| 1. |
- Torsson, Emeli, et al.
(författare)
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Detection of peste des petits ruminants and concurrent secondary diseases in sheep and goats in Ngorongoro district, Tanzania
- 2019
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Ingår i: Comparative Clinical Pathology. - : Springer Science and Business Media LLC. - 1618-5641 .- 1618-565X. ; 28, s. 755-759
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Tidskriftsartikel (refereegranskat)abstract
- Small ruminants play an important role in the livelihoods of resource-constrained communities. This study was initiated because of a massive outbreak of a respiratory disease in sheep and goats in Loliondo area in Ngorongoro district of Arusha region in Tanzania in 2016. During flock examination, a total of 240 serum samples and 61 nasal swabs were collected. Antibodies to small ruminant morbillivirus, causative agent of peste des petits ruminants (PPR), were detected from sera using a competitive enzymelinked immunosorbent assay. A multiplex reverse transcription real-time polymerase chain reaction assay was used to detect four pathogens: small ruminant morbillivirus, Mycoplasma capricolum subspecies capripneumoniae, Pasteurella multocida, and Capripoxvirus from the nasal swabs. Overall seroprevalence of PPR was 74.6%, with all four pathogens detected from nasal swabs. Co-infections of small ruminant morbillivirus and Mycoplasma capricolum subspecies capripneumoniae, small ruminant morbillivirus and Capripoxvirus, small ruminant morbillivirus and Pasteurella multocida, and Mycoplasma capricolum subspecies capripneumoniae and Capripoxvirus were also detected. Presence of PPR and the other diseases in this study provided insight into the severity of the outbreak in sheep and goats in Ngorongoro district. Thus, laboratory confirmation is critical for prompt and appropriate interventions to be made for control of diseases in sheep and goats with similar clinical signs. The findings also call for research into development of combined vaccines targeting common diseases of small ruminants in Tanzania.
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| 2. |
- Torsson, Emeli, et al.
(författare)
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Filter paper is a simple and cost-effective transport medium for serological diagnosis of Peste des petits ruminants
- 2019
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Ingår i: Small Ruminant Research. - : Elsevier BV. - 0921-4488. ; 170, s. 154-159
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Tidskriftsartikel (refereegranskat)abstract
- Peste des petits ruminants (PPR) is a highly contagious disease caused by peste-des-petits-ruminants virus. Following the successful eradication of the related rinderpest virus, a program to control and eradicate PPR was launched by the FAO and OIE. PPR is today present in many tropical countries where maintaining the cold chain for sample transportation is one of the major barriers for timely processing. Transport of samples on filter paper is a simple and cost-effective method, however validation and optimization is required to fully adapt this approach. The objective of this study was to evaluate and validate the use of filter paper in serological diagnosis of PPR. Blood samples (serum and filter paper) were collected from sheep and goats in both Tanzania and Pakistan and analysed using a PPRV-specific cELISA. The positive proportion was 10.7% in Tanzania and 80% in Pakistan when performing the analysis on serum. These results were then considered as reference and compared to the results from the filter papers analysed by the same cELISA. According to the statistical analysis the cut-off for a positive results for samples stored on filter paper was adjusted from < 50 % competition percentage to < 84% in Tanzania and to < 69% in Pakistan.These results demonstrate that filter papers are an acceptable and cost-effective transport method of whole blood samples for later use in serological analysis.
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| 3. |
- Torsson, Emeli
(författare)
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Peste des petits ruminants virus—in the field and in the host
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sheep and goats are one of the most important sources of food and income for many people around the world. They are especially important among vulnerable groups in Africa and Asia who may depend solely on them for their livelihood. The disease peste des petits ruminants (PPR) mainly affects domestic sheep and goats, and is caused by the highly contagious PPR virus (PPRV). PPRV is currently the goal of a control and eradication program launched by the Food and Agriculture Organ of the United Nations (FAO) and the World Organization for Animal Health (OIE). This thesis has explored aspects of PPR with the hope of helping the eradication effort. Among other things, the thesis has looked at prevalence and risk factors for PPRV, development of better diagnostic methods, and studied the virus-host interactions.The prevalence and risk factors for infection among sheep and goats in Tanzania was studied during two years. PPRV circulated with a prevalence of 49.3% in 2014 and 10.0% in 2015. The main risk factors for the animals were being female and increasing age. Interaction with wildlife was also evaluated as a risk factor, but did not lead to increased infection. The transport of serum samples was improved by validating the use of filter papers in a commercial cELISA. By adjusting the cut-off for a positive result, filter papers were a viable option for transport with unreliable cold-chains.Long transports are also a problem in molecular diagnosis, as the sensitive nucleic acid may degrade. A protocol was developed for a field-adapted full genome sequencing of PPRV. A portable miniPCR and a minION sequencing device, allow analysis at the disease outbreak or in a minimally equipped laboratory. A genetic marker of 255 nucleotides is commonly used for molecular epidemiology, but use of the full genome allows more precise tracing of the infection and viral evolution.A major symptom of PPR is a severe immunosuppression, mainly produced by the PPRV C and V proteins. The effects of these proteins were studied on the type I and II interferon (IFN) signaling pathways. The V protein was a strong inhibitor of both pathways, whereas the C protein inhibited the type I pathway, but stimulated the type II.
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