Content

Introduction

Cholera is an "acute infection of the intestine" which comes on suddenly with disorders (symptoms) such as watery diarrhea, vomiting and rapid dehydration.

It is caused by bacteria, said vibrions, belonging to the species Vibrio cholerae, of which there are various types (serogroups). Some produce a potent toxin (cholera toxin) that causes the disturbances (symptoms) of the disease. In particular, the serogroups O1 and O139 of V. cholerae are associated with cholera outbreaks.

The transmission of the disease occurs by contact between the faeces and the mouth (fecal-oral contact), both directly (for example, through poor hygiene of the hands that are brought to the mouth), and through contaminated water or food from the feces.

It can cause death from severe dehydration, especially in children or the elderly, however, with appropriate treatment, mortality is contained below 1%.

During the nineteenth century, cholera from its native area around the Ganges delta (Indian subcontinent) spread to the rest of the world and caused six pandemics that killed millions of people. Today the disease is considered to be constantly present (endemic) in many countries in Africa, Asia and the Americas.

Despite the worldwide spread of cholera, few cases are found every year in Europe, all among people returning from countries where the disease is present. Furthermore, the risk of spread in Europe is negligible thanks to the high hygiene and sanitary standards and the availability of "adequate health care."

Symptoms

In a person who becomes infected, cholera, after a short incubation which can range from a few hours to 4-5 days, suddenly manifests itself with diarrhea, often intense, which can cause rapid and dangerous loss of fluids (dehydration).

Diarrhea is characterized by liquid, pale and milky-looking stools that resemble the water in which rice has been rinsed (“rice water” stools).

Dehydration can be aggravated if the affected person also has vomiting and loss of appetite in addition to diarrhea. Dehydration causes disorders such as irritability, lethargy, sunken eyes, dry mouth, kidney failure, low blood pressure, irregular heartbeat (arrhythmia), muscle cramps and in severe cases hypovolemic shock (caused by the acute decrease in circulating blood volume due to fluid loss) which can be fatal. Cholera is always serious when it affects children, because their water and electrolyte balance is very delicate.

In most cases, however, the complaints (symptoms) are mild or even absent. Some infected people can become healthy carriers, that is, they do not have any disorders but eliminate the cholera vibes with their feces for weeks or months.

Causes

Cholera is an acute infectious disease caused by the bacterium Vibrio cholerae.

The bacterium is mainly present in water, and can contaminate foods, such as shellfish and fishery products, which if eaten raw or undercooked can transmit the infection.

The bacterium, once ingested, arrives in the intestine (colonizes it) and releases a toxin (the cholera toxin). The toxin in the cells of the intestine interferes with the normal flow of sodium and chlorine and causes a rapid loss of fluids and electrolytes, which collect in the intestine and cause diarrhea.

Diagnosis

If a person returning from countries where cholera is always present (endemic) has intense and watery diarrhea, he must consult the doctor who can prescribe specific tests for the search for the cholera bacterium and other microorganisms. In fact, cholera must be distinguished from infections that cause similar ailments caused by other bacteria, parasites or viruses.

Cholera is confirmed only if the bacterium is isolated Vibrio cholerae in faeces or rectal swabs (which can obtain a small amount of faecal material). Subsequent microbiological tests allow the identification of serogroups O1 or O139. Recently, specialized laboratories also carry out rapid molecular tests that identify the bacterium and the serogroup.

Therapy

Cholera therapy is very simple and is based on the use of aqueous solutions rich in sugars and electrolytes, to be taken by mouth (orally) to rehydrate the patient. In severe cases, fluids are administered intravenously to rehydrate faster. the patient.

With "adequate rehydration, mortality in severe patients is reduced to 1%, while those with mild disease often recover spontaneously after rehydration.

The World Health Organization (WHO) recommends the use of antibiotics only for those who are severely dehydrated or in the elderly, and it is the doctor who assesses the situation and prescribes them.

Prevention

The prevention of cholera epidemics is directly related to the improvement of hygiene, the availability of drinking water and vaccination.

In countries where cholera is always present (endemic), compliance with hygienic precautions such as washing hands with soap before starting to cook or eat, drink only bottled water, avoid the use of ice in soft drinks, do not consume fruit and vegetables if not cooked or washed thoroughly with water and chlorine-based disinfectants help reduce the spread of the infection. The vibrations of cholera are, in fact, extremely sensitive to the action of common detergents and disinfectants.

The World Health Organization recommends that travelers and workers traveling to countries where cholera is endemic to be vaccinated. Currently, the vaccines used are:

  • vaccine containing killed (inactivated) bacteria of serogroup 01, along with a portion of the cholera toxin called the "B subunit" which has no toxic activity
  • vaccine containing killed bacteria of the two epidemic serogroups 01 and 0139

Although vaccination against cholera is not considered very effective because 30 to 80% of vaccinated people are immune (depending on age and type of vaccine used), and immunity is very short (3-6 months in children and 2-3 years in adults), however it reduces the risk of getting sick, especially if the proportion of vaccinated people in the population is high. This phenomenon is called herd immunity. Vaccination, in areas where cholera is always present, by reducing the number of infected people has also reduced the presence of V. cholerae in the environment and, consequently, the risk of contagion.

Bibliography

National Institutes of Health (NIH). Cholera Treatment and Prevention (English)

Mayo Clinic. Cholera (English)

In-depth link

EpiCentro (ISS). Cholera

NHS. Cholera (English)

European Center for Disease Prevention and Control (ECDC). Cholera (English)

World Organization de la Santé (WHO). Cholera (English)

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