In this blog post, we explore how cholera—a disease that once struck fear into the hearts of humanity—has become preventable and treatable thanks to advances in modern medicine.
In the Korean novel *Land* by Park Kyung-ni, there is a scene where a scholar dies in agony after contracting cholera. A person who had been perfectly healthy suddenly frantically searches for a bathroom and dies within just a few days. Shortly after that incident, villagers also meet their deaths one after another in a similar manner. This tragedy was caused by a disease that struck terror not only into Joseon at the time but across the entire world: “hoyeolja,” or cholera. Cholera claimed countless lives from the 19th century through the early 20th century, and it remains a deadly threat in the developing world to this day.
Infection with cholera is accompanied by severe diarrhea and vomiting, leading to rapid loss of fluids and electrolytes. If left untreated, this condition can lead to death within a short period of time. The toxin secreted by the cholera bacterium (Vibrio cholerae) acts on the epithelial cells of the small intestine to cause these symptoms; therefore, a systematic understanding of the toxin’s mechanism of action is necessary for effective treatment of cholera. This toxin disrupts the G-protein signaling system within the body, causing the small intestinal epithelial cells to lose their normal ability to regulate ion concentrations. This disrupts the balance of water and electrolytes inside and outside the cells, leading to rapid dehydration.
The common route of infection for Vibrio cholerae is through contaminated food or water. When spoiled food is consumed or contaminated water is drunk during the summer, large quantities of Vibrio cholerae reach the small intestine via the digestive tract. Once attached to the small intestinal wall, particularly the epithelial cells, Vibrio cholerae synthesizes toxin proteins known as CT, CTX, or enterotoxins, which have a detrimental effect on the body. This toxin is a complex composed of six protein subunits, five of which serve to firmly bind the toxin to epithelial cells. Once binding occurs, the remaining subunit enters the interior of the epithelial cell and disrupts the G protein signaling system.
This mechanism of action of cholera has become a major topic in contemporary biochemical research. In particular, understanding how the cholera toxin prevents the inactivation of G proteins is essential for developing effective treatment and prevention strategies for this disease. G proteins play a central role in intracellular signaling; they amplify necessary biological responses within the cell in response to external stimuli, thereby enabling specific functions. However, the cholera toxin blocks the natural inactivation process of G proteins, preventing cells from functioning normally. In the case of small intestinal epithelial cells, this causes chloride ions to continuously leak out of the cells while sodium ions are unable to enter, exacerbating the imbalance in ion concentrations. Consequently, water also continuously leaks out of the cells, leading to rapid dehydration.
This rapid loss of fluids due to dehydration is the primary cause of death in cholera patients. Therefore, the primary treatment for cholera is fluid therapy; antibiotics are also used, but they are typically reserved for urgent situations. In fact, even without antibiotics, the body’s immune system can produce antibodies to eliminate the cholera bacterium. Thanks to advances in these treatments, the mortality rate from cholera has decreased significantly compared to the past.
However, the best way to deal with diseases like cholera is prevention. Since cholera is a disease accompanied by severe suffering, preventing it in advance is of utmost importance. The basic methods for preventing cholera are frequent handwashing and thoroughly cooking food. Since the cholera bacterium is killed by heating at 55°C for just 10 minutes, these measures are highly effective. Additionally, although a vaccine has been developed, it has not yet proven to be highly effective. This is likely related to the short incubation period of the cholera bacterium, which is only 1–2 days, but the exact reason remains unclear and requires further research.
If more in-depth research is conducted on the exact mechanism of cholera, there is a high probability that a more effective vaccine will be developed. Furthermore, if such a vaccine is widely distributed in the developing world, cholera will become a manageable disease rather than a major threat to humanity. Historically, cholera has left deep scars on human society, but with the advancement of modern medicine, its lethal impact is gradually diminishing. While it was once so threatening that it could devastate entire communities, it is now recognized as a disease that can be systematically prevented and treated. If research and countermeasures against infectious diseases like cholera continue to advance, we will eventually be able to completely free ourselves from such threats.
