Vomiting and diarrhea - how to deal with cholera?

Author: Ge Ziruo, attending physician at Beijing Ditan Hospital, Capital Medical University

Reviewer: Chen Zhihai, Chief Physician, Beijing Ditan Hospital, Capital Medical University

Cholera is an intestinal infectious disease caused by infection with Vibrio cholerae of group O1 or O139. It is a Class A infectious disease in my country. Clinically, it mainly manifests as acute onset, vomiting and diarrhea. Severe patients may suffer from dehydration, muscle cramps or acute renal insufficiency. More serious patients may die from shock, uremia or acidosis.

1. What kind of bacteria is Vibrio cholerae?

Vibrio cholerae is a very large group, belonging to the Vibrio family and Vibrio genus. Based on the bacterial antigen O, Vibrio cholerae can be divided into more than 200 species. Among these more than 200 species of Vibrio cholerae, most of them are actually not very harmful to the human body. Traditionally, only the O1 group can really cause diarrhea in humans and lead to cholera.

Figure 1 Original copyright image, no permission to reprint

We used to call all bacteria groups other than O1 group non-O1 group, and O1 group Vibrio cholerae has caused great harm in human history. Historically, 200 years ago, cholera was actually an endemic disease in the Ganges Delta region of India. It did not have much impact on the world, such as China, America, and Africa.

However, in the past two hundred years, due to trade, pilgrimage, war, and the increasing movement and communication of people, cholera spread from India to the rest of the world, such as Asia, Africa, America, and even Oceania. During this process of spread, there were about seven major cholera pandemics.

The first six cholera outbreaks were caused by the classical biotype of Vibrio cholerae in the O1 group. Monitoring has found that in the past fifty or sixty years, the traditional classical biotype of bacteria in the O1 group has become rare. The main type currently prevalent is called the El Tor type, and some people also call this cholera paracholera. The seventh cholera pandemic was caused by the El Tor type of Vibrio cholerae in the O1 group.

In 1992, cholera broke out in India again. The results of the test showed that the pathogen was a non-O1 Vibrio cholerae. After identification, it was an O139 Vibrio cholerae. Since then, we have said that the Vibrio cholerae that can cause cholera include O1 and O139. So among the more than 200 types of Vibrio cholerae, only O1 and O139 can produce cholera toxins and cause cholera.

2. Why does Vibrio cholerae cause nausea and vomiting?

Vibrio cholerae enters the gastrointestinal tract through food and has no pathogenic effect itself. After entering the stomach, most of the Vibrio cholerae are inactivated by gastric acid, and a small number of those that are not killed enter the duodenum through the pylorus. These Vibrio cholerae multiply in large numbers in the duodenum, jejunum and other parts of the small intestine, and produce a cholera enterotoxin. This toxin enters the intestinal mucosal epithelial cells, thereby activating the intestinal fluid secretion system of the intestinal mucosal epithelial cells. A large amount of fluid is secreted into the intestinal cavity, including electrolytes such as potassium, sodium, chloride, and bicarbonate. The toxin also inhibits the absorption of fluid, causing vomiting and diarrhea. Since Vibrio cholerae itself has no pathogenic effect, cholera patients generally do not have fever, and do not have systemic discomfort symptoms such as respiratory system, cardiovascular system, and joints.

The first symptom of cholera is diarrhea, followed by vomiting. In severe cases, vomiting and diarrhea are very severe, and if not treated in time, dehydration may occur. In the case of acute dehydration, dry skin and loss of elasticity, or sunken eyes and decreased urine output may occur. More severe cases may experience low blood pressure or even acute renal failure.

Figure 2 Original copyright image, no permission to reprint

Therefore, during the entire cholera process, the main symptoms of mild patients are vomiting and diarrhea, and further development will lead to a series of manifestations caused by dehydration.

3. How to treat cholera?

The treatment of cholera is actually very simple, because Vibrio cholerae itself is not very pathogenic. The main problem is the diarrhea caused by cholera enterotoxin, and the dehydration caused by the loss of a large amount of fluid and electrolytes, which leads to a series of subsequent symptoms. Therefore, fluid rehydration is the main treatment method. As long as the problem of dehydration is solved, the patient will basically not have major problems. The treatment is mainly based on the patient's degree of dehydration, and fluid rehydration is performed by calculating the amount of fluid lost by vomiting and diarrhea.

For patients with milder symptoms, oral fluid rehydration can be used directly. For example, there is a formula called oral rehydration salts, which contain sodium, potassium, chloride, bicarbonate, and some glucose to promote intestinal absorption. If there are enough oral rehydration salts and enough fluid is replenished, the disease is unlikely to progress further.

Some patients have severe vomiting and diarrhea, and their condition is serious. Oral rehydration cannot solve the problem, so intravenous rehydration can be used. The amount of rehydration is calculated according to the degree and amount of dehydration of the patient, and sufficient fluid, potassium, sodium, chloride, sodium bicarbonate and glucose are given. Correcting dehydration through intravenous rehydration can also achieve good treatment results for patients.

Although Vibrio cholerae itself does not cause much harm, when it multiplies in large numbers in the intestines, it will produce more enterotoxins, so antibacterial treatment is also necessary.

Antibacterial drugs, tetracycline antibiotics are currently used, among which doxycycline is more commonly used. In addition, quinolone drugs are also more effective, and levofloxacin and other drugs are more commonly used in clinical practice. Antibacterial drugs can reduce the amount of bacteria excreted, shorten the course of the disease, alleviate symptoms, and also reduce infectiousness.

Generally speaking, the first treatment for cholera is fluid therapy, and the second is antibacterial therapy. These two aspects are the basic treatment. If the patient develops severe conditions such as acute renal failure and shock, further targeted treatment measures are needed.