In an initial screen only one isolate, W96, yielded PCR amplicons consistent with those previously reported in the literature for the zwittermicin A genes. Later a further sixteen isolates grouped with W96 on the basis of the RAPD-PCR fingerprinting profiles, were screened for the presence of these genes. Of these, only six showed PCR amplification products similar to W96. Sequence homology testing against the GenBank database confirmed the presence of the zwittermicin A genes in these isolates. Isolate W96 was selected for further extraction and characterization of its antifungal compound(s). However, after culturing in various broth media cell free supernatants of W96 failed to show antifungal activity in vitro even when the supernatants were concentrated 20-fold.
These findings provide a general overview of the diversity of aerobic endospore-forming bacteria present in an undisturbed indigenous grassland soil that exhibited antifungal activity in vitro and the limited influence tested crop rhizospheres have on this diversity. Combined use of ITS-PCR, 16S rRNA sequencing and RAPD-PCR techniques served as a rapid and effective means of grouping isolates for further investigations of their potential use as biocontrol agents and plant growth promoting rhizobacteria
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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