Yellow fever virus
TEM micrograph: Multiple yellow fever virions (234,000x magnificatio). The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings A00-A79 - Bacterial infections and other intestinal infectious diseases and STDs (A00-A09 Intestinal Infectious diseases ( The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books A micrograph, microphotograph or photomicrograph is a Photograph or similar image taken through a Microscope or similar device to show
Virus classification
Group: Group IV ((+)ssRNA) Family: Flaviviridae Genus: Flavivirus
Type species
Yellow fever virus

Yellow fever (also called yellow jack, black vomit or sometimes American Plague) is an acute viral disease. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable ^[1] It is an important cause of hemorrhagic illness in many African and South American countries despite existence of an effective vaccine. Bleeding, technically known as hemorrhaging / haemorrhaging (see American and British spelling differences) is the loss of Blood from South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease The yellow refers to the jaundice symptoms that affect some patients. Jaundice, also known as icterus (attributive adjective "icteric" is yellowish discoloration of the Skin, sclerae (whites of the eyes ^[2]

Yellow fever has been a source of several devastating epidemics. In Epidemiology, an epidemic (from Greek epi- upon + demos people is a classification of a disease that appears as new cases in a French soldiers were attacked by yellow fever during the 1802 Haitian Revolution; more than half of the army perished from the disease. Year 1802 ( MDCCCII) was a Common year starting on Friday of the Gregorian calendar or a Common year starting on Wednesday of the The Revolution (1791–1804 was the most successful of African Slave rebellions in the Western Hemisphere ^[3] Outbreaks followed by thousands of deaths occurred periodically in other Western Hemisphere locations until research, which included human volunteers (some of whom died), led to an understanding of the method of transmission to humans (primarily by mosquitos) and development of a vaccine and other preventative efforts in the early 20th century. The Western Hemisphere, also Western hemisphere or western hemisphere, is a geographical term for the half of the Earth that lies West Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs

Despite the costly and sacrificial breakthrough research by Cuban physician Carlos Finlay, American physician Walter Reed, and many others over 100 years ago, unvaccinated populations in many developing nations in Africa and Central and South America continue to be at risk. Carlos Juan Finlay (born Juan Carlos Finlay y Barrés on December 3 1833, Puerto Principe Cuba &ndash August 20 1915 Major Walter Reed, MD, ( September 13 1851 - November 23 1902) was a U ^[4] As of 2001, the World Health Organization (WHO) estimates that yellow fever causes 200,000 illnesses and 30,000 deaths every year in unvaccinated populations. ^[5]

Pathogenesis

The female Aedes aegypti mosquito on a human host, about to obtain a blood meal

Yellow fever is caused by an arbovirus of the family Flaviviridae, a positive sense single-stranded RNA virus. The yellow fever mosquito, Stegomyia aegypti (= Aedes aegypti, = Aedes (Stegomyia aegypti) is a Mosquito Arbovirus is a shortened name given to viruses that are transmitted by arthropods, or ar thropod- bo rne viruses. The Flaviviridae are a family of Viruses that are primarily spread through arthropod vectors (mainly ticks and mosquitoes Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Human infection begins after deposition of viral particles through the skin in infected arthropod saliva. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " For the band see Saliva (band; for the village in Azerbaijan see Səliva. The mosquitos involved are Aedes simpsaloni, A. africanus, and A. aegypti in Africa, the Haemagogus genus in South America,^[5] and the Sabethes genus in France. The yellow fever mosquito, Stegomyia aegypti (= Aedes aegypti, = Aedes (Stegomyia aegypti) is a Mosquito Yellow fever is frequently severe but moderate cases may occur as the result of previous infection by another flavivirus. After infection the virus first replicates locally, followed by transportation to the rest of the body via the lymphatic system. The lymphatic system in Vertebrates is a network of conduits that carry a clear fluid called Lymph. ^[6] Following systemic lymphatic infection the virus proceeds to establish itself throughout organ systems, including the heart, kidneys, adrenal glands, and the parenchyma of the liver; high viral loads are also present in the blood. In Mammals the adrenal glands (also known as suprarenal glands) are the triangle-shaped Endocrine glands that sit on top of the Kidneys their Parenchyma is a term used to describe a bulk of a substance It is used in different ways in Animals and in Plants. ^[1] Necrotic masses (Councilman bodies) appear in the cytoplasm of hepatocytes. A Councilman body, also known as a Councilman hyaline body is an Eosinophilic globule often found in the Liver of individuals suffering from Yellow The cytoplasm is the contents of a cell that is enclosed within the Plasma membrane. Hepatocytes make up 70-80% of the Cytoplasmic mass of the Liver. ^[6],[7]

