Explain how a loss of chloride ions and sodium ions from the intestinal epithelial cell will result in water leaving the cell.
The main treatment for cholera is oral rehydration therapy (ORT) with oral rehydration salts (ORS). This means drinking a solution containing electrolytes (mineral ions) and glucose. Fig. 4.2 outlines the movement of glucose and sodium ions across an intestinal epithelial cell.
In severe cholera, the rehydrating solution is given intravenously, as a drip straight into a vein. Suggest one reason why the rehydrating solution is given as a drip directly into a vein rather than into an artery.
Tetracycline binds to a ribosomal subunit. Suggest what effect this has on the metabolism of $V.\,cholerae$.
A study was done to compare how effective the antibiotic tetracycline was in treating 118 patients with cholera. The patients were split into four treatment groups: • Group A, given one dose of $1\,\text{g}$ tetracycline • Group B, given one dose of $2\,\text{g}$ tetracycline • Group C, given a multiple dose (one dose of $500\,\text{mg}$ tetracycline every $6$ hours for $24$ hours) • Group D, given no antibiotic. After treatment, the volume of diarrhoea collected from each patient was measured every $16$ hours for $128$ hours. Fig. 4.3 shows the mean volume collected for each group.
Describe the patterns shown in Fig. 4.3.
Explain whether the results support, or fail to support, the use of tetracycline to treat very severe cholera cases.
Some strains of $V.\,cholerae$ are antibiotic resistant. Explain why this means that medical practitioners prefer to treat cholera with a single dose of antibiotic, rather than a multiple dose of the same antibiotic.
Describe the patterns shown in Fig. 4.3.
Explain whether the results support, or fail to support, treating very severe cases of cholera with tetracycline.
Most people who have recovered from cholera rarely become ill with the disease again. In these people, antibodies have been identified that bind either to the cholera toxin, or to the bacterial flagellum, or to the main bacterial cell. Explain why the antibodies are different, with each one specific to its target.
Evidence suggests that newborn babies of mothers who have had cholera are protected against the disease. State precisely what type of immunity these babies are likely to have.