Thesis (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2019 / Poultry is a good source of animal protein for many households due to its affordability. However, it is prone to bacterial infections which can be passed on to consumers, hence chickens that are reared without constant health checks present a potential health threat to humans. The objective of the study was to identify the zoonotic bacterial pathogens in poultry feeds and water resources in Blouberg poultry value chain project. A total of 88 samples comprising of 14 feed samples, 14 water samples, 60 mouth and rectal swab samples were collected from the farms. The samples were screened for the presence of Escherichia coli, Salmonella spp. and Shigella spp. through selective cultivation. Only coliforms and the dominant isolates were identified as Escherichia coli, Klebsiella spp., and Enterobacter spp., Salmonella and Shigella spp. were not detected in all the samples. E. coli strains that were isolated from the water sources and mouth and rectal swabs of the chickens showed a significant resistance to gentamycin, neomycin, penicillin, streptomycin, tetracycline, erythromycin, nalidixic acid, ciprofloxacin and ampicillin (p<0.05). Klebsiella pneumoniae showed resistance to neomycin; penicillin; erythromycin (p<0.05) while K. oxytoca and E. absuriae showed similar antibiotic resistance profile as penicillin, erythromycin, nalidixic acid and ampicillin. E. coli and K. pneumonia are mostly implicated in poultry disease outbreaks and they are enteric pathogens in humans as well. The presence of pathogens in poultry presents a great risk of secondary infection in humans and this will lead to socio-economic problems for the affected communities. The information generated in this study will guide the relevant stakeholders who handle poultry feeds and water resources in following good management practices. 1 / National Research Foundation (NRF)

The main aim of the current study was to determine the prevalence and diversity of potentially zoonotic bacterial genera in accurately identified indigenous rodents from South Africa. Bacterial prevalence and diversity were determined by PCR amplification and sequence analyses. Rodents were molecularly identified by amplification and sequence analysis of the mitochondrial cytochrome b gene region. Three species (Aethomys ineptus, Mastomys coucha and Otomys angoniensis) belonging to murid species complexes were identified. Furthermore, phylogenetic analyses revealed that both the proposed subspecies (R. dilectus dilectus and R. d. chakae) within the recently erected Rhabdomys dilectus occur in Hammanskraal and at the University of Pretoria Experimental farm, both in the Gauteng Province of South Africa. An overall bacterial prevalence of 38.6 % was observed in kidney samples of commensal and natural indigenous rodents after molecular screening with broad range 16S rRNA gene primers. Nucleotide sequence analyses identified a diverse range of bacterial genera namely, Bartonella, Anaplasma, Helicobacter, Burkholderia, Streptococcus, Aerococcus and Lactobacillus. Some members of these genera have been identified as causative agents of human and animal diseases, being transmitted either through environmental contamination or through haematophagous arthropod vectors. Subsequent genus-specific bacterial screening focussed on vector-borne genera identified in the commensal and natural rodent populations sampled. Bartonella prevalence and genetic diversity was compared between a natural and commensal population of the southern multimammate mouse (M. coucha) using two gene regions (Citrate synthase gene and NADH dehydrogenase gamma subunit gene). A significantly higher infection prevalence was detected in the commensal population (92.9 %) as compared to the natural population (56.9 %). No differences however, were detected between infection status and the ectoparasite loads calculated for both rodent populations. Apart from several novel Bartonella strains identified in both M. coucha populations, phylogenetic analyses also identified a species of known zoonotic potential (B. elizabethae) in both populations. The present study represents one of the first to screen indigenous rodents for tick-borne members of the bacterial family Anaplasmataceae. Anaplasma bovis-like DNA was detected in five of the six rodent species sampled (A. ineptus, Lemniscomys rosalia, M. coucha, O. angoniensis and R. dilectus) at an overall prevalence of 39.2 %. The potentially zoonotic Ehrlichia ewingii was detected in M. coucha samples only at a prevalence of 5.3 %. The diverse bacterial genera detected in commensal and natural populations of indigenous rodents comprise members of zoonotic potential and agricultural significance, highlighting the importance of continuous disease surveillance of indigenous rodents. / Dissertation (MSc)--University of Pretoria, 2014. / National Research Foundation (NRF) / Zoology and Entomology / MSc / Unrestricted

