An epidemiological study on the genetic relationships of foot-and-mouth disease viruses in East Africa

Within East African countries many of the known infectious diseases of animals occur commonly and are poorly controlled. Foot-and-mouth disease (FMD) is one of the contagious viral diseases that has great impact on economic development both in terms of direct and indirect losses. The epidemiology of the disease is complex due to the presence of six of the seven serotypes and the presence of large numbers of both wild and domestic susceptible animals in the region. Decision-making to determine the importance of FMD control relative to the economic consequences and what FMD control strategies should be applied based on the epidemiological information is required. In this regard the first step is to investigate the genetic relationships/variability of East African isolates and their phylogeographic distribution. These can provide base-line information for designing control strategies by vaccination as well as the determination of the sources of infection. Sufficient genetic information on the FMO serotypes O, SAT-1 and SAT-2 are lacking and therefore the number of viral Iineages and genotypes or topotypes from East African countries could not be determined. Published studies on the relative occurrence and genotype distribution of FMO are largely confined to the southern and western part of the continent. In this study, the genetic profile of the 3 most prevalent serotypes (0, SAT-2 and SAT-1) recovered from outbreaks in East Africa between 1957 and 2003 was addressed. Phylogenetic analysis of partial and complete sequences of the 10 gene revealed the presence of distinct lineages and genotypes for East Africa as well as historical relationships of some of the genotypes with isolates from other regions. A great variation in the occurrence and distribution of these serotypes were found. All the African and the Middle East/South East Asian isolates of serotype O included in this study clustered into one lineage having 8 distinct topotypes. These results indicated that between countries as well as inter-regional (east and west Africa) spread of viruses occurred in the past. Inter-regional spread of the virus between eastern Africa and western Africa was also confirmed for SAT-1 viruses. The fact that phylogenetic links are found with both serotypes implies that the spread of viruses was possibly associated with unrestricted animal movement due to nomadic movement in Africa. The phylogenetic relationships of SAT-1 viruses are more diversified in Africa. Eight lineages and 11 genotypes were identified when the optimal nucleotide sequence differences of ≥ 23% for lineages and ≥ 6% for genotypes were used as a cut-off values. It was observed that viruses from Uganda are evolving independently from viruses elsewhere on the continent and clustered into 3 discrete lineages. In contrast, viruses from countries neighbouring Uganda, Kenya and Tanzania, clustered into one lineage. Uganda also harboured 3 topotypes of SAT-2 virus isolates, one is distinct for Uganda and the other are shared with Kenya and Zaire (DRC). This study highlighted distinct lineages found in Uganda and needs further investigation. Within SAT-2, 67 isolates from 22 African countries and Saudi Arabia clustered into 5 lineages which consisted of 15 genotypes. Clustering of viruses into distinct genotypes (topotypes) according to year of isolation and geographical origin was observed showing countries with common boundaries shared common epizootics in the past. These results also showed a link between eastern and southern African countries. Attempts were also made to investigate the incidence of FMD in Ethiopia using sera collected from cattle, small ruminants and wildlife. The results obtained from the liquid phase blocking ELISA and the 3ABC ELISA indicated the presence of SAT-1 and SAT-2 in buffalo populations in the southern part of Ethiopia while results from small ruminants and other wildlife were not indicative of any significant role in the epidemiology of FMD. Serological results also indicated that SAT-1 is present in cattle, although this serotype has not been previously identified. The cumulative molecular epidemiological results from this and previous studies indicated that genetic variability of FMD viruses can be independently maintained within country/countries or regions as well as inter-regions of Africa. The serological results from buffaloes in East Africa are also suggestive of a possible reservoir of the SAT types FMD in the region which has a great impact on the control of the disease. Furthermore, the numerous lineages and genotypes of FMD virus isolates in Africa having distinct or overlapping distributions as well as the genetic linkage between regions will complicate the epidemiology of the disease. Therefore, it is strategically important to consider a regional approach and the use of a vaccine which contains a cocktails of antigens of FMD virus strains.Thesis (PhD)--University of Pretoria, 2004.Veterinary Tropical Diseasesunrestricte

Genetic Characterization of Foot-and-Mouth Disease Viruses, Ethiopia, 1981–2007

Virus diversity indicates a virus reservoir in this country

Nature’s contributions to people from church forests in a fragmented tropical landscape in southern Ethiopia

Despite expanding interest in nature's contributions to people (NCP) studies, understanding of sacred natural sites’ contributions to human society and the restoration of fragmented landscapes remains relatively limited. This study examines the diversity and extent of NCP by church forests in a fragmented tropical landscape in southern Ethiopia. We identify 339 church forests in the Gurage Zone and examine them using a combination of historical (1967) aerial photographs and recent (2017) orthophoto images, supplemented by vegetation sampling and in-depth interviews with key informants from 42 selected church communities. Church forests can be found in all agro-ecological zones and across the entire vegetation types in the Gurage socio-ecological landscape. In the last five decades, the extent of church forests has been remarkably persistent, and 67% of the forests have seen an increase in size even while surrounding state- and community-controlled forestland has been degraded over time. Interview findings suggest the church forests' persistence is in large part due to the church compound being seen as a sacred space and hence respected and protected by the community. This powerful social norm has allowed for multiple uses of the church forest to continue over time through sustained forest management. More than 15 distinct contributions of church forests to local communities were identified including material, nonmaterial, and regulating NCP categories, suggesting church forests deliver a wide range of NCP in addition to their well-established ecological and conservation value. Findings underscore the current contributions of church forests to local people in southern Ethiopia, as well as the potential for church forests to support the restoration of degraded landscapes through integration into regional landscape planning and management policies

