Browsing by Subject "arbovirus"
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(2022)Crimean Congo haemorrhagic fever (CCHF) is an emerging, tick-borne viral pathogen. Found on three continents, it is the most widespread of all tick-borne pathogens, but accurate geographical limits and epidemiology in Africa are still mostly unknown. Ticks act as both vectors and reservoirs, and the transmission cycle involves both wild and domestic animals and may occasionally spill over to humans. Further healthcare-related infections from human to human are common. With a high mortality rate and no cure or vaccine, CCHF is considered a major public health threat in endemic countries. This licentiate thesis consists of a literature review and an experimental work section. The literature review covers the basics of tick ecology, tick-borne diseases and viral haemorrhagic fevers with a focus on Africa and Kenya. These are used as foundations to understand CCHF in detail, encompassing virology, epidemiology, diagnostics, symptoms, treatment and prevention. The experimental work entails PCR-screening of ticks collected from South-eastern Kenya for the CCHF virus. The main objective of the study was to find whether CCHF is circulating in free-roaming ticks collected from two conservancies in the Taita Hills area. Taita Hills are located in Taita-Taveta county, near the Helsinki University research centre in Wundanyi. The ticks were collected by the Vapalahti virology team in 2018. This thesis involved the RNA extraction and measurement from the ticks and screening for CCHF virus with RT-qPCR. The results were negative for all 57 units of ticks processed. The study was a part of a larger research project, “Preparedness for emerging zoonotic infections in Kenya”. Previous publications on CCHF are lacking from this part of Kenya, so this study was a valuable part of primary research to establish the geographical limits and members of the enzootic cycle in Taita Hills. It would be essential to continue examining ticks from animal sources in addition to human serology, to further establish evidence of possible CCHF occurrence in the area. Mapping the prevalence and epidemiology of zoonotic and tick-borne pathogens is especially critical now, when climate change and diminishing biodiversity stir and alter disease emergence in an unprecedented manner.
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(2022)Crimean Congo haemorrhagic fever (CCHF) is an emerging, tick-borne viral pathogen. Found on three continents, it is the most widespread of all tick-borne pathogens, but accurate geographical limits and epidemiology in Africa are still mostly unknown. Ticks act as both vectors and reservoirs, and the transmission cycle involves both wild and domestic animals and may occasionally spill over to humans. Further healthcare-related infections from human to human are common. With a high mortality rate and no cure or vaccine, CCHF is considered a major public health threat in endemic countries. This licentiate thesis consists of a literature review and an experimental work section. The literature review covers the basics of tick ecology, tick-borne diseases and viral haemorrhagic fevers with a focus on Africa and Kenya. These are used as foundations to understand CCHF in detail, encompassing virology, epidemiology, diagnostics, symptoms, treatment and prevention. The experimental work entails PCR-screening of ticks collected from South-eastern Kenya for the CCHF virus. The main objective of the study was to find whether CCHF is circulating in free-roaming ticks collected from two conservancies in the Taita Hills area. Taita Hills are located in Taita-Taveta county, near the Helsinki University research centre in Wundanyi. The ticks were collected by the Vapalahti virology team in 2018. This thesis involved the RNA extraction and measurement from the ticks and screening for CCHF virus with RT-qPCR. The results were negative for all 57 units of ticks processed. The study was a part of a larger research project, “Preparedness for emerging zoonotic infections in Kenya”. Previous publications on CCHF are lacking from this part of Kenya, so this study was a valuable part of primary research to establish the geographical limits and members of the enzootic cycle in Taita Hills. It would be essential to continue examining ticks from animal sources in addition to human serology, to further establish evidence of possible CCHF occurrence in the area. Mapping the prevalence and epidemiology of zoonotic and tick-borne pathogens is especially critical now, when climate change and diminishing biodiversity stir and alter disease emergence in an unprecedented manner.