Yellow fever begins suddenly after an incubation period of three to five days in the human body. In mild cases only fever and headache may be present. The severe form of the disease commences with fever, chills, bleeding into the skin, rapid heartbeat, headache, back pains, and extreme prostration. Nausea, vomiting, and constipation are common. Jaundice usually appears on the second or third day. After the third day the symptoms recede, only to return with increased severity in the final stage, during which there is a marked tendency to hemorrhage internally; the characteristic “coffee ground” vomitus contains blood. The patient then lapses into delirium and coma, often followed by death. During epidemics the fatality rate was often as high as 85%. Although the disease still occurs, it is usually confined to sporadic outbreaks.

There is a difference between disease outbreaks in rural or forest areas and in towns. Disease outbreaks in towns and non-native people may be more serious because of higher densities of mosquito vectors and higher population densities. Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs In Epidemiology, a vector is an Organism that does not cause Disease itself but which transmits Infection by conveying Pathogens from ^[8]

Prevention

In 1937, Max Theiler, working at the Rockefeller Foundation, developed a safe and highly efficacious vaccine for yellow fever that gives a ten-year or more immunity from the virus. Max Theiler ( January 30, 1899 &ndash August 11, 1972) was a South African Swiss virologist. The Rockefeller Foundation (RF is a prominent Philanthropic organization and Private foundation based at 420 Fifth Avenue New York City. A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease The vaccine consists of a live, but attenuated, virus called 17D. The 17D vaccine has been used commercially since the 1950s. The mechanisms of attenuation and immunogenicity for the 17D strain are not known. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium Immunogenicity is the ability of a particular substance which is called the Antigen, to provoke an Immune response. However, this vaccine is very safe, with few adverse reactions having been reported and millions of doses administered, and highly effective with over 90% of vaccinees developing a measurable immune response after the first dose.

Although the vaccine is considered safe, there are risks involved. The majority of adverse reactions to the 17D vaccine result from allergic reaction to the eggs in which the vaccine is grown. Persons with a known egg allergy should discuss this with their physician prior to vaccination. Egg allergy is a type of Food allergy. It is a Hypersensitivity to dietary substances from the yolk or whites of eggs, causing an overreaction In addition, there is a small risk of neurologic disease and encephalitis, particularly in individuals with compromised immune systems and very young children. Encephalitis is an acute Inflammation of the Brain, commonly caused by a viral Infection. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor The 17D vaccine is contraindicated in infants, pregnant women, and anyone with a diminished immune capacity, including those taking immunosuppressant drugs. In Medicine, a contraindication (pronounced as contra-indication is a condition or factor that increases the Risks involved in using a particular drug, For a list of immunosuppressive drugs see the Transplant rejection page.

According to the travel clinic at the University of Utah Hospital, the vaccine presents an increased risk of adverse reaction in adults aged 60 and older, with the risk increasing again after age 65, and again after age 70. The reaction is capable of producing multiple organ failure and should be evaluated carefully by a qualified health professional before being administered to the elderly.

