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Three outbreak investigations on norovirus
Literature review on norovirus disease
Literature review on norovirus disease
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Recommended: Three outbreak investigations on norovirus
Introduction
Norovirus is one of the leading causes, if not the leading cause of gastroenteritis worldwide (6).
Transmission Norovirus is extremely contagious and is transmitted primarily via the fecal-oral route and is transmitted by way of fomites, consuming contaminated food or water, or contact with an infected person (2). It can also be transmitted if the vomit of an infected person becomes aerosolized (2). One study estimated that the average number of norovirus particles necessary to cause infection is as low as 0.5, meaning that of people who contracted a single norovirus virion, half will become infected (3). As of 2008, that is the lowest of any virus that has been studied (3). Norovirus is one of the few viruses that is transmitted mostly through contaminated food. This usually happens when an infected person fails to properly wash his or her hands after using the bathroom and before preparing food. Many people infected with norovirus are asymptomatic which increases the spread of the virus. Infected but asymptomatic food handlers have been the cause of several norovirus outbreaks (4). The virus can also build up inside filter feeding shellfish such as oysters, mussels, and clams if surrounding water becomes contaminated with human waste (5). A study performed in South Korea that collected shellfish and tested them for norovirus showed that it was present in approximately 27.9
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Using genetic analysis, the virus has been further divided into many genogroups: GI, GII, GIII, GIV, and GV (8). Of the five genogroups only GI, GII, and GIV infect humans (8). Norovirus is a T=3 icosahedral and does not have an envelope (9). Its mass is approximately 56-76 kDaltons and its capsid diameter is anywhere from 23 to 38 nm (9,10). Its genome is linear and is approximately 7.3 to 8.3 kb
This extremely pathogenic zoonotic virus is now understood to travel from bat species, to equine intermediate hosts, to humans.[8, 10] The Hendra virus is listed as a Bio-Safety Level (BSL)-4, and can only be studied at a few adequately equipped laboratories worldwide due to its virulence.[1, 2] Case fatality rates
In crowded conditions, the rate of infection is even more rapid. The diseases brought over to America were mainly spread by the respiratory method. The pathogenesis of infection is through the ingestion of contaminated food and water. Throughout Europe during the 15th century, food and water were contaminated with fecal matter and by unsanitary habits ( i.e. the lack of bathing). The traumatic route of infection is through insect and animal bites.
The norovirus is small and round. It is only 27-35 nm in diameter. The virus contains a single- stranded RNA genome. Noroviruses are divided into five genogroups, G1- G5. Of these five genogroups, only G1, G2, and G4 are known to infect humans. G2 is the most common in adult cases of gastroenteritis. 1 “Noroviruses are not enveloped and contain an outer protein capsid encapsulating an RNA genome.”2
The virus is primarily spherical shaped and roughly 200nm in size, surrounded by a host-cell derived membrane. Its genome is minus-sense single-stranded RNA 16-18 kb in length. It contains matrix protein inside the envelope, hemagglutinin and neuraminidase, fusion protein, nucleocapsid protein, and L and P proteins to form the RNA polymerase. The host-cell receptors on the outside are hemagglutinin and neuraminidase. The virus is allowed to enter the cell when the hemagglutinin/ neuraminidase glycoproteins fuse with the sialic acid on the surface of the host cell, and the capsid enters the cytoplasm. The infected cells express the fusion protein from the virus, and this links the host cells together to create syncitia.
HAV is known to be an infectious disease that usually occurs in children and young adults .The disease is usually transmitted from person to person through contaminated food, liquids or oral fecal route. An example would be when someone is carrying the virus and doesn’t wash their hands after using the restroom and then puts food in their mouth. HAV is most common in developing countries because of the living conditions and inadequate water, poor sewage facilities and sanitary conditions. The highest HAV levels in the world are from India,” Earlier reports suggest that India is hyperendemic for HAV infection2,4-6 with very high infection rates,” (Sowmyanarayanan). Most HAV are without severe complications, “Virus HAV infection rarely causes fulminant hepatic failure in people…,” (Vento,p.1) . The symptoms for HAV are high fever, nausea, vomiting and jaundice...
Salmonella is one of the most common causes of food poisoning. It is a gram-negative, aerobic (oxygen requiring), rod-shaped bacterium that can infect humans, birds, reptiles, and other animals. It results in the swelling of the lining of the stomach and intestines. Salmonella food poisoning occurs worldwide, however it is most frequently reported in North America and Europe. In the United States, Salmonella is responsible for about 15% of all cases of food poisoning (Salmonella food poisoning).
