Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2000. / Härtill 4 uppsatser.

Examensarbete.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Lic.-avh. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser.

Diss. (sammanfattning) Uppsala, Sweden : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2008. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2010. / Härtill 5 uppsatser.

Introduction In sub-Saharan Africa, rapid urbanisation and per capita consumption of animal source foods are expected to accelerate in the short-medium term and to increase the movements of live animals and animal products in the region. In Cameroon, where the livelihood of most of the rural population depends on the agricultural and livestock sector, a wide range of endemic transboundary infectious diseases (TADs) affect livestock production and trade, and have direct detrimental effects on animal, human and environmental health. Livestock mobility represents a central economic activity in the livestock value chain of the country as well as a central strategy of seasonal adaptation to the ecosystem. Livestock movements, however, are also a central driver of infectious diseases dynamics and contacts between livestock populations are major risk factors for disease introduction and circulation. In countries where financial and technical resources are constrained, such as Cameroon, strategic interventions aiming at the surveillance and control of multiple infectious diseases simultaneously are essential for optimising their cost-effectiveness. The overall aim of this study was to apply a methodological framework to contribute to the understanding of cattle movements in Cameroon and of their implications for disease circulation. Methods This project used a variety of epidemiological and statistical methods to characterise cattle movements in the country across different scales. The collection of primary data and information targeted both the formal cattle trade system, across the country, and the informal seasonal transhumance, across the main livestock production areas. Between September 2014 and May 2015 diverse strategies were applied for collecting empirical data and various data sources from multiple Regions of the country were combined. Cattle trade in Cameroon mainly occurs via multiple trading points owned and managed either by the veterinary authorities or the municipalities. A total of 62 livestock markets, and the relevant offices of the Ministry of Livestock, Fisheries and Animal Products (MINEPIA), were targeted for collecting official data on cattle trade referring to a 12-month period ranging between September 2013 and August 2014. Additionally, a questionnaire-based survey with the various livestock markets stakeholders (herders, traders, butchers and veterinary officials) was carried out to collect a variety of information on the cattle market system. During this 9-month period of field work, data on cattle seasonal transhumance were simultaneously collected using a combination of GPS-tracking technology and questionnaire-based survey. Results Volumes of cattle trade, the type of traded animals and their commercial values varied over the year and across the Regions of the country included in this study. Nevertheless, the market supply of live cattle showed similar temporal trends over the year and across the Regions. Although for almost the entire study area the peak of traded animals in the market system was in December 2013, the trade volume was consistently higher during the rainy season (May to September). On the contrary, the reduction in the trade volume during the dry season was accompanied by an opposite trend in the cattle price, with their commercial value being higher during the dry season. Furthermore, a cattle price differential was highlighted between production Regions and high consumption Regions of the country. The highest volume of cattle trade was recorded in the Adamawa Region, which was the main source of cattle for the country while also receiving animals from neighbouring countries, such as Chad and Central African Republic. In contrast, major urban markets in the Littoral and Central Regions were the main receivers of cattle originating from almost all the other areas of the country. Interestingly, the North-West Region appeared to be more independent and isolated within the cattle trade network of Cameroon, particularly receiving few animals from other Regions. Importantly, there was little variation in the structural characteristics of the cattle trade network as well as in its properties across seasons, showing that, despite the seasonality in traded numbers, the network of cattle moving between markets in Cameroon is very stable. This consistent structure of the network over the year increases the robustness of strategic targeted interventions. We found that targeting the top 20% of the most connected markets would significantly reduce the network cohesiveness providing opportunities for strategic disease surveillance, communication and risk mitigation interventions. The centrality of the market within the trading network was also found to be positively associated with the price of live cattle, which tended to be heavily affected by phenotypic characteristics of the traded cattle. The seasonal cattle transhumance has been found as a common and widespread practice for herders attending the market system across whole the study area, highlighting the close relation between formal trading movements and informal pastoral movements across the country. Transhumant herds were observed to undertake migrations across multiple Regions for period exceeding 6 months and showing the potential for multiple types of interactions with domestic and wild animals. Discussion Multiple livestock infectious diseases were identified as being related to the cattle trade system. As neighbouring and non-neighbouring countries were found to be epidemiologically connected it is clear that national strategies for surveillance and control are likely to have limited effectiveness. Regional coordination for designing and implementing prevention and mitigation strategies against infectious diseases is essential to improve animal health also at national level. This study highlights the opportunity for strategic surveillance, control and communication interventions targeting key livestock markets and Regions of Cameroon. Live cattle price and centrality of markets, represented by their connectedness within the trading network, highlights the need to further investigate the links between economic factors and drivers of disease dynamics, such as livestock movements. The complexity of cattle movements in this context was further evidenced by the seasonal transhumance representing an established common mechanism for managing livestock, and closely interacting with the formal trading system as well as with other domestic and wild animal populations. Better data collection and analysis of livestock movements is required for improving the effectiveness of surveillance and control of infectious diseases. Although animal identification and registration systems would represent an ideal step for increasing traceability of cattle movements, enhancing animal health management and the overall competitiveness of the livestock industry, in the short-term a cost-effective intervention should aim at further developing the current data recording and management systems. Pastoralism, for long seen as an economic and environmental activity with little future, also needs to be acknowledged as a key component of the livestock production system in the country and to be considered accordingly in the management of infectious diseases.

