Clinical aspects of Cholera

The incubation period is brief: 1 to 5 days (usually 2 days). Asymptomatic infections are common, but chronic carriers are very rare. Sometimes there is an initial transient fever. Massive watery diarrhoea starts suddenly. The faeces very rapidly look like water in which rice has been boiled: watery with flakes of mucus. The faeces have a fish-like smell. The volume of faeces may rise to 500 ml per hour. Vomiting is common, but abdominal cramps are unusual. The onset of thirst, oliguria or anuria and weakness is rapid. In a short time the patient develops severe dehydration and can die within 24 hours. In other cases the diarrhoea is less severe, especially with infections with El Tor. As the patient’s condition deteriorates, hoarseness of the voice and temporary deafness are often observed.

The signs of dehydration are thirst, dry mouth and lips, hollow eyes and sunken fontanel in children. The skin turgor diminishes. The skin becomes wrinkled (washerwoman’s hands). The voice becomes weak and hoarse, the pulse quickens and is difficult to feel. Blood pressure falls. There is little or no urine production. Respiration becomes faster due to metabolic acidosis secondary to loss of bicarbonate in the faeces (bicarbonate is alkaline). This acidosis causes vomiting and muscle cramps. There is also significant potassium loss in the faeces. If rehydration is carried out using fluid without potassium, severe hypokalaemia may result. Nevertheless, quite often normokalaemia is found, together with an increased anion gap. The increase in the anions (= negative ions) is multifactorial due to the hyperproteinaemia (haemoconcentration), hyperphosphataemia (internal shifts and renal failure) and lactate acidosis (shock). Ketones play little if any role. The mortality from classic cholera may reach 50 %, but can be brought down to <>

Category: Medical Subject Notes , Microbiology Notes