Hantavirus is a virus in the Bunyaviridae family of viruses. Dr. Lee Ho Wang from Korea discovered Hantavirus in the early 1950s. Though the virus is commonly found in rodents, it does not cause disease in the rodents. Disease results when the virus is transmitted to humans. A common way of contracting Hantavirus is from breathing in dust that has been contaminated by an infected rodent’s saliva, feces or urine or the infected dust gets into broken skin. It is also transmitted by the bite of an infected rodent. So far, it has not been confirmed that Hantavirus can be passed on from person to person. The most common places to contract Hantavirus are Korea, China or most countries in Asia. In Korea, Hantavirus seems to have two major “seasons;” May to June and October to November are the times of year when the disease is more prevalent because the rodent populations are higher during these times. There are two forms of Hantavirus, the mild illness found in Scandinavia, and the more severe illness found in the Far East and Central Europe.
Viruses can be transmitted in many ways. Being in contact with an infected person will most likely transfer the virus. One can also obtain the virus through swallowing, inhaling, and unsafe sex. Poor hygiene and eating habits usually increase the risk of catching a viral infection. Contracting a viral infection is followed by adverse s...
Recent research shows that, there are three major means by which infections can be transmitted and they include direct transmission, indirect transmission and airborne transmission (Hinman,Wasserheit and Kamb,1995). Direct transmission occurs when the physical contact between an infected person and s susceptible person takes place (division of public health, 2011). An example is a health care worker who attends to an Ebola patient, without gloves, gown and mask plus forget to wash his or her hand with soap and hot water and or a person having flu without the use of mask or washes his hand after sneezing easily passes the infection to the other through hand shake or surface touch, living the bacteria there for another vulnerable person to also touch if the surface is not disinfected with bleach. Studies makes it clear that, the spreads takes effect when disease-causing microorganisms pass from the infected person to the healthy person through direct physical contact such as touching of blood, body fluids, contact with oral secretion, bites kissing, contact with body lesions and even sexual contact. However, measles and chicken pox are said to be conditions spread by direct
Food-borne transmission refers to any illness that results due to the consumption of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as chemical or natural toxins such as poisonous mushrooms (cdc.gov). Bacteria is the most often the pathogen that causes food-borne illness. This is usually due to improper handling of foods, improper preparation of food and improper food storage. According to the CDC, the top 5 contributing pathogens to food-borne illness are Norovirus, non-typhoidal Salmonella, Clostridium perfringens, Campylobacter spp. and Staphylococcus aureus.
However, some of them can cause intestinal infection. Bacteria which can cause infections can enter to human body of different ways. Meat contaminated with E.coli bacteria during processing, contaminated water, from person to person and through improper food handling. Infected faeces of animals or human sometimes get into lakes, water supplies or pools so people can become infected when they use this contaminated water. The infected meat needs to be cooked to 160 F0 (71C0) if it is cooked below that the bacteria can survive and affect the person who eats that meat. Any food, which is in contact with row meat, can become
The most commonly recognized food borne infections are those caused by the bacteria Campylobacter, Salmonella, and E. coli 0157:H7, and by a group of viruses called Calicivirus, also know as the Norwalk viruses. “Thousands of types of bacteria are naturally present in our environment, but not all bacteria cause disease in humans.” (Schmutz 1)
The most common cause of gastroenteritis in adults is the transmission of norovirus; a viral infection that spreads from fecal matter. Noroviruses are highly contagious and can spread directly from person to person, or indirectly through contaminated water and food. When a person is infected, the norovirus attacks their small intestine, entering a host cell by attaching to receptors and triggering endocytosis. It then proceeds to replicate itself, increasing the number of infected cells in the body. Symptoms appear roughly 1-2 days after the initial exposure to the virus, and lasts between 1-3 days. Nausea, vomiting, diarrhoea and a loss of appetite are common symptoms of norovirus, however sufferers may also experience muscle aches, weakness and mild fevers and headaches. Rotavirus is another prevalent agent that causes gastroenteritis, however it only affects infants and young children, due to the fact that immunity against it is developed after infection. It is incredibly common and virtually every child in the world experiences symptoms of the rotavirus before they reach the age of
Brown, G. S. (2013, March 8). Royal Caribbean Cruisers Ill With Apparent Norovirus. ABC News. Retrieved from http://abcnews.go.com/Travel/royal-caribbean-passengers-sick-apparent-norovirus/story?id=18687875
As per the eighth report of the International Committee on Taxonomy of Viruses (ICTV), the family Iridoviridae is subdivided into five genera, Iridovirus, Chlo-riridovirus, Ranavirus, Lymphocystisvirus and Megalocytivirus. Prominently, Megalocytivirus has gotten the most consideration in examine because of its wide host extend and on the grounds that it causes critical mortality in the aquaculture industry (Subramaniam et al.,