Cholera | Biology for GCSE/IGCSE - Year 11 PDF Download

Cholera causes diarrhoea

• Diarrhea: Diarrhea refers to the passing of loose or watery stools from the anus.
• Severity and Fatality: If diarrhea is severe and prolonged, it can result in death due to excessive fluid loss.
• Dehydration Effects: Severe diarrhea can lead to significant loss of water and essential ions from the body, disrupting the normal functioning of tissues and organs.
• Treatment with ORT: Oral rehydration therapy (ORT) is an effective method to manage cholera by replenishing lost fluids and electrolytes.
• ORT Composition: ORT typically consists of a solution containing a precise balance of salt and sugar dissolved in water.
• Causes of Diarrhea: Various factors can cause diarrhea, including infections such as Vibrio cholerae bacteria, the pathogen responsible for cholera.

How does Vibrio cholerae cause diarrhoea?

How Cholera Leads to Diarrhoea

Ingestion: Cholera is contracted by ingesting contaminated water or food. When the bacteria enter the small intestine, it triggers the following illness:

• Bacterial Attachment: The bacteria attach themselves to the wall of the small intestine.
• Toxin Production: They produce a harmful toxin.
• Stimulation of Cells: The toxin stimulates the cells lining the intestine to release chloride ions into the intestine's lumen.
• Chloride Ion Accumulation: Chloride ions accumulate in the intestine's lumen, reducing its water potential.
• Water Movement: When the water potential in the intestine is lower than that of the cells, water moves out of the cells into the intestine through osmosis.
• Fluid Loss: This leads to a significant loss of water from the body in the form of watery feces.
• Imbalance in Blood: The blood ends up with lower levels of chloride ions and water.