Finally, there is a very small risk of more severe yellow fever-like disease associated with the vaccine. This reaction occurs in ~1-3 vaccinees per million doses administered. This reaction, called YEL-AVD, causes a fairly severe disease closely resembling yellow fever caused by virulent strains of the virus. Virulence (also called pestiferousness) refers to the degree of Pathogenicity of a Microbe, or in other words the relative ability of a Microbe The risk factor/s for YEL-AVD are not known, although it has been suggested that it may be genetic. The 2`-5` oligoadenylate synthetase (OAS) component of the innate immune response has been shown to be particularly important in protection from Flavivirus infection. Immune system|Adaptive immune systemThe innate immune system comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner In at least one case of YEL-AVD, the patient was found to have an allelic mutation in a single nucleotide polymorphism (SNP) of the OAS gene. A single nucleotide polymorphism ( SNP, pronounced snip) is a DNA sequence variation occurring when a single Nucleotide - A, T People most at risk of contracting the virus should be vaccinated. Woodcutters working in tropical areas should be particularly targeted for vaccination. Insecticides, protective clothing, and screening of houses are helpful, but not always sufficient for mosquito control; people should always use an insecticide spray while in certain areas. An insecticide is a Pesticide used against Insects in all developmental forms In affected areas, mosquito control methods have proven effective in decreasing the number of cases. The Mosquito Control EP is the first studio release by American Post-metal band Isis, released in 1998 by Escape Artist ^[9]

Recent studies have noted the increase in the number of areas affected by a number of mosquito-borne viral infections and have called for further research and funding for vaccines. ^[10],[11]

Treatment

There is no true cure for yellow fever, therefore vaccination is important. Treatment is symptomatic and supportive only. Fluid replacement, fighting hypotension and transfusion of blood derivates is generally needed only in severe cases. Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating bleeding fluid shifts or other pathologic processes In Physiology and Medicine, hypotension refers to an abnormally low Blood pressure. Blood substitutes, often called artificial blood, are used to fill fluid volume and/or carry Oxygen and other Blood gases in the Cardiovascular system In cases that result in acute renal failure, dialysis may be necessary. Acute renal failure ( ARF) also known as acute kidney failure or acute kidney injury, is a rapid loss of Renal function due to damage to the In Medicine, dialysis (from Greek "dialusis" meaning dissolution "dia" meaning through and "lusis" meaning loosening is primarily A fever victim needs to get a lot of rest, fresh air, and drink plenty of fluids.

Current research

In the hamster model of yellow fever, early administration of the antiviral ribavirin is an effective early treatment of many pathological features of the disease. Ribavirin (Copegus Rebetol Ribasphere VilonaVirazole also generics from Sandoz Teva Warrick is an Anti-viral drug which is active against a number of DNA and ^[12] Ribavirin treatment during the first five days after virus infection improved survival rates, reduced tissue damage in target organs (liver and spleen), prevented hepatocellular steatosis, and normalized alanine aminotransferase (a liver damage marker) levels. In cellular Pathology, steatosis (also called fatty change, fatty degeneration or adipose degeneration) is the process describing The results of this study suggest that ribavirin may be effective in the early treatment of yellow fever, and that its mechanism of action in reducing liver pathology in yellow fever virus infection may be similar to that observed with ribavirin in the treatment of hepatitis C, a virus related to yellow fever. ^[12] Because ribavirin had failed to improve survival in a virulent primate (rhesus) model of yellow fever infection, it had been previously discounted as a possible therapy. ^[13]

In 2007, the World Community Grid launched a project where by computer modeling of the yellow fever virus (and related viruses) thousands of small molecules are screened for their potential anti-viral properties in fighting yellow fever. This is the first project to utilize computer simulations in seeking out medicines to directly attack the virus once a person is infected. This is a distributed process project similar to SETI@Home where the general public downloads the World Community Grid agent and the program (along with thousands of other users) screens thousands of molecules while their computer would be otherwise idle. SETI@home ("SETI at home" is a Distributed computing ( Grid computing) project using Internet -connected computers hosted by the Space If the user needs to use the computer the program sleeps. There are several different projects running, including a similar one screening for anti-AIDS drugs. The project covering yellow fever is called "Discovering Dengue Drugs – Together. " The software and information about the project can be found at:

• World Community Grid web site

Prognosis

Historical reports have claimed a mortality rate of between 1 in 17 (5. 8%) and 1 in 3 (33%). CDC has claimed that case-fatality rates from severe disease range from 15% to more than 50%. ^[14] The WHO factsheet on yellow fever, updated in 2001, states that 15% of patients enter a "toxic phase" and that half of that number die within ten to fourteen days, with the other half recovering. ^[15]

