El Tor
Encyclopedia
El Tor is the name given to a particular strain of the bacterium Vibrio cholerae
, the causative agent of cholera
. Also known as V. cholera biotype eltor, it has been the dominant strain in the seventh global 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 serotype
s. It is also distinguished from classic biotypes by the production of hemolysins.
in El-Tor
, Egypt
by a German physician, E. Gotschlich. The vibrios were found in the guts of six pilgrims returning from Mecca
. Though the pilgrims failed to show ante or post mortem evidence of cholera, the vibrios isolated from the guts were agglutinable within the anti-cholera serum.
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. cholera, 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. cholera: however, Hugh believed the differing features between the two could be of epidmiological importance, so El Tor vibrios were further classified as V. cholerae biotype eltor (serogroup O1).
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. 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 the African subcontinent. In the country of Guinea-Bissau, it was responsible for an epidemic that began in October 1994 and continued into 1996.
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 antibiotic
s. El Tor outbreaks can be prevented by better standards of sanitation, filtering and boiling water, thoroughly cooking seafood, and washing vegetables and fruits before consumption.
Vibrio cholerae
Vibrio cholerae is a Gram-negative, comma-shaped bacterium. Some strains of V. cholerae cause the disease cholera. V. cholerae is facultatively anaerobic and has a flagella at one cell pole. V...
, the causative agent of cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
. Also known as V. cholera biotype eltor, it has been the dominant strain in the seventh global pandemic
Pandemic
A pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...
. It is distinguished from the classic strain at a genetic level, although both are in the serogroup
Serotype
Serotype or serovar refers to distinct variations within a subspecies of bacteria or viruses. These microorganisms, viruses, or cells are classified together based on their cell surface antigens...
O1 and both contain Inaba, Ogawa and Hikojima serotype
Serotype
Serotype or serovar refers to distinct variations within a subspecies of bacteria or viruses. These microorganisms, viruses, or cells are classified together based on their cell surface antigens...
s. It is also distinguished from classic biotypes by the production of hemolysins.
History
It was first identified in 1905 at a quarantine camp on the Sinai PeninsulaSinai Peninsula
The Sinai Peninsula or Sinai is a triangular peninsula in Egypt about in area. It is situated between the Mediterranean Sea to the north, and the Red Sea to the south, and is the only part of Egyptian territory located in Asia as opposed to Africa, effectively serving as a land bridge between two...
in El-Tor
El-Tor
El-Tor , also transliterated as Al-Tur and At-Tur and known as Tur Sinai, formerly Raithu, is the capital of South Sinai Governorate of Egypt, located at the Sinai Peninsula...
, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
by a German physician, E. Gotschlich. The vibrios were found in the guts of six pilgrims returning from Mecca
Mecca
Mecca is a city in the Hijaz and the capital of Makkah province in Saudi Arabia. The city is located inland from Jeddah in a narrow valley at a height of above sea level...
. Though the pilgrims failed to show ante or post mortem evidence of cholera, the vibrios isolated from the guts were agglutinable within the anti-cholera serum.
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. cholera, 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. cholera: however, Hugh believed the differing features between the two could be of epidmiological importance, so El Tor vibrios were further classified as V. cholerae biotype eltor (serogroup O1).
El Tor was identified again in an outbreak in 1937 but the pandemic did not arise until 1961 in Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
. El Tor spread through Asia (Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
in 1963, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
in 1964) and then into the Middle East, Africa and Europe. From North Africa it spread into Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
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. 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 the African subcontinent. In the country of Guinea-Bissau, it was responsible for an epidemic that began in October 1994 and continued into 1996.
Epidemiology
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 choleraCholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
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
Human feces
Human feces , also known as a stool, is the waste product of the human digestive system including bacteria. It varies significantly in appearance, according to the state of the digestive system, diet and general health....
. Treatment of a cholera infection consists of replenishing lost fluid and electrolytes by intravenous or oral solutions, and by antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s. El Tor outbreaks can be prevented by better standards of sanitation, filtering and boiling water, thoroughly cooking seafood, and washing vegetables and fruits before consumption.