Infectious Diseases

Vibrio Cholera - bacterium

• Produces enterotoxins (released from bacteria)
  • Enters enterocytes (cells lining the surface of the intestine) by endocytosis
  • Activates the CFTR protein (cystic fibrosis transmembrane regulator)
  • Causes secretion of sodium, chloride and bicarbonate ions from enterocytes
  • Water follows sodium into the intestinal lumen
• Osmotic loss of up to 10L of water per day!
  • Results in severe watery diarrhoea of sudden onset
  • Dehydration leads to death within hours if untreated
• Giving oral sodium would cause more water to be secreted into the intestine, worse!
• Giving oral glucose and sodium (oral rehydration therapy)
  • Glucose is still absorbed through the intestinal wall
  • This is done by a glucose-sodium co-transporter
  • Carries one glucose molecule and one sodium ion across the intestine into the blood
  • Water always follows sodium
  • Diarrhoea is less severe and body becomes rehydrated
• Oral rehydration therapy (ORT) also contains potassium and bicarbonate ions
  • Prevents electrolyte imbalance
  • Prevents metabolic acidosis
    
    
    

Tuberculosis (TB)

• Cause an attack by the body's own immune system
• Symptoms

o Weight loss

o Night sweats

o Cough

o Rash

• Transmitted by coughing and sneezing
• Body tries to destroy the invading bacteria in the lungs
• But the inflammation causes damage to the surrounding cells
• Lesions may become hard or spongy, leaving "holes" in the lungs
• Treated with a cocktail of antibiotics for 6 month