History

Photograph taken during the 1965 Aedes aegypti eradication program in Miami, Florida

Yellow fever has had an important role in the history of Africa, the Americas, Europe, and the Caribbean. The yellow fever mosquito, Stegomyia aegypti (= Aedes aegypti, = Aedes (Stegomyia aegypti) is a Mosquito Florida ( is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the The Americas are the lands of the Western hemisphere or New World, consisting of the Continents of North America and South America The Caribbean (ˌkærəˡbiən kæ'rəbiən Cariben|Caraïben or Caraïben; Caraïbe or more commonly Antilles; Caribe is a Region consisting

Europe 541-549

Fragile after the fall of Rome, Europe was further weakened by "Yellow Plague" (yellow fever). The Decline of the Roman Empire, leading to the Fall of the Roman Empire, or the Fall of Rome, was the end of the Western Roman Empire. The Byzantine Empire suffered as well. ^[16]

Cuba: 1762-1763

British and American colonial troops died by the thousands in the British expedition against Cuba between 1762 and 1763. The British expedition against Cuba was a military action from March to August 1762 as part of the Seven Years' War. Epidemics struck coastal and island communities throughout the area during the next 140 years, with 10% of the population dying as a result. ^[17]

Haiti: 1802

In 1802, an army of forty thousand sent by First Consul Napoleon Bonaparte of France to Haiti to suppress the Haitian Revolution was dwindled out by an epidemic of yellow fever (including the expedition's commander and Bonaparte's brother-in-law, Charles Leclerc). Year 1802 ( MDCCCII) was a Common year starting on Friday of the Gregorian calendar or a Common year starting on Wednesday of the Napoleon Bonaparte (15 August 1769 – 5 May 1821 was a French military and political leader who had a significant impact on the History of Europe. This article is about the country For a topic outline on this subject see List of basic France topics. Haiti ( English: ˈheɪ·tiː or haɪ·ˈjiː·tiː French Haïti a·i·ti Haitian Creole: The Revolution (1791–1804 was the most successful of African Slave rebellions in the Western Hemisphere Charles Victor Emmanuel Leclerc ( Pontoise, Val-d'Oise, France, March 17, 1772 - Saint Domingue, November 2, Some historians believe Haiti was to be a staging point for an invasion of the United States through Louisiana (then still under French control). The United States of America —commonly referred to as the For the film see Louisiana Purchase (film. The Louisiana Purchase (French Vente de la Louisiane "Louisiana Sale" ^[18]

Norfolk, Virginia: 1855

A ship carrying persons infected with the virus arrived in Hampton Roads in southeastern Virginia in June 1855 . Hampton Roads is the name of both a body of water and the region of land areas which surround it in southeastern Virginia in the USA. The Commonwealth of Virginia ( is an American state ^[14] The disease spread quickly through the community, eventually killing over 3,000 people, mostly residents of Norfolk and Portsmouth. Norfolk is an Independent city in the Commonwealth of Virginia in the United States Portsmouth is an Independent city located in the US Commonwealth of Virginia. The Howard Association, a benevolent organization, was formed to help coordinate assistance in the form of funds, supplies, and medical professionals and volunteers which poured in from many other areas, particularly the Atlantic and Gulf Coast areas of the United States. Howard Association, a benevolent organization was formed in Norfolk Virginia during the 1855 Yellow Fever Epidemic which killed 1 in 3 residents of Norfolk and sister The Gulf of Mexico ( Spanish: Golfo de México) is the ninth largest Body of water in the world The United States of America —commonly referred to as the See also The Mermaids and Yellow Jack: A NorFolktale a children's historical fiction written by Norfolk author Lisa Suhay, telling of the event and founding of the Bon Secours DePaul Hospital system in the United States in response to the epidemic. ^[19]

Memphis, Tennessee: 1878

The worst yellow fever epidemic in U. S. history occurred in 1878, with over 5,000 deaths in Memphis alone and 20,000 deaths in the whole of the Mississippi Valley.

