Gastroenteritis is an infectious disease of the gastrointestinal tract involving both the stomach and small intestine, which results in diarrhoea and vomiting, and sometimes abdominal pain. It can be caused by several types of virus: most commonly rotavirus and norovirus, but also adenovirus and astrovirus. Other major causes include Campylobacter, Escherichia coli, Vibrio cholerae and some other bacteria, as well as parasites. 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 can decrease incidence by as much as 30%. An estimated 3–5 billion cases of gastroenteritis occur globally each year, mainly among children and people in developing countries, resulting in 1.4 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.
Although vaccines protecting against viral infections were pioneered in the late 18th century, the history of virology is usually considered to begin over a century later. The first evidence for the existence of viruses came from experiments using filters with pores small enough to retain bacteria. Dmitry Ivanovsky showed in 1892 that sap from a diseased tobacco plant remained infectious despite having been filtered; this agent, later known as tobacco mosaic virus, was the first virus to be demonstrated. In 1898, Friedrich Loeffler and Paul Frosch showed that foot-and-mouth, an animal disease, was caused by a filterable agent. That year, Martinus Beijerinck (pictured) called the filtered infectious substance a "virus" – often considered to mark the beginning of virology, the scientific study of viruses and the infections they cause.
In 1926, Thomas Milton Rivers defined viruses as obligate parasites. Viruses were demonstrated to be particles, rather than a fluid, by Wendell Meredith Stanley in the 1930s.
24 March: A small study of a multivalent norovirus virus-like particle vaccine shows a broad antibody response is generated, which covers novel virus variants. PLOS Med
24 March: An Ebola vaccine (virus pictured) based on the 2014 strain is shown to be safe and to generate an immune response in a phase I clinical trial in China. Lancet
23 March: A novel virus, ANMV-1, believed to infect anaerobic archaea in a deep-sea methane seep, is shown to have the first diversity-generating retroelement found in archaea or their viruses, which has the potential to generate rapid genetic diversity in the virus. Nat Comm
22 March: The lowest weekly total of new cases of Ebola virus disease in 2015 has been recorded in the ongoing West African outbreak; since the outbreak began, there have been nearly 25,000 suspected cases and 10,326 deaths. WHO
18 March: A test to distinguish viral from bacterial infections is developed, based on TRAIL (pictured) and other host proteins induced after infection. PLOS ONE
10 March: In the ongoing outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV; pictured), cases continue to be reported in Saudi Arabia; since the outbreak started in September 2012, there have been 1075 cases with at least 404 deaths. WHO
9 March: Real-time imaging of SIV in macaques using immuno-PET reveals unexpectedly high levels of virus in the nasal cavity, lung and male genital tract in antiretroviral-treated animals. Nat Meth
4 March: The International Committee on Taxonomy of Viruses formally ratify their 2014 species list, with one new family of double-stranded DNA bacteriophages, Sphaerolipoviridae, one new subfamily of Myoviridae, Eucampyvirinae, fifty new genera and 359 new species recognised. ICTV
3 March: Four RNA viruses found in farmed honeybees – acute bee paralysis, black queen cell, deformed wing and slow bee paralysis viruses – are widespread among wild bumblebee species in a survey across Britain. J Anim Ecol
2 March: A 3D image of Acanthamoeba polyphaga mimivirus at 125 nm resolution is constructed from multiple high-energy X-ray diffraction patterns of single virions, rather than crystals, in the first application of this technique to a virus. Nature
25 February: H7N9 avian influenza infection continues in China, with 59 cases reported since 21 January. WHO
25 February: WHO calls for increased measles vaccination coverage in the light of outbreaks across Europe; the ongoing outbreak in North America continues. WHO,CDC
24 February: A clinical trial in England shows that pre-exposure prophylaxis with tenofovir/emtricitabine (Truvada) reduces the risk of HIV infection by 86% in gay men engaging in high-risk sex. CROI
18 February: Varicella zoster virus antigens are found in 74% of giant cell arteritis biopsies but only 8% of normal ones, suggesting the virus might have a role in triggering disease. Neurology
29 January: A total of 112 novel negative-sense RNA viruses of arthropods, including a putative new family of circular RNA viruses, are identified in a study of 70 arthropod species in China. e-Life