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Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces
Dissertation (MSc (Veterian Epidemiology))--University of Pretoria, 2017.
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| Format: | Thesis |
| Language: | English |
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2026
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| _version_ | 1867613467055226880 |
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| access_status_str | Open Access |
| author2 | Thompson, P.N. (Peter N.) |
| author_browse | Thompson, P.N. (Peter N.) |
| author_facet | Thompson, P.N. (Peter N.) |
| collection | Thesis |
| description | Dissertation (MSc (Veterian Epidemiology))--University of Pretoria, 2017. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110108 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:36:36.461Z |
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| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110108 Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces Thompson, P.N. (Peter N.) lida.avenant@up.ac.za Paweska, Janusz Tadeusz Avenant, Alida Rift valley fever Risk factors Surveillance Seroprevalence Sheep Dissertation (MSc (Veterian Epidemiology))--University of Pretoria, 2017. Rift Valley fever (RVF) is an emerging, vector-borne, infectious disease that has significant effects on public health and livestock farmers in Southern Africa as well as the potential to spread extensively and become established in new areas if not effectively controlled. It causes periodic large outbreaks in livestock, inducing abortion storms and high mortalities in young domestic ruminants, particularly sheep. The disease impacts human lives significantly due to its zoonotic nature, as well as due to losses of livestock and, through this, loss of income and animal products. The last outbreak of RVF in South Africa occurred in 2010-2011. The seroprevalence of RVF has been reported in various species in studies elsewhere in Africa and neighbouring regions. However, no baseline antibody level information is available in South Africa and the level of herd immunity during interepidemic periods in the high risk areas is unknown. The objective of this study was therefore to determine the seroprevalence and associated risk factors for RVF seropositivity in sheep in a high risk area of South Africa. A cross sectional observational survey was performed in the western Free State and adjacent Northern Cape provinces, extending from Bloemfontein in the east to Mokala National Park in the west and to 100 km north and south of these landmarks to form an approximately 200 km _ 200 km study area. A total of 250 random geographic points were generated and 9 sheep were randomly sampled from different age groups from the farm closest to each point. Farmers or farm managers were also asked to complete a questionnaire on animal, environmental and management factors on the farm. xi Collected blood samples were screened with a RVF recombinant nucleoprotein IgG indirect ELISA and positive results were confirmed with an inhibition ELISA test. Blood from a total of 1 525 sheep, from 143 farms in 18 districts, was tested and 9.9% were seropositive (151/1525). The adjusted population seroprevalence estimate, taking into account clustering and sampling weights, was 14.2% (95% CI: 9.7-20.3%). Potential risk factors were analysed using multiple logistic regression and factors found to be associated with seropositivity to RVF were increased age (P < 0.001), addition of new sheep (bought in or given) in the past 12 months (P = 0.002) and last farm level vaccination against RVF from 2014-2016 (P = 0.043). The low seroprevalence for RVF in the study area suggests that the population is likely to be highly susceptible to the disease and may once again be subject to large outbreaks when viral transmission is sufficient to cause clinical disease. Veterian Epidemiology MSc (Veterian Epidemiology) 2026-05-15T17:26:19Z 2026-05-15T17:26:19Z 17/07/04 2017 Dissertation http://hdl.handle.net/2263/110108 en application/pdf |
| spellingShingle | Rift valley fever Risk factors Surveillance Seroprevalence Sheep Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title | Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title_full | Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title_fullStr | Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title_full_unstemmed | Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title_short | Seroprevalence and factors associated with Rift Valley fever in sheep in the Free State and Northern Cape provinces |
| title_sort | seroprevalence and factors associated with rift valley fever in sheep in the free state and northern cape provinces |
| topic | Rift valley fever Risk factors Surveillance Seroprevalence Sheep |
| url | http://hdl.handle.net/2263/110108 |