Carlos Finlay and Walter Reed

An entomologist demonstrates the attraction of female yellow fever mosquitoes to his hand in an olfactometer.

Carlos Finlay, a Cuban doctor and scientist, first proposed proofs in 1881 that yellow fever is transmitted by mosquitoes rather than direct human contact. Carlos Juan Finlay (born Juan Carlos Finlay y Barrés on December 3 1833, Puerto Principe Cuba &ndash August 20 1915 Mosquitoes are insects in the family Culicidae. They have a pair of scaled wings a pair of Halteres, a slender body and long legs ^[20] Walter Reed, M. Major Walter Reed, MD, ( September 13 1851 - November 23 1902) was a U D. , (1851-1902) was an American Army surgeon who led a team that confirmed Finlay's theory. The United States Army is a military organization whose primary mission is to "provide necessary forces and capabilities. This risky but fruitful research work was done with human volunteers, including some of the medical personnel such as Clara Maass and Walter Reed Medal winner surgeon Jesse William Lazear who allowed themselves to be deliberately infected and died of the virus. Clara Louise Maass ( June 28, 1876 &ndash August 24, 1901) was an American Nurse who died as a result of volunteering The Walter Reed Medal is a military decoration of the United States Army which was created by an act of the United States Congress Jesse William Lazear ( 2 May 1866, Baltimore - 26 September 1900 in Quemados, Cuba) was an American ^[21] The acceptance of Finlay's work was one of the most important and far-reaching effects of the Walter Reed Commission of 1900. ^[22] Applying methods first suggested by Finlay, the elimination of yellow fever from Cuba was completed, as well as the completion of the Panama Canal. Lamentably, almost 20 years had passed before Reed and his Board began their efforts, twenty years during which most of the scientific community ignored Finlay's theory of mosquito transmission.

Finlay and Reed's work was put to the test for the first time in the United States when a yellow fever epidemic struck New Orleans in 1905, although efforts had been successful in Havana since 1901; according to the PBS American Experience documentary The Great Fever, houses were fumigated, cisterns for drinking water were inspected, and pools of standing water were treated with kerosene. New Orleans (nʲuːˈɔrliənz nʲuːˈɔrlənz French: La Nouvelle-Orléans) is a major United States port city and the largest city in Louisiana Year 1905 ( MCMV) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar (or a Common year starting The Public Broadcasting Service ( PBS) is a Non-profit Public broadcasting Television service with 354 member TV stations in the American Experience (sometimes abbreviated AmEx) is a Television program airing on the PBS network in the United States Kerosene, sometimes spelled kerosine in scientific and industrial usage is a Combustible Hydrocarbon liquid The result was that the death toll from the epidemic was much lower than that from previous yellow fever epidemics, and that there has not been a major outbreak of the disease in the United States since. Although no cure has yet been discovered, an effective vaccine has been developed, which can prevent and help people recover from the disease.

References

Further reading

• Downs, Wilbur H. , et al. . "Virus diseases in the West Indies". Caribbean Medical Journal 1965 (XXVI(1-4)): –.  
• Theiler, Max and Downs, W. G. The Anthropod-Borne Viruses of Vertebrates: An Account of the Rockefeller Foundation Virus Program, 1951-1970. Yale University Press, 1973.

External links

• WHO site on yellow fever
• Health Information for International Travel, 2005-2006:from Centers for Disease Control and Prevention

Historical yellow fever information

• The Great Fever on PBS
• PBS website on the 1793 Philadelphia yellow fever epidemic.
• Yellow Fever in Norfolk and Portsmouth 1855 an extensive website
• Interactive Internet article on the 1855 Yellow Fever Epidemic from Pilot Online, Hampton Roads: a detailed story with maps, slides, and quiz
• New Orleans, 1905: Housing Conditions and the Yellow Fever: a case study
• Yellow fever deaths in New Orleans.
• Enzootic transmission of yellow fever virus in Peru.
• World Health Organization report on yellow fever

Vaccine development

• Turning Yellow - article by Christine Soares