Incubation period varies from a 12 hours to five days (1).
- symptoms are not present in 75% of people infected with V. cholerae
- among people who develop symptoms, 80% have mild or moderate symptoms, while around 20% develop acute watery diarrhoea with severe dehydration (2)
Clinical presentation of cholera includes:
- massive watery diarrhoea
- maybe upto 1L per hour
- can lead to hypotensive shock and death within hours of the first symptom - so-called cholera gravis)
- typically painless and not accompanied by tenesmus; some may have abdominal discomfort or cramping caused by fluid distension of the bowel
- in the early phase of the disease, stools of patients with cholera may contain faecal matter or bile while the characteristic rice-water stool is seen with continued purging
- vomiting
- common specially early in the disease
- features of dehydration e.g. - lethargic, sunken eyes, dry mouth, cold clammy skin, decreased skin turgor, wrinkled hands and feet
- muscle cramping and weakness - due to electrolyte losses and ion shifts (particularly potassium and calcium)
- in children, altered consciousness, seizures, or even coma - due to severe hypoglycaemia caused by depletion of glycogen stores and inadequate gluconeogenesis (1)
In a more severe illness there are three phases that are recognised.
- evacuation phase - abrupt onset of profuse, watery diarrhoea (rice water stools - because mucus flecks may be seen floating in the watery stools). There may be vomiting associated with this stage of the disease.
- collapse phase - features of circulatory shock, e.g. tachycardia, cold clammy skin, peripheral cyanosis, hypotension. Also, features of dehydration, e.g. decreased urine output, sunken eyes. The patient is often apathetic but not usually delirious. The patient may suffer severe muscle cramps. A child may present with convulsions due to hypoglycaemia. In this stage of the illness renal failure may be a major problem.
- recovery phase - if the patient survives the collapse phase then there is a gradual return to clinical and biochemical normality over a 1-3 day period.
Cholera sicca is an uncommon presentation of cholera.
- fluid is accumulated in the intestinal lumen resulting in circulatory collapse and sometimes even death before the passage of the first loose stool (1).
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