The growth of almost every major epidemic is facilitated by the so-called super-distributors, that is, infected people who infect an unusually large number of those around them.
It is clear that they do not do this intentionally, but make a significant contribution to the expansion of the epidemic.
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The current case of the outbreak of the Covid-19 viral disease, the focus of which was the Chinese city of Wuhan, was no exception.
Briton Steve Walsh, who visited Singapore, is believed to have infected five British, five French, and probably one resident of the Spanish island of Mallorca.
Who are super distributors?
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This is a rather vague term; it does not have a clear scientific definition. In essence, it means that a person infects more people than usual.
On average, according to statistics, the carrier of the infection infects two to three people with the coronavirus.
But this is an average. There are cases when infected people don’t pass the infection to anyone, or vice versa - they infect much more people.
How many people are able to infect a superspreader?
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In most cases, people have become infected with the Ebola virus from a small group of patients.
In short, very many. And this seriously affects the growth dynamics of the epidemic.
In 2015, during an epidemic caused by the Middle East respiratory syndrome coronavirus (Mers), one patient infected 82 people.
And during the Ebola epidemic in Africa, the source of most infections (61%) was a small group of cases (3%).
“After a funeral in June 2014, more than 100 people contracted the infection and then began to infect other people,” said Dr. Natalie McDermott of King's College London.
Why do people become superspreaders?
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Some people come in contact with a large number of people - for example, due to their work or living conditions. Therefore, they actively spread the infection, sometimes without even knowing it, because at first they do not show symptoms.
“Usually this is common for children, so it’s wise to quarantine schools as a precaution,” said Dr. John Edmunds of the London School of Hygiene and Tropical Medicine.
“Sex workers have played a major role in the spread of HIV,” said Professor Mark Woolhouse of the University of Edinburgh.
There are so-called super-nebulizers, that is, those who produce and secrete the virus in unusually large quantities, so people in contact with them are more likely to get sick.
During the SARS epidemic, a huge mass of people became infected in hospitals. The reason is that patients who were in the most serious condition were also the most infectious, and in hospitals a large number of doctors came into contact with such patients.
How do they influence the spread of the epidemic?
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"At the very beginning of an outbreak, they can significantly affect its growth when the virus tries to reach as many people as possible," explains John Edmunds.
The source of new infections, including coronaviruses, are animals.
When the first person becomes infected, he can get sick without infecting anyone else or infecting a small number of people, but this does not turn into an epidemic.
But if a super-distributor becomes infected, then the outbreak immediately gets a strong boost. The same thing happens when an infection enters a country where it did not exist before.
“If several super-distributors are close to each other, suppressing the flash will be extremely difficult,” says McDermott.
How to stop the epidemic if the virus is spread by superpreparants?
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The superproliferation of coronaviruses is not unusual and does not require any radical measures that are very different from standard disease control practices.
Currently, we are completely dependent on how quickly we can identify the infected people and those with whom they contacted.
"Therefore, this requires special attention - no mistakes can be made, no super-distributors can be identified," says Professor Woolhouse.
Are there any faults of the superpreisers?
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Mary Mallon accused of typhoid fever
Historically, there has been a tendency towards demonization of disease super-distributors
Irish cook Mary Mallon (1869-1938), nicknamed Typhoid Mary, inadvertently infected many people in the United States with typhoid fever. She continued to work when she had no symptoms of the disease. As a result, she spent dozens of years in exile or quarantine
In fact, there is no blame for the sick person. "You need to be very careful in choosing the words," says Natalie McDermott. "They have not done anything wrong. They have become infected, and they are not guilty of this. They are probably scared, and they need care and attention."
