A study was conducted (November 2012) on the communal dipping system in Mnisi, Mpumalanga Province of South Africa to detect levels of blue tick resistance to commonly used acaricides. The larvae obtained from engorged females of the one host tick Rhipicephalus (B). microplus from twelve communal dipping areas were tested against various concentrations of amitraz, chlorfenvinphos and cypermethrin using the Shaw Larval Immersion Test method. Only R. (B). microplus ticks were identified from all sample areas, indicating a displacement of the indigenous R. (B). decoloratus tick in this area. Resistance testing using the Shaw Larval Immersion Test showed that no resistance to chlorfenvinphos was detected at any of the dip tanks, which was in keeping with the absence of known use of this product in the area. An important finding was the rapid development of resistance to the pyrethroids, which had only been in use for four months prior to conducting the study. Only one area (Hlalakane) yielded a R(B).spp population that was wholly susceptible to all three compounds. Resistance to amitraz was variable, with half (six out of 12) of the dip tanks comprising susceptible R(B).spp populations and two dip tanks with emerging resistance to amitraz. Possible risk factors which caused the resistance problems are discussed and acaricide management strategies recommended. / Dissertation (MSc)--University of Pretoria, 2015. / tm2016 / Veterinary Tropical Diseases / MSc

The Mnisi community is in the north-eastern corner of the Bushbuckridge Municipal Area, Mpumalanga Province, South Africa. This community is located at the livestock/wildlife interface sharing borders with several game reserves, and livestock are likely to be exposed to diseases with a wildlife reservoir, such as Corridor disease. Known tick vectors of important diseases such as Corridor disease, redwater, heartwater and anaplasmosis are present in the area. Although the farmers frequently dip their cattle in acaricide-filled dip tanks to control the tick burden, tick-borne diseases (TBDs) are still a major problem. This study was undertaken to determine if the symptoms of cattle in poor health in the Mnisi community could be attributed to TBDs. Corridor disease has previously been identified in cattle in the Mnisi community. Recent experimental studies have shown that T. parva DNA can be detected in infected cattle that survive the disease in the field. An additional aim of the study was therefore to identify T. parva carrier cattle in the area, and to search for evidence of selection of cattle-adapted T. parva parasites in carrier cattle. The study was conducted from July 2012 to June 2013. During the study period, samples from clinically sick cattle suspected of TBDs were collected to determine the cause of their symptoms. Blood smears from the clinically sick cattle were analysed using light microscopy while some cases were subjected to histopathology and T. parva-specific quantitative real-time polymerase chain reaction (qPCR). DNA extracted from blood samples and in some cases tissue samples collected from clinically sick cattle (n=137) was tested for the presence of haemoparasite DNA using the reverse line blot (RLB) hybridization assay. To identify T. parva carrier cattle, records from Hluvukani Animal Clinic and Bushbuckridge State Veterinary office were scrutinized to identify herds that may have been exposed to T. parva infection. Blood samples (n=670) were collected from herds that had recorded Corridor disease cases in the past three years, as well as herds that may have shared grazing with buffalo from the Kruger National Park and surrounding private game reserves. The indirect fluorescent antibody test (IFAT) was used to check for T. parva antibodies. Seropositive herds were revisited, as well as herds that had confirmed Corridor disease cases during the study period, and blood samples were collected (n=432). DNA extracted from these samples was screened for the presence of T. parva DNA using the T. parva-specific qPCR. In an attempt to find evidence of selection of cattle-adapted T. parva, the p67, p104 and PIM parasite genes were amplified from qPCR positive samples, and the amplicons were cloned and sequenced. Out of the 137 clinical disease cases examined from the study area, 24 cases of TBDs were diagnosed, of which 19 were Theileria related. The RLB hybridization assay confirmed the presence of tick-borne haemoparasites in the Mnisi community: 89 of the 137 clinical disease cases (65.0%) were found positive for one or more haemoparasite (Theileria, Babesia, Anaplasma and/or Ehrlichia species) while 48 (35.0%) were negative or below the detectable limit of the test. IFAT results indicated that there is a high seroprevalence of theileriosis (63.6%) in the Mnisi community area, but this may be due to cross reactions with other Theileria parasites known to be present (e.g. T. taurotragi). Fewer cattle (13.4%) were seropositive at the highest titre tested (160), and these are most likely to be associated with T. parva. In DNA extracted from blood samples from these seropositive herds, the T. parva-specific qPCR detected T. parva in eleven samples (2.6%). Eight of the eleven cattle were re-sampled six months later, but only one was still qPCR positive. All of the p104 and PIM sequences and two of the three p67 sequences were characteristic of buffalo-type T. parva alleles previously identified, implying that the T. parva infections in the cattle were transmitted directly from buffalo to cattle, and providing no evidence of selection of cattle-type alleles in the carrier animals. The study revealed that TBDs are a problem in the Mnisi community and surrounding area. Most important of the TBDs identified was Corridor disease, a notifiable disease in South Africa, which was the cause of most deaths among the cattle that were sampled. There was no evidence for the selection of cattle-derived T. parva alleles in any of the samples from T. parva carrier cattle, but a p67 sequence obtained from a clinical case was closely related to previously-identified alleles from cattle-derived isolates. Theileria parva DNA could only be detected in carrier cattle for a limited time post-exposure, suggesting that the infection will be cleared in infected animals before larvae or nymphs are available to pick up infections the following season. However, one bovine was still qPCR positive six months post-exposure, albeit with a very high Cp value (indicating a very low parasitaemia). The selection of T. parva parasites in cattle from the diverse T. parva population in African buffalo, therefore, remains a concern in the Mnisi community area, and at other livestock/wildlife interfaces in South Africa, but the risk is probably very low. / Dissertation (MSc)--University of Pretoria, 2015. / tm2016 / Veterinary Tropical Diseases / MSc

