Vibrio choleraestr.El Tor | |
---|---|
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Vibrionales |
Family: | Vibrionaceae |
Genus: | Vibrio |
Species: | V. cholerae |
Strain: | 'El Tor' |
Trionomial name | |
Vibrio choleraestr. 'El Tor' |
El Tor is a particular strain of the bacterium Vibrio cholerae , the causative agent of cholera. Also known as V. cholerae biotype eltor, it has been the dominant strain in the seventh global cholera pandemic. It is distinguished from the classic strain at a genetic level, although both are in the serogroup O1 and both contain Inaba, Ogawa and Hikojima serotypes. It is also distinguished from classic biotypes by the production of hemolysins.
At the turn of the 20th century, the Ottoman government established six medical stations along the coast of the Sinai Peninsula to cater to pilgrims returning from Mecca. One of them was in El Tor (A' Tur as it is called today). Sick passengers were dropped off in one of the stations for treatment. In 1905, Felix Gotschlich, a German physician at the El Tor station identified vibrios in stool specimen of two pilgrims returning from Mecca. Though the pilgrims failed to show ante or post mortem evidence of cholera, the vibrios isolated agglutinated with the anti-cholera serum. He did not think it was cholera, since it was hemolytic for human and animal red cells, while the true Vibrio cholerae is not. At that time, there was no cholera epidemic in Mecca or at the El Tor station, and the two pilgrims died from other causes. [1]
Later in 1905, Kraus and Pribram found that the bacteria, which produced soluble hemolysin, were more related to non-cholera vibrios; therefore, referred to all hemolytic vibrios as El Tor vibrios. In the early 1930s, A. Shousha, A. Gardner and K. Venkatraman, all researchers, suggested that only hemolytic vibrios agglutinated with anti-cholera serum should be referred to as El Tor vibrios. In 1959, R. Pollitzer designated El Tor as its own species V. eltor separate from V. cholerae, but six years later, in 1965, R. Hugh discovered that V. cholerae and V. eltor were similar in 30 positive and 20 negative characteristics. Thus, they were classified as a single species V. cholerae: however, Hugh believed the differing features between the two could be of epidemiological importance, so El Tor vibrios were further classified as V. cholerae biotype eltor (serogroup O1). [2]
El Tor was identified again in an outbreak in 1937 but the pandemic did not arise until 1961 in Sulawesi. El Tor spread through Asia (Bangladesh in 1963, India in 1964) and then into the Middle East, Africa and Europe. From North Africa it spread into Italy by 1973. The extent of the pandemic has been due to the relative mildness (lower expression level) of El Tor, the disease has many more asymptomatic carriers than is usual, outnumbering active cases by up to 50:1. The outbreaks during this time frame are believed to be due to the rapid development of transportation and communication on an international level, as well as decreased sanitation levels in areas with increasing populations. [2] In the late 1970s there were small outbreaks in Japan and in the South Pacific.
Molecular evidence, that is, a specific pulsed-field gel electrophoresis profile, suggests that the distinct genotype of El Tor strain which appeared in Calcutta in 1993, may have spread to Africa. In the country of Guinea-Bissau, it was responsible for an epidemic that began in October 1994 and continued into 1996. [3]
An El Tor infection is relatively mild, or at least rarely fatal, and patients are asymptomatic for about a week. El Tor is able to survive in the body longer than classical cholera vibrios. This characteristic allows carriers to infect a greater population of people. In fact, V. cholerae biotype eltor can be isolated from water sources in the absence of an outbreak of cases. In extreme cases, persons can become long-term carriers; for example, Cholera Dolores, who tested vibrio positive nine years after her primary infection. El Tor is transmitted by the fecal-oral route. This route is the consequence of infected persons defecating near a water source, and uninfected persons consuming contaminated water. In addition, the bacteria can be transmitted by consuming uncooked food fertilized with human feces. Treatment of a cholera infection consists of replenishing lost fluid and electrolytes by intravenous or oral solutions, and by antibiotics. [2] El Tor outbreaks can be prevented by better standards of sanitation, filtering and boiling water, [4] thoroughly cooking seafood, and washing vegetables and fruits before consumption.
Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholerae. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea that lasts a few days. Vomiting and muscle cramps may also occur. Diarrhea can be so severe that it leads within hours to severe dehydration and electrolyte imbalance. This may result in sunken eyes, cold skin, decreased skin elasticity, and wrinkling of the hands and feet. Dehydration can cause the skin to turn bluish. Symptoms start two hours to five days after exposure.
Vibrio cholerae is a species of Gram-negative, facultative anaerobe and comma-shaped bacteria. The bacteria naturally live in brackish or saltwater where they attach themselves easily to the chitin-containing shells of crabs, shrimps, and other shellfish. Some strains of V. cholerae are pathogenic to humans and cause a deadly disease cholera, which can be derived from the consumption of undercooked or raw marine life species.
Shigellosis is an infection of the intestines caused by Shigella bacteria. Symptoms generally start one to two days after exposure and include diarrhea, fever, abdominal pain, and feeling the need to pass stools even when the bowels are empty. The diarrhea may be bloody. Symptoms typically last five to seven days and it may take several months before bowel habits return entirely to normal. Complications can include reactive arthritis, sepsis, seizures, and hemolytic uremic syndrome.
