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Asfarviridae
African Swine Fever (ASF)
| Question | Answer |
|---|---|
| What is special about this disease? | REPORTABLE and hemorrhaging in internal organs |
| Who are the hosts? | all breeds and types of domestic pigs and wild boars |
| Who are the resevoirs hosts? | warthogs, bush pigs, and giant forest pigs |
| What are some characteristics of this virus? | Variations in virulence. High stability (15 weeks or longer in chilled carcasses and up to 5-6 months in processed meat products). Cytopathic effects. Syncytia. Intracytoplasmic inclusions. |
| What are two important characteristics of this virus? | ONLY REPLICATES IN SWINE. Buffy coat cells HEMADSORB pig RBCs |
| How can you tell the difference between Hog Cholera and ASF? | NO Hemadsorb in Hog Cholera |
| What type of cycle is Asfivirus maintained in and who are the players? | Sylvatic cycle. ASYMPTOMATIC infection in wild pigs and argasid ticks |
| Describe the sylvatic cycle. | Primary infection causes young pigs to develop a viremia that can be passed on to ticks when they take a blood meal. The virus replicates in the tick and allows the tick to now pass on the virus to other pigs. |
| Ornithodoros sp. are both ? and ? of the virus. | Biological vectors and reservoirs |
| What three types of transmission are possible inside the tick once they have the virus? | transstadial, transovarial, and sexual transmission |
| What is the ONLY arbovirus among the DNA viruses? | ASFIVIRUS |
| What does a DOMESTIC cycle occur? | bites from infected ticks, ingestion of infected uncooked garbage or infected pigs, urination aerosols |
| What is the major source of virus dissemination? | Carrier pigs |
| During the viremic phase, where do the virions multiply? | RBCs, endothelial cells, and leukocytes (esp. macrophages...leads to leukopenia) |
| Where are gross lesions most prominent? | lymphatic and vascular systems |
| What is pathogenesis is seen? | edema and hemorrhage into intestines...no damage to vili |
| How long does the pig have to live if it has a peracute infection? | it can die suddenly or have a high fever, hyperpnea, and cutaneous hyperemia for 1-3 days before death |
| What are two major things one should know about the acute phase of this infection? | (1)Diarrhea is seldom seen because the virus does NOT multiply in the intestinal epithelial cells. (2)Pregnant sows often abort regardless of the stage of pregnancy and these viruses are free of virus. Sows that abort often die within 3-6 days. |
| Compare mortality in PRIMARY exposure to the next time around. | 95-100% vs. 20-40% |
| Subcute and chronic infections are seen in pigs where? | Pigs in regions that are overrun with the virus and have adapted to it |
| Why has developing a vaccine for this virus been unsuccessful? | Sera from infected pigs doesn't neutralize the virus, so the humoral immune response does not have any susbtantial protective value. |
| What prevention/control measures should be taken by endemic countries? | Avoid feeding uncooked waste and double fence yards. |
| What prevention/control measures should be taken by ASF-free countries? | Prohibition of importation of live swine and swine products. Monitor the destruction of all waste food scraps. |