as soon as the world was enveloped coronavirus pandemic, scientists learned about his strange and dangerous behavior. While many patients experienced cough, lost sense of taste and smell, and increased temperature, other infected, the disease does not manifest itself, and they were not aware that they have become carriers of Covid-19.
the Researchers said that it is necessary to understand how many people have no symptoms, and is it really a pandemic feed such that “Pacific distributors”.
When January 19 at one of the churches of Singapore gathered congregation, no one could not imagine that this will have global repercussions in the spread of coronavirus.
On the occasion of one of the Sunday sermons were traditionally conducted in Mandarin Chinese. Among the participants were married, middle-aged couple in the morning arrived from China.
the Guests looked perfectly healthy, and nobody could have imagined that they are carriers of the infection.
And no symptoms — no infection, believed then.
the Chinese soon left the Church, but very quickly things took a sad turn, and no one could understand what was happening. Already on January 22, the woman fell ill two days later fell ill and her husband. It caused much surprise, because both of them flew in from Wuhan, where there was the epicenter of coronavirus.
But next week for no apparent reason was ill for three Singaporeans — it was the first, the most mysterious at that time, the infection cases in the country. It is the investigation of the cause of disease led to the discovery of new and very disturbing details of how the coronavirus so successfully used to find new victims.
“We were very surprised, — says the head of the Department of infectious diseases at Ministry of health Singapore Dr. Vernon Lee. — People who did not know each other, managed to portaraits are not showing any symptoms of the disease”.
Therefore, Dr. Lee, together with his colleagues and with police and special “virus hunters” began an investigation, creating a detailed map of when and where you were infected. This process is called “identification of contacts”, and now it is used in the UK and in many countries. The process is to identify all those involved in the outbreak, with a view to its eradication. And Singapore became known for its speed and efficiency in the execution of this process.
in Just a few days, investigators were able to interview 191 parishioner of the same Church and find out that 142 of them on Sunday was in the service. Just as quickly it turned out that two cases of Singaporeans attended the service, together with a Chinese couple.
“They could talk d��HS with each other, to shake hands during the service,” said Dr. Lee.
It was an important step in the investigation, which could explain how infection was transmitted, but was missing one key factor.
there were still far more complex mystery. Confirmed the fact of infection another Singaporean women, which, however, the Church service was not present. However, in the Church that day, she was still, only a little later. So how could she catch a virus?
In search of evidence, investigators decided to examine the footage taken on that Sunday. And here’s the then , they found something completely unexpected. It turned out that the infected woman who visited the Church after left the Chinese, sitting on the very chair that a few hours before occupied by one of the spouses.
As it turned out, although the husband and wife showed no symptoms and felt fine, they were still carriers of the virus. Perhaps the virus has moved to the chairs with their finger, or separated during respiration, this is not exactly known, but the consequences were most serious.
When Dr. Lee collated all the evidence, he found only one explanation: the virus is transmitted by people who were infected, but did not realize it.
But if the virus is spreading and no symptoms, quietly, then how can you stop this disease? Lee recalls how he was struck with an Epiphany: “Every time you make a scientific discovery, I want to shout “Eureka”! You realize that thanks to the hard work of individuals and entire teams you’ve acquired something is very important.”
the opening was in what is called “presentano transfer,” when a person does not know that is already a vector, because cough, fever and other classical symptoms has not yet appeared.
a New study has shown that for day-two before the appearance of obvious signs of disease people may already be contagious, it is possibly the most contagious period.
this is Potentially a very important factor, because once you realize that you can be sick, all who were with you in close contact, may be warned of the need for isolation.
That is, such insulation can be provided during key phases of infection, when symptoms are not yet manifested. However, the question of how the disease can spread without cough, which in the air get viruses, remains open.
If a virus is reproduced in the upper respiratory tract, it is quite possible that some of the viruses excreted with each exhalation. And all who is nearby, especially in the closed premises.NII, can easily become infected.
the Virus can get on your hands when you touch an infected person or door handles or while sitting in Church. Whatever the route of infection, the virus uses the fact that people lose focus when people are unaware of the possibility of catching infections.
This is even more puzzling scenario, and scientists still have no answers. It’s one thing to know that people can be contagious before they have symptoms, and quite another — when people are infected, but the symptoms never manifest.
One of the most striking historical examples considered cook-Irish, which worked in new York, at the beginning of the last century.
In all the houses where Mary Mallon was hired as a cook, people were sick with typhus, and at least three people died from the disease. While Mary herself remained perfectly healthy.
