Introduction
Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholerae which may lead to large amounts of watery diarrhoea that last a few days. Vomiting and muscle cramps may also occur (World Health Organisation (WHO), 2010). This diarrhoea can be so severe that it leads within hours to severe dehydration and electrolyte imbalance. According to Bailey (2011), this may result in sunken eyes, cold skin, decreased skin elasticity, wrinkling of the hands and feet and skin turning bluish.
Cholera is associated with a number of types of Vibrio cholerae, with some types producing more severe disease than others. It is spread mostly by water and food that has been contaminated with human faeces containing the bacteria and insufficiently cooked seafood is a common source (Centre for Disease Prevention and Control, (CDC), 2014).This disease is usually common in areas with poor sanitation, not enough clean drinking water, and poverty.
WHO (2010) stated that cholera affects an estimated 3–5 million people worldwide and causes 58,000–130,000 deaths a year as of 2010. Cholera occurs as both outbreaks and chronically in certain areas. Areas with an ongoing risk of disease include Africa and south-east Asia. While the risk of death among those affected is usually less than 5%, it may be as high as 50% among some groups who do not have access to treatment.
Historical perspective of cholera
The word cholera is a Greek word for “bile”. Cholera likely has its origins in the Indian subcontinent as evidenced by its prevalence in the region for centuries (Sack, Sack, Nair & Siddique, 2014). Early outbreaks in the Indian subcontinent are believed to have been the result of poor living conditions as well as the presence of pools of still water, both of which provide ideal conditions for cholera to thrive. The disease first spread by trade routes (land and sea) to Russia in 1817, later to the rest of Europe, and from Europe to North America and the rest of the world (Rosenberg, 2007).
The first cholera pandemic occurred in the Bengal region of India, near Calcutta starting in 1817 through 1824. The disease dispersed from India to Southeast Asia, the Middle East, Europe, and Eastern Africa through trade routes.The second pandemic lasted from 1827 to 1835 and particularly affected North American and Europe due to the result of advancements in transportation and global trade, and increased human migration, including soldiers. The third pandemic erupted in 1839, persisted until 1856, extended to North Africa, and reached South America, for the first time specifically affecting Brazil. The fourth pandemic lasted from 1863 to 1875 spread from India to Naples and Spain. The fifth pandemic was from 1881-1896 and started in India and spread to Europe, Asia, and South America. The sixth pandemic started 1899–1923. These epidemics were less fatal due to a greater understanding of the cholera bacteria. Egypt, the Arabian peninsula, Persia, India, and the Philippines were hit hardest during these epidemics, while other areas, like Germany in 1892 and Naples from 1910–1911, also experienced severe outbreaks. The final pandemic originated in 1961 in Indonesia and is marked by the emergence of a new strain, nicknamed El Tor, which still persists today in developing countries (Aberth, 2011).
Since the early 19th century till date, cholera has killed tens of millions of people. In Russia alone, between 1847 and 1851, more than one million people perished of the disease. It killed 150,000 Americans during the second pandemic. Between 1900 and 1920, perhaps eight million people died of cholera in India. Cholera became the first reportable disease in the United States due to the significant effects it had on health.John Snow, in England, was the first to identify the importance of contaminated water as its cause in 1854. Cholera is now no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects populations in developing countries (Kelley, 2013).
Mode of transmission of cholera
Transmission of cholera is usually through the faecal-oral route of contaminated food or water caused by poor sanitation (WHO, 2010). Most cholera cases in developed countries are a result of transmission by food, while in the developing world it is more often water (Sack et al., 2014). People infected with cholera often have diarrhoea, and disease transmission may occur if their highly liquid stool, colloquially referred to as “rice-water”, contaminates water used by others (Ryan & Ray, 2009). The source of the contamination is typically other cholera sufferers when their untreated diarrheal discharge is allowed to get into waterways, groundwater or drinking water supplies. Drinking any infected water and eating any foods washed in the water, as well as shellfish living in the affected waterway, can cause a person to contract an infection. Cholera is rarely spread directly from person to person (Starr, 2007).
