Cholera

　　Cholera is an acute enteric infectious disease caused by Vibrio cholerae. Vibrio cholerae is divided into two biological types: one is the classical biological type, which is the causative agent of cholera, and the other is the El Tor biological type, which is the causative agent of par cholera. These two biological types are almost identical in morphology and serological properties, except for some biological characteristics. Vibrio cholerae is Gram-negative and sensitive to dryness, sunlight, heat, acid, and general disinfectants.

　　The pathogenic factors of Vibrio cholerae are endotoxins and exotoxins. Normal gastric acid can kill the vibrio. When gastric acid is temporarily low or the number of invasive bacteria increases, the vibrio that is not killed by gastric acid enters the small intestine, rapidly multiplies in the alkaline intestinal fluid, and produces a large amount of strong exotoxins. This exotoxin causes a large amount of intestinal fluid secretion, which is so great that it exceeds the absorption capacity of the intestinal tract, resulting in severe diarrhea and vomiting in clinical practice, severe dehydration, and a significant decrease in plasma volume, blood concentration, and peripheral circulatory failure. Due to severe diarrhea and vomiting, electrolyte loss, hypokalemia, hyponatremia, muscle cramps, acidosis, and even shock and acute renal failure may occur.

　　Cholera, if not treated promptly, can easily lead to various complications, therefore, it requires high attention.

　　1, Renal failure. Caused by inadequate correction of shock and hypokalemia, it is manifested by decreased urine output and azotemia. In severe cases, anuria may occur, and death can result from uremia.

　　2, Acute pulmonary edema. Metabolic acidosis can lead to pulmonary hypertension, which is further exacerbated by the administration of large amounts of saline without alkali.

　　3, Other complications include hypokalemia syndrome, arrhythmia, and abortion, etc.

　　Cholera has an acute onset, characterized mainly by severe, painless diarrhea, rice water-like stools, which may be accompanied by vomiting, severe dehydration, and other symptoms.

　　1, Incubation Period: The vast majority of cases are 1 to 2 days, which can be as short as a few hours or as long as 5 to 6 days. Symptoms include dizziness, fatigue, abdominal distension, and mild diarrhea.

　　2, Diarrhea and Vomiting Phase: Most cases present with sudden, severe diarrhea followed by vomiting, with a few cases vomiting before diarrhea. Diarrhea is painless and without tenesmus. The number of stools per day can range from several to more than a dozen, even to the point of being innumerable. Initially, the stool is loose and watery, with a large amount, and then changes to a milky rice water-like consistency. A few cases may present with blood-tinged stools. Vomiting is projectile, not frequent, and also gradually becomes milky rice water-like, with some cases accompanied by nausea. Rectal temperature can reach 37.2℃ to 38.5℃. This phase lasts for several hours, usually not more than 2 days.

　　3. Dehydration collapse period: Disoriented, panic or apathetic expression, deep eye sockets, hoarse voice, thirst, extremely dry lips and tongue, skin wrinkles, wet and cold, and loss of elasticity, wrinkled fingerprints, abdominal depression in the shape of a boat, and a decrease in body surface temperature. Patients with circulatory collapse are extremely weak and无力, confused, blood pressure drops, pulse thin and rapid, heart sound weak and heart rate fast, and in severe cases, pulse disappearance, blood pressure cannot be measured, shallow breathing, cyanosis of the skin, lips, and mucosa. It may be electrolyte imbalance and metabolic acidosis, and severe acidosis may cause confusion, deep breathing, and blood pressure drop.

　　4. Reaction period and recovery period: After correcting dehydration, most patients' symptoms disappear and gradually return to normal, with an average course of 3 to 7 days, and a few can last more than 10 days (mostly elderly patients or those with serious complications). Some patients may experience febrile reactions, more common in children, which may be due to the absorption of a large amount of enterotoxins after the improvement of circulation. The body temperature can rise to 38 to 39℃, generally lasting for 1 to 3 days and then spontaneously regressing.

　　Cholera is one of the two class A infectious diseases, with an acute onset, rapid transmission, and great harm. Prevention of cholera requires efforts from three aspects: controlling the source of infection, interrupting the route of transmission, and protecting susceptible populations.