Neu auftretende Viruskrankheiten zoonotischen Ursprungs stellen eine zunehmende Gefahr für die globale Gesundheit dar. Wie das unerwartete Auftreten von dem Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Ende 2019 zeigte, gibt es allerdings trotz jahrelanger intensiver Forschung Verständnislücken, wo und wann mit Tieren assoziierte Krankheitserreger auftauchen, oder durch welche evolutionären Vorgänge diese Übertragungen möglich werden. Diese Arbeit befasst sich mit dem Thema der genetischen Adaptation von Viren bevor und nachdem ein Wirtswechsel stattgefunden hat und leistet damit einen Beitrag zum besseren Verständnis von Wirtswechselprozessen und ihren zugrundeliegenden Mechanismen. / Emerging viral diseases of zoonotic origin pose an increasing threat to global health. Despite intense research, we do not understand where and when animal-associated pathogens emerge, or by what evolutionary processes these transmissions become possible; best illustrated by the unexpected emergence of the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the end of 2019. This thesis is concerned with the topic of viral genetic adaptation before and after cross-species transmissions, contributing to a better understanding of host switching processes and their underlying mechanisms.

No description available.

No description available.

No description available.

In der vorliegenden Arbeit wurde das Colicin V-codierende Plasmid p1ColV5155 des aviär pathogenen E. coli-Stammes (APEC) IMT5155 (O2:K1:H5) weitestgehend sequenzanalysiert und seine virulenzassoziierten Eigenschaften untersucht. Das ~ 180 kb große p1ColV5155 weist mit EitABC, EtsABCD, Salmochelin, SitABCD und Aerobaktin fünf ABC-Transportsysteme auf, deren Bedeutung für die Aufnahme von Eisenionen für die letztgenannten zwei Systeme mit Hilfe von Cosmidklonen (GB5155cD34, GB5155cD27) in einer Enterobaktin-negativen E. coli 1017-Transformante mittels CAS-Assays nachgewiesen werden konnte. Eine signifikante regulatorische Bedeutung von Eisenionen für die Expression plasmidcodierter virulenzassoziierter Faktoren konnte durch beta-Galaktosidase-Expressionsassays in einer IMT5155-Mutante (Iln) für das Serumresistenz steigernde Protein Iss, nicht jedoch für das Temperatursensitive Hämagglutinin (Tsh) nachgewiesen werden. Eine Aktivitätssteigerung beider Promotoren wurde durch eine gute Nährstoffversorgung bei einer Wachstumstemperatur von 37 °C erreicht. Insgesamt lassen die Studienergebnisse darauf rückschließen, dass der Promotor von tsh im Gegensatz zu iss sehr viel schwächer ist und spezifischer reguliert wird. In vivo-Versuche mit einer p1ColV5155-E. coli K12-Transformante (IMTp1D01) hatte weder Morbidität noch Mortalität der infizierten 5 Wochen alten SPF-Hühner zur Folge. Verschiedene in vitro-Versuche ergaben, dass das Plasmid nicht konjugationsfähig und über Generationen sehr stabil in der E. coli K12-Transformante nachzuweisen war. Das Plasmid vermittelte der Transformante eine erhöhte Resistenz beim Wachstum in Hühnerserum sowie eine erhöhte Tenazität in Makrophagen (Maus, J774). Damit weist das ColV-Plasmid eine Reihe genetischer Eigenschaften auf, die den APEC und anderen extraintestinal pathogenen E. coli-Stämmen sowohl eine Steigerung der Fitness in der Umwelt als auch ihre Vermehrung im Blut von Mensch und Tier ermöglichen. / In this study a high molecular weight, colicin V encoding plasmid p1ColV5155 of APEC strain IMT5155 (O2:K1:H5) was nearly complete sequenced and analysed. The most prevalent virulence traits of the ~ 180 kb plasmid are serum resistance (increased serum survival protein, Iss), adhesion (temperature-sensitive hemagglutinin, Tsh) and five different ABC-transport systems (EitABC, EtsABCD, salmochelin, SitABCD and aerobactin), the latter three being acquisition systems for iron. Studies with cosmids (GB5155cD34, GB5155cD27) which possess only sequences of p1ColV5155 salmochelin and aerobactin in an enterobactin-deficient E. coli1017, confirmed their importance for iron acquisition. The importance of iron in the regulation of the assumed virulence associated genes of the ColV-plasmid was tested especially for the promoter activity of iss and tsh. Expression studies in beta-galactosidase mutated strain of IMT5155 (Iln) corroborated the importance of environmental factors including source of sugar and a temperature of 37 °C of both promoter activities. The lack of iron decreases, and growth on serum increased the promoter activity of iss. In contrast the activity of the tsh promoter was much weaker and there was no indication found for iron-depending factors which regulate the promoter in a special way. Results of in vivo assays with a p1ColV5155-transformant of E. coli K12 (IMTp1D01) in five week old SPF-chickens did not result in disease. However, the presence of p1ColV5155 in the E. coli K12-strain was solid and increased the ability of the transformant to avoid destruction by bactericidal effects of macrophages (mouse, J774) and to survive in serum in vitro. In summary the ColV-plasmid seams to increase the fitness of the APEC and other extraintestinal pathogenic E. coli. Multiple iron acquisition and a potent defending system of the host serum help to remain to the environmental and in blood of human and animals alike.