Susceptibility to cholera attack
About 100 million bacteria must typically be ingested to cause cholera in a normal healthy adult. This doses, however, is less in those with lowered gastric acidity. Children are also more susceptible, with two- to four-year-olds having the highest rates of infection. Individuals’ susceptibility to cholera is also affected by their blood type, with those with type O blood being the most susceptible (Sack et al., 2014). Persons with lowered immunity, such as persons with AIDS or children who are malnourished, are more likely to experience a severe case if they become infected. Any individual, even a healthy adult in middle age, can experience a severe case, and each person’s case should be measured by the loss of fluids, preferably in consultation with a professional health care provider (Ramamurthy, 2008).
Signs and symptoms of cholera
The primary symptoms of cholera are profuse diarrhoea and vomiting of clear fluid. These symptoms usually start suddenly, half a day to five days after ingestion of the bacteria (Azman, Rudolph, Cummings &Lessler, 2012). The diarrhoea is frequently described as “rice water” in nature and may have a fishy odour. An untreated person with cholera may produce 10 to 20 litres of diarrhoea a day. Severe cholera, without treatment, kills about half of affected individuals. If the severe diarrhoea is not treated, it can result in life-threatening dehydration and electrolyte imbalances (Sack et al., 2014).
Fever is rare and should raise suspicion for secondary infection. Patients can be lethargic, and might have sunken eyes, dry mouth, cold clammy skin, decreased skin turgor, or wrinkled hands and feet. Kussmaul breathing, a deep and laboured breathing pattern, can occur because of acidosis from stool bicarbonate losses and lactic acidosis associated with poor perfusion. Blood pressure drops due to dehydration, peripheral pulse is rapid and thread, and urine output decreases with time. Muscle cramping and weakness, altered consciousness, seizures, or even coma due to electrolyte losses and ion shifts are common, especially in children (Sack et al., 2014).
Health implication of cholera outbreak
Cholera can quickly become fatal. In most severe cases, the rapid loss of large amounts of fluids and electrolytes can lead to death within two to three hours. In less extreme situations, people who donot receive treatment may die of dehydration and shock hours to days after cholera symptoms first appear.
According to Byrne (2008), although shock and severe dehydration are the most devastating implications of cholera, other problems can occur, such as:
- Low potassium levels (hypokalemia): People with cholera lose large quantities of minerals, including potassium, in their stools. Very low potassium levels interfere with heart and nerve function and are life-threatening.
- Kidney (renal) failure: When the kidneys lose their filtering ability, excess amounts of fluids, some electrolytes and wastes build up in your body — a potentially life-threatening condition. In people with cholera, kidney failure often accompanies shock.
Measures to combat cholera outbreak
World Health Organization (WHO) (2010) recommends focusing on prevention, preparedness, and response to combat the spread of cholera. They also stress the importance of an effective surveillance system.Governments can play a role in all of these areas, and in preventing cholera or indirectly facilitating its spread.
Prevention of cholera outbreak
Although cholera may be life-threatening, prevention of the disease is normally straightforward if proper sanitation practices are followed. Effective sanitation practices, if instituted and adhered to in time, are usually sufficient to stop an epidemic. Pyle (2010) stated that there are several points along the cholera transmission path at which its spread may be halted which include:
- Sterilization: Proper disposal and treatment of infected faecal waste water produced by cholera victims and all contaminated materials (e.g. clothing, bedding, etc.) are essential. All materials that come in contact with cholera patients should be sanitized by washing in hot water, using chlorine bleach if possible. Hands that touch cholera patients or their clothing, bedding, etc., should be thoroughly cleaned and disinfected with chlorinated water or other effective antimicrobial agents.
- Sewage:Antibacterial treatment of general sewage by chlorine, ozone, ultraviolet light or other effective treatment before it enters the waterways or underground water supplies helps prevent undiagnosed patients from inadvertently spreading the disease.
- Sources: Warnings about possible cholera contamination should be posted around contaminated water sources with directions on how to decontaminate the water (boiling, chlorination etc.) for possible use.
