Cholera, a disease that is caused by Vibrio cholera (bacteria), is often referred to as the ‘disease of the poor’ due to its occurrence in underdeveloped and developing countries of the world. The causes of cholera are often attributed to poor sanitation and improper water treatment facilities, which are common mainly in developing countries.
The Causes Of Cholera – The Causative Organism
Cholera in humans is mainly caused by the bacterium Vibrio cholera, which belongs to the genus Enterobacteriaceae. They are slightly comma shaped, motile (moving) organisms.
The Causes Of Cholera Explained – How It Spreads
The causes and spread of cholera can be explained in three key points:
- Reservoir of infection
- Sources of infection
- Mode of transmission
Reservoir Of Infection
Humans and water are the two main reservoirs (or carriers) of cholera and the virus constantly cycles between the environment and the human body.
The primary habitat of this salt water organism is the marine ecosystem, where it is often associated with zooplanktons. An outbreak of cholera is often marked by a zooplankton bloom, and this is why cholera is considered to be a zoonotic disease (passed from animals).
The cholera bacterium is usually harbored in the environment by:
- Brackish water
- Coastal waters (attached to tiny crustaceans called copepods)
- Ponds and estuaries
- Zooplanktons and shellfish (especially oysters)
Humans can serve as a reservoir for the cholera bacterium when they contract the disease or act as carriers.
Carriers harbor the bacterium in their intestines and shed it out through their feces, sometimes for prolonged periods, without showing any evidence of the disease. Even though the bacterium’s carrier state is short lived, it plays a major role in spreading the disease widely.
Sources Of Infection
To understand the causes of cholera, you should be able to identify the source of infection.
Food items and water-based drinks that have been contaminated with the feces of cholera-infected individuals serve as major sources of infection. For this very reason, cholera is also known as ‘fecal disease’.
The following are some of the cases that rank among the causes of cholera.
- When untreated diarrheal discharge is mixed with drinking water
- When the soil is contaminated with cholera-infected feces
- Raw or undercooked shellfishes that carry the bacterium
- Fruits and vegetables that are washed in contaminated water
- When manure fertilizers or irrigation water get contaminated with sewage while farming
- Ice made from contaminated water
Mode Of Transmission
Cholera is transmitted through infected water or food, and no direct human to human transmission has been indicated. For this reason, casual contact with infected individuals will not pose a threat. Methods of cholera prevention can be undertaken to prevent getting the infection.
Close to 100 million organisms must be ingested in order to initiate the infection.
Once inside the stomach, the bacteria produces the cholera toxin, which interrupts the normal flow of sodium and chloride in the body and increases the release of water from the intestinal cells. This disruption in the body’s functioning causes watery diarrhea that is rich in electrolytes. The bacteria are also shed through the feces.
The Causes Of Cholera – Environmental And Host Risk Factors
When it comes to the causes of cholera, the following environmental conditions play a major role.
- Crowded living conditions
- Poor sanitation and personal hygiene
- Situations of war, famine, or natural calamities
- Military refugee camps
- Improper water treatment facilities with unsafe drinking water
- Improper disposal of faeces
- Poor countries or slums without basic infrastructure
- Global warming (increase the susceptibility of infection)
Host factors that can increase the susceptibility of infection are:
- Gastric surgery
- Helicobacter pylori infection
- The use of H2 blockers in ulcer disease
- Type O blood group (unknown cause)
- Vagotomy, where the vagus nerve is surgically removed to reduce acid secretion in the stomach
Cholera is prevalent and confined to certain regions including Southeast Asia (and India), Sub-Saharan Africa, and Latin America. It can be introduced to any area by a person who has contracted the disease after travelling to such cholera endemic areas. In case you feel you have any of the cholera symptoms, it is of extreme importance to reach out to a doctor to get a proper cholera diagnosis. With proper sanitary measures, the causes of cholera can be combated against.