Participatory disease surveillance (PDS) of sheep and goats deseases in selected districts of Afar Regional State: Particular focus on Pestes des petit ruminants (PPR) and sheep and goat pox disease (SGP)

Participatory disease surveillance uses a participatory technique for the collection of qualitative epidemiological information within the community observations and existing veterinary knowledge. Participatory disease surveillance wasconductedto assess and prioritize the majordiseases of sheep and goat in selected districts of Afar Regional statefrom July to September 2012 andspecifically to understand the status of PPR and SGP diseases. Three Kebeles from each district were selected out of four districts based on representativeness and a total number of twelve  Kebeles were selected. Elite informantswereselected purposivelyto collect in-depth informationand 1O to 12 community informants were included in each PDS process.A total of 500 sera samples were also tested for antibody against PPR virus using competitive Enzyme Linked Immuno-Sorbent (C-ELISA). The informants ranked the livestock species based on the economic value fortheir livelihoodas goats, camel, cattle, sheep, donkey and chickenfrom the top priority to the least in descending order.Among listed diseases, respiratory syndrome/CCPP, SGP and tick and tick-borne diseases for goats and respiratory syndrome, diarrhea syndrome, tick infestation and SGP diseases for sheepwere the most priority disease problems top ranked by proportional piling. PPR outbreak was reported in Chifra district and the informants ranked among the top priority disease in goats. High sero-prevalence of antibody against PPR 78% (95%CI: 74.4-81.6) was detected in the study population which might be from natural infectionor PPR vaccination carried out in all districts. The sero-prevalence in goats was higher than in sheep 84.1 % and 70. 7%, respectively. In conclusion, the priority disease problems identified should be given due attention and further epidemiological studies are required to generate information used for the future control endeavor.Keywords: Afar,Goat, Participatory disease surveillance, Sheep, PPR, Sheep and goat pox disease

Land use and land cover changes driven by expansion of eucalypt plantations in the Western Gurage Watersheds, Centeral-south Ethiopia

Land use and land cover (LULC) change is a common trend in all parts of the globe. The possible reasons might be economic, political, social or cultural motives. In Ethiopia, most of the rural and urban people are highly dependent on eucalypts for various purposes, particularly, for fuel wood and construction materials. In the study area, Western Gurage Watersheds of Omo-Gibe Basin, eucalypt plantations have become the emergent and dominant activity next to growing Enset. The specific objectives of this study were to assess the land use and land cover changes driven by eucalypt plantations over time and agro-ecological extent, and to identify socio-economic, demographic, and environmental factors that facilitated expansion of eucalypts plantation.Landsat images from 1987 (TM), 2001 (ETM) and 2017 (Landsat 8 OLI) were used for detecting LULC changes. Digital image processing operations, i.e. haze removal, geo-referencing, contrast enhancement and classification, were completed using ERDAS Imagine 2011 Software. During the period between 1987 and 2017, the area cover of LULC types, namely plantation forest, Enset-based agroforestry, cereal crop and built-up areas increased in the study watersheds at the expenses of natural forests and grassland. The total forest cover declined in the study period from 1987-2000 and, then, increased from 2001-2017 as a result of expansion of eucalypts in bare land, grazing land and cereal crop land use types. The drivers for the expansion of eucalypts in the watersheds are population growth, ‘Meskel’ and ‘Arafah’ celebrations, land degradation and conservation, road development, increased access to markets, and economic factors, such as the growing need for fuel wood, construction materials, and growing need for money. The divergent interest of stakeholders, skepticism and debate around eucalypts are presented; call for further scientific investigations and management options are recommended

Protective efficacy of a single immunization with capripoxvirus-vectored recombinant peste des petits ruminants vaccines in presence of pre-existing immunity

International audienceSheeppox, goatpox and peste des petits ruminants (PPR) are highly contagious ruminant diseases widely distributed in Africa, the Middle East and Asia. Capripoxvirus (CPV)-vectored recombinant PPR vaccines (rCPV-PPR vaccines), which have been developed and shown to protect against both Capripox (CP) and PPR, would be critical tools in the control of these important diseases. In most parts of the world, these disease distributions overlap each other leaving concerns about the potential impact that pre-existing immunity against either disease may have on the protective efficacy of these bivalent rCPV-PPR vaccines. Currently, this question has not been indisputably addressed. Therefore, we undertook this study, under experimental conditions designed for the context of mass vaccination campaigns of small ruminants, using the two CPV recombinants (Kenya sheep-1 (KS-1) strain-based constructs) developed previously in our laboratory. Pre-existing immunity was first induced by immunization either with an attenuated CPV vaccine strain (KS-1) or the attenuated PPRV vaccine strain (Nigeria 75/1) and animals were thereafter inoculated once subcutaneously with a mixture of CPV recombinants expressing either the hemagglutinin (H) or the fusion (F) protein gene of PPRV (10(3) TCID50/animal of each). Finally, these animals were challenged with a virulent CPV strain followed by a virulent PPRV strain 3 weeks later. Our study demonstrated full protection against CP for vaccinated animals with prior exposure to PPRV and a partial protection against PPR for vaccinated animals with prior exposure to CPV. The latter animals exhibited a mild clinical form of PPR and did not show any post-challenge anamnestic neutralizing antibody response against PPRV. The implications of these results are discussed herein and suggestions made for future research regarding the development of CPV-vectored vaccines