Cholera - symptoms and treatment
Cholera is an acute infectious diarrheal disease that poses a particular danger to people. It is caused by the bacteria Vibrio cholerae. Penetrating through the mouth, bacteria affect the intestinal mucosa, disrupting the functioning of the digestive tract. In the absence of adequate treatment, the disease can quickly lead to dehydration, seizures and death [8].
Etiology
Taxonomy of the causative agent of cholera:
- domain - bacteria;
- type - proteobacteria;
- class - gamma bacteria;
- order - Vibrionales;
- family - Vibrionaceae;
- genus - Vibrio (vibrios);
- species - Vibrio cholerae (Vibrio cholerae).
There are many varieties of Vibrio cholerae, but only two serogroups - O1 and O139 - are capable of causing cholera outbreaks. Each of them has its own biotypes:
- Vibrio cholera O1 classica - classic biotype;
- Vibrio cholera O1 El Tor - predominates at present;
- Vibrio cholera O139 Bengal - known since 1992, has caused a major cholera epidemic in Bangladesh, India and other neighboring countries.
The causative agents of cholera are short, curved gram-negative bacteria. In their shape they resemble commas. Their size reaches 0.4-0.6 microns in width and 1.5-3 microns in length.
The bacteria are mobile and do not form spores or capsules. When sowing material, their bluish colonies resemble a school of fish. They are facultative anaerobes, as they are able to obtain energy both in conditions of oxygen and without it. They grow well in alkaline nutrient media.
Vibrios cholerae have a species-specific antigen A and a type-specific antigen O. They contain the genetic information of bacteria and cause an immune response in the body.
The pathogenicity factors of Vibrio cholerae include:
- flagella - make bacteria motile;
- mucinase enzyme - thins the intestinal mucous barrier, facilitating access to the surface of its epithelium;
- neuraminidase enzyme - promotes the production of toxins.
The causative agent of cholera produces two types of toxins :
- endotoxin lipopolysaccharide - does not play a significant role in the development of cholera disease, but can potentially provoke an immune response;
- Cholerogen exotoxin - has a toxic effect only on the intestinal mucosa, causing a massive release of electrolytes and fluid from its cells, leading to diarrhea and dehydration.
Bacteria are very sensitive to acids and alcohol. In feces with sufficient humidity and lack of sunlight they live up to 150 days, in cesspools - over 100 days, in soil - up to 60 days, on fruits and butter - up to 30 days. They survive quite well in low temperatures and freezing conditions. When boiled they die instantly, at a temperature of 56 °C - in 30 minutes. Most antibiotics (mainly tetracyclines and fluoroquinolones) contribute to their destruction [1][2][5][6].
Epidemiology
The source of infection is only humans (patient and carrier). It is most contagious in the first week of illness.
The main foci of cholera are in Africa, Southeast Asia and Haiti, but small outbreaks and isolated cases of the disease are reported throughout the world. The average annual number of cases of the disease is about 5 million people, deaths are about 130 thousand [11].
The transmission mechanism is fecal-oral (water, food and household contact). The main mode of transmission is water. The second most important route is the food route: through meat, seafood, milk, vegetables and fruits that have not undergone adequate heat treatment.
A person, being in the same room with other people, cannot directly infect them. Only the patient’s secretions (feces and vomit) are dangerous if they enter the mouth of a healthy person.
The group at increased risk of developing the disease includes people with blood group O, chronic diseases of the gastrointestinal tract and other organs, the absence or reduced amount of hydrochloric acid in the stomach (achlorhydria or hypochlorhydria).
Cholera spreads much more easily than other acute intestinal infections: it sooner leads to massive release of the cholera pathogen in feces and vomit, which do not have an unpleasant odor or color.
Once in bodies of water (including coastal waters), cholera vibrios can persist for a long time and even multiply. This is facilitated by warm, stagnant, slightly brackish water. Also, reproduction and concentration of the pathogen is possible in zooplankton. In general, cholera is a problem in regions where there is no adequate disinfection and purification of drinking water and hygiene rules are not observed.
Susceptibility to the disease is high. Seasonality is usually summer-autumn. In cities, the incidence is higher than in rural areas. Men get sick more often.
The immunity is strong, but it does not protect the body from infection with other types of Vibrio cholerae. Mortality in the modern world is 1-3% [1][3][5][8].
When to see a doctor?
The risk of a cholera outbreak in industrialized countries is low. Even in regions where it exists, the likelihood of infection is minimal if food safety recommendations are followed. However, cases of cholera occur throughout the world.
Therefore, if a person develops severe diarrhea after visiting an area with recent cases of cholera, it is time to seek immediate medical attention².
Features of cholera in children
At the age of under 3 years, the dehydration characteristic of cholera is much more severe. Because of this, children quickly develop signs of dysfunction of the nervous system in the form of severe general lethargy, convulsions and even loss of consciousness. Moreover, unlike adults, the body temperature of children with cholera often rises to 37.5-38.0°C.
Therapeutic measures
Treatment of cholera, like other quarantine infectious diseases, is carried out exclusively in an infectious diseases hospital with strict adherence to the anti-epidemic regime (staff works in special clothing, the patient’s utensils and biological media are disinfected).
The primary therapeutic measure is the treatment of dehydration, for which the patient is soldered with saline solutions, saline solutions are administered intravenously, etc. The sooner you start rehydration, the more favorable the outcome of the disease, infectious disease doctors say.
