Disease outbreak in the context of "SARS-related coronavirus"

A disease cluster is an unusually large aggregation of a relatively uncommon disease (medical condition) or event within a particular geographical location or period. Recognition of a cluster depends on its size being greater than would be expected by chance. Identification of a suspected disease cluster may initially depend on anecdotal evidence. Epidemiologists and biostatisticians then assess whether the suspected cluster corresponds to an actual increase of disease in the area. Typically, when clusters are recognized, they are reported to public health departments in the local area. If clusters are of sufficient size and importance, they may be re-evaluated as outbreaks.

John Snow's pioneering investigation of the 1854 cholera outbreak in Soho, London, is seen as a classic example of the study of such a cluster.

An emergent virus (or emerging virus) is a virus that is either newly appeared, notably increasing in incidence/geographic range or has the potential to increase in the near future. Emergent viruses are a leading cause of emerging infectious diseases and raise public health challenges globally, given their potential to cause outbreaks of disease which can lead to epidemics and pandemics. As well as causing disease, emergent viruses can also have severe economic implications. Recent examples include the SARS-related coronaviruses, which have caused the 2002–2004 outbreak of SARS (SARS-CoV-1) and the 2019–2023 pandemic of COVID-19 (SARS-CoV-2). Other examples include the human immunodeficiency virus, which causes HIV/AIDS; the viruses responsible for Ebola; the H5N1 influenza virus responsible for avian influenza; and H1N1/09, which caused the 2009 swine flu pandemic (an earlier emergent strain of H1N1 caused the 1918 Spanish flu pandemic). Viral emergence in humans is often a consequence of zoonosis, which involves a cross-species jump of a viral disease into humans from other animals. As zoonotic viruses exist in animal reservoirs, they are much more difficult to eradicate and can therefore establish persistent infections in human populations.

Emergent viruses should not be confused with re-emerging viruses or newly detected viruses. A re-emerging virus is generally considered to be a previously appeared virus that is experiencing a resurgence, for example measles. A newly detected virus is a previously unrecognized virus that had been circulating in the species as endemic or epidemic infections. Newly detected viruses may have escaped classification because they left no distinctive clues and/or could not be isolated or propagated in cell culture. Examples include human rhinovirus (a leading cause of common colds which was first identified in 1956), hepatitis C (eventually identified in 1989), and human metapneumovirus (first described in 2001, but thought to have been circulating since the 19th century). As the detection of such viruses is technology driven, the number reported is likely to expand.

Severe acute respiratory syndrome–related coronavirus (SARSr-CoV or SARS-CoV, Betacoronavirus pandemicum) is a species of virus consisting of many known strains. Two strains of the virus have caused outbreaks of severe respiratory diseases in humans: severe acute respiratory syndrome coronavirus 1 (SARS-CoV or SARS-CoV-1), the cause of the 2002–2004 outbreak of severe acute respiratory syndrome (SARS), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the pandemic of COVID-19. There are hundreds of other strains of SARSr-CoV, which are only known to infect non-human mammal species: bats are a major reservoir of many strains of SARSr-CoV; several strains have been identified in Himalayan palm civets, which were likely ancestors of SARS-CoV-1.

These enveloped, positive-sense single-stranded RNA viruses enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. The SARSr-CoV species is a member of the genus Betacoronavirus and the only species of the subgenus Sarbecovirus (SARS Betacoronavirus).

In May 2022, the World Health Organization (WHO) made an emergency announcement of the existence of a multi-country outbreak of mpox, a viral disease then commonly known as "monkeypox". The initial cluster of cases was found in the United Kingdom, where the first case was detected in London on 6 May 2022 in a patient with a recent travel history from Nigeria where the disease has been endemic. On 16 May, the UK Health Security Agency (UKHSA) confirmed four new cases with no link to travel to a country where mpox is endemic. Subsequently, cases have been reported from many countries and regions. The outbreak marked the first time mpox had spread widely outside Central and West Africa. The disease had been circulating and evolving in human hosts over several years before the outbreak and was caused by the clade IIb variant of the virus.

On 23 July 2022, the director-general of the WHO, Tedros Adhanom Ghebreyesus, declared the outbreak a public health emergency of international concern (PHEIC), stating that "we have an outbreak that has spread around the world rapidly, through new modes of transmission, about which we understand too little". A global response to the outbreak included public awareness campaigns in order to reduce spread of the disease, and repurposing of smallpox vaccines.

The Lebanese liquidity crisis is an ongoing financial crisis affecting Lebanon, that became fully apparent in August 2019, and was further exacerbated by the COVID-19 pandemic in Lebanon (which began in February 2020), the 2020 Beirut port explosion and the Russian invasion of Ukraine. The country experienced liquidity shortages in the years prior to 2019 but the full extent of the fragility of the economy was concealed through financial engineering by the governor of the central bank. Lebanon's crisis was worsened by sanctions targeting Syria's former government and Iran-backed Hezbollah, which intensified under Donald Trump.

The currency was devalued by over 98% between January 2023 and March 2024, with an annual inflation rate of 221.3% in 2023. Public services have collapsed; without using a private generator, households can expect only an hour or so of power a day. Shortages of drinking water have contributed to disease outbreaks, including the first cholera cases in decades. Parents are sending their children to orphanages because they cannot feed them. A growing number of citizens have resorted to armed robbery as the only way to extract their own deposits (now vastly reduced in real terms) from banks when they desperately need to pay for basic services such as healthcare. The collapse of Lebanon, formerly known as the "Paris of the Middle East", has been described by Western media as one of the most devastating and worst financial recessions since at least the 19th century.

Virus crystallisation is the re-arrangement of viral components into solid crystal particles. The crystals are composed of thousands of inactive forms of a particular virus arranged in the shape of a prism. The inactive nature of virus crystals provide advantages for immunologists to effectively analyze the structure and function behind viruses. Understanding of such characteristics have been enhanced thanks to the enhancement and diversity in crystallisation technologies. Virus crystals have a deep history of being widely applied in epidemiology and virology, and still to this day remains a catalyst for studying viral patterns to mitigate potential disease outbreaks.