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

Table 2

Expert opinion ranking of risk transmission pathways identified by the stakeholders for in-country and transboundary introduction and transmission of ASF virus.

Identified pathway	Ranking
Infected pigs movement (formal/informal) from affected areas within the country (Tanzania)	1
Contaminated pork product movement (formal/informal) from affected areas within the country (Tanzania)	2
Fomites (humans (service providers, other value chain actors and visitors), vehicles, and equipment)	3
Animal health practitioners, visitors and dog and cat movement within pig house, unsupervised slaughtering slabs, wild pigs/warthogs, and laboratory samples	3
Contaminated feeds (and drinking water) movement from affected areas within Tanzania	5
Infected live pigs imported (informal) through the international borders from areas known to be affected with ASF	6
Contaminated pork products (formal and informal) through the borders from areas known to be affected with ASF	7
Contaminated water/environmental materials from infected animals/products	8
Infected live pigs imported (informal) through the international borders from areas not known to be affected with ASF	9
Contaminated pork products (formal and informal) through the borders from areas not known to be affected with ASF	10
Infected live pigs imported (formal) through the international borders from areas known to be affected with ASF	10
Manure and beddings	12
Infected live pigs imported (formal) through the international borders from areas not known to be affected with ASF	12
Arthropods (flies, ticks, Stomoxys)	14
Laboratory personnel	15

Note. 1 = the riskiest and 15 = the least risky. Experts’ opinions were provided based on selection of persons with significant contributions in the field of ASF research and diagnostics, field practice, teaching, and/or years of experience. All responses were based on independent empirical evaluations of ASF in farms. Full details of the reasoning behind the ranking are available in the Supplementary Table 4a. It should be understood that wild boars do not occur naturally in sub-Saharan Africa. The environment to pig cycle was described for a cycle identified in northern Europe where wild boars die of ASF and their carcasses contaminate the environment if not rapidly removed, helping to keep the infection going [13]. The ticks to pig cycles are related either to warthogs or to ticks that live in pigsties (as described in Malawi). Whether this affected the low ranking of arthropods and the relationship to wild pig was not evaluated. Perhaps, the ranking may differ in other territories. ^∗Means veterinarians, para veterinarians, and input suppliers who are direct service providers to the farms.