swifco_rs.asf.disease_course module

swifco_rs.asf.disease_course.default_disease_course(lethality=0.95, duration_transient_shedder=2, duration_transient_non_shedder=6, duration_lethal=1, full_mab_protection=12, partial_mab_protection=6)

Default disease course for African swine fever (ASF).

The disease course following infection is explicitly modelled for each infected individual. The probability of lethal infection is given by parameter lethality. Each host is infectious for duration_lethal or duration_transient_shedder weeks and thereafter either becomes immune lifelong (probability 1-lethality) or dies (probability lethality).

Depending on the disease state of the breeding individual, its piglets’ disease states have to be adjusted. The epidemiological data are not yet available for ASF in wild boar. Therefore, the process was parameterised in accordance with existing evidence for Classical Swine Fever (CSF) in wild boar. However, at time of this study, lethality due to virus infections was observed to be at the maximum and rather fast. Hence the knowledge gap does not conflict with the simulation rules: If assigned to reproduction, susceptible and infected but not yet infectious individuals produce susceptible offspring. Immune individuals produce offspring that are temporarily immune due to maternal antibodies.

Non-lethally infected animals recover from the infection and are converted to immune. An offspring individual protected by maternal antibodies turns susceptible after reaching the maximum age of maternal immunity full_mab_protection. Seropositivity due to maternal antibodies vanishes on reaching a maximum age of maternal antibody presence full_mab_protection+partial_mab_protection.

Parameters:

lethality - disease lethality (default value based on [Blome_2012])

duration_transient_shedder - number of ticks transiently infected hosts are shedders/infectious

duration_transient_non_shedder - number of ticks transiently infected hosts are non-shedders/non-infectious

duration_lethal - number of ticks lethally infected hosts survive and are infectious (default value based on [Blome_2012] and [Guinat_2014])

full_mab_protection - duration of full protection through maternal antibodies, in ticks (default value based on [Depner_2000])

partial_mab_protection - duration of partial protection through maternal antibodies after full protection, in ticks (default value based on [Depner_2000])