Table 1 Overview of the main characteristics of the ONCHOSIM and EPIONCHO models
Characteristics | ONCHOSIM | EPIONCHO |
|---|---|---|
Basic model structure | ||
Number and type of spatial locations modelled | Single place | Single place |
Population-based or individual-based | Individual-based regarding humans and worms | Population-based |
Way of representing infection in hosts | Presence and density at individual level | Mean density in population subgroups (e.g. age, sex, treatment compliance group). Prevalence as a function of mean density assuming an underlying negative binomial distribution |
Role of chance | Stochastic | Deterministic |
Interventions considered in previous publications | Mass treatment, selective treatment (test and treat), vector control, | Mass treatment, vector control |
Features included in the model | ||
Human population demographics | Birth and death rate dynamically modelled; age and sex composition | Birth and death rate, age and sex composition |
Heterogeneities in the human population | Age, sex, life expectancy, level of exposure to blackflies, compliance with MDA, efficacy of treatment | Age, sex, life expectancy, level of exposure to blackflies, compliance with MDA |
Blackfly population density | Fixed input as annual biting rate (ABR); seasonal monthly biting rates | Fixed input as ABR; seasonality in biting rates can be included |
Exposure to blackfly vectors | Heterogeneous (dependent on age, sex, personal attractiveness to blackflies) | Heterogeneous (dependent on age and sex) |
Uptake of infection by blackfly vectors | Varying non-linearly (density-dependent) with infection intensity in human hosts | Varying non-linearly (density-dependent) with infection intensity in human hosts |
Infection in blackfly vectors | Density (average L3 load per fly) | Density (average L3 load per fly) |
Excess mortality of infected flies | No | Yes |
Parasite acquisition in humans | Proportional to mean number of L3 larvae inoculated, denoted by the success ratio | Non-linearly (density-dependent) related to rate of exposure to L3 larvae |
Infection in humans | Density (immature or mature worms, mf per skin snip) | Density (non-fertile and fertile worms, mf per mg of skin) |
Diagnostic outcomes | Mf count sampling to relate model predictions to data | Sampling process and diagnostic performance of skin snipping not yet included |