Semiquantitative Risk Evaluation Reveals Drivers of African Swine Fever Virus Transmission in Smallholder Pig Farms and Gaps in Biosecurity, Tanzania

Figure 1

Modelled epidemic curve of African swine fever introduction and transmission in the United Republic of Tanzania, 2003–2021, based on pattern of reporting. Phase I: incursion (from 2003 to 2008), Rt = 0.5 ≤ N ≥ 0.8, sporadic events in the rural areas (Katavi and Mikumi areas); phase II: establishment/persistence (from 2009 to 2016), Rt = 1.3 ≤ N ≥ 1.7, persisting epizootics in the more urban areas (Kinondoni); phase III: dispersion (from 2017 to 2021 and continuing), Rt = 1.7 ≤ N ≥ 2.6, new territories are now infected. Based on seasonality, the Rt ≥ 2 for the period between November and February of the following year. Note that the 2021 outbreak is continuing and the cumulative number of cases may exceed what was documented in the graph above.