The South African poultry industry has been beset by sporadic H6N2 avian influenza infection (sub-lineage I and II) in chickens since the early 2000s, with economic losses resulting from reduced egg production and co-infection with other pathogens. An egg-based inactivated H6N2 vaccine (AVIVAC® AI; Deltamune (Pty) Ltd.) based on a 2002 sub-lineage I isolate is available, although substantial antigenic drift has occurred in H6N2 viruses since its implementation. Globally, seasonal and pandemic plant-produced hemagglutinin (HA)- based influenza virus-like particle (VLP) vaccines are in advanced clinical trials with proven efficacy, speed of production, cost-effectiveness, scalability and safety, although not yet established for poultry. In this study, H6 avian influenza VLPs (sub-lineage I and II, respectively) were transiently produced in Nicotiana benthamiana and tested for protective efficacy in the target host. A production platform has been established for H6 VLPs in N. benthamiana by optimising protein expression and purification to maximize yield and by assessing the feasibility of large-scale production and downstream processing in a preliminary study. Subsequently, the respective plant-produced H6 VLPs were formulated into vaccines and their capacity to reduce viral replication and shedding upon challenge with a 2016 H6N2 field isolate were established in specific-pathogen-free (SPF) chickens, in comparison to the commercial H6N2 vaccine. The plant-produced sub-lineage I VLP vaccine (768 HA units/dose) was highly immunogenic (mean hemagglutination inhibition (HI) titer 10.7 log2), reduced the oropharyngeal and cloacal viral shedding by more than 100- and 6-fold, respectively, and shortened the duration of oropharyngeal shedding by at least a week in comparison to the non-vaccinated control. Due to initial low yield of sub-lineage II VLPs, the maximum antigenic mass vaccine dose (48 HA units/dose)) resulted in substantially lower HA-specific antibody titers (mean HI titer > 4 log2), but still reduced viral shedding from the oropharynx by more than 5-fold in comparison to the non-vaccinated control. In contrast, the commercial vaccine not only failed to effectively reduce shedding in comparison to the non-vaccinated control, but exacerbated oropharyngeal shedding until day 21 after viral challenge, illustrating the antigenic dissimilarity between the commercial vaccine and a recent field virus. Plant-produced VLP vaccines, which facilitates differentiation between infected and vaccination animals (DIVA), presents a new generation of poultry vaccines that is highly efficacious and cost-effective with the major advantage of producing a tailored antigenically-matched vaccine candidate within a short space of time and holds enormous potential for the poultry industry. / Thesis (PhD)--University of Pretoria, 2020. / Production Animal Studies / PhD / Unrestricted

