Cholera as One of the Deadliest Diseases - Research Paper Example

Cholera Cholera Cholera is an acute diarrheal condition, which is characterized as a highly infectious disease. It is caused by certain serotypes of Vibrio Cholera which lead to massive diarrhea and water loss, with death ensuing mainly because of hypovolemia (Tierney, Papadakis & McPhee 2007). Cholera mainly occurs in areas of war, hunger, famine or in refugee camps, arising from unsanitary conditions. Cholera spreads as an epidemic and history exhibits many deadly outbreaks of cholera in various places of world. Cholera should be considered as an important differential diagnosis of secretory diarrhea, specifically in those individuals who have a travel history to affected areas. The severe symptoms and worsening clinical course of cholera can be controlled or prevented by simple and basic methods of sanitation and personal hygiene. Moreover, new vaccinations against the pathogen are also evolving on the medical horizon, which is a sign of better cholera preventive methods. The outbreaks of cholera, are indeed a result of unsanitary conditions, however the conditions of war, the inefficiency of governments to provide adequate food supplies and poor socioeconomic conditions are major factors which lead to the development of such state of affairs. To understand the pathology and causes of cholera, it is not only imperative to focus on the symptoms, treatment and preventions, but also to highlight the socioeconomic and political factors which lead to the instigation of such dreaded outbreaks. A major epidemic of cholera originated during the time period of 1960s and 1970s. The outbreak started from Southeast Asia and spread to the areas in Africa, Europe and the rest of Asia (Levinson, 2008). The very first pandemic started in 1817-1823 in the Ganges River region which spread to Kolkata, India. The outbreak then spread to Southeast Asia, eastern Africa and the Mediterranean. The second pandemic broke in India from 1829-1849 and was transmitted to Russia, Poland and Finland by traders and merchants. In 1831 cases were seen in England too. Irish immigrants carried it to Canada and then it entered United States through Detroit, New York and Michigan (Bjorklund, 2011). Major cases of cholera were not seen in United States, until 1991 when an epidemic broke out in Western Hemisphere, specifically in the coastal cities of Peru (Tierney, Papadakis & McPhee 2007, 2007; Levinson, 2008). During the 19th century six pandemics of cholera had taken place and ended in 1923. In 1961 the seventh pandemic originated in Indonesia, spreading to Indian sub-continent and the Middle East, moving to Africa in 1970s and finally ending in United States in 1990s (Reidl & Klose, 2002). The history of cholera outbreaks has been dominated by sudden and swift spread of the pathogen, affecting more than one continent in very few period of time. Currently in United States, many toxigenic strains of V. cholerae are persistent in Gulf Coasts in Louisiana and Texas marshes. This poses a threat, as shipment of seafood takes place from these areas to all the possible regions of United States. Although, the highly hygienic conditions in United States make the outbreaks very less likely, but the reservoirs of the pathogen in the Gulf Coast are a possible cause of sporadic cases or outbreaks. Presently the EI strain is the biotype which is the cause of the pandemic around the world, and it is important for the physicians to be highly cautious of cholera cases especially in warm months of between July October (Blake, 1993). Nevertheless, in other areas of the world, poor socioeconomic conditions, underprivileged water quality, shortage of food, air pollution, inappropriate waste management systems and polluted sites are significant factors leading to cholera outbreaks or sporadic cases. In Iraq, many provinces have been a victim of fatal cholera outbreaks due to poor water sanitation. According to the studies of the water supply to Baghdad, it was observed that the outskirts of Baghdad was receiving very poor quality of water. Water contamination is caused by several biological, chemical and radiological agents and it is fatal for millions of residents in the Iraqi provinces. Sewage is thrown directly into the river and many areas have sewerage systems that are broken in some places. These factors lead to mixing of water in both the systems and such contaminated water is supplied to houses, shops and other places (Allaa & Singh, 2012). Poor international funding strategies in emergency crisis and the government instabilities are an important factor leading to the emergence of cholera outbreaks. Malawi is another region which faced a fatal cholera outbreak in 2002 along with a devastating food crisis, and thousands of people died because of the hazardous crisis. It was observed through critical analysis that the food crisis was mainly because of defects in pricing, inaccessibility to resources and the donor-government crisis rather than the mere shortage of food. The Malawi government was unable to rely on external sources of food and funding because of the worsening international relations with the creditors. Since Malawi government had sold its strategic grain reserve to the debts, the government was not able to recover from the mounting crisis. The financial irregularities resulted in cancellation