Cholera
Etiology/Bacteriology
Taxonomy
Domain: Bacteria | Phylum: Proteobacteria | Class: Gammaproteobacteria | Family: Vibrionaceae | Order: Vibrionales | Genus: Vibrio | Species: V. cholerae
NCBI: Taxonomy Genome: Vibrio cholerae |
Description
Pathogenesis
Transmission
The first recorded outbreak of cholera occurred in India in 1817, specifically near the mouth of the Ganges River [1]. Vibrio cholerae naturally attach to the chitinous exoskeleton of zooplankton in fresh, brackish rivers and coastal salt water. Because of this, cholera outbreaks often coincide with zooplankton blooms [2]. The transmission of V. cholerae is usually by water and food contaminated with zooplankton and/or fecal matter. Because the pathogen is ingested, it is also transmitted through oral-fecal transmission. The transmission of V. cholerae is often related to the inadequate sanitation and water treatment procedures of an area [3].”
Infectious dose, incubation, and colonization
V. cholerae lacks the acid resistance genes found in many other intestinal pathogens and therefore has a high infectious dose. One must ingest over one million microbes in order to contract cholera because many of the bacteria will die in the stomach due to its highly acidic environment. The incubation period is dependent upon how many organisms successfully passed through the stomach into the small intestine where V. cholerae can colonize. Therefore, the incubation period before showing symptoms ranges from a few hours to five days, typically taking two days before causing symptoms. Once in the small intestine, studies show that some of the bacteria use their flagella to swim towards the epithelial cells and adhere in the crypts of the intestine using their toxin-coregulated pilus to keep from being flushed out [4].
Epidemiology
Virulence factors
The virulence factors of V. cholerae include type IV pilli, toxin co-regulated pillus, cholera toxin, and motility.
Clinical features
Symptoms
Morbidity and Mortality
Diagnosis
As the excrement of infection with V. cholerae is so distinct, diagnosis typically can be made upon obtaining and culturing a stool sample. Typical clinical manifestations, such as the "rice water" stool and vomiting, as well as recent consumption of a contaminated water or food source, can lead to investigation into cholera by the physician. A rectal swab or fecal sample when cultured will correctly indicate the source of the infection [5].
Treatment
Prevention
Host Immune Response
References
1 Despommier D, Chen S. "Cholera". Medical Ecology. 2004.
2 News-Medical "Cholera Transmission". 2013.
3 Centers for Disease Control and Prevention (CDC). Cholera - Vibrio cholerae infection. General Information. "Where is Cholera Found". 2013, July 9.
Created by Bhumi Patel, Dehra McGuire, and Gracen Conway, students of Tyrrell Conway at the University of Oklahoma.