Animal diseases have always been one of the main constraints on animal production, especially in Africa where there are a variety of tropical and subtropical diseases. Knowledge of these diseases and the development of approaches to combat them is highly relevant to the socio-economic development of Africa and its fight against poverty. Serological tests were performed to determine seroprevalence and important risk factors for occurrence of respiratory pathogens in cattle on 423 biobanked sera collected from cattle at 11 dip tanks in the Mnisi communal farming area which is on the edge of the Kruger National Park. These pathogens are known to cause significant production losses in livestock by predisposing animals to secondary infections including pneumonia. A pentavalent, indirect ELISA test was performed to estimate seroprevalence of bovine herpesvirus-1, bovine respiratory syncytial virus, bovine viral diarrhea virus, parainfluenza virus-3 and bovine adenovirus-3 infections in cattle at the wildlife-livestock interface in the Mnisi communal farming area. Previous exposure to the five pathogens was determined. Additionally, the data was analyzed using the statistical software R to determine important risk factors that predicted exposure to the pathogens in cattle, namely population factors (distance from interface and month of collection) and individual characteristics (age, sex, body condition and breed). Age and body condition of the animals were found to have an effect on seropositivity while breed, sex, spatial distribution of the animals and month of sample collection did not have an effect. Recommendations to reduce pathogen exposure and improve production are made to the livestock owners in the Mnisi community. / Dissertation (MSc)--University of Pretoria, 2016. / Veterinary Tropical Diseases / MSc / Unrestricted

Anaplasmosis, babesiosis, and heartwater are the three most important tick-borne diseases of cattle in South Africa and result in a large number of mortalities. Endemic stability contributes to disease control, but little is known about the conditions required for maintenance of endemic stability. Through the on-going Health and Demographic Surveillance System in Livestock in the study area of the Mnisi One Health Platform, Mpumalanga, a great deal of information is being collected about cattle in the area, with the eventual aim of developing mathematical models to describe and predict infections. More than 15000 cattle have been identified for tick burden assessment, serological analyses and parasite identification. However, little is known about the time-course of infection of cattle with various tick-borne haemoparasites. Therefore, this study aimed to investigate the time-course of infection in new-born calves (n=10) and the presence of haemoparasites in adult ticks over a one year period using reverse line blot (RLB) hybridization and quantitative polymerase chain reaction assays. Blood samples and adult ticks were collected monthly from new-born calves in two areas of the Mnisi communal area: five located in a peri-urban area and five at the wildlife/livestock interface. A total of 119 blood samples and 805 adult ticks were collected. The RLB results confirm the exposure of most new-born calves in the Mnisi communal area to non-pathogenic and pathogenic tick-borne haemoparasites in the genera Anaplasma, Babesia, Ehrlichia and Theileria in their first year of life. A total of 805 adult ticks were identified to species level using identification keys and molecular methods. Only two tick species, Amblyomma hebraeum and Rhipicephalus microplus, were found on the calves during the year. Non-pathogenic and pathogenic haemoparasites in the genera Anaplasma, Babesia, Ehrlichia and Theileria were detected in pooled DNA extracted from ticks that had digested their blood meal. Pathogen-specific qPCR results indicated that some of the pathogens could not be detected in the calves until six to seven months of age and A. marginale was not detected at all in three calves at the wildlife/livestock interface. These calves were either infected at levels below the detection limit of our assays, or they were not infected at all. If the latter, it is possible that exposure to related non-pathogenic haemoparasites might help to establish and maintain endemic stability. Factors such as cattle density and dipping methods within different areas in the Mnisi communal area may play a role in the number of infected tick vectors in an area, and thus in the time-course of infection in new-born calves. It is clear that detailed information for cattle in different localities in the Mnisi communal area will be required in order to build accurate mathematical models to describe and predict infections. / Dissertation (MSc)--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc / Unrestricted