Vibrio is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Typically found in salt water, Vibrio species are facultative anaerobes that test positive for oxidase and do not form spores. All members of the genus are motile. They are able to have polar or lateral flagellum with or without sheaths. Vibrio species typically possess two chromosomes, which is unusual for bacteria. Each chromosome has a distinct and independent origin of replication, and are conserved together over time in the genus. Recent phylogenies have been constructed based on a suite of genes.
Vibrio vulnificus is a species of Gram-negative, motile, curved rod-shaped (bacillus), pathogenic bacteria of the genus Vibrio. Present in marine environments such as estuaries, brackish ponds, or coastal areas, V. vulnificus is related to V. cholerae, the causative agent of cholera. At least one strain of V. vulnificus is bioluminescent.
Vibrio parahaemolyticus(V. parahaemolyticus) is a curved, rod-shaped, Gram-negative bacterium found in the sea and in estuaries which, when ingested, may cause gastrointestinal illness in humans. V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores. Like other members of the genus Vibrio, this species is motile, with a single, polar flagellum.
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The discovery of disease-causing pathogens is an important activity in the field of medical science. Many viruses, bacteria, protozoa, fungi, helminthes and prions are identified as a confirmed or potential pathogen. In the United States, a Centers for Disease Control program, begun in 1995, identified over a hundred patients with life-threatening illnesses that were considered to be of an infectious cause, but that could not be linked to a known pathogen. The association of pathogens with disease can be a complex and controversial process, in some cases requiring decades or even centuries to achieve.
The first cholera pandemic (1817–1824), also known as the first Asiatic cholera pandemic or Asiatic cholera, began near the city of Calcutta and spread throughout South and Southeast Asia to the Middle East, eastern Africa and the Mediterranean coast. While cholera had spread across India many times previously, this outbreak went further; it reached as far as China and the Mediterranean Sea before subsiding. Millions of people died as a result of this pandemic, including many British soldiers, which attracted European attention. This was the first of several cholera pandemics to sweep through Asia and Europe during the 19th and 20th centuries. This first pandemic spread over an unprecedented range of territory, affecting almost every country in Asia.
The third cholera pandemic (1846–1860) was the third major outbreak of cholera originating in India in the nineteenth century that reached far beyond its borders, which researchers at UCLA believe may have started as early as 1837 and lasted until 1863. In Russia, more than one million people died of cholera. In 1853–54, the epidemic in London claimed over 10,000 lives, and there were 23,000 deaths for all of Great Britain. This pandemic was considered to have the highest fatalities of the 19th-century epidemics.
The fourth cholera pandemic of the 19th century began in the Ganges Delta of the Bengal region and traveled with Muslim pilgrims to Mecca. In its first year, the epidemic claimed 30,000 of 90,000 pilgrims. Cholera spread throughout the Middle East and was carried to Russia, Europe, Africa and North America, in each case spreading via travelers from port cities and along inland waterways.
The fifth cholera pandemic (1881–1896) was the fifth major international outbreak of cholera in the 19th century. It spread throughout Asia and Africa, and reached parts of France, Germany, Russia, and South America. It claimed 200,000 lives in Russia between 1893 and 1894; and 90,000 in Japan between 1887 and 1889. The 1892 outbreak in Hamburg, Germany was the biggest European outbreak; about 8,600 people died in that city. Although many residents held the city government responsible for the virulence of the epidemic, it continued with practices largely unchanged. This was the last serious European cholera outbreak of the century.
The 1961–1975 cholera pandemic was the seventh major outbreak of cholera and occurred principally from the years 1961 to 1975; the strain involved persists to the present. This pandemic, based on the strain called El Tor, started in Indonesia in 1961 and spread to East Pakistan, by 1963. Then it went to India in 1964, followed by the Soviet Union by 1966. In July 1970, there was an outbreak in Odessa and in 1972 there were reports of outbreaks in Baku, but the Soviet Union suppressed this information. It reached Italy in 1973 from North Africa. Japan and the South Pacific saw a few outbreaks by the late 1970s. In 1971, the number of cases reported worldwide was 155,000. In 1991, it reached 570,000. The spread of the disease was helped by modern transportation and mass migrations. Mortality rates, however, dropped markedly as governments began modern curative and preventive measures. The usual mortality rate of 50% dropped to 10% by the 1980s and less than 3% by the 1990s.
Sambhunath De ; was an Indian medical scientist and researcher, who discovered the cholera toxin, the animal model of cholera, and successfully demonstrated the method of transmission of cholera pathogen Vibrio cholerae.
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Seven cholera pandemics have occurred in the past 200 years, with the first pandemic originating in India in 1817. Additionally, there have been many documented cholera outbreaks, such as a 1991–1994 outbreak in South America and, more recently, the 2016–2021 Yemen cholera outbreak.
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Nirmal Kumar Dutta (1913–1982) was an Indian pharmacologist, medical academic and the director of Haffkine Institute, Mumbai. He was known for his contributions to the studies on cholera and was an elected fellow of the National Academy of Medical Sciences, National Academy of Sciences, India and the Indian National Science Academy. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards for his contributions to Medical Sciences in 1965.
Cholera epidemic in Lexington, Kentucky was a major cholera epidemic in 1833. An estimated 502 out of 7,000 people died as a result of this epidemic and resulted in major changes in the city. Cholera is "an acute, diarrheal illness caused by infection of the intestine with the toxigenic bacterium Vibrio cholerae serogroup O1 or O139".
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