Improved Diagnostics & Management of Classical Swine Fever in the Lao People’s Democratic Republic
Classical Swine Fever (CSF) is a highly contagious viral disease of swine that causes major losses to pig production. CSF virus is a member of the genus Pestivirus of the family Flaviviridae and is closely related antigenically to other Pestiviruses, Bovine Viral Diarrhoea (BVD) virus and Border Disease (BD) virus. In the Lao People’s Democratic Republic (Laos), CSF has been recognised as a disease that causes significant loss to the smallholder pig sector. However, there exists in Laos a deficiency in fully understanding the epidemiology and impact of CSF, together with limitations in being able to reliably detect CSF outbreaks in a timely manner.The research presented in this thesis is divided into three components. The first component describes the smallholder pig sector in general and seeks to address the impact CSF has on production. In comparison to accepted standards of international and tropical pig production, the performance of the smallholder pig sector of Laos was quite poor. Classical Swine Fever was found to be an important disease impacting on pig production, where the incidence of CSF in Bolikhamxay province was 18 outbreaks per 100 village years. The second and major component describes the development of a new diagnostic test to improve the rapid identification of CSF outbreaks. This thesis describes the development and assessment of a rapid and sensitive ELISA-based test for the diagnosis of CSF virus using immunomagnetic beads (IMBs) as the solid phase. The majority of the research was conducted in Laos where the IMB-ELISA for CSF virus was developed and compared to an antigen capture (AC)-ELISA. Initial estimates of diagnostic specificity and sensitivity show 100 % agreement with the AC-ELISA and the IMB-ELISA has up to 64-fold greater analytical sensitivity. The rapid test is a highly robust and stable test format and much simpler to perform than the AC-ELISA. The IMB-ELISA has the added advantage that the test can be read by eye, lending it to the possibility of adaptation to a near-to-field test with minimal equipment needed. The new test is comparable in cost to the current AC-ELISA; however it can be performed in approximately 3 hours upon receipt of specimens compared to 1 to 2 days for the AC-ELISA. The third and final component addresses the issue of CSF vaccine quality through the assessment of storage temperature and vaccine shelf-life. The CSF vaccine used in Laos is a locally produced lapinised C-strain vaccine with a recommended shelf life of 12 months when stored at – 20 °C. The results presented in this thesis show the vaccine to be stable for only 4 months when stored at – 20 °C and stable for less than 3 months when stored at 4 °C. CSF is important in Laos and has a detrimental impact on pig production; however its presence is not ubiquitous. With improvements in diagnostic capabilities in provincial centres through the further development of the rapid test, outbreaks of CSF will be more readily detected allowing control measures to be enacted. However, control measures utilising the vaccine produced in Laos should be closely controlled to ensure the delivery of a quality product.
Source Type:Master's Thesis
Keywords:classical swine fever lao pdr immunomagnetic beads disease diagnosis
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