　　1. Control the source of infection: ① Perfect the reporting system for infectious diseases, discover patients early; ② Strengthen health quarantine; ③ Isolate and treat patients and carriers in accordance with regulations until symptoms disappear, and the continuous stool culture (once every other day) is negative for 3 times; ④ Isolate contacts for 5 days, while conducting medical observation and 3 stool inspections.

　　2. Interrupt the route of transmission: Improve environmental hygiene, strengthen drinking water disinfection and food management, protect water sources, prevent pollution, and improve drinking water supply conditions; advocate the use of tap water, educate the masses not to drink raw water, not to eat raw, cold, decayed, or deteriorated food, not to eat raw or semi-cooked aquatic products; strengthen the routine health supervision of food, strictly implement the food hygiene management regulations, and do a good job in food hygiene. Carry out thorough disinfection of the feces, other excretions, utensils, clothing, and bedding of patients and carriers, as well as contaminated environments. The bodies should be cremated. Actively carry out mass patriotic health campaigns, vigorously eliminate flies and cockroaches, pay attention to personal hygiene, and these are all of great significance in controlling the spread of diseases.

　　3. Protect susceptible populations: Exercise, improve resistance to diseases. Vaccinate key populations such as environmental health workers, food service personnel, medical staff, and water residents with cholera vaccine. The specific method is subcutaneous injection twice, with an interval of 7 to 10 days. The first dose is 0.5ml, and the second dose is 1ml; for children under 6 years old, it is 0.2ml and 0.4ml; for children aged 7 to 14, it is 0.3ml and 0.6ml. The immunity period is 3 to 6 months, and a booster injection is given once a year, with the same dose as the second shot. It should be noted that fever, serious heart, liver, and kidney diseases, hypertension, active tuberculosis, menstrual period, pregnant women, lactating women, and allergic individuals are all contraindications for immunization. For residents in epidemic areas, general administration of doxycycline, tetracycline, or norfloxacin for 2 days is recommended.

　　The diagnosis of cholera requires not only clinical manifestations but also some auxiliary examinations.

　　First, blood routine and biochemical examination

　　Due to dehydration, red blood cells, hemoglobin, and hematocrit increase, white blood cell count is 10～20×109/L or higher, and neutrophils and large monocytes increase. Serum potassium, sodium, chloride, and bicarbonate are all reduced, blood pH decreases, blood urea nitrogen and creatinine increase. Before treatment, due to the outward movement of potassium ions from the cells, serum potassium may be within the normal range. When acidosis is corrected, potassium ions move into the cells and hypokalemia appears.

　　Second, routine urine examination

　　There may be protein, red blood cells, and casts. The urine specific gravity is between 1.010 and 1.025.

　　Third, serological examination

　　Serum agglutination test. Take one serum sample on the 1st to 3rd day and the 10th to 15th day after onset, if the antibody titer of the second serum is 4 times or more than 4 times higher than that of the first serum, it has diagnostic reference value.

　　Fourth, pathogen examination

　　1. Smear staining: Perform Gram staining and microscopic examination on smears of feces or early culture, and you can see Gram-negative slightly curved Vibrio.

　　2. Hovering drop examination: Perform a hovering drop or dark field microscopy examination on fresh feces, and you can see Vibrio with active and穿梭-like movement.

　　3.制动试验: Take the surface growth of the water sample or alkaline peptone water enrichment culture for about 6 hours from the acute stage patients, first perform dark field microscopy to observe motility. If there is a穿梭样motional object, add a drop of O1 group polyvalent serum. If it is O1 group Vibrio cholerae, due to the antigen-antibody reaction, it will clump together, and the Vibrio movement will stop. If the movement cannot be stopped after adding O1 group serum, the test should be repeated with O139 serum.

　　4. Enrichment culture: All feces from suspected cholera patients should be subjected to enrichment culture in addition to microscopic examination. Collect feces before the use of antimicrobial drugs and send them to the laboratory for culture as soon as possible. The culture medium is generally alkaline peptone water with a pH of 8.4, and a bacterial film can form on the surface after 6 to 8 hours of culture at 36～37℃. At this time, further isolation culture should be performed, and motility observation and制动试验 should be conducted, which will help improve detection rates and early diagnosis.

