Overview of Cholera
Cholera is a virulent intestinal infection caused by ingestion of food or water contaminated with Vibrio cholerae. It manifests as watery diarrhea, which can lead to dehydration within a short period of time, and in severe cases, to circulatory failure and death. Vibrio cholerae infects the human body through contaminated water or food and produces enterotoxins, which cause the disease to develop, which requires mandatory isolation and rehydration, antimicrobial and other treatments
Definition
Cholera is an intestinal infectious disease caused by ingesting food or water contaminated with Vibrio cholerae. It is classified as Class A infectious disease in China.
Incidence
Cholera has been endemic for more than two centuries. Since 1817, there have been seven worldwide pandemics of cholera.
Cholera was introduced into China in 1820. From 1924 to 1948, cholera occurred almost every year in China, and in some years, the number of reported patients reached tens of thousands to more than one hundred thousand, and the death rate often exceeded 30%.
At present, cholera has been effectively controlled in China, and the patients are mainly light.In 2020, a total of 11 cases of cholera patients were reported in China’s mainland, and there were no fatal cases. The peak of cholera epidemic in the north temperate zone is from July to November, with high incidence in coastal areas.
Causes
Causes
The cause of cholera is Vibrio cholerae infection.
Sources of infection
The main sources of infection are patients and Vibrio cholerae infected people.
The onset of illness in patients can usually last up to 5 consecutive days, or more than 2 weeks.
Vibrio cholerae may be present in large numbers in the vomit and diarrhea of patients.
Patients with mild symptoms and those with hidden infection are often difficult to diagnose and cannot be isolated and treated in time, which is more likely to cause the spread of the disease.
Transmission pathway
Water and food contaminated with Vibrio cholerae can cause cholera outbreaks.
It can be spread by flies or daily contact.
Vibrio cholerae can spread through contaminated fish, shrimp and other aquatic products.
Susceptible Population
The population is generally susceptible to Vibrio cholerae, and there are more people with hidden infection.
After the disease can obtain a certain immunity, can produce antibacterial antibodies and anti-enterotoxin antibodies, but the immunity does not last after infection, there are reports of re-infection.
Predisposing factors
Poor sanitation: Cholera outbreaks are more likely to occur when drinking water hygiene cannot be guaranteed. It is more common in refugee camps, war-torn areas, and poor countries.
Too little or lack of stomach acid: Vibrio cholerae should not survive in an acidic environment, so stomach acid is a barrier for the human body. Children, the elderly, people taking antacids, and people with low levels of stomach acid after major gastrectomy or after eating a lot of water are not conducive to resisting Vibrio cholerae, and are more susceptible to the disease.
Poor immunity: children and the elderly with imperfect or low immune function are more likely to get sick when infected with Vibrio cholerae.
Symptoms
Early symptoms
The incubation period may be as short as a few hours or as long as 7 days, with an average of 1 to 3 days.
A few may have prodromal symptoms such as abdominal distension and mild diarrhea, and most start suddenly.
Symptoms are more severe in those caused by classical organisms and Vibrio cholerae type O139; Elto organism infections are often mild, and stealth infections are more common.
Main symptoms
Typical cases are divided into the following three phases according to the course of the disease:
diarrhea and vomiting
Diarrhea
Diarrhea is the first symptom after the onset of the disease, usually without fever, no acute and severe sensation, most of them are not accompanied by pain, and feel light after defecation.
The character of stools is dilute at the beginning, and then watery stools. Yellow watery or clear watery stools are common, and a few are rice slop or flesh-washing (bloody).
The amount of feces increases, and the frequency of bowel movements increases, up to dozens of times a day, or even defecation incontinence.
Vomiting
Generally, diarrhea is followed by vomiting, which is mostly in the form of jet, rarely with nausea.
Vomiting starts with food in the stomach, then watery, and in severe cases, “rice slop-like” liquid.
In mild cases, there may be no vomiting.
Dehydration
Frequent diarrhea and vomiting can lead to dehydration, electrolyte disorders and metabolic acidosis, and in severe cases, circulatory failure and acute renal failure. The dehydration period usually lasts for 2 to 3 days, and the duration of the disease depends mainly on whether the treatment is timely and correct.
Dehydration
Mild dehydration can be seen in slightly dry skin, mucous membrane, skin elasticity is slightly poor.
Moderate dehydration can be seen as poor skin elasticity, sunken eye sockets, mild hoarseness, decreased blood pressure, and decreased urine output.
Severe dehydration can be seen as dry skin, inelasticity, hoarse voice, and extreme weakness with sunken eyes, deeply concave cheeks, and confusion. Patients may develop renal dysfunction such as oliguria and anuria.
