Cholera

Overview

Definition of illness. Causes of the disease
Cholera is a severe infectious diarrheal illness that is very dangerous to humans. The bacterium vibrio cholerae causes it. Bacteria that enter the mouth impact the intestinal mucosa, affecting digestion. Without proper care, the condition can swiftly progress to dehydration, convulsions, and death. 
There are many varieties of vibrio cholerae, but only two serogroups, o1 and o139, can cause outbreaks of cholera. Each of them has its own biotypes:
•    Vibrio cholera ?1 classica — classical biotype;
•    Vibrio cholera o1 el tor - prevails 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 form, they resemble commas. Their size reaches 0.4-0.6 microns in width and 1.5-3 microns in length .
Bacteria are motile, do not form spores and capsules. When sowing the material, their bluish colonies resemble a flock of fish. They are facultative anaerobes, as they are able to obtain energy both in conditions of oxygen and without it. They grow well on alkaline nutrient media.
Vibrio 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 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;
•    Exotoxin cholerogen - 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 moisture and no sunlight, they live up to 150 days, in cesspools - over 100 days, in the soil - up to 60 days, on fruits and butter - up to 30 days. 



Symptoms

The incubation period of cholera lasts from several hours to five days. On average, it is 1-3 days.
The disease always begins acutely, suddenly. The main thing that you need to pay attention to is the normal body temperature and the absence of abdominal pain: at first, only diarrhea occurs (usually at night or in the morning), vomiting joins later.
Complaints of patients are almost always associated with dehydration, i.e. Loss and lack of fluid in the body. They are concerned about thirst, dry mouth, hoarseness, loss of appetite, nausea, vomiting (sometimes with a fountain), lethargy, weakness, weakness and copious watery stools. At the same time, there is no pain - only rumbling and discomfort in the navel. Tongue dry, coated with chalk colour. The skin and mucous membranes are pale, dry, the firmness and elasticity of the skin is reduced. The amount of urine excreted (oliguria) decreases, muscle cramps appear.
In appearance, vomiting resembles cloudy white water, there is no smell. The frequency of vomiting and the volume of vomit increase. The urges themselves are not accompanied by tension and nausea.
The stool is initially of a fecal nature, then it acquires a typical appearance of "rice water". It becomes translucent, hazy white with floating greyish flakes. There is no smell. The intervals between acts of defecation decrease, and the volume of discharge, on the contrary, increases, up to a liter at a time.
The patient's facial features sharpen as the illness worsens, the eyes droop, black circles form around them, the stare becomes unblinking, the skin turns ashy, and the lips, ears, and nose turn blue. Splashing and fluid transfusion can be heard when the abdomen is probed (palpated). The stomach is drawn inside on its own. The blood pressure is low, and the pulse is sluggish.
If the patient is not helped, then the disease passes into the terminal (last) stage: body temperature drops to 34-35 ° c, shortness of breath increases, breathing becomes pathological (unhealthy), due to tonic convulsions, a "fighter's posture" is observed, urine is not excreted , the volume of circulating blood sharply decreases, leading to hypovolemic shock, stupor occurs (deep depression of consciousness). The muscle strength of the stomach and intestines decreases: vomiting is replaced by hiccups, diarrhea stops, the so-called. "gaping anus" - when pressing on the stomach, the liquid freely flows out. Sopor is replaced by a coma, and then death occurs.