An important role is played by cleansing the body of cholera bacteria toxins: the intestinal sorbent Enterosgel is successfully used for this. To destroy the pathogen, the doctor prescribes antibiotics.
The patient is discharged from the department only when he stops secreting vibrios - in order to determine this, a special bacterial study is carried out three times. People working in the food industry are examined five times at intervals of 24 hours, and are discharged if the bacteriological results are negative.
If treated in a timely manner, cholera can be successfully treated - which is why you should not self-medicate! At the first signs of illness, you need to take Enterosgel and seek medical help!
Causes of the disease
The causative agent of the disease is a motile, comma-shaped bacterium (vibrio). This microbe has two varieties - Vibrio classic and Vibrio El Tor. By the way, the bacterium was isolated by Koch in 1883, which is why it received the unofficial name “Koch’s comma.” (Not to be confused with Koch's bacillus, the tuberculosis bacterium!)
The cholera pathogen will release toxins that cause dehydration.
How does infection occur?
Interestingly, the cholera bacterium thrives in sewers and natural bodies of water. If wastewater enters the city water supply, outbreaks of disease occur, in other words, there is a waterborne route of transmission.
Infection occurs by drinking contaminated water, swallowing river or sea water while swimming, or eating shellfish or salted fish contaminated with vibrios.
In addition, the infection is transmitted through dirty hands and carried by flies.
Cholera is an anthroponotic infectious disease. This means that the source of the disease is usually a person with cholera or a carrier of this bacterium.
Complications
Without proper treatment, cholera can quickly become fatal. In the most severe cases, loss of large amounts of fluid and electrolytes can cause death within hours. In other cases, people who do not receive the necessary care may die from dehydration and dehydration shock 1-2 days after the first symptoms of cholera² appear.
Although severe dehydration is considered the most dangerous complication of cholera, other problems can occur with this pathology:
- Low blood sugar (hypoglycemia). Low levels of sugar (glucose) in the blood - the main source of energy for the body - are characteristic of severe forms of cholera. Hypoglycemia can be accompanied by convulsions, loss of consciousness and lead to death. Children are most susceptible to low glucose levels due to cholera.
- Low potassium levels (hypokalemia). Patients with cholera, due to diarrhea, lose a large amount of electrolytes, including potassium, as a result of which the functioning of the heart and nervous system is disrupted, which poses a threat to the patient’s life.
- Kidney failure. When the kidneys lose their filtering ability, excess fluid, some electrolytes and metabolic products accumulate in the body, which is also life-threatening.
- Secondary infection. Against the background of cholera, the body becomes more susceptible to other bacteria. This can lead to complications such as pneumonia, abscesses, and sepsis.
Classification
Several classifications of cholera are used in clinical practice. This is due to differences in the symptoms of the disease and treatment approaches in different cases. Also, some forms of the disease may have a course uncharacteristic of classical cholera.
Depending on the developing symptoms, cholera is divided into the following forms:
- Typical or gastrointestinal. The classic form of cholera, accompanied by gastrointestinal disorders.
- Atypical. It includes several subspecies that differ significantly from the typical variant of the disease. Atypical forms of cholera include:
- Lightning fast. It is characterized by extremely rapid development with pronounced vomiting and diarrhea, due to which severe dehydration quickly develops, and dehydration shock occurs within 3-4 hours.
- Dry. It is characterized by a sharp deterioration in the general condition of a person. Even before the onset of diarrhea, a coma may develop.
- Erased. It has relatively mild symptoms: the frequency of bowel movements per day ranges from 1 to 3 times, and the stool is not modified. The general condition is often satisfactory; the diagnosis is established only at the stage of laboratory tests.
- Asymptomatic. A variant of infection that occurs without any clinical manifestations. It is detected only after laboratory diagnostics.
It is customary to distinguish vibration carriers separately. This is a condition in which an infected person releases Vibrio cholerae into the environment, but does not show signs of illness. He may have the following options:
- Convalescent. It is observed in people who are recovering from cholera.
- Transitional. Characteristic for people who are in the center of a cholera outbreak. They become infected, but their body successfully fights off the infection. As a rule, it lasts no more than 3 months.
- Chronic. A condition in which cholera vibrios remain active in the body and a person continues to release them into the environment for more than 3 months.
Depending on the patient’s condition, the severity of damage to the gastrointestinal tract and the degree of dehydration, the following degrees of severity of cholera are distinguished:
- Easy. It is characterized by the accumulation of Vibrio cholerae toxins in the body. Defecation is repeated 3-5 times a day, general health remains satisfactory. There are minor feelings of weakness, thirst, dry mouth. The illness lasts 1-2 days.
- Average. Intoxication of the body is moderate. In this case, diarrhea is accompanied by vomiting, which is not accompanied by nausea. There is intense thirst and other signs of dehydration. Stool up to 15 times a day, copious. Single muscle cramps may be observed. The duration of the disease is 4–5 days.
- Heavy. Pronounced consequences of severe intoxication of the body. There are pronounced signs of dehydration due to copious (up to 1–1.5 liters per bowel movement) stool with a frequency of up to 35 times a day. Repeated vomiting in a fountain. Painful muscle cramps in the limbs and abdomen. The skin of the hands and feet becomes wrinkled (“washerwoman’s hand”). The face takes on a characteristic appearance: sharpened features, sunken eyes, cyanosis of the lips, ears, earlobes, nose.
“Washerwoman’s hands” is a characteristic symptom of cholera. Photo: PHIL CDC
