Portal:Viruses

Gastroenteritis is an inflammation of the gastrointestinal tract involving both the stomach and small intestine, which results in diarrhoea and vomiting, and sometimes abdominal pain. It is usually caused by a virus: most commonly rotavirus and norovirus, but also adenovirus and astrovirus. Other major infectious causes include Campylobacter, Escherichia coli, Vibrio cholerae and some other bacteria, as well as protozoa. Viruses, particularly rotavirus, cause about 70% of gastroenteritis episodes in children, while norovirus is the leading cause of gastroenteritis among adults in America, causing over 90% of outbreaks.

Transmission can be from consumption of improperly prepared foods or contaminated water, or by close contact with infectious individuals. Good sanitation practices and a convenient supply of uncontaminated water are important for reducing infection. Personal measures such as hand washing with soap can decrease incidence by as much as 30%. An estimated 2 billion cases of gastroenteritis occurred globally in 2015, mainly among children and people in developing countries, resulting in 1.3 million deaths. Gastroenteritis is usually an acute and self-limiting disease that does not require medication; the main treatment is rehydration using oral rehydration therapy. A rotavirus vaccine is available.

Biosafety level 3 equipment is used for research with viruses such as influenza that can cause serious disease but for which treatment is available. The biosafety cabinet uses HEPA filters to filter viruses out of the air. This researcher is examining reconstructed 1918 pandemic influenza virus, or "Spanish flu".

Credit: CDC (2005)

Map showing the prevalence of SARS-CoV-2 cases; black: highest prevalence; dark red to pink: decreasing prevalence; grey: no recorded cases or no data

26 February: In the ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more than 110 million confirmed cases, including 2.5 million deaths, have been documented globally since the outbreak began in December 2019. WHO

18 February: Seven asymptomatic cases of avian influenza A subtype H5N8, the first documented H5N8 cases in humans, are reported in Astrakhan Oblast, Russia, after more than 100,0000 hens died on a poultry farm in December. WHO

14 February: Seven cases of Ebola virus disease are reported in Gouécké, south-east Guinea. WHO

7 February: A case of Ebola virus disease is detected in North Kivu Province of the Democratic Republic of the Congo. WHO

4 February: An outbreak of Rift Valley fever is ongoing in Kenya, with 32 human cases, including 11 deaths, since the outbreak started in November. WHO

21 November: The US Food and Drug Administration (FDA) gives emergency-use authorisation to casirivimab/imdevimab, a combination monoclonal antibody (mAb) therapy for non-hospitalised people twelve years and over with mild-to-moderate COVID-19, after granting emergency-use authorisation to the single mAb bamlanivimab earlier in the month. FDA 1, 2

18 November: The outbreak of Ebola virus disease in Équateur Province, Democratic Republic of the Congo, which started in June, has been declared over; a total of 130 cases were recorded, with 55 deaths. UN

Reverse transcriptase is an enzyme that generates complementary DNA from an RNA template, in contrast to the usual information flow from DNA to RNA. It was discovered in Rous sarcoma virus and murine leukaemia virus, two retroviruses, by Howard Temin and David Baltimore, working independently in 1970, for which the two shared the Nobel Prize in Physiology or Medicine.

Reverse transcription is essential for the replication of retroviruses, allowing them to integrate into the host genome as a provirus. The enzyme is a target for reverse-transcriptase inhibitors, a major class of anti-HIV drugs. Reverse transcription is also used by Hepadnaviridae and Caulimoviridae, DNA viruses that replicate via an RNA intermediate, such as hepatitis B. The process is important in the movement of retrotransposons, a type of mobile genetic element, and in the extension of chromosome ends in eukaryotic genomes. The enzyme is widely used in the laboratory for molecular cloning, RNA sequencing, polymerase chain reaction and genome analysis.

The 1918–20 influenza pandemic, the first of the two involving H1N1 influenza virus, was unusually deadly. It infected 500 million people across the entire globe, with a death toll of 50–100 million (3–5% of the world's population), making it one of the deadliest natural disasters of human history. It has also been implicated in the outbreak of encephalitis lethargica in the 1920s. Despite the nickname "Spanish flu", the pandemic's geographic origin is unknown.

Most influenza outbreaks disproportionately kill young, elderly or already weakened patients; in contrast this predominantly killed healthy young adults. Contemporary medical reports suggest that malnourishment, overcrowded medical facilities and poor hygiene promoted fatal bacterial pneumonia. Some research suggests that the virus might have killed through a cytokine storm, an overreaction of the body's immune system. This would mean the strong immune reactions of young adults resulted in a more severe disease than the weaker immune systems of children and older adults.

Viruses & Subviral agents: bat virome • elephant endotheliotropic herpesvirus • HIV • introduction to viruses • Playa de Oro virus • poliovirus • prion • rotavirus • virus

Diseases: colony collapse disorder • common cold • croup • dengue fever • gastroenteritis • Guillain–Barré syndrome • hepatitis B • hepatitis C • hepatitis E • herpes simplex • HIV/AIDS • influenza • meningitis • myxomatosis • polio • pneumonia • shingles • smallpox

Epidemiology & Interventions: 2007 Bernard Matthews H5N1 outbreak • Coalition for Epidemic Preparedness Innovations • Disease X • 2009 flu pandemic • HIV/AIDS in Malawi • polio vaccine • Spanish flu • West African Ebola virus epidemic

Virus–Host interactions: antibody • host • immune system • parasitism • RNA interference

Methodology: metagenomics

Social & Media: And the Band Played On • Contagion • "Flu Season" • Frank's Cock • Race Against Time: Searching for Hope in AIDS-Ravaged Africa • social history of viruses • "Steve Burdick" • "The Time Is Now" • "What Lies Below"

People: Brownie Mary • Macfarlane Burnet • Bobbi Campbell • Aniru Conteh • people with hepatitis C • HIV-positive people • Bette Korber • Henrietta Lacks • Linda Laubenstein • Barbara McClintock • poliomyelitis survivors • Joseph Sonnabend • Eli Todd • Ryan White