Cholera

Cholera is an acute diarrheal infection caused by the bacterium Vibrio cholerae. It primarily affects the small intestine, leading to severe dehydration and electrolyte imbalances if untreated.

Signs and Symptoms

The hallmark symptom of cholera is profuse watery diarrhoea, often described as "rice water" stool, which may have a fishy odour. This can lead to rapid dehydration, characterised by sunken eyes, dry mouth, cold clammy skin, and wrinkled hands and feet. Other symptoms include vomiting and muscle cramps. Fever is rare and might indicate a secondary infection. Severe dehydration can result in lethargy, decreased blood pressure, rapid pulse, reduced urine output, and in children, altered consciousness or seizures due to electrolyte imbalances.

Cause and Transmission

Cholera is caused by the ingestion of Vibrio cholerae, often through contaminated water or food. Risk factors include poor sanitation, inadequate clean drinking water, and poverty. The bacterium can also be found in shellfish and plankton. Infected individuals excrete large quantities of the bacteria in their stool, contaminating water sources and thus perpetuating the cycle of infection.

Diagnosis

Cholera can be diagnosed using stool tests or rapid dipstick tests, though the latter is less accurate. In epidemic situations, clinical diagnosis based on patient history and examination may suffice. Laboratory confirmation is essential for identifying antibiotic resistance and managing outbreaks effectively.

Prevention

Effective prevention relies on improved sanitation, access to clean water, and public health education. Cholera vaccines, such as the oral vaccines Dukoral, Sanchol, and Euvichol, provide reasonable protection. The World Health Organisation (WHO) also recommends the use of surveillance systems to detect and contain outbreaks rapidly.

Treatment

The cornerstone of cholera treatment is prompt and adequate rehydration. Oral rehydration therapy (ORT) using slightly sweet and salty solutions is effective for most cases. In severe dehydration, intravenous fluids such as Ringer's lactate are necessary. Zinc supplementation is beneficial in children, reducing the severity and duration of symptoms. Antibiotics can shorten the disease course and reduce fluid requirements, with doxycycline commonly used first-line, although resistance is increasing.

Prognosis

With prompt and appropriate treatment, the mortality rate for cholera is less than 1%. However, untreated cholera can have a mortality rate as high as 50-60%. Rapid rehydration and electrolyte replacement are very important to improving outcomes.

Epidemiology

Cholera remains a significant global health challenge, particularly in developing countries with poor sanitation. The disease affects an estimated 3-5 million people annually, causing up to 130,000 deaths. Major recent outbreaks include the 2010 Haiti and the 2016–2022 Yemen cholera outbreaks. Effective public health measures and prompt treatment can significantly reduce the impact of cholera.

Historical Perspective

Cholera has a long history, with pandemics dating back to the early 19th century. The disease has been a driving force in the development of modern epidemiology, notably through John Snow's work in linking cholera to contaminated water sources. Despite advances in water treatment and sanitation, cholera remains endemic in many parts of the world, highlighting the ongoing need for vigilance and improved public health infrastructure.

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Self-assessment MCQs (single best answer)

What bacterium causes cholera?

Which of the following symptoms is the hallmark of cholera?

How is cholera primarily transmitted?

What is the main treatment for cholera?

What kind of solution is typically used in oral rehydration therapy for cholera?

Which of the following is NOT a common symptom of severe dehydration due to cholera?

Which antibiotic is commonly used as a first-line treatment for cholera, though resistance is increasing?

What is an effective preventive measure against cholera?

What is the estimated annual global incidence of cholera?

Who is notably credited with linking cholera to contaminated water sources, contributing to modern epidemiology?