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What is a coronavirus
What is a coronavirus
I. introduction to novel coronavirus
Coronaviruses belong to the order cassiviridae, family coronaviruses and genus coronaviruses. The 5 'end of the viral genome has A methylated cap structure, and the 3' end has A poly(A) tail. With A total length of 27 ~ 32kb, the virus is the largest known RNA virus. Coronaviruses are widely found in nature and are so named because of their appearance of many small protuberances (spines) that they resemble corollas (figure 1).
Coronavirus only infects vertebrates and is related to a variety of diseases in humans and animals. It can cause respiratory, digestive, nervous and cardiovascular diseases in humans and animals.
According to the phylogenetic tree, the coronaviruses can be divided into four genera:,,,,, and. Animal coronaviruses include mammalian coronaviruses and avian coronaviruses. Mammalian coronaviruses mainly belong to the genus coronaviruses, which can infect bats, pigs, dogs, cats, mice, cattle, horses and other animals. Avian coronaviruses mainly come from the genus and coronaviruses, which can cause diseases of many birds such as chickens, turkeys, sparrows, ducks, geese and pigeons.
The coronavirus that infects humans is called the human coronavirus. To date, in addition to the new coronavirus (2019-ncov) that caused the outbreak of viral pneumonia in wuhan, a total of six human coronavirus infections (hcov-229e, hcov-oc43, sars-cov, hcov-nl63, hcov-hku1 and mers-cov) have been detected. Among them, four coronaviruses cause common human infections, but are less pathogenic and generally cause only minor respiratory symptoms similar to the common cold. Two other coronaviruses, severe acute respiratory syndrome coronaviruses and Middle East respiratory syndrome coronaviruses, commonly known as SARS coronaviruses and MERS coronaviruses, can cause severe respiratory disease. According to the study by the world health organization (WHO) and domestic experts, the source of infection of the new pneumonia was the seventh member of the coronavirus family, temporarily known as the new coronavirus (2019-ncov).
Human coronavirus to thermal sensitive, virus under 4 ℃ suitable for moderate stability in maintaining fluid, 60 ℃ can be saved for years, but as the temperature increases, the virus resistance drop, such as HCoV - 229 e in 56 ℃ under 10 minutes or hours under 37 ℃ can be loss of infectious SARS - CoV in 37 ℃ for 4 days, 56 ℃ 90 minutes, 75 ℃ heat for 30 minutes can be inactivated virus. Human coronavirus is not resistant to acid or alkali, and is sensitive to organic solvents and disinfectants. 75% alcohol, ether, chloroform, formaldehyde, chlorine-containing disinfectants, peroxyacetic acid and ultraviolet light can inactivate the virus. In human coronavirus, sars-cov can survive for at least 10 days in urine at room temperature of 24℃, more than 5 days in sputum and feces of diarrhea patients, about 15 days in blood, and 2-3 days in plastic, glass, Mosaic, metal, cloth, copy paper and other surfaces. At present, the survival time of the novel coronavirus at room temperature is unknown, but it has great similarity with SARS virus and many analogies can be made.
The novel coronaviruses are similar to human coronaviruses in nature and are heat sensitive. They can be inactivated in 30 minutes at 56℃, while 75% alcohol, peroxyacetic acid and chlorine-containing disinfectants (except chlorhexidine) can effectively kill the novel coronaviruses.
Second, domestic and foreign popular status
The outbreak of the new coronavirus pneumonia began in wuhan and has since spread rapidly. 24 to February 2, the national health committee received 31 provinces (autonomous regions and municipalities directly under the central government) and the xinjiang production and construction corps has reported 17205 cases of confirmed cases (Beijing subtract 3 cases, subtract 1 case) in jiangxi province, the existing 2296 cases of serious illness case of illness, and death cases of 361 cases, cure the hospital cases 475 cases, a total of 21558 cases of suspected cases. So far, a total of 189,583 people with close contacts have been traced, and 10,055 people have been released from medical observation on the same day. A total of 152,700 people are under medical observation. We have received a total of 33 confirmed cases from Hong Kong, Macao and Taiwan: 15 from the Hong Kong special administrative region, 8 from the Macao special administrative region and 10 from the Taiwan region. By February 2, 2020, a total of 27 countries and regions worldwide had announced the discovery of confirmed cases of pneumonia caused by novel coronavirus infection, with a total of 14,569 confirmed cases, 305 deaths and 346 cures.