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(2019)Sindbis virus belongs to the Alphavirus genus and it has spread around the globe. Sindbis virus is transmitted by mosquitoes and spread birds. Mosquitoes from Culex and Culiseta genera are able to spread Sindbis virus. In Finland game birds from Tetrao genus have been observed to act as host for Sindbis virus thus enabling viral amplification. In Finland Sindbis virus causes annual disease called Pogosta disease. Typically, Pogosta disease occurs from August to September. Symptoms of Pogosta disease include for example joint pain, arthritis, rash and fever. Pogosta disease is endemic in Finland and known endemic regions are e.g. Ilomantsi region. Even though Sindbis virus causes annual disease in Finland there is currently only six Sindbis virus strains isolated from Finland. These isolations were done in 2002 and in 2005. There is a need for new data. In this master thesis the aims were to describe how two new Finnish Sindbis virus strains were isolated and to compare them to each other and to other Sindbis virus strains isolated from Finland and around the globe. Mosquito samples were collected from Ilomantsi region in 2018 summer. Serum samples from serologically diagnosed patients with Sindbis virus infection were obtained from HUSLAB and included in this study. The mosquito and patient serum samples were cultivated on cells and later virus isolates were plaque purified. Conventional nested reverse transcriptase polymerase chain reactions (RT-PCR) for Alphavirus and Bunyavirus genera were used in order to screen mosquito and patient serum samples for viruses. Later a Sindbis virus specific real time reverse transcriptase PCR was used to test mosquito and patient serum samples. Cell cultures were also tested with immunofluorescence assays. Isolated Sindbis viruses were sent for next generation sequencing and based on that a phylogenetical tree was constructed. The phylogenetical tree represents the new Sindbis virus strains relation to Finnish and to other Sindbis virus strains around the globe. Mosquito samples were morphologically identified and subjected to genetic species identification analysis via COI sequences. These COI PCR products were sent for Sanger sequencing and compared to sequences in NCBI database in order to determine the mosquito species. In this master thesis two new Finnish Sindbis virus strains were isolated from mosquito and from human serum sample. This is the first time in Finland when Sindbis virus has been isolated from human serum sample. These two new Finnish Sindbis virus strains differ from each other. The strain isolated from the patient sample is more closely related to German strains than to Finnish Sindbis virus strains. The strain isolated from mosquitoes is closely related to pre-existing Finnish Sindbis virus strain Ilomantsi region-2005M which is isolated from mosquitoes. These finding suggest that currently there is two different Sindbis virus strains circulating in Finland. This master thesis provides valuable information of Finnish Sindbis virus strains which can be used in future studies e.g. when studying Sindbis virus pathogenesis, distribution, relation to other Sindbis virus strains or mapping Sindbis virus prevalence in Finland.
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(2019)Sindbis virus belongs to the Alphavirus genus and it has spread around the globe. Sindbis virus is transmitted by mosquitoes and spread birds. Mosquitoes from Culex and Culiseta genera are able to spread Sindbis virus. In Finland game birds from Tetrao genus have been observed to act as host for Sindbis virus thus enabling viral amplification. In Finland Sindbis virus causes annual disease called Pogosta disease. Typically, Pogosta disease occurs from August to September. Symptoms of Pogosta disease include for example joint pain, arthritis, rash and fever. Pogosta disease is endemic in Finland and known endemic regions are e.g. Ilomantsi region. Even though Sindbis virus causes annual disease in Finland there is currently only six Sindbis virus strains isolated from Finland. These isolations were done in 2002 and in 2005. There is a need for new data. In this master thesis the aims were to describe how two new Finnish Sindbis virus strains were isolated and to compare them to each other and to other Sindbis virus strains isolated from Finland and around the globe. Mosquito samples were collected from Ilomantsi region in 2018 summer. Serum samples from serologically diagnosed patients with Sindbis virus infection were obtained from HUSLAB and included in this study. The mosquito and patient serum samples were cultivated on cells and later virus isolates were plaque purified. Conventional nested reverse transcriptase polymerase chain reactions (RT-PCR) for Alphavirus and Bunyavirus genera were used in order to screen mosquito and patient serum samples for viruses. Later a Sindbis virus specific real time reverse transcriptase PCR was used to test mosquito and patient serum samples. Cell cultures were also tested with immunofluorescence assays. Isolated Sindbis viruses were sent for next generation sequencing and based on that a phylogenetical tree was constructed. The phylogenetical tree represents the new Sindbis virus strains relation to Finnish and to other Sindbis virus strains around the globe. Mosquito samples were morphologically identified and subjected to genetic species identification analysis via COI sequences. These COI PCR products were sent for Sanger sequencing and compared to sequences in NCBI database in order to determine the mosquito species. In this master thesis two new Finnish Sindbis virus strains were isolated from mosquito and from human serum sample. This is the first time in Finland when Sindbis virus has been isolated from human serum sample. These two new Finnish Sindbis virus strains differ from each other. The strain isolated from the patient sample is more closely related to German strains than to Finnish Sindbis virus strains. The strain isolated from mosquitoes is closely related to pre-existing Finnish Sindbis virus strain Ilomantsi region-2005M which is isolated from mosquitoes. These finding suggest that currently there is two different Sindbis virus strains circulating in Finland. This master thesis provides valuable information of Finnish Sindbis virus strains which can be used in future studies e.g. when studying Sindbis virus pathogenesis, distribution, relation to other Sindbis virus strains or mapping Sindbis virus prevalence in Finland.
Now showing items 1-4 of 4