- Water purification: All water used for drinking, washing, or cooking should be sterilized by either boiling, chlorination, ozone water treatment, ultraviolet light sterilization (e.g. by solar water disinfection), or antimicrobial filtration in any area where cholera may be present. Chlorination and boiling are often the least expensive and most effective means of halting transmission. Cloth filters or sari filtration, though very basic, have significantly reduced the occurrence of cholera when used in poor villages in Bangladesh that rely on untreated surface water. Better antimicrobial filters, like those present in advanced individual water treatment hiking kits, are most effective. Public health education and adherence to appropriate sanitation practices are of primary importance to help prevent and control transmission of cholera and other diseases.
Handwashing with soap and/or ash after visiting toilets and before handling food or eating is also recommended for cholera prevention by WHO in Africa(WHO, 2010).
Surveillance
Surveillance and prompt reporting allow for containing cholera epidemics rapidly. Cholera exists as a seasonal disease in many endemic countries, occurring annually mostly during rainy seasons. Surveillance systems can provide early alerts to outbreaks, therefore leading to coordinated response and assist in preparation of preparedness plans. Efficient surveillance systems can also improve the risk assessment for potential cholera outbreaks. Understanding the seasonality and location of outbreaks provides guidance for improving cholera control activities for the most vulnerable. For prevention to be effective, it is important that cases be reported to national health authorities (Sinclair, Abba, Zaman, Qadri& Graves, 2011).
Vaccine
A number of safe and effective oral vaccines for cholera are available. Dukoral, an orally administered, inactivated whole cell vaccine, has an overall efficacy of about 52% during the first year after being given and 62% in the second year, with minimal side effects. It is available in over 60 countries. One injectable vaccine was found to be effective for two to three years. The protective efficacy was 28% lower in children less than 5 years old. The World Health Organization (WHO) (2010) recommends immunization of high-risk groups, such as children and people with HIV, in countries where this disease is endemic.If people are immunized broadly, herd immunity results, with a decrease in the amount of contamination in the environment (Sinclair et al., 2011).
Sari filtration
An effective and relatively cheap method to prevent the transmission of cholera is the use of a folded sari (a long cloth garment) to filter drinking water. In Bangladesh this practice was found to decrease rates of cholera by nearly half.It involves folding a sari four to eight times. Between uses the cloth should be rinsed in clean water and dried in the sun to kill any bacteria on it. A nylon cloth appears to work as well (Merrill, 2010).
Summary
Cholera is a waterborne infectious disease usually transmitted through faecal-oral route of contamination which is common in areas with poor sanitation. Cholera is associated with a number of types of vibrio cholera, with some types producing more severe diseases than others. It is spread mostly by water and food that has been contaminated. The incubation period is usually between 7 to 14 days. Signs and symptoms include vomiting, diarrhoea, dry mouth and loss of weight.
Based on the threat associated which cholera outbreaks and the difficulty in its management once an outbreak occurs, it is recommended that adequate preventive measures such as good hygiene practices (washing of hand regularly before and after meals and after using the toilet) is very important. Also drinking water and those meant for the preparation of food should be kept safe from contamination.
Conclusion/Recommendations
Based on the threat associated with cholera outbreaks and the difficulty in its management once an outbreak occurs, it is recommended that adequate preventive measures should be put in place. Some of these measures include:
Drink and use save water
- Bottled water with unbroken seals and canned/bottled carbonated beverages are safe to drink and use.
- Use safe water to brush your teeth, wash and prepare food, and to make ice.
- Clean food preparation areas and kitchenware with soap and safe water and let dry completely before reuse.
Be sure water is safe to drink and use
- Boil it or treat it with a chlorine product or household bleach.
- If boiling, bring your water to a complete boil for at least 1 minute.
- To treat your water with chlorine, use one of the locally available treatment products and follow the instructions.
- Always store your treated water in a clean, covered container.
Wash hands often with soap and safe water
- Before you eat or prepare food
- Before feeding your children
- After using the latrine or toilet
- After cleaning your child’s bottom
- After taking care of someone ill with diarrhoea
Use latrines or bury your faeces
- Use latrines or other sanitation systems, like chemical toilets, to dispose of faeces.
- Wash hands with soap and safe water after defecating.
- Clean latrines and surfaces contaminated with faeces using a solution of 1 part household bleach to 9 parts water.
Cook food well (especially seafood)
- Be sure to cook shellfish (like crabs and crayfish) until they are very hot all the way through.
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