Cholera (El Tor)
Cholera is an acute bacterial entric diseases of the GIT characterized by profuse diarrhea, vomiting, massive loss of fluid and electrolytes that could result to hypovolemic shock, acidosis and death.
Sometimes known as Asiatic or epidemic cholera
Cholera was originally endemic to the Indian subcontinent, with the Ganges River likely serving as a contamination reservoir. The disease spread by trade routes (land and sea) to Russia, then to Western Europe, and from Europe to North America during the Irish immigration period. Cholera is now no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects populations in developing countries.
Source of Infection:
Vomitus and feces of infected persons and feces of convalescent or healthy carriers. Contacts may be temporary carriers.
Vibrio Cholerae/Vibrio coma
- The organisms are slightly curved rods (coma shape), gram negative (-) and motile with a single polar flagellum.
- The organisms survive well at ordinary temperature and can grow well in temperature ranging from 22-40 degrees centigrade.
- They can survive well in ordinary temperature and can survive longer in refrigerated foods.
- An enterotoxin, choleragen, is elaborated by the organism as they grow in the intestinal tract.
The incubation period ranges from a few hours to five days; usually one to three days.
Period of Communicability:
The organisms are communicable during stool positive stage, usually a few days after recovery, however occasionally the carrier may have the organism for several months.
Mode of Transmission:
- Fecal transmission passes via oral route form contaminated water, milk, and other foods.
- The organisms are transmitted through ingestion of food or water contaminated with stool or vomitus of patient.
- Flies, soiled hands and utensils also serve to transmit the infection.
Pathogenesis and Pathology:
- Fluid loss is attributed to the enterotoxin elaborated by the organism as they lie in opposition with the lining cells of the intestines.
- The toxin stimulates adenylate cyclase, which results in the conversion of the adenosine truphosphate (ATP) to cyclic adesine monophasphate (CAMP).
- The mucosal cell is stimulated to increase secretion of chloride, associated with water and bicarbonate loss.
- The toxin acts upon the intact epithelium on the vasculator of the bowel, thus, resulting in outpouring of intestinal fluids.
- Fluid loss of 5 to 10 percent of the body weight resulting in dehydration and metabolic acidosis.
- If treatment is delayed or inadequate, acute renal failure and hypokalemia become secondary problems.
- There is an acute, profuse, watery diarrhea with no tenesmus or intestinal cramping.
- Initially, the stool is brown and contains fecal materials, but soon becomes pale gray, “rice-water” in appearance with an inoffensive, slightly fishy odor.
- Vomiting often occurs after diarrhea has been established.
- Diarrhea causes fluid loss amounting to 1 to 30 liters per day owing to subsequent dehydration and electrolyte loss.
- Tissue turgur is poor and eyes are sunken into the orbit.
- The skin is cold, the fingers and toes are wrinkled, assuming the characteristic “washer-moman’s hand”.
- Radial pulse become imperceptible and the blood pressure unobtainable.
- Cyanosis is present.
- The voice becomes hoarse and then, is lost, so that the patient speaks in whisper (aphonia).
- Breathing is rapid and deep.
- Despite marked diminished peripheral circulation, consciousness is present.
- Patients develops oliguria and may even develop anuria.
- Temperature could be normal at the onset of the disease but becomes subnormal in later stage especially if the patient is in shock.
- When the patient is in deep shock, the passage of diarrhea stops.
- Death may occur as short as four hours after onset, but usually occurs on the first or second day if not properly treated.
Susceptibility, Resistance Occurrence:
- Susceptibility and resistance general although variable. Frank clinical attacks confer a temporary immunity which may afford some protection, for several years.
- Immunity artificially induced by vaccine is of variable and uncertain duration.
- Appears occasionally in epidemic form in the Philippines and in other parts of the world.
- Rectal Swab
- Darkfield or phase microcopy
- Stool Exam
Modalities of Treatment:
Treatment of cholera consist in correcting the basic abnormalities without delay – restoring the circulating blood volume and blood electrolytes to normal levels.
- Intravenous treatment is achieved by rapid intravenous infusion of alkaline saline solution containing sodium, potassium, chloride and bicarbonate ions in proportions comparable to that in water-stool.
- Oral therapy rehydration can be completed by oral route (Oresol, Hydrites) unless contraindicated or, if the patient is not vomiting.
- Maintenance of the volume of fluids and electrolytes to ensure rehydration. This is done by careful intake and output measurement.
- Tetracycline 500mg every 6 hours might be administered to adults, and 125 mg/kg body weight for children every 6 hours to 72 hours.
- Furazolidone 100 mg for adults and 125mg/kg for children, might be given every 6 hours for 72 hours.
- Chlorampenicol may also be given 500 mg for adults and 18 mg/kg for children every 6 hours for 72 hours.
- Cotrimoxazole can also be administered 8mg/kg for 72 hours.
- Medical septic protective care must be provided.
- Enteric isolation must be observed.
- Vital signs must be recorded accurately.
- Intake and output must be be accurately measured.
- A thorough and careful personal hygiene must be provided.
- Excreta must be properly disposed of.
- Concurrent disinfection must be applied.
- Food must be properly prepared.
- Environmental sanitation must be observed.
- Food and water supply must be protected from fecal contamination.
- Water should be boiled or chlorinated.
- Milk should be pasteurized.
- Sanitary disposal of human excreta is a must.
- Sanitary supervision is important.
Handbook of Common Communicable and Infectious Diseases 2006 Ed