Muscle spasms
Vomiting leads to large amounts of sodium loss, and hyponatremia leads to spasms of the gastrocnemius and rectus abdominis muscles, which are spasmodic and painful, and the muscles are toned.
Hypokalemia
Frequent diarrhea leads to a large loss of potassium, which can cause decreased muscle tone, loss of tendon reflexes, decreased bowel sounds, and even cardiac arrhythmia.
Recovery period
Most patients gradually return to normal after diarrhea stops and dehydration is corrected. The average duration of the disease is 3-7 days, and a few of them can be as long as 10 days or more (mostly elderly patients or those with serious comorbidities).
In a few patients, due to the improvement of blood circulation, the endotoxin remaining in the intestinal cavity is absorbed into the blood stream, which may cause fever, usually with a temperature as high as 38~39℃, which will subside after 1~3 days. It is more common in children.
A small number of patients with severe shock can be complicated by acute renal failure. If after dehydration and circulatory failure are corrected, there is still oliguria or anuria, urine specific gravity is low, plasma urea nitrogen and creatinine are still rising day by day, and metabolic acidosis is more serious, then acute renal failure may have been complicated.
Complications
Acute renal failure
It occurs when hypovolemic shock is not corrected in time, and hypokalemia can also aggravate renal damage.
It occurs 7-9 days after the onset of the disease.
It is characterized by oliguria, and in severe cases, urinary shutdown, and death may occur due to acute renal failure.
Acute pulmonary edema
Metabolic acidosis can lead to pulmonary hypertension and pulmonary edema, which can also be exacerbated by large amounts of non-alkaline saline supplementation.
Manifestations include chest tightness, dyspnea or telangiectasia, cyanosis, coughing up pink frothy sputum, or jugular venous rage.
Circulatory failure
It is a hypovolemic shock due to severe water loss, in which the patient presents with cold extremities, a thin rapid pulse, and a drop in blood pressure.
Due to the lack of blood supply to the brain leading to cerebral hypoxia, the patient appears to have impaired consciousness, starting with agitation, followed by drowsiness, lethargy or even coma.
Consultation
Department
Infectious Diseases
The Department of Infectious Diseases is recommended in cases of severe acute diarrhea, loose watery stools, wash watery stools, and projectile vomiting, especially if there are people in the surrounding area with similar symptoms, or if there is a history of close living with the diagnosed patient.
Gastroenterology
If you have the above symptoms, you may also consult the Gastroenterology or Intestinal Clinic and be referred to the Department of Infectious Diseases for further treatment after confirmation of the diagnosis.
Emergency Medicine
In the event of an emergency such as a drop in blood pressure, decreased urine output, confusion, drowsiness, etc., it is recommended that the patient be seen by the Emergency Department immediately.
Preparation for medical treatment
Preparation for medical consultation: registration, preparation of documents, common problems
Tips for seeking medical treatment
When cholera-like symptoms occur, immediately call 120 or contact your local CDC to explain the situation, while practicing strict self-isolation until a professional arrives or guides you on what to do next.
Avoid contact with people around you. Disinfect vomit and feces and do not dispose of them.
Medical Preparation Checklist
Symptom checklist
Pay particular attention to the time of onset of symptoms, specific manifestations, etc.
Is there diarrhea? What kind of stools?
Was there nausea or vomiting? How many times did you vomit? What color was the vomit?
Is there a fever?
When did the symptoms appear?
Medical History Checklist
Are there any patients with similar symptoms in or around the family?
Did you drink unclean water, unwashed fruits or vegetables, or eat raw seafood before the onset of symptoms?
Checklist
Test results from the last six months, which can be brought to the doctor’s office
Laboratory tests: blood test, liver and kidney function, blood electrolytes, stool routine
Medication List
Medication in the last 3 months, bring along the box or package if available
Antibiotics: Ciprofloxacin, Levofloxacin
Others: Chlorpromazine, Montelukast, Flavoxate, etc.
Diagnosis
Diagnosis is based on
Medical history
The patient lives in a cholera-endemic area or has traveled to a cholera-endemic area within 5 days.
History of drinking raw water or eating seafood or other unclean food and drink within 5 days before the onset of illness.
History of close contact or co-exposure with cholera patients or carriers.
Clinical manifestations
Signs of dehydration, muscle cramps, acidosis, or signs of circulatory collapse.
Laboratory Tests
Blood: elevated red blood cells, hemoglobin and hematocrit due to water loss, elevated white blood cell count, neutrophils and monocytes. Blood pH is decreased and urea nitrogen and creatinine are elevated.
Blood electrolytes: serum potassium, sodium, chloride and carbonate are decreased, which is used to determine whether hypokalemia and hyponatremia are present. Doctors will also review blood electrolytes during treatment to prevent oversupplementation of sodium and potassium.
Liver and kidney function: blood tests are used to clarify whether liver and kidney function are affected.
