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2023 Author: Alfred Shackley | [email protected]. Last modified: 2023-05-21 13:14
Cholera until the middle of the last century was considered one of the most dangerous diseases. The mortality rate from it reached 80-90%. And this is despite the fact that at the end of the 19th century, Robert Koch discovered its causative agent - Vibrio cholerae.
Even today, it is important to know how the causative agent of cholera develops in the human body and what symptoms accompany the pathology.
Symptoms of cholera appear after 24 hours - 5 days after the pathogen enters the body, this is how long the incubation period lasts. In most cases, the symptoms are nonspecific, as they are characteristic of almost any other intestinal infection. The most important symptom is diarrhea. Clinically, it is difficult to distinguish it from other causes. But with cholera, the stool is watery with a tendency to increase.
There are 3 degrees of severity of the disease:
- Mild severity. Symptoms are rare - loose stools and vomiting. The latter can generally be single. The loss of fluid during diarrhea does not exceed 1-3%, so the patient is practically not disturbed by thirst, dry mouth. In addition, due to the relatively short period of illness (2-3 days) of a person, the sick rarely seeks medical help. In this case, bacterial excretion continues for several more days;
- Moderate course. It is one of the most typical cholera species. Vomiting for the first 1-2 days can exceed 5 times, and diarrhea reaches 20-25 times per day. Moreover, it lasts more than 5-7 days. Such significant diarrhea leads to dehydration by the end of the first day. The person experiences dry mouth, intense thirst. On days 2-3, signs such as muscle twitching appear. There may even be leg cramps;
- Severe cholera. It develops in a matter of days. Vomiting is strong during the first 12-24 hours and exceeds 10 times a day. And diarrhea does not stop during the entire period of the disease and exceeds 20-25 times per day. Dehydration occurs within a few hours after the onset of the disease. The patient, due to developing dehydration, quickly develops tachycardia (increased heart rate), tachypnea (rapid breathing). Blood pressure decreases by the end of the first day. And the latter may develop shock (the so-called hypovolemic shock). The depression of consciousness begins in just 20-25 hours. Together with hypovolemic shock, it quickly leads to internal disorganization and death.
A symptom typical of other infections, such as fever, is optional in cholera. The fact is that the causative agent of the disease lives only in the intestinal lumen, the toxins act locally and there is practically no resorption (in this case it means "absorption from the intestine").
Cholera is caused by a gram-negative aerobic bacterium from the genus Vibrio, a family of the same name. Morphologically, it is a rod of about 1.5 microns with a curved end in the form of a comma. It has one flagellum that allows bacteria to move.
There are about 130-140 serovars of this type. But the greatest interest for science (due to their greater distribution and frequency of occurrence in patients) is the Asian subspecies and subspecies El Tor (after the name of the quarantine station in Egypt, where it was first isolated). The first causes the so-called classic cholera. The second is a more erased version of the disease.
Cholera caused by the subspecies El Tor, of course, has a more favorable course. It is less likely to cause complications and less likely to result in death. But due to the fact that the subspecies often causes asymptomatic carriage, it has no less epidemiological significance. Maybe more than the classic Asian subspecies.
Bacteria thrive in the plankton of fresh and salt waters. A humid hot climate is ideal for him. Therefore, the Ganges delta is considered the primary focus of cholera. Here, mainly until the beginning of the 19th century, was the main source of cholera. The disease spread worldwide after 1816. Then it spread widely beyond India, to Europe, Russia, Africa. In the middle of the same century, the Americans faced him.
The main route of transmission of the pathogen is fecal-oral. Therefore, the disease has become widespread. Until the first half of the 19th century, there was no thought of separating wastewater. In addition, remembering the plague that took place some 500 years ago, the spread of diseases was associated with the so-called "miasms" (invisible substances that spread through the air in dark places). Doctors of that time saw the salvation from the epidemic in quarantine measures, but did not attach importance to disinfection.
Only by the end of the first half of the 19th century, they began to carry out not only quarantine, but disinfectant measures. The water supply systems of populated cities have been improved. But vibrio managed to spread throughout the world.
With the advent of the era of antibiotics, the development of medicine, the disease has ceased to be so fatal. But even now, outbreaks of mass infection are occasionally observed in third world countries (including in the homeland of the disease - India). They lead to the deaths of more than one tens of thousands of adults and children.
Sometimes there are such ways of transmission of vibrio, as through molluscs, for example, when eating oysters.
Three factors are important contributors to the spread of cholera:
- heat and moisture;
- lack of communications;
- crowded population.
Sometimes another ("fourth") lack of medical care is considered. All this is characteristic of backward and developing countries. But it may well be in case of catastrophes of a national and interregional scale.
A sick person of any severity should be hospitalized in a medical institution of the appropriate profile, since this disease is especially dangerous.
Treatment of the disease is carried out in 2 stages:
- correction of water-salt imbalance.
Rehydration - restoring water balance. But in relation to this disease, this term means fluid replenishment, equal in volume to the body's water losses. Rehydration should be started during the prehospital phase of treatment.
For this, any isotonic (in their osmotic properties close to blood plasma) crystalloid solutions are suitable.
For example, 0.9% NaCl solution, 5% glucose, sterofundin, chlorosalt, trisol. The last three are considered the most optimal, as they contain a set of several electrolytes. Accordingly, the second stage is facilitated.
The second stage is also carried out by infusion of solutions. But here, in addition to crystalloid solutions, various protein and carbohydrate-containing drugs can be added: polyglucin, albumin, etc.
Etiotropic treatment (directed against the cause of the disease) is carried out simultaneously with the second stage. In the first place are tetracycline antibiotics. Of these, tetracycline is currently optimal.
It is allowed, especially at the prehospital stage of treatment, a single dose of doxycycline. However, the above drugs are contraindicated in children under 8 years of age. In addition, an allergy to them is possible. Fluoroquinolones (ciprofloxacin) and macrolides (erythromycin) can be used as analogs.
Disease prevention is closely related to anti-epidemic measures, personal hygiene. The latter are the prerogative of the person himself, while anti-epidemic measures are organized at the level of authorities at all levels.
- the correct organization of the central water supply system (here we mean not only correct communications from an engineering point of view, but also measures for water disinfection);
- vaccine prophylaxis;
- timely detection and treatment of sick adults and children;
- preventive treatment of contact;
- isolation of the outbreak and prevention of its spread;
- quarantine for everyone in the outbreak.
Personal protective measures:
- compliance with the rules of personal hygiene, which should be taught to the child;
- swimming only in reservoirs "clean" from infection;
- drinking clean water.
Vaccine prophylaxis should be mentioned separately.
The vaccine is used only for emergency prophylaxis, as it gives a fairly reliable (85-100%), but short-lived (no more than 3-4 months) positive effect. Therefore, it can be used only in contact, healthy and non-bacterial carriers in the outbreak of cholera.