Molecular diagnosis and epidemiology of African swine fever outbreaks in Tanzania.

摘要

The objective of this study was to identify specific fingerprints for each African swine fever (ASF) outbreak that occurred in Tanzania from 2001-04. Standard postmortem examination was conducted on all dead pigs in situ: Dar Es Salaam outbreak in 2001 (a total of 13 specimens of lymphoid organs from 3 dead pigs); Arusha outbreak in 2003 (one spleen and 2 lymph nodes from one dead pig); and Kigoma outbreak in 2004 (a total of one, two and three spleen samples from Kasulu, Kibondo and Kigoma districts, respectively). ASF viruses were isolated from samples, confirming the diagnosis of ASF. Specific bands corresponding to the expected 278 bp product size were detected in the samples using the diagnostic primers ASF-1 and ASF-2. Specific bands corresponding to the 478 bp product size were detected in the samples using the epidemiological primers p72U and p72D. Nucleotide sequence data and phylogenetic analysis from the Mbeya and Dar Es Salaam outbreaks revealed that the isolate designated as TAN/1/1 clustered in a group of ASF viruses isolated in Malawi (1978) and Mozambique (1998 and 2001), with 99% homology. The Arusha isolates designated as TAN 2003/1 and TAN 2003/2 clustered with TAN 1/1 isolated in 2001 during the Dar Es Salaam outbreak but belonged to a different genotype. The source of ASFV that caused outbreaks in Arusha was unknown. The ASFV isolates from Kigoma and Kasulu districts designated as TAN 2004/1-4 were 100% homologous. These isolates clustered with ASF from Uganda and Burundi with 100% homology. However, these isolates did not cluster with Tanzanian ASFV isolates. This was the first study to provide a comprehensive insight into the molecular epidemiology of ASF outbreaks in Tanzania..