Cholera in pregnant women
The disease, as a rule, proceeds in a severe form, can lead to spontaneous abortion, especially in the third trimester.
Cholera in young children
Children under 3 years of age do not tolerate dehydration very well, therefore, with cholera, they quickly develop gross lesions of the nervous system - generalized convulsions, severe lethargy and coma. Against this background, body temperature often rises to 37.1-38.0 ° c or becomes even higher. This symptom can make it difficult to make a correct diagnosis.
If cholera treatment is carried out in a timely manner and in full, then the severe course of the disease and death, as a rule, can be prevented 
Cholera pathogenesis
The digestive system serves as the infection's entry point. Cholera vibrioes partially die when they are struck in the stomach. All germs can perish in a person whose stomach juice has a high acidity level, keeping him healthy. The infectious dosage for a person with a healthy immune system is at least 10 million microbial bodies. 
After overcoming the gastric barrier, the bacteria reach the small intestine. With the help of fimbriae (villi), they attach to the intestinal epithelium without penetrating into it, begin to actively multiply and secrete exotoxin. This toxin causes a massive release of water and electrolytes (sodium, potassium, chlorine) into the intestines, comparable to a flood. The large intestine does not have time to absorb all the liquid back, as a result, its tone is disturbed - profuse diarrhea with water with electrolytes and vomiting begin.
Due to the developing dehydration, the volume of circulating blood decreases, its consistency thickens. To compensate for the changes that have occurred, the fluid from the intercellular space moves into the vascular bed. This leads to hypovolemia (a further decrease in blood volume), circulatory disorders, dehydration shock, acute renal failure and acidosis (increased acidity). Muscle weakness increases, intestinal tone decreases, the work of the heart muscle is disrupted, and energy production decreases. The low temperature together with the accumulated lactic acid leads to convulsions. If the process is not stopped and the volumes of the lost fluid and electrolytes are not replenished, vascular collapse occurs (a sharp drop in blood pressure) and the failure of the internal organs, due to which the patient dies.
 



Prevention

Measures to prevent the occurrence and spread of cholera include:
•    Sanitary and epidemiological supervision of the state and operation of water supply facilities, the food industry and public catering facilities;

•    In the event of a focus of the disease - immediate isolation of the patient, identification of the source of infection, final disinfection, examination of people who have been in contact with the patient, and treatment of carriers of the disease.
According to epidemiological indications, if there is a threat of the spread of infection and infection of people, vaccination with a cholera vaccine is carried out , it is also possible to take antibiotics for prophylactic purposes. 



Treatment

The main tasks of therapy :
•    Restore the volume of circulating blood and the electrolyte composition of tissues to support the life of the patient;

•    Influence the pathogen in order to shorten the duration of the disease (antibiotic therapy).

Recovery of lost fluid
At the first stage, primary rehydration is mandatory - replenishment of lost water and salts. Next, compensatory rehydration is carried out - correction of the ongoing loss of water and electrolytes. Fluid must be replenished after each bowel movement. The total volume of incoming fluid should be 1.5 times the volume of fluid lost.
 
Antibacterial drugs
Against the background of ongoing rehydration therapy, etiotropic treatment is indicated - taking antibiotics of the tetracycline or fluoroquinolone group together with replacement drugs.
As means aimed at combating the causative agent of the disease, it is possible to prescribe potassium and sodium preparations. There has also been information about the benefits of zinc preparations, which significantly reduce the amount of excreted feces and reduce the duration of diarrhea.
With cholera , cardiac glycosides, the introduction of blood substitutes, colloidal solutions and the separate administration of glucose and 0.9% sodium chloride is unacceptable. Colloidal solutions will only aggravate the lack of fluid in the vessels and cause collapse, and glucose and sodium chloride, administered without saline solutions, will not make up for the loss of electrolytes, without which a simple infusion of water is meaningless.



Tests Required for Diagnosis

Clinical blood test - the number of erythrocytes and leukocytes increases, the number of neutrophils moderately increases, the level of monocytes decreases, ESR is normal or slightly above normal, hyperchromia is observed (intense staining of erythrocytes);

•    General urinalysis - protein and pathological cylinders are found in the test material;

•    Biochemical blood test - the level of potassium and chlorine decreases, the level of sodium rises as compensation;

•    Coprogram (fecal analysis) - there is a violation of digestion and absorption;

•    Bacteriological cultures of feces, vomit and water on various media (alkaline agar, 1% peptone water with potassium telurite, monsur, cary-blair media, etc.) - bacterial growth is observed after 18-48 hours, if suspected , the study is carried out three times ;

•    The reaction of indirect blood hemagglutination (RIHA) with cholera erythrocyte diagnosticum - allows you to detect blood serum antibodies, informative from the 5th day of illness, the presence of cholera indicates a diagnostic titer of 1:160 and above;

•    Polymerase chain reaction (PCR) of the material from the patient - detects the DNA of cholera vibrio. The study may also use water or products that are suspected to be a factor in the transmission of infection;

•    Rapid tests with monoclonal antibodies - allow you to identify the causative agent of the disease within 5 minutes.