of direct development funding by the United States, Britain, Denmark and the European Union. The government was unable to re-stock their food reserves or even import emergency funds, which lead to the worsening of the crisis (Attwell, 2013). Conditions of conflict or war lead to many unwanted and ominous factors which affect the general population. Africa is a victim of long-term conflicts between international bodies and has been a target of several poor socio-economic and health related conditions. Deaths, forced migrations, poverty, environmental degradations, development of drug resistances and break down of infectious control mechanisms are only some of the implications of conflict and war. These are some of the several factors which lead to the sporadic cases and outbreaks of cholera cases in Africa, which have been difficult to control. In December 2008, approximately 418 people died from cholera in the politically deranged region of Zimbabwe. According to the analysis of data sources, it has been estimated that cholera occurs more in countries with civil unrest and war, a significant example would the outbreaks in the northern Iraq. The relation with a country’s social and economic development can be supported by the example of Europe, where cholera cases have been almost ceased. In 2006, cholera was reported in 33 countries of Africa and it was estimated that 88% cases were from conflict-stricken areas of Africa (Okonko, 2009). Countries which are under an endless state of war are exposed to severe environmental, social and economic deterioration. Residents have inaccessibility to hygienic food and water; many are forced to live in refugee camps and have to live among insanitary conditions. All these factors are important causes of cholera outbreaks. Vibrio Cholera are gram negative organisms and have more than 200 recognized O serogroups. However, only O1 serotype and O139 serotype are associated with severe disease and the cholera pandemics. V. cholerae exists in aquatic ecosystems and functions as a facultative human pathogen. Within marine environment, it resides on plants, algae, copepods, crustaceans and insects. Contaminated water therefore is the main origin of epidemics, and by a lesser extent by contaminated food such as the seafood like crabs, shellfish and oysters (Reidl & Klose, 2002). Infection of cholera starts with oral ingestion of the pathogen either by food or water. The bacteria penetrate the mucus lining of the intestinal epithelium and also overcome the gastric acid barrier of the stomach. The bacteria colonizes the intestinal epithelium, produces the cholera toxin and the cholera symptoms. The bacteria produce an enterotoxin which is called choleragen. It is composed of an A (active) subunit and a B (binding) subunit. The B subunit binds to ganglioside receptor on surface of enterocytes and the A subunit is involved in ADP ribosylation. The watery diarrhea is so immense that it can lead to hypovolemic shock and death with 12 hours if not treated promptly. The toxin has an ADP ribosylation property which targets the stimulatory component of the G protein. It activates the adenylate cyclase leading to increased activity of the cAMP. cAMP inhibits the absorption of the sodium chloride from the gut lumen and increases bicarbonate and chloride secretion, leading eventually to hypovolaemia and hypo perfusion of critical organs (Reidl & Klose, 2002; Levinson, 2008). The diarrhea in cholera is often termed as rice-water stool because of absence of any red blood cells and neutrophils. It is not accompanied with abdominal pain and symptoms are marked by severe dehydration. Dehydration is characterized by loss of skin elasticity, sunken eyes, low blood pressure, low volume pulses, increased pulse rates and cold clammy skin (Coleman & Alcamo, 2003). The liquid stool can lead to a fluid loss of up to 1 L per hour. The stool is grey, without faecal odor, pus and turbid in appearance. The subsequent signs are caused by electrolyte disturbances and hypo-perfusion of critical organs leading to renal and cardiac failure. Acidosis and hypokalemia are also important consequences due to loss of bicarbonate and potassium in stool (Levinson, 2008; Tierney, Papadakis & McPhee 2007, 2007). Hypoglycemia is also another critical consequence and forty percent of children who reach this stage die of cholera (Coleman & Alcamo, 2003). V. cholerae has several virulence factors which are carried on the single-stranded DNA bacteriophage called CTX. The CTX phage transduces the genes for conversion of the non-toxin strains to toxin-producing strains. The pilli are another important virulence factor which help the organism to attach to the gut mucosa (Levinson, 2008). V. cholera is evolving as a pathogen, for example a new serotype O139 appeared which was due to the newly found LPS synthesis-encoding gene. These strains were derived from O1 EI strains. This new strain was able to overcome the developed human immunity and also led to the large outbreaks in 1992/93 in Bangladesh and India (Reidl & Klose, 2002). The laboratory diagnosis of cholera depends on the circumstances. In cases of epidemics, clinical diagnosis is sufficient and laboratory diagnosis is not required. For diagnosis of sporadic cases, culture of the stool shows V. cholerae colourless colonies on MacConkey’s agar. The organisms are oxidase positive, which