Cholera: Diagnosis, Treatment And Transmission Of Cholera
It is almost impossible to distinguish a single patient with cholera from a patient infected by another pathogen that causes acute watery diarrhea without testing a stool sample.
A review of clinical features of multiple patients who are part of a suspected outbreak of acute watery diarrhea can be helpful an identifying cholera because of the rapid spread of the disease.
While management of patients with acute watery diarrhea is similar regardless of the illness, it is important to identify cholera because of the potential for a wide spread outbreak.
How to Diagnose
Isolation and identification of Vibrio cholerae serogroup O1 or O139 by culture of a stool specimen remains the gold standard for the laboratory diagnosis of cholera.
Cary Blair media is ideal for transport, and the selective thiosulfate–citrate–bile salts agar (TCBS) is ideal for isolation and identification. Reagents for serogrouping Vibrio cholerae isolates are available in all state health department laboratories in the U.S. Commercially available rapid test kits are useful in epidemic settings but do not yield an isolate for antimicrobial susceptibility testing and subtyping, and should not be used for routine diagnosis.
In areas with limited to no laboratory testing, the Crystal VC® dipstick rapid test can provide an early warning to public health officials that an outbreak of cholera is occurring.
However, the sensitivity and specificity of this test is not optimal. Therefore, it is recommended that fecal specimens that test positive for V. cholerae O1 and/or O139 by the Crystal VC® dipstick be confirmed using traditional culture-based methods suitable for the isolation and identification of V. cholerae.
TRANSMISSION OF CHOLERA
A person can get cholera by drinking water or eating food contaminated with the cholera bacterium. In an epidemic, the source of the contamination is usually the feces of an infected person that contaminates water and/or food. The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water. The disease is not likely to spread directly from one person to another; therefore, casual contact with an infected person is not a risk for becoming ill.
In the developed world, seafood is the usual cause, while in the developing world it is more often water. Most cholera cases in developed countries are a result of transmission by food.
People infected with cholera often have diarrhea. The source of the contamination is typically other cholera sufferers when their untreated diarrheal discharge is allowed to get into waterways, groundwater or drinking water supplies.
Drinking any infected water and eating any foods washed in the water can cause a person to contract an infection. Cholera is rarely spread directly from person to person. Both toxic and nontoxic strains exist. Nontoxic strains can acquire toxicity through a temperate bacteriophage. Coastal cholera outbreaks typically follow zooplankton blooms, thus making cholera a zoonotic disease.
Most persons infected with the cholera bacterium have mild diarrhea or no symptoms at all. Only a small proportion, about 10%, of persons infected with Vibrio cholerae O1 have illness requiring treatment at a health center.
Cholera patients should be evaluated and treated quickly. With proper treatment, even severely ill patients can be saved. Prompt restoration of lost fluids and salts through rehydration therapy is the primary goal of treatment.
Antibiotic treatment, which reduces fluid requirements and duration of illness, is indicated for severe cases of cholera.
Zinc treatment has also been shown to help improve cholera symptoms in children.