This blog post explores how cholera, once a disease that terrorized humanity, has become preventable and treatable through advances in modern medicine.
In the Korean novel ‘Land’ by Park Kyung-ni, a scene depicts a scholar dying painfully from ho-yeol-ja. A seemingly healthy person suddenly frantically seeks the toilet, only to die within days. Shortly after, villagers also meet their deaths in similar fashion, one after another. This horror was caused by a disease that terrorized not only Joseon at the time but the entire world: ‘ho-yeol-ja’, or cholera. Cholera claimed countless lives from the 19th to the early 20th century and remains a deadly threat in the Third World today.
Infection with cholera causes severe diarrhea and vomiting, leading to rapid loss of fluids and essential minerals. Without treatment, this condition can lead to death within a short time. The toxin secreted by the cholera bacterium (Vibrio cholerae) acts on the epithelial cells of the small intestine, causing these symptoms. To effectively treat cholera, a systematic understanding of how this toxin works is essential. This toxin disrupts the G protein signaling pathway within the body. As a result, the small intestinal epithelial cells lose their normal ion concentration regulation function. This causes the balance of water and salts inside and outside the cells to collapse, leading to rapid dehydration.
The typical route of cholera infection is through contaminated food or water. When spoiled food is consumed in summer or contaminated water is drunk, large quantities of cholera bacteria pass through the digestive tract and reach the small intestine. Cholera bacteria attached to the small intestinal wall, particularly the epithelial cells, synthesize a toxin protein called CT, CTX, or enterotoxin, causing adverse effects in the body. This toxin is a complex composed of six protein subunits, five of which firmly bind the toxin to the epithelial cell. Once bound, the remaining subunit enters the epithelial cell interior and disrupts the G protein signaling pathway.
Understanding this mechanism of cholera action is a key focus in contemporary biochemical research. Understanding how cholera toxin prevents G protein inactivation is essential for developing effective treatment and prevention strategies against this disease. G proteins play a central role in intracellular signaling, amplifying necessary biological responses within cells in response to external stimuli, thereby enabling specific functions. However, cholera toxin blocks the natural inactivation process of G proteins, preventing cells from functioning normally. In small intestinal epithelial cells specifically, this leads to a continuous outward flow of chloride ions and an inability for sodium ions to enter, exacerbating ion concentration imbalance. Consequently, water also continuously leaks out of the cells, causing rapid dehydration.
This rapid fluid loss due to dehydration is the primary cause of death in cholera patients. Therefore, the primary treatment for cholera is fluid replacement therapy. Antibiotics are also used, but they are primarily reserved for critical situations. In fact, even without antibiotics, the body’s immune system can produce antibodies to eliminate the cholera bacteria. Thanks to advances in these treatments, the mortality rate from cholera has decreased significantly compared to the past.
However, the best approach to diseases like cholera is prevention. Since cholera is a disease accompanied by severe suffering, preventing it beforehand is paramount. The fundamental methods for preventing cholera are frequent handwashing and thoroughly cooking food before consumption. Cholera bacteria are killed by heating at 55°C for just 10 minutes, making these measures highly effective. Additionally, a vaccine has been developed, but it has not yet proven highly effective. This is likely related to the short incubation period of 1-2 days, though the exact reason remains unclear and requires further research.
If deeper research into the precise mechanism of cholera’s action is conducted, the development of a more effective vaccine becomes highly probable. Furthermore, if such a vaccine were universally distributed in the developing world, cholera would cease to be a major threat to humanity and become a manageable disease. Historically, cholera has been a disease that inflicted deep wounds on human society. However, with the advancement of modern medicine, its deadly impact is gradually diminishing. While it was once a threat capable of devastating 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 may one day be able to completely rid ourselves of this threat.