abstract: Teleosts have the most primitive adaptive immune system. However, in terms of functionality the teleost immune system is similar to birds and mammals. On the other hand, enteric bacterial pathogens of mammals and birds present conserved regulatory mechanisms that control virulence factors. In this context, deletion of conserved genes that control virulence factors have been successfully used as measure to construct live attenuated bacterial vaccines for mammals and birds. Here, I hypothesize that evolutionary conserved genes, which control virulence factors or are essential for bacterial physiology in Enterobacteriaceae, could be used as universal tools to design live attenuated recombinant bacterial vaccines from fish to mammals. The evolutionary conserved genes that control virulence factors, crp and fur, and the essential gene for the synthesis of the cell wall, asd, were studied in Edwardsiella ictaluri to develop a live recombinant vaccine for fish host. The genus Edwardsiella is one of the most ancient represent of the Enterobacteriaceae family. E. ictaluri, a host restricted pathogen of catfish (Ictalurus punctatus), is the causative agent of the enteric septicemia and one of the most important pathogens of this fish aquaculture. Although, crp and fur control different virulence factors in Edwardsiella, in comparison to other enterics, individual deletion of these genes triggered protective immune response at the systemic and mucosal level of the fish. Deletion of asdA gene allowed the creation of a balanced-lethal system to syntheses heterologous antigens. I concluded that crp, fur and asd could be universally used to develop live attenuate recombinant Enterobacteriaceae base vaccines for different hosts. / Dissertation/Thesis / Ph.D. Microbiology 2012

Master of Science / Department of Diagnostic Medicine/Pathobiology / Raymond R. R. Rowland / Pestiviruses such as classical swine fever virus (CSFV) and bovine viral diarrhea virus (BVDV) are some of the most economically important livestock diseases in the world. The antigenic similarities between members of the pestivirus genus allow for both BVDV and CSFV to infect swine. Infections with heterologous pestiviruses in swine can interfere with diagnostic tests for CSFV. The identification of cross-reactive and cross-neutralizing epitopes between CSFV and BVDV for the development of improved diagnostics and vaccines that allow for the differentiation of infected animals from vaccinated animals (DIVAs) are necessary to accurately detect and control CSFV. The overall goal of this research was to identify epitope regions recognized by antibodies that can differentiate between CSFV and BVDV. The approach was to use serum neutralization assays to confirm the presence of neutralizing antibodies to BVDV in swine serum collected from animals immunized with one of three separate Alphavirus vaccine constructs: BVDV-1b, CSFV E2, and CSFV E[superscript]rns. Results showed that animals immunized with the Alphavirus BVDV-1b construct had high neutralizing titers against BVDV-1a and animals immunized with Alphavirus CSFV E2 and E[superscript]rns constructs had low, but detectable, neutralizing activity. Polypeptide fragments of CSFV and BVDV E2 were then expressed in E. coli and purified using affinity chromatography. Serum from a pig immunized with the CSFV E2 Alphavirus construct was tested against two fragments of CSFV E2, 2/4 and 4/4, and four fragments BVDV E2, 1/4, 2/4, 3/4, and 4/4, using western blot analysis. Reactivity to fragments CSFV E2 2/4 and 4/4 and BVDV E2 1/4 and 4/4 was observed. The results of this study identified CSFV amino acid positions 774 through 857 and BVDV amino acid positions 783 through 872 as the regions that contain the epitopes recognized by cross-reactive antibodies between BVDV and CSFV E2. These results provide more specific sequence regions to improve CSFV diagnostic assays and DIVA vaccines.