Animal diseases impact on livestock production and threaten food security through loss of animal protein. Additionally, disease impacts may cause major production losses by adding to the cost of livestock production through the necessity to apply costly disease control measures. Taken together, farm animal diseases have been shown to increase poverty levels particularly in poor communities in Africa that have a high dependence on livestock farming for sustenance (Perry et al., 2009). Research to learn more about animal diseases is necessary for the development of appropriate policies and strategies to prevent, control and possibly eradicate costly animal diseases in order to increase socio-economic development and improve livelihood, especially in Africa (Perry et al., 2009). The purpose of this study was to investigate five viruses that cause upper respiratory tract infections in cattle: bovine alphaherpesvirus-1 (BoHV-1), bovine viral diarrhoea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (PI-3) and bovine mastadenovirus-3 (BAV-3), in the rural Mnisi farming community in the Mpumalanga Province, South Africa which is located adjacent to the Kruger National Park (KNP) and private game reserves (Figure 1). The Mnisi Community Project (MCP) is a University of Pretoria initiative that is based on an One Health approach at the human/livestock/wildlife/ecosystem interface. Within the Mnisi community there are a number of dip tanks to which cattle are obligated to attend weekly for FMD inspection. In return, cattle are plunge-dipped free of charge in acaricides, as an aid to control tick-borne diseases such a theileriosis, anaplasmosis, heartwater and redwater. These viruses are known to cause pathology of the respiratory tract and lead to morbidity and even mortality in some cases. In addition, two of the viruses studied here, BoHV-1 and BVDV, can suppress the immune system of the host and also increase the risk of secondary bacterial infections (Valarcher & Hägglund, 2006). This study used a cross sectional design to determine the spatially explicit herd-level antibody seroprevalence of five respiratory tract viruses. A total of 423 sera stored in the Hans Hoheisen Wildlife Centre biobank were collected at 11 dip tanks in the Mnisi communal farming area. A commercially available pentavalent, indirect enzyme linked immunosorbent assay (ELISA) was performed to estimate the seroprevalence of each. The overall proportion of sera that contained antibodies against each pathogen were as follows: 43.3% for BoHV-1; 30.5% for BVDV; 82.5% for BRSV; 44.4% for PI-3 and 83.2% for BAV-3. The prevalence of antibodies against the five respiratory viruses did not appear to be influenced by location, distance from the adjacent wildlife conservation area, time of the year, or sex. However, age was a risk factor as antibodies appeared less frequently in animals less than 12 months of age compared to animals between 12 and 24 months, or older than 24 months. Findings from this study should provide information for the cattle farmers and animal health sector that provide animal health and extension services about the risk of bovine respiratory disease in the Mnisi communal farming area. Appropriate measures to minimize exposure to viral respiratory tract infections are discussed. / Dissertation (MSc)--University of Pretoria, 2018. / Veterinary Tropical Diseases / MSc / Unrestricted

Rhipicephalus microplus transmit two important diseases of livestock in South Africa, namely Babesiosis and Anaplasmosis. As cattle still play a key role in the livelihood of rural communities in the Eastern Cape province, animal health is of utmost importance to maintain and strengthen these communities. In most rural areas of the Eastern Cape, the South African government provides free dipping of cattle with amitraz. Deltamethrin, a synthetic pyrethroid (SP), has been used as pour-on dip in a few locations where there are no functional dips. Of concern, is the growing number of global reports on the increase of acaricide resistance. Routine screening for resistance to acaricides is therefore needed. In this study we investigated allele frequencies of acaricide resistance-associated single nucleotide polymorphisms (SNPs) in R. microplus ticks from the Engcobo Local Municipality. The estimated frequencies of amitraz resistance-associated SNPs were 0.58 (at locus 1) and 0.32 (at locus 3). Resistance against formamidines (amitraz) appears to be on the rise. The published mutation in the voltage gated sodium channel (VGS) receptor gene (domain II segment 4-5 region), known to confer resistance to synthetic pyrethroids, was not found. This could be attributed to the low selection pressure against pyrethroids in the study area. / Dissertation (MSc)--University of Pretoria, 2018. / Veterinary Tropical Diseases / MSc / Unrestricted

BACKGROUND In South Africa, bovine TB (bTB) is a state-controlled disease but the monitoring of bTB in small ruminants is largely neglected, whereas bTB diagnosis and surveillance in cattle and buffalo are prioritised due to limited resources. In communities where bTB surveillance is not conducted regularly in herds, bTB surveillance data in cattle and other susceptible livestock are lacking. Goats co-existing with cattle, especially in areas where the prevalence of TB is high in both the cattle and the human populations, are not tested for TB. The prevalence of bTB in goats is unknown though they are known to be susceptible to Mycobacterium bovis. Thus, there was an opportunity to gather information from state veterinarians on their observations of bTB in goats. This information would assist to make a decision on whether to pursue further studies on bTB in goats in South Africa. METHODS A survey study design using a quantitative research approach was used. Data were collected through face-to-face interviews using a semi-structured questionnaire. Contacts of state veterinarians where obtained from the Department of Agriculture Forestry and Fisheries (DAFF) website. Participants were initially contacted via email. In the e-mail the participants were given a brief introduction of the researcher as well as his intention of carrying out the questionnaire. Participants that were willing to participate would either do so via email in which they would read and sign the consent form and then proceed to answer the questions on the questionnaire. They could either fill in with a pen or, type in their responses electronically. During the face-to-face interviews, participants were given the option to complete the questionnaire themselves or let the interviewer read out the questions and complete the questionnaire on their behalf. They were however requested to go through the consent form and fill it in before the interview could start. Other participants preferred to go through the questionnaire themselves while in the presence of the interviewer. RESULTS None of the 25 interviewed veterinarians had tested for or diagnosed bTB in goats. When asked the reason for not testing for bTB in goats, 55% said it was not mandatory and 25% cited limited resources as the reason. From the literature search, Spain and the United Kingdom had the most reported cases in Europe of TB in goats at 36% (n=355) and 27% (n=45) respectively. M. bovis was the most commonly encountered species and the mediastinum lymph nodes was the organ most often affected. In Africa, Ethiopia and Nigeria had the most reported cases of TB in goats with 54% (n=184) and 15.4% (n=9) respectively. M. bovis was most commonly encountered in these cases and unlike the European cases; the lungs were most frequently affected with a frequency of just under 80%. The only reported case of bTB in goats from South Africa was reported in 1928. CONCLUSION There is limited knowledge of bTB in goats in South Africa primarily driven by a bTB disease policy that is biased to focus on cattle and pay little attention to small stock such as goats. / Mini Dissertation (MSc (Tropical Animal Health))--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc (Tropical Animal Health) / Unrestricted