In the end the connection between the disease and the cook was installed, it turned out to be carriers of the infection, even though she was healthy. The press dubbed her “typhoid Mary”, and the authorities sent a woman under the castle, where it sat for 23 years until his death in 1938.
the 23-year-old nurse Amelia Powell was shocked to find out that is an asymptomatic carrier of the infection. In that moment, when the doctor called her and said the test results, she was working in the house of the Cambridge clinic Addenbrook.
Amelia felt fine and believed that is fully secure, as when working with patients who have Covid-19, used personal protection equipment. However, all of her confidence immediately evaporated when, to her horror, tests have shown positive results.
“it felt like I was informed about the death of a loved, it was something unreal. I thought this can’t be, not with me, because I’m fine,” recalls Amelia.
She had to immediately leave work and to isolate themselves at home.
“of Course I’m worried because I’ve seen the seamy side, so to speak, I saw how quickly it worsens the condition of patients with coronavirus and thought, what will happen to me”. However, to her great surprise, she never got sick. “With me literally nothing happened: at home I continued to workout, normal eating, normal sleep,” says Amelia.
Amelia learned that she coronavirus, only because all the medical staff of the hospital were obliged to pass the test. The result surprised experts from more than a thousand people, up to 3% showed a positive result, without showing any symptoms.
more asymptomatic infected was on a cruise ship “diamond Princess”, which is an epidemic I��La off the coast of Japan. Liner dubbed the “Petri dish” that is a real hotbed of infection, because on Board it was found about 700 infections.
And in one of the homes for the elderly in Washington, more than half of the inhabitants tested positive for coronavirus, but did not show signs of disease.
Various studies give very different data on the number of asymptomatic infections, ranging from 5% to 80%. To such conclusion the Professor of Oxford University, Carl heneghan, who along with colleagues examined the results of 21 research project on this topic.
moreover, if the tests Covid-19 will take only people showing symptoms of the disease, and this is the current practice in the UK, then something cases are overlooked, perhaps many cases, experts add.
One of the main concerns of nurses Amelia was the fact that she could, herself without knowing it, infect with virus someone of his colleagues or patients for whom she cared.
“I don’t think this has happened because the tests of all my colleagues gave a negative result, but still frustrating to feel that I was a carrier of the infection, says Amelia. — And continue don’t know whether contagious asymptomatic carriers. It’s very strange, but yet we have minimal information on this subject.”
an Alarming signal for the authorities were the results of one study conducted in China, according to which the number of asymptomatic infected actually even higher than the number of patients with symptoms.
a Group of specialists who studied the situation on Board the ship “diamond Princess”, have suggested that asymptomatic infected people less contagious than people with symptoms, but they could still be an important source of infection.
In an attempt to find answers, researchers led by Professor Neil Hall offer to do tests for coronavirus the entire population of Norwich.
“of Asymptomatic cases may be the “dark matter” of the current epidemic,” says Professor Hall. It is a notorious invisible substance from which, presumably, for the most part is the matter of our Universe, but which is still not discovered.
Professor Hall fears that asymptomatic cases despite government measures to protect public health, continue to fuel the current epidemic.
“If there are people who are unaware that they are sick, and use public transport and medical facilities, this inevitably leads to an increase in infections, — says the scientist. — Any action against the people who applied in medical institutions with symptoms of the disease, are only a halfway solution to the problem.”
They are convinced that the only way to stop the spread of the disease is to detect all infected persons by testing, regardless of whether they have symptoms.
And the special attention they offer to pay for employees health care system and social security that come into contact with risk group.
a Similar approach, only on a larger scale, has been adopted in Wuhan, which, apparently, became the first hotbed of the epidemic.
There for 9 days were tested 6.5 million residents to identify all carriers, including hidden ones.
as soon as quarantine measures are weakened, and more and more people begin to use public transport to commute to work and shopping, the risk invisible risk increases significantly.
that is why governments around the world are telling their citizens how important the joint efforts to identify all infected contacts and to observe the rules of isolation. They also remind us that one of the most reliable and effective means of protection is to observe social distance. Well, where this is not possible, people should wear the mask even if the mask is homemade.
When the US government announced these measures, they referred to the discovery made in the Church of Singapore in January. The meaning of the message is that you have to think not only about their own protection, but also protect others from ourselves in case you are ill, but not aware of it.
Many experts in the field of health fear that wearing masks can distract people from hand washing and social distancing, or even increase the risk of infection, if these masks mishandled. However, more and more countries, including the United Kingdom, convinced of the effectiveness of masks.
of Course, the mere wearing of a mask will not stop the pandemic, but since we still know too little about asymptomatic transmission of the virus, any attempt to protect yourself from it is worth it.
David Shukman
Scientific editor of the bi-Bi-si