Stool smear staining: Gram staining followed by microscopic visualization of Gram stain negative Vibrio cholerae can be used to initially determine infection with Vibrio cholerae.
Vibrio cholerae culture: feces, vomitus or anal swab can confirm the diagnosis if Vibrio cholerae group O1 or O139 is isolated by bacterial culture.
Rapid auxiliary test: Currently commonly used is Vibrio cholerae colloidal gold rapid test, which mainly detects the antigenic components of group O1 and group O139. It is simple to operate, and can rapidly detect Vibrio antigens in the feces, which can provide the basis for definitive diagnosis.
Nucleic acid test: positive cholera enterotoxin gene is detected in feces, vomitus or anal swab specimen, and the diagnosis can be confirmed by combining with clinical manifestations.
Serum immunologic examination: after Vibrio cholerae infects human body, it can produce antimicrobial antibody and anti-enterotoxin antibody. Serum immunological examination is mainly used for epidemiological retrospective diagnosis and diagnosis of fecal culture-negative but suspected infected patients.
Diagnostic criteria
Any of the following criteria can be recognized as a confirmed case.
Clinical manifestations of either type of cholera and isolation of Vibrio cholerae group O1 and/or O139 on bacterial culture of feces, vomitus or anal swab.
Those with fecal culture detection of Vibrio cholerae group O1 and/or O139 in an outbreak search who have diarrhea symptoms within 5 days before or after.
Differential Diagnosis
Acute gastroenteritis
Similarities: Severe diarrhea, vomiting, etc., with dehydration and electrolyte disorders.
Differences: Most cases of acute gastroenteritis have a history of eating unclean food, and people who eat the same meal tend to have a collective onset of the disease, with a rapid onset of fever and other symptoms of poisoning in the early stages. Acute gastroenteritis is usually preceded by vomiting and followed by diarrhea, cholera is usually preceded by diarrhea and followed by vomiting.
Acute Bacterial Dysentery
Similarities: Clinical manifestations include diarrhea, mucus, pus and blood stools, and abdominal pain.
Differences: acute bacillary dysentery in adults is not obvious at the beginning of intestinal symptoms, the main manifestation of frequent pus and blood stools, circulatory system symptoms are obvious. The causative organisms are different. Acute bacillary dysentery is caused by Shigella, which can be identified by fecal or anal swab specimen testing.
Enterotoxin-producing Escherichia coli infection
Similarities: Patients have nausea and vomiting, diarrhea, and dehydration in severe diarrhea.
Differences: Patients with enterotoxin-producing Escherichia coli infection have yellow or watery stools, without pus or blood. The causative organisms of the two diseases are different and can be identified by fecal culture.
Salmonella typhimurium infection
Similarity: Both diseases can cause diarrhea.
Difference: Salmonella typhimurium infection is more common in infants under 6 months of age and is particularly severe in newborns. The causative organisms of the two diseases are different. Salmonella typhimurium infection can be detected in the feces of patients.
Campylobacter jejuni enteritis
Similarities: diarrhea can occur in both diseases.
Differences: Campylobacter jejuni enteritis may have fever or symptoms such as malaise, headache and myalgia at the beginning, followed by abdominal pain and diarrhea, and stool culture may be positive for Campylobacter.
Rotavirus enteritis
Similarity: Rotavirus enteritis can affect all age groups, can be epidemic in nature, with soft or yellowish watery stools, and the clinical manifestations are similar to those of mild cholera.
Differences: Rotavirus enteritis occurs in fall and winter, mostly in infants and young children, some patients are accompanied by upper respiratory tract infections and fever, and the symptoms of toxicity are mild and often self-limiting. Stool culture is negative for Vibrio cholerae and positive for rotavirus.
Treatment
Cholera patients should go to the hospital as soon as possible to receive treatment and undergo strict isolation.
Treatment principle: timely rehydration therapy, supplemented by antibacterial therapy and symptomatic treatment. When the disease is serious, it needs to strengthen nursing care, monitor the condition in time, monitor the changes of vital signs, and record the changes of in and out volume.
Rehydration therapy
Usually, cholera patients have varying degrees of dehydration and need rehydration therapy.
Oral rehydration
Oral rehydration solution is not only suitable for patients with mild or moderate dehydration, but also suitable for patients with severe dehydration. It can reduce the amount of intravenous rehydration for patients with severe dehydration, thus reducing the adverse reaction of intravenous infusion and the medical electrolyte disorder, and it is especially important for the old and frail patients, patients with cardiorespiratory insufficiency and patients who need to replenish potassium in time.
Oral rehydration can also be used in patients with vomiting, and the rate of rehydration should be slower, especially in children.
Intravenous rehydration
Suitable for severe dehydration, moderate dehydration that cannot be taken orally, and rare cases of mild dehydration.
