Table 1.
Parameters and variables for hybrid schistosome system outlined in Figures 2 and 3 and key factors that may influence them
| Parameter/Variable | Description | Notes/Factors influencing |
|---|---|---|
| H | Human population | Birth rate, death rate, immigration, migration |
| C | Cattle population | Birth rate, death rate, immigration, migration |
| G | Goat population | Birth rate, death rate, immigration, migration |
| O | Sheep population | Birth rate, death rate, immigration, migration |
| S | Snail population | Snail habitat, natural lifespan of snails, interventions targeting snail population |
| m i,j | Mean number of worms in definitive host i, of schistosome species j | Definitive host i can be: H = human, C = cattle, G = goats, O = sheep. Schistosome species j can be: Sh = S. haematobium Sb = S. bovis Hyb = Hybrid of S. haematobium and S. bovis. m i,j and κi,j determined by number and dispersion of worms in the definitive host populations |
| κi,j | Clumping parameter for distribution of schistosome species j in host species i | |
| q i,j | Proportion of females of schistosome species j in host i | |
| ϕi,j_k | Probability that a female of species j will form a pair with male of species k in host species i | Function of m and κ and q |
| ψi,j_k | Total number of couples of pairing j_k in host species i | |
| s j | Number of snails shedding cercariae of species j | |
| B i,j | Transmission rate of schistosome species j from definitive host species i to snails | Determined by worm pair fecundity, contact rate of definitive host with water, miracidia viability and probability of miracidia penetrating snail |
| A i,j | Transmission rate of schistosome species j from snails to definitive host species i | Determined by contact rate of definitive host with snail habitats, cercariae‐shedding rate, probability of cercariae penetration |
| μ i,j | Death rate of mature schistosomes of species j in host species i | Natural lifespan of schistosomes, death rate due to interventions such as praziquantel treatment: efficacy and frequency of drug treatment |
| γ s (γ s,j ) | Death rate of snails (death rate of snails infected with schistosome species j) | Seasonality, habitat, (infection status) |