In accordance with the ihr (2005), who director-general Dr Tandesay reconvened the emergency committee on novel coronavirus (2019-ncov) on Thursday, 30 January 2020. In the early hours of January 31, Beijing time, he declared the outbreak of the new coronavirus pneumonia to be a "public health emergency of international concern" (PHEIC) and made seven recommendations. Supporting and protecting countries with relatively fragile health systems; Accelerate scientific research and vaccine-related research; (4) to fight rumors and false information; Countries actively seek plans to prevent, treat and prevent further transmission; Countries actively share information with the WHO; All countries are working together to fight the virus. The who explains that these procedures are not binding but are practical and political and can cover travel, trade, quarantine, inspection and treatment, and that the who can set global standards of practice.
At present, significant community transmission has been formed in wuhan and some areas of hubei province. In addition, the early symptoms of the disease are relatively mild and there are mild cases and asymptomatic cases, so it is difficult to be diagnosed and isolated in a timely manner, resulting in the accumulation of infectious sources in the community and the difficulty in controlling the spread of the disease. In the future, the number of patients in wuhan and a few other areas of hubei will continue to increase. In wuhan, huanggang and xiaogan, hubei province, measures were taken to suspend public transportation, stop crowd gathering, strengthen community prevention and control, actively detect and screen patients with fever, and strengthen the admission and treatment of patients. Implementation of these measures will have a positive impact on the effective control of the epidemic. The provinces (autonomous regions and municipalities directly under the central government) outside hubei are still in the stage of mainly importing the epidemic disease to wuhan, and there is no obvious community transmission yet. At present, all provinces have launched a high-level emergency response, taken strong prevention and control actions, adopted a variety of measures and technical means, strict investigation and control, timely detection and early isolation of imported cases and close contacts, strengthen community disease publicity and elimination work, and resolutely curb community transmission.
Iii. Harmfulness of novel coronavirus
At present, the new coronavirus is in the epidemic period, and the information of the new coronavirus is still in the stage of discovery and continuous understanding. The clinical manifestations and epidemiological data of the new coronavirus pneumonia cannot be simply compared with the mortality and transmissibility of SARS virus from human to human. Moreover, China is at a critical juncture in the prevention and control of the new coronavirus pneumonia. The claim that "the new coronavirus is mildness than SARS virus" may be misleading, even weakening the public's attention to the protection of the new coronavirus, and even causing some people's laxity and flukedness, which is not conducive to the control of the epidemic.
The results of the study published by Chinese scholars in the lancet showed that from the 41 cases of 2019-ncov infection in wuhan, the clinical symptoms of 2019-ncov infection were similar to those of SARS, and the mortality was not negligible. Therefore, the severity and active prevention and control of this epidemic disease must be attached great importance.
Chan, J., Yuan, s., Kok, K., et al. (2020). A familial cluster of root associated with the 2019 will be - coronavirus indicating the person - to - person transmission: A study of a family cluster.
The transmissibility of novel coronavirus
Usually, the virus spreads through the following ways: first, it spreads by droplets. Droplets generated by coughing, sneezing and talking enter the susceptible mucosal surface and cause infection. The second is contact transmission, in which an infected person touches his or her mouth, nose or eyes after touching something he or she has touched. Three is the air transmission, pathogens can spread for a long time after the long distance is still infectious; Recent case studies suggest that pathogens may also be transmitted through the digestive tract. For novel coronaviruses, isolation and protection measures of these pathways should be done well.
On January 21, Prof. Zhong nanshan pointed out that there is human-to-human transmission of pneumonia caused by the new coronavirus infection, and relevant experts at home and abroad and the world health organization have confirmed that human-to-human transmission of the new coronavirus pneumonia is occurring.
As for the origin of the new coronavirus, some scholars proposed that the new coronavirus may originate from bats. But the virus in bats cannot infect humans directly under normal conditions, and may infect humans through an "intermediate host." So who is the intermediate host? There are scientific research papers and popular social views that point "criminal suspects" to snakes, jackals and other animals, which need to be further confirmed.
In fact, the determination of intermediate hosts requires rigorous and generally accepted scientific processes, including: isolation of viruses in intermediate hosts that can reproduce and replicate in them; The virus can show pathogenicity and pathology in animal model. Identify the location of the virus in the transmission chain of infection (is it transmitted to humans from animals that carry the virus, or is it transmitted to animals from people who already have the virus?). And so on. In conclusion, the intermediate host of the novel coronavirus cannot be determined by the present study, and further scientific studies are needed.