Desheng analyzes for you how to prevent and control "asymptomatic infections"?

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The current “asymptomatic infection” is a headache for the new crown virus. The first report was that a woman living in Wuhan returned to her hometown before the outbreak of the new crown. She has not been infected with the new coronavirus. However, her parents and the other three The family members were infected with the new coronavirus and were subsequently diagnosed and treated in isolation. This is a case that occurred in Anyang, Henan. Then the National Health Commission held a press conference and identified the case in Anyang, Henan as an asymptomatic infection.

What is an asymptomatic infection?

When the human body is exposed to the virus, most people will develop symptoms, which is a dominant infection. Correspondingly, some people have no symptoms after being infected. This is a recessive infection, also known as asymptomatic infection. Although patients with invisible infection have no obvious symptoms, the virus has been replicating and detoxifying. How can such patients be discovered? Want to know how to find asymptomatic patients with COVID-19?

Why do asymptomatic infections occur?

Whether there are symptoms or not is related to the number and virulence of viruses that invade the body, as well as the body's immunity. After the virus invades the human body, the immune system in the human body will respond accordingly. The symptoms such as fever and cough that we show are the "external manifestations" of the immune system against the virus.

In different populations, the strength of the immune response is different, and the symptoms will be different. For example, children may have a weaker immune response than adults and are less likely to show symptoms.

In addition, asymptomatic after virus infection may also be related to the individual's unique physique. In the past, a woman named Mary Mellen in the United States carried typhoid bacilli for life, but never showed any symptoms. However, as an asymptomatic infection, she directly transmitted 52 cases of typhoid fever, 7 of which died, and countless indirectly infected people . The same may be true of the asymptomatic infection of the new coronavirus.

What is the difference between asymptomatic infection and incubation period infection?

The incubation period refers to the period from when a pathogen invades the body to the appearance of the earliest clinical symptoms. The incubation period of different infectious diseases is different, some are only a few days, and some can last for several years. According to the "2019 Novel Coronavirus Epidemic Progress and Risk Assessment" issued by the Chinese Center for Disease Control and Prevention, the average incubation period of the novel coronavirus is 10 days ( 1-14 days).

Most infectious diseases are infectious in the late incubation period. However, there is currently no reliable evidence that this new coronavirus is infectious during the incubation period. Asymptomatic infections are contagious because they have been detoxifying their body. In addition, regardless of the length of the incubation period, symptoms will eventually appear, but asymptomatic infections may remain asymptomatic.

How do doctors determine asymptomatic infections?

At present, clinically, for all patients, the diagnosis of new coronavirus infection requires the following two steps:

1. Determine suspected cases, including:

Although asymptomatic, there was travel history or residence history in Wuhan within 14 days before the onset of illness, or had contact with patients from Wuhan with fever and respiratory symptoms in the 14 days before the onset of illness, or had a cluster of illnesses or had a confirmed case or a positive test. Epidemiological association.

The clinical manifestations have fever, imaging features of pneumonia, normal or decreased white blood cell counts, or decreased lymphocyte counts in the early stages of onset.

2. The suspected patient’s sputum, throat swab, lower respiratory tract secretions, blood and other specimens will be tested for pathogens, if real-time fluorescent RT-PCR is positive for the new coronavirus nucleic acid; or the new coronavirus with known viral gene sequencing results A high degree of homology can be diagnosed.

The 10-year-old boy reported in the previous "Lancet" study had been to Wuhan without any symptoms, but the viral nucleic acid test was positive and chest imaging showed ground-glass changes in both lungs, so he was diagnosed as an asymptomatic infection. The specific situation of the patient in Anyang has not yet been disclosed.

How to prevent and control?

In the previous press release of the National Health Commission, Li Xingwang, a member of the National Medical Expert Group and chief expert of the Infectious Disease Diagnosis and Research Center of Beijing Ditan Hospital, said that asymptomatic infections were found among close contacts, according to existing requirements , They need to be medically observed or isolated at home to ensure the control of the source of infection.

"Whether it is symptomatic or asymptomatic, the more important effective countermeasure is to control the source of infection, so that the spread of the epidemic can be alleviated to the greatest extent." Li Xingwang said that it is also important for individuals to take reasonable prevention, such as wearing them. Masks, try to minimize close contact (between 1-2 meters), or keep a distance of more than 1.5 meters to avoid spread.