The Jeopardy of Cholera

Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium called Vibrio cholerae. There are more than 60 cholera bacteria; however, current outbreaks in Africa are generally caused by El Tor bio­type of Vibrio cholerae serogroup 01. The serotype of El Tor biotype prevalent in Africa is Inaba. Vibrio cholerae 0139 serovar is the major causative agent of epidemics in Asia.

It causes cholera infection that is the result of a potent toxin, called CTX which is produced in small intestine. Cholera works by attacking cell membranes, changing the balance of water and dissolved particles inside and outside the cell. Investigators found that when someone has the disease cholera, Vibrio cholera sticks to the walls of the intestines and makes many tiny holes, or pores, through the cell membranes of the cells of the intestinal walls. Since all cells have water, the cells lost water through its pores. It interferes with the normal flow of sodium and chloride.

Cholera is typically transmitted by either contaminated food or water. In the developed world, seafood is the usual cause, while in the developing world it is more often water. Cholera has been found in only two other animal populations: shellfish and plankton.

The cholera bacterium may also live in the environment in brackish (saltwater) rivers and coastal waters. Shellfish, when eaten raw, have been a source of cholera, and a few people in the United States have contracted cholera after eating raw or undercooked shellfish from the Gulf of Mexico. The main cause of cholera is actually poor sanitation. It leads to rapid-spread of Vibrio cholerae. When an infected person eats a contaminated food, it will effect the feces as well. Then, if the person throw his feces to a water supply such as river, it will contaminate the whole water as well. For instance, another person consumes the water from the river, he will be infected. Cholera is rarely spread directly from person to person. Both toxic and nontoxic strains exist. Nontoxic strains can acquire toxicity through a temperate bacteriophage. Coastal cholera outbreaks typically follow zooplankton blooms, thus making cholera a zoonotic disease.

The primary symptoms of cholera are profuse, painless diarrhea and vomiting of clear fluid. These symptoms usually start suddenly, one to five days after ingestion of the bacteria. The diarrhea is frequently described as “rice water” in nature and may have a fishy odor. An untreated person with cholera may produce 10 to 20 litres (3 to 5 US gal) of diarrhea a day with fatal results. As this is happening, the sufferer will experience dry mucus membrane or mouth, dry skin, excessive thirst, lack of tears, low urine output, rapid dehydration, lethargy, nausea, rapid pulse, unusual sleepiness or tiredness, and even sunken eyes. For every symptomatic person, 3 to 100 people get the infection but remain asymptomatic. Cholera has been nicknamed the “blue death” due to a patient’s skin turning a bluish-gray hue from extreme loss of fluids. The person who is suffering this disease will also experience an abdominal cramps as he/she suffers diarrhea.

Cholera was originally endemic to the Indian subcontinent, with the Ganges River likely serving as a contamination reservoir. It spread by trade routes (land and sea) to Russia, then to Western Europe, and from Europe to North America. It is now no longer considered an issue in Europe and North America, due to filtering and chlorination of the water supply.

Throughout history, devastating outbreaks of cholera have resulted in millions of cases and hundreds of thousands of deaths. Altogether seven cholera pandemics have been re-corded. The latest one, which is still ongoing, started in Indonesia in 1961, reached the African continent in the 1970s and South America in 1991. By 1994, over 1 million cases and nearly 10 000 deaths had been reported on the American continent. The cause of this is from El Tor bio­type of Vibrio cholerae serogroup 01. The serotype of El Tor biotype prevalent in Africa is Inaba. Vibrio cholerae 0139 serovar is the major causative agent of epidemics in Asia.

Cholera outbreaks can occur sporadically in any part of the world where water supplies, sanitation, food safety and hygiene practices are inadequate. Overcrowded communities with poor sanitation and unsafe drinking-water supplies are most frequently affected.

In addition to human suffering caused by cholera, cholera outbreaks cause panic, disrupt the social-economic structure and can impede development in the affected communities. Unjustified panic-induced reactions by other countries include curtailing or restricting travel from countries where a cholera outbreak is occurring, or import and export restrictions on certain foods. For example, when the country is suffered by cholera, they cannot do the import and export activities. This is done to prevent the spreading of cholera caused by importing or exporting contaminated food. In other hand, the people will not travel to the place where the cholera is occured as their sanitation is poor in quality.

Then how  can this disease be prevented? It can be done through social-economic-biological way. The community should be informed about sources of contamination and ways to avoid infection. Attention to sanitation can markedly reduce the risk of transmission of cholera including other intestinal pathogens. This is especially true where lack of good sanitation may lead to contamination of water sources. High priority should be given to observing the basic principles of sanitary human waste disposal and particularly the protection of water sources from faecal contamination. The development of sanitary systems appropriate to local conditions should be facilitated and their siting in relation to water sources emphasised. Basic hygiene involving thorough hand washing following contact with excreta should be encouraged for adults, children and infants.

For instance, there are people who are willing to help reducing the disease. Then travellers from areas free of cholera to those where cholera is endemic  used to be advised to be vaccinated, although the vaccine only provides short-term protection. This recommendation has now largely been dropped. In other hand, other countries may collect their fund to help to develop good sanitation systems. For example they can build the toilet facilities, give the vaccines to the people who haven’t got the disease, send the medicines for the victim, or even fix the transportation system in purpose to make an easy access to reach the place.

As we know that water supplies are at risk of contamination, households should be taught the necessity and the tech­niques of sanitising water in the home. The simplest and most cost effective method is chlorination of water in the storage container using household bleach. Boiling is also effective. Filtration may be necessary in addition to boiling if the only water available contains much partic­ulate matter. Chlorination alone is not sufficient in such circumstances. Even when drinking water is rendered safe, infection may still be transmitted by contaminated surface water used for bathing and for washing cloth­ing, food, or cooking utensils. In an outbreak, all water sources with the potential for contamination must be tested, rendered safe if contaminated, or otherwise closed to usage and alternative sources provided.

Since food is an important vehicle for the transmission of enteric pathogens, attention to food safety is an essential preventive measure, which should be intensi­fied when there is a threat of cholera. Street vendors and communal food sources will require particular attention, since they pose a special risk. Flies play a relatively small role in spreading cholera but their presence in large numbers indicates poor sanitary conditions, which favour transmission of the disease. The discharge of the ship’s sewage into the sea may have been responsible. Seafood, especially filter-feeders such as oyster and mussels, become contaminated because they concentrated cholera bacteria bacteria when sewage is pumped into the sea. Fish and shellfish are often eaten raw.  Then people will consume those fishes and they will be contaminated automatically.