　　5. Isolation culture: Use gentamicin agar plates or alkaline agar plates. The former is a strong selective culture medium, where Vibrio cholerae can grow into small colonies within 8 to 10 hours at 36～37℃. The latter requires 10 to 20 hours for culture. Select suspicious or typical colonies, and perform a slide agglutination test using the O antigen antiserum of Vibrio cholerae.

　　6. Nucleic acid detection: Distinguish between cholera strains and non-cholera Vibrio by detecting the subunit gene of cholera toxin CtxA and the toxin synergistic pilus gene (TcpA) of Vibrio cholerae using PCR technology. Then, distinguish between classical biotype and El Tor biotype Vibrio cholerae based on the different DNA sequences of TcpA gene. Results can be obtained within 4 hours, and up to 10 Vibrio cholerae per milliliter of alkaline peptone water can be detected.

　　Cholera patients should pay attention to their diet during the onset and recovery period, which is helpful for recovery.

　　During the acute stage, stop eating.

　　After the condition improves, start with liquid food, then semi-liquid food, and gradually increase it thereafter.

　　3. First provide carbohydrates, and then transition to protein diet.

　　4. Oily foods and alcohol need to be restricted.

　　5. Encourage patients with cholera to drink water and eat during the treatment and recovery period as much as possible, and continue breastfeeding for infants and young children.

　　6. Pay attention to personal hygiene, wash hands before and after meals, and avoid reinfection.

　　Traditional Chinese medicine has a certain understanding of cholera, believing that cholera is caused by feeling summer dampness, evil blocking the middle Jiao, and turbidity disturbing the gastrointestinal tract, leading to copious diarrhea and vomiting. Treatment can be based on the辨证论治 of the condition.

　　(One) Diarrhea and vomiting stage:

　　1. Summer heat syndrome:

　　(1) Principal symptoms: Sudden onset of vomiting and diarrhea, foul-smelling vomit, restlessness, thirst for drinking, short and red urine, yellowish rough tongue coating, slippery and rapid pulse.

　　(2) Treatment: Clearing heat and avoiding pollution, the formula is the addition or subtraction of the Huangqin Dingluan decoction in the Huoran Lun.

　　(3) Patent medicine: Yuju Dan (Zijin tablet), for those with vomiting, take this pill 1-5g first, the vomiting will stop slightly after taking it, and then take the decoction.

　　2. Summer dampness syndrome:

　　(1) Principal symptoms: Sudden diarrhea and vomiting, chest and epigastric oppression, no desire to drink or prefer hot drinks, fatigue and desire to sleep, white greasy tongue coating, slow pulse.

　　(2) Treatment: Using the method of aromaticizing turbidity and warming the middle Yang, the formula is the addition or subtraction of the Huoxiang Zhengqi powder.

　　(3) Patent medicine: Huoxiang Zhengqi water (pill), 2 bottles (6g) each time, taken 2 to 3 days a day.

　　(Two) Dehydration and collapse stage:

　　1. Deficiency of both Qi and Yin:

　　(1) Principal symptoms: Severe vomiting and diarrhea, both Qi and Yin injured, flushed skin, withered and slightly sweating, body heat and thirst, leg and abdominal cramps, abdominal distension and urinary retention, fine and rapid pulse, pale red tongue with yellow or white and dry coating.

　　(2) Treatment: Double supplementation of Qi and Yin, reinforcing the body and expelling evil. The formula is the addition or subtraction of the Sheng Mai powder or emergency rescue Yang decoction.

　　2. Cardiac Yang failure syndrome (Yang loss type):

　　(1) Principal symptoms: Pale complexion, sunken eye sockets, hoarse voice, cold limbs, dripping cold sweat, twisted hands and feet, spasms of tendons and pulses, deep and fine pulse, white greasy tongue coating.

　　(2) Treatment: Using the method of warming the middle Yang and activating blood to remove stasis. The formula is the addition or subtraction of the Fuzi Lizi decoction in the Shang Han Lun.

　　(Three) The reaction period and recovery period:

　　1. Principal symptoms: Weakness and fatigue, poor appetite, lack of spirit, slight fever in the afternoon, pale tongue with thin yellowish rough coating, fine pulse.

　　2. Treatment: Using the method of clearing heat and supporting the body. The decoction for clearing summer heat can be added or subtracted.