Cholera used to be a deadly infectious disease, but modern medical advances have made it possible to treat and prevent it. As a result, cholera has been transformed into a manageable disease, and more effective vaccines and countermeasures are expected in the future.
In Korean novelist Park Kyung-ri’s Land, there is a scene in which a monk dies of the disease. He suddenly becomes frantically searching for the restroom and dies within a few days. Soon afterward, other villagers die in a similar fashion. This is the result of a disease that terrorized not only Joseon, but the entire world at the time: cholera, also known as the “feverish disease”. Cholera claimed countless lives in the 19th and early 20th centuries, and it remains a deadly threat in the Third World today.
Cholera infection is accompanied by severe diarrhea and vomiting, which leads to a rapid loss of water and mineral salts. If left untreated, the condition can lead to death within a short period of time. The toxin secreted by Vibrio cholerae acts on the epithelial cells of the small intestine to cause these symptoms, and effective treatment of cholera requires a systematic understanding of how the toxin works. The toxin disrupts the G protein signaling system in the body, and as a result, small intestinal epithelial cells lose their ability to regulate normal ion concentrations. This disrupts the water and salt balance in and around the cells, leading to rapid dehydration.
The common route of infection for cholera bacteria is through contaminated food or water. During the summer months, when people eat spoiled food or drink contaminated water, large amounts of cholera bacteria pass through the digestive system and reach the small intestine. Once attached to the walls of the small intestine, especially the epithelial cells, cholera bacteria synthesize a toxin protein called CT, CTX, or enterotoxin. This toxin is a complex of six protein subunits, five of which are responsible for tightly binding the toxin to the epithelial cells. Once bound, the remaining subunit enters the epithelial cell and disrupts the G protein signaling system.
This mechanism of action of cholera is an important topic of biochemical research today. In particular, understanding the process by which cholera toxins inactivate G proteins is essential for developing effective treatment and prevention strategies for the disease. G proteins play a key role in intracellular signal transduction, amplifying the necessary biological responses within the cell in response to external stimuli and, as a result, performing specific functions. However, cholera toxin blocks the natural inactivation of G proteins, preventing cells from functioning normally. In the case of small intestinal epithelial cells in particular, this results in an imbalance of ion concentrations, as chlorine ions continue to leave the cell, while sodium ions cannot enter. As a result, water is also constantly leaving the cells, leading to rapid dehydration.
This rapid loss of water due to dehydration is the main cause of death in cholera patients. Therefore, the main treatment for cholera is fluid therapy, and antibiotics are also used, but they are usually only chosen in an emergency. In fact, even without antibiotics, the body’s immune system can produce antibodies to eliminate the cholera bacteria. Thanks to these advances in treatment, the death rate from cholera is much lower than in the past.
However, the best way to deal with a disease like cholera is prevention. Cholera is a very painful disease, so it’s important to prevent it from happening in the first place. The basic ways to prevent cholera are to wash your hands frequently and cook your food thoroughly. These measures are very effective, as the cholera bacteria can be killed by heating water at 55°C for just 10 minutes. In addition, vaccines have been developed, but they’re not yet very effective. This is likely related to the short incubation period of the cholera bacteria, which is only one to two days, but the exact reason for this is unknown and needs further study.
As more research is done into the exact mechanisms of action of cholera, it is likely that a more effective vaccine will be developed, and if this vaccine is universally available in the third world, cholera will become a manageable disease rather than a major threat to humanity. Historically, cholera has left a deep scar on human societies, but with the advancement of modern medicine, its deadly effects are becoming less and less common. Once a threat that could devastate communities, it is now recognized as a disease that can be systematically prevented and treated. With continued advances in research and countermeasures against infectious diseases like cholera, we may one day be free of this threat altogether.
