Table 1 Parameters assumed or fitted based on selected published mathematical models of cholera (partly adapted from Grad et al., 2012[18])
From: Cholera transmission dynamic models for public health practitioners
| Symbol | Parameters | Range | Comments | Potential data from field epidemiology |
|---|---|---|---|---|
| β | Rate of “contact” with reservoir water (days-1) | 10-5 to 1 | Difficult to convert empirical data into this “contact” rate. | Identity and location of drinking water sources; frequency of water usage and volume drawn from these sources |
| 1/γ | Duration of cholera infection (days) | 2.9 to 14 | The most certain among the 5 parameters | Clinical data |
| 1/δ | Cholera life span in water reservoir (days) | 3 to 41 | Usually not measured; depending on local environment (temperature, salinity), nature of the water source (running or static), cholera phage concentration. Historical experimental data available. | Water samples for microbiological experiments |
| ξ | Rate of water contamination by humans, i.e. rate of increase in V. cholerae concentration in the water reservoir (cells * mL-1 * person-1 * day-1) | 0.01 to 10 | Usually not measured; depending on infection severity, sanitation provision and water reservoir size. | Clinical data: frequency and volume of watery stool and especially concentration of vibrios in watery stool. |
| κ | Concentration of cholera that yields 50% chance of infection (cells/mL) | 105 to 106 | The dose–response curves depend on strain and biological context (e.g. gastric acidity). While empirical data provided data for doses (number of bacteria), the parameter measures in concentration. | Based on the volume of water intake per person per day and the vibrio concentration in the water samples, one can estimate the dose of vibrio intake per person per day |