This project was conducted in order to ascertain the presence or absence of acaricide resistance in ticks in an area of KwaZulu-Natal (KZN) where tick-borne diseases pose a real and dire threat to communal and commercial livestock. The results of this study will assist farmers and state veterinarians in their tick control strategies and aid in the battle against stock losses due to ticks and tick-borne diseases. The aim of the project was to collect one-host Rhipicephalus spp. (blue ticks) from cattle presented at communal dip tanks and from cattle on commercial dairy and/or beef farms to test for the presence of acaricide resistance. The ticks were identified as either R. microplus or R. decoloratus, then the engorged female ticks were incubated and the hatched larvae subjected to the Shaw Larval Immersion test (SLIT). The Shaw Larval Immersion test was developed in 1966 by RD Shaw (Shaw, 1966) to determine the spectrum of acaricide resistance in tick populations. The three acaricides selected for the laboratory bio-assay are included in the classes of topical acaracides most frequently used in KZN, namely amidines, organophosphors and pyrethroids. Both tick species were present in the study area and two commercial farms showed a mixed population of both tick species. All fifteen populations of ticks tested in this study showed resistance to at least one class of acaricide, and four of the 15 (26%) showed resistance to two classes of acaricides. 80% of the tick samples tested was resistant to cypermethrin, a synthetic pyrethroid. It can be concluded from this study that: 1. acaricide resistance is present in one-host Rhipicephalus spp. in the KwaZulu-Natal Midlands and this poses a real and significant threat to tick control efforts in this region of KwaZulu-Natal, 2. resistance to pyrethroids is developing at a faster rate than other acaricides and, 3. both blue tick species were identified in the study area however only one or the other species was represented at almost all of the 15 sites sampled. The exceptions were two commercial farms, where both R. decoloratus and R. microplus were identified in a mixed population. / Dissertation (MSc (Tropical Animal Health))--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc (Tropical Animal Health) / Unrestricted

Tabanidae (Diptera) is a diverse haematophagous fly family, known to transmit over 35 livestock pathogens both mechanically and biologically. Kruger National Park (KNP) (in Limpopo and Mpumalanga provinces), South Africa, has a high diversity of tabanids, representing 26 of the total indigenous species (n=213) present in South Africa. Little modern taxonomical work has been done on tabanids within South Africa despite their medical, veterinary and environmental importance. This study aimed to determine a cost-effective DNA extraction method as well as comparing the traditional alpha-taxonomic approach to species delimitation with molecular methods using two gene regions, mitochondrial cytochrome oxidase I (COI) and nuclear alanyl-tRNA-synthetase (AATS) of tabanids collected in KNP. Furthermore, the study aimed to elucidate the role of tabanids in the transmission of Besnoitia besnoiti as this pathogen has found to ciculate in impala (Aepyceros melampus) and blue wildebeest (Connochaetes taurinus). A comparative study on DNA extraction methods were conducted, of which the most effective method was selected for DNA extractions. Tabanids were captured in three locations within KNP. The flies were morphologically identified then homogenized. DNA was pooled for the B. besnoiti screening, followed by sequencing and phylogenetic analysis. In total, 856 flies were captured belonging to 16 species under five genera. The COI barcode indicated that some species are genetically uniform while others formed co-occurring haplotypes. This study found that COI alone was not adequate in distinguishing between all the species of the South African Tabanidae. It is apparent that the classification of Tabanidae should be placed under scrutiny. A larger sample size, especially with regards to the Tabanus genus, or the use of several markers will aid in clarifying their relationships. No B. besnoiti positives were detected in the screened tabanids. Furthermore, in-depth research should also be conducted in other regions of South Africa; not only on tabanid ecology and composition but their role as pathogen vectors. / Dissertation (MSc)--University of Pretoria, 2019. / Veterinary Tropical Diseases / MSc / Unrestricted