For the elderly, infants and young children, and those with cardiopulmonary insufficiency, rehydration should not be too fast, and the response to treatment should be observed while rehydrating.
In young children, due to poor renal sodium excretion, electrolyte concentrations should be adjusted compared with adult patients to avoid hypernatremia.
The amount of rehydration fluid should be decided according to the degree of water loss.
When dehydration is corrected and urination is present, attention should be paid to potassium chloride supplementation.
Timely potassium supplementation is particularly important in pediatric cases because of the high potassium content of their feces, which predispose them to hypokalemia during diarrhea.
The volume and rate of rehydration 24 hours after the start of treatment should be readjusted according to the condition, and too rapid infusion of fluids may lead to acute heart failure.
Antibacterial treatment
Applicable people: patients over 2 years old with more than moderate dehydration.
Antibacterial treatment can shorten the course of the disease and reduce the frequency of diarrhea, but it can only be used as an adjunctive treatment.
Commonly used drugs include ciprofloxacin, levofloxacin and doxycycline.
Other treatments
Correction of acidosis
If the patient has metabolic acidosis, sodium bicarbonate drip can be used to treat acidosis.
Correction of hyperkalemia
Intravenous drip of potassium chloride can be used for patients with hyperkalemia, and oral potassium supplementation can be used for patients with mild hyperkalemia.
Correction of shock and heart failure
If the blood pressure remains low after fluid replacement and correction of acidosis in severely ill patients, adrenocorticotropic hormone and vasoactive drugs dopamine and mesalamine can be used.
In case of heart failure and pulmonary edema, the infusion should be suspended or slowed down, cediran should be applied slowly intravenously, furosemide should be applied intravenously if necessary, and pethidine can be used in patients who need to be sedated.
Anti-enterotoxin therapy
Chlorpromazine and safranin may counteract enterotoxins and reduce diarrhea.
Criteria for release from isolation
After the patient’s symptoms disappear, fecal culture once every other day, if two consecutive fecal cultures are negative, the quarantine can be lifted.
Prognosis
Cure
The prognosis is related to the type of infection, the severity of symptoms, and whether the treatment is timely and correct. In the past 30 years, the mortality rate of cholera has been reduced to about 1% due to the improvement of diagnosis and treatment technology.
The prognosis is usually good after timely and adequate treatment.
In the absence of new strains of Vibrio cholerae, patients will not relapse for several years after an outbreak through the mucosal immune response.
Hazards
Renal failure can occur if rehydration is not prompted after the onset of dehydration, and in severe cases, death can occur due to uremia.
When excessive potassium is lost due to defecation, failure to correct electrolyte disorders in a timely manner may disrupt cardiac and neurologic function and jeopardize life.
Daily
Daily Management
Dietary management
Avoid oily, spicy food and alcohol.
Fasting for a period of time is needed when vomiting is severe.
Give fluids first and gradually transition to a semi-fluid diet.
Eat sugar (carbohydrates) first, then gradually transition to a protein diet.
Pay attention to food and water hygiene, and process food to be fully cooked before consumption.
Life management
Thoroughly disinfect items used by patients or carriers, and patients or carriers should use separate tableware.
During the recovery period, pay attention to rest, avoid exertion and ensure sufficient sleep.
Do not drink raw water and pay attention to water hygiene.
Pay attention to prevention to avoid re-infection.
Disease monitoring
Strictly isolate the patient. Stool culture should be performed every other day after the symptoms disappear, and the isolation can be lifted if the results are negative twice in a row.
Observe and record the defecation situation, and carry out daily monitoring of vital signs according to the doctor’s requirements.
Electrolytes should be rechecked regularly after discharge to prevent electrolyte disorders, and diabetic patients need to test their blood glucose.
Patients with renal insufficiency need strict monitoring of urine output to prevent dehydration from progressing and further aggravating the burden on the kidneys.
Prevention
Pay attention to water hygiene and do not drink unsterilized water in the field.
Avoid contact with flies and other vectors.
Wash your hands after defecation and before touching food. After applying soap to your hands, follow the seven-step washing method, or use a hand sanitizer containing alcohol to sterilize your hands.
Do not eat raw food, it needs to be fully cooked before consumption, especially pay attention to sea (water) products.
Avoid contact with patients with suspected symptoms in areas where the disease is endemic.
Close contacts of confirmed patients can be given prophylactic medication, usually doxycycline or norfloxacin.
Oral cholera vaccine: WHO believes that the vaccine provides short-term protection in areas where cholera is endemic, as well as in areas with outbreaks of cholera. There are two currently recognized oral cholera vaccines: Dukoral (produced in the UK and Sweden) and Shanchol (produced in India). Both are whole-cell inactivated vaccines.