is a distinguishing property. On TSI agar, an acid slant and an acid butt are seen, without production of gas or H2S, because of sucrose fermenting properties. Diagnosis can be confirmed by agglutination of the organism by polyvalent O1 or non-O1 antiserum (Levinson, 2008). As deadly as cholera’s clinical course can be, if prompt and early treatment is provided, cholera can be managed easily and efficiently. The main goal of cholera’s management is to restore body fluids lost by diarrhea or vomiting. Oral Rehydration Solution or ORS should be started as early as possible as it can be taken orally and can prevent the progression of the disease to exacerbated stages. A simple oral replacement fluid can be made at home by mixing 1 teaspoon of table salt and 4 teaspoons of sugar to 1 L of water. In severe cases of cholera, intravenous fluids should be given as early as possible to prevent electrolyte imbalance. Ringer’s Lactate is satisfactory in replacing fluids. Antimicrobial therapy is not effective in treating the disease, however it shortens the disease course. Antimicrobials mostly prescribed are tetracycline, ampicillin, chloramphenicol, tri-methoprim-sulfamethoxazole and flouroqinolones (Tierney, Papadakis & McPhee 2007; Coleman & Alcamo, 2003). Although antibiotic resistances are emerging, they should be prescribed wisely after susceptibility testing. Affected indivduals should continue their fluid intake even after the diarrhea subsides to compensate the massive fluid loss. Cholera prevention is mainly achieved by public health measures and they can signifacnlty reduce cholera cases and outbreaks. Proper water supply, sanitary management of seweage and hygienic living conditions control cholera outbreaks to a great extent. Clean food resources should also be supplied, specifically seafoods which are highly contaminated by V. cholerae. East Pakistan or Bangladesh was considered as the ‘incubator’of world’s cholera and a very high incidence of Asiatic cholera was estimated in Bangladesh. Family living habits, population density, transportation facilities, education factors and water and wastewater systems all contributed to the high incidence.According to a study carried out by United States, water and wastewater systems were constructed in Dacca, East Pakistan to combat the cholera outbreaks (McCabe, 1970). It has been proved that through efficient and sanitary water systems, cholera outbreaks can be controlled to great extent. Currently vaccinations against V. cholerae are also available. Vaccine currently available provides short-term protection against cholera and is required for entry or re-entry into a country. It is administered in two doses 1-4 weeks apart and a booster dose every 6 months is given for people living in hazardous environments (Tierney, Papadakis & McPhee 2007). Currently modern vaccinations are also under study which are focused on developing attenuated live vaccine strains. The non-invasive property of V. cholerae can be used to make a live vaccine that can induce a natural infection and would be helpful in generating stronger immunity response. However such vaccines still produce significant symptoms in humans and investigations are under study (Reidl & Klose, 2002). The acute diarrheal illness, cholera, has shown through the historical evidences that it is one of the deadliest water and food-borne diseases worldwide. Cholera emergence is highly associated with poor water quality due to contamination or contaminated food resources especially seafood such as oysters, shellfish or crabs. Cholera as an epidemic has particularized that it is not only associated with contaminated water ingestion, but the socio-economic conditions which lead to the emergence of such germ-infested circumstances. Evidences have supported that countries in a state of conflict have higher incidence of cholera, a noteworthy example is Africa. Similarly, countries which are facing financial loopholes are also faced with food shortages and inadequacy to provide emergency funding in cases of crisis. State of conflict leads to poverty, forced migrations into refugee camps, environmental degradation and inability to control emerging infectious diseases. Cholera is considered a dreaded outbreak because of its severe clinical course which can lead to death if management is not provided immediately. The cholera toxin has the ability to produce massive amount of fluid loss through diarrhea which leads to loss of blood volume, dehydration, electrolyte imbalances and critical organ failure. It is important to treat the disease, early in its course to prevent progression to end-stage by early fluid replacement and intense monitoring. Provision of clean water and food are the basic preventive methods for controlling sporadic cases as well as outbreaks. Although vaccinations are also available but public health awareness is the best preventive method for cholera. Even though cholera can turn out to be a clinically deadly condition, but simple and early preventive habits can be adapted to evade it. It is not only vital to provide sanitary conditions, but also to reflect and consider the underlying pathologies such as poverty, war, hunger crisis, forced migrations, poor government strategies and water and wastewater developments, leading to the advent of such perilous circumstances. 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