Differential diagnosis
Cholera should be differentiated from the following diseases:
•    Other acute intestinal infections ( dysentery , typhoid fever , salmonellosis , rotavirus infection ) - characterized by fever, chills, abdominal pain, different color and consistency of stools, unpleasant odor of stools and painful defecation (not always), dehydration rarely develops;

•    Substance poisoning - there is a connection with the use of a specific chemical, there are no signs of dehydration, mental and consciousness disorders are often observed, the volume of saliva secreted increases or decreases, an acute disruption of the organs occurs;

•    Botulism - there is a connection with the use of canned foods, especially home-made products, there are no signs of dehydration, vision and breathing are disturbed.



Useful info

Classification and stages of development of cholera
According to the type of clinical picture:
1.    Typical (gastrointestinal).

2.    Atypical (may occur against the background of pregnancy, immunodeficiency, alcoholism , prophylactic antibiotics, cholera vaccination, dystrophy and other conditions):

•    Fulminant - characterized by a rapid, stormy onset with very frequent defecation and vomiting, dehydration shock occurs in the first 3 hours from the onset of the disease;

•    "Dry" - a stormy onset is characteristic, before the development of diarrhea, pronounced toxicosis and coma occurs;

•    Eliminated - starts gradually, the frequency of defecation reaches 1-3 times per day, the stool is mushy, and minor weakness ensues; the diagnosis is only proven in the laboratory, and in the event of an epidemic - on the basis of the medical history (anamnesis);

•    Asymptomatic - there are no signs of cholera, diagnosis is possible only after a laboratory examination;

•    Vibrio carrier - can be convalescent (in convalescents), transient (in healthy people in the focus of infection, when the body successfully copes with the infection in the early stages of the disease; lasts less than three months) and chronic (when the pathogen is present in the body for more than three months).
By severity (degree of dehydration):
•    Mild - there is an accumulation of toxins, weakness and lethargy are minimal, vomiting and diarrhea occur up to 5 times a day and last up to 3 days, there is no visible dehydration (fluid loss) and complications, the duration of the disease is not more than 5 days;

•    Moderate - moderate intoxication is observed, diarrhea and vomiting occur up to 15 times a day and persist for at least 3 days, dehydration of 1-2 degrees, complications are possible, the duration of the disease is at least 5-7 days;
•    Severe (develops on average in 10% of all patients) - intoxication becomes pronounced, diarrhea and vomiting occur up to 20 times a day and persist for more than 3 days, dehydration of 2-3 degrees, complications develop, the duration of the disease is more than a week;

•    Extremely severe - characterized by a sudden onset, indomitable vomiting and diarrhea during the first 12 hours from the onset of symptoms lead to dehydration shock.
Complications of cholera
•    Acute renal failure - weakness increases, the amount of urine discharge decreases until anuria (its complete absence), tachycardia , arterial hypotension , nausea occurs;

•    Cardiovascular insufficiency ( cardiomyopathy ) - the heart rhythm is disturbed, blood pressure decreases, cough appears, weakness increases;

•    Cholera algid (a complex of symptoms that develops with 4 degrees of dehydration) - facial features sharpen, blood pressure drops sharply, body temperature drops below 34.5 ° c, the skin becomes earthy-cyanotic, cold and sticky, easily gathers into folds that do not straighten out , prolonged convulsions occur, impaired consciousness smoothly turns into shock and, without assistance, into death;

•    Secondary bacterial complications (sepsis, pneumonia , abscess, etc.).



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