The prevalence of Brucella canis in South Africa is unknown and suspected to be under-detected. The majority of dogs in South Africa are not tested for Brucella canis, not only because of the level of awareness of Brucella canis in South Africa, but also because of the lack of clinical suspicion. It is not known how the infection entered South Africa. Brucella canis, a zoonotic organism that causes canine brucellosis in dogs, is a significant cause of reproductive failure in dogs worldwide. Canine brucellosis is a chronic infectious zoonotic disease whose main etiological agent, the Brucella canis bacterium, are rough, intracellular proteobacteria in the Brucellaceae family. Clinical signs in bitches are mainly infertility and abortion, while in males, epididymitis and orchitis occur. However, discospondylitis may develop in both sexes. A serological survey was conducted to determine the prevalence of Brucella canis infection in dogs from the Nelson Mandela Bay Metropolitan (NMBM) Port Elizabeth (PE) area. A total of 400 samples were collected, 350 of which were collected in seven different townships and 50 were collected in the three different welfare organisations in the study area. Of the 400 serum samples collected, 39 (9.75%) tested serologically positive by using the Tube Agglutination Test (TAT), the 2-Mercaptoethanol-TAT (2ME-TAT) or the Compliment Fixation Test (CFT). The results of the CFT showed that nine of the 39 positive samples had a maximum antibody titre of 784 IU/ml. The prevalence rate varied tremendously between the samples from the townships and those from the welfare organisations. The prevalence rate of seropositive animals in PE ranged between 5% and 16% in the study area. No positive cases were found in KwaMagxaki and the Animal Welfare Society of PE, but both were surrounded by areas that had positive cases of Brucella canis infection. The female dogs in the study area had a higher sero-prevalence of only 0.0169 (95% CI, 0.0631 to 0.1489) differences in proportion, and were thus not significant (p > 0.05). However, the female spayed dogs had a much higher significant difference of 0.1898 (95% iv CI, 0.1058 to 0.2738) in proportion to the male neutered dogs and were thus statistically significant (p < 0.05). Despite those results, out of all the dogs positive for Brucella canis only two were neutered males and five were spayed females, and the rest were all intact. In conclusion, according to the results, Brucella canis antibodies were detected in sera of dogs mostly from the townships surveyed. Preventive measures against this contagion should be taken into consideration to eliminate Brucella canis infection from the entire dog population. Reservoir dogs and actively infected dogs either should be kept in quarantine or should be euthanized, because not only can they spread the disease and end the reproductive life of any breeding animal, but they are also a risk to human health. Even though this is the first survey conducted in the Eastern Cape, the results are still high dogs in the study area had a higher sero-prevalence of only 0.0169 (95% CI, 0.0631 to 0.1489) differences in proportion, and were thus not significant (p > 0.05). However, the female spayed dogs had a much higher significant difference of 0.1898 (95% iv CI, 0.1058 to 0.2738) in proportion to the male neutered dogs and were thus statistically significant (p < 0.05). Despite those results, out of all the dogs positive for Brucella canis only two were neutered males and five were spayed females, and the rest were all intact. In conclusion, according to the results, Brucella canis antibodies were detected in sera of dogs mostly from the townships surveyed. Preventive measures against this contagion should be taken into consideration to eliminate Brucella canis infection from the entire dog population. Reservoir dogs and actively infected dogs either should be kept in quarantine or should be euthanized, because not only can they spread the disease and end the reproductive life of any breeding animal, but they are also a risk to human health. Even though this is the first survey conducted in the Eastern Cape, the results are still high / College of Agriculture and Environmental Sciences / M. Sc. (Agriculture)

No description available.

No description available.