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CMAAO CORONA FACTS and MYTH BUSTER : Super Spreader Series 14

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Healthy Soch
23rd May, 2020 12:15 IST

Author: Dr. K K Aggarwal, President Confederation of Medical Associations of Asia and Oceania, HCFI, Past National President IMA, Chief Editor Medtalks .With inputs from Dr. Monica Vasudev

India

healthysoch

New Delhi, May 23, 2020 :

Super-spreader a must for becoming a hot spot of Corona. Without a Super spreader the cases in the Country may die out of its own :

Superspreader, is a loosely defined term for people who infect a disproportionately large number of others, whether because of genetics, social habits or simply being in the wrong place at the wrong time. Super-spreader is a feature of nearly every outbreak. In fact the primary cause of every epidemic is a super spreader. China cases in Wuhan also might have started with a super spreader.

On average, each person infected with the new coronavirus is passing it on to between two and three other people. But this is only an average; some people will pass it on to nobody while others pass their infection on to far more.

In 2015, a super-spreading event led to 82 people being infected from a single hospital patient with Middle East respiratory syndrome (Mers). And in the Ebola epidemic in West Africa, most cases (61%) came from just a tiny handful of patients (3%).

Some just encounter far more people – either because of their job or where they live – and that means they can spread more of the disease, whether they themselves have symptoms.

Others are “super-shedders”, who release unusually large amounts of virus (or other bug) from their bodies, so anybody encountering them is more likely to become infected. Hospitals treating SARS became a major centre of super-spreading because the sickest patients were also the most infectious and they encountered lots of healthcare workers.

It plays a big role at the beginning of any outbreak when the virus is trying to get established. When it makes the jump into the first patient, the disease might fizzle out before it can cause a large outbreak. But if it can quickly find its way into a super-spreader, then it gives the outbreak a boost. The same rules apply when cases are imported into other countries.

“Typhoid Mary”, Irish cook Mary Mallon (1869-1938), unknowingly passed on typhoid fever when she had no symptoms and ended up spending decades in exile and forced quarantine.

HIV person coinfected with STI becomes a super spreader. A heterosexual man co-infected with HIV, hepatitis C virus, and herpes simplex 2 virus has unusually high semen HIV RNA levels.

20/80 rule, a small percentage of individuals within any population control control most transmission events. :

A study from Israel has found that so-called super spreaders in Israel have been unusually potent: While, with many viruses, 20 percent of patients are often responsible for 80 percent of cases, the Israeli coronavirus data showed that only five percent of patients were responsible for spreading the disease to 80 percent of those ultimately infected.

Example after example have shown the microbe’s affinity for density : 

The virus has spread easily in nursing homes, prisons, cruise ships and meatpacking plants — places where many people are living or working in proximity. A recent CDC report described how a choir practice in Washington state in March became a super-spreader event when one sick person infected as many as 52 others.

Distinguishing between those who are more infectious and those less infectious could make an enormous difference in the ease and speed with which an outbreak is contained. If the infected person is a super-spreader, contact tracing is especially important. But if the infected person is the opposite of a super-spreader, someone who for whatever reason does not transmit the virus, contact tracing can be a wasted effort.

There has to be a link between people in order to transmit an infection. A link is necessary but not sufficient and the second factor is how infectious a person is.

It can be easy to misattribute multiple infections to an individual — possibly exposing the person to public attack — when the spread has nothing to do with the person’s infectiousness. If you are the first person in a crowded room to get infected and if this is an easily spread disease, you will look like a super spreader. Anyone in that room could have had the same impact. You were just the first in line.

Superspreading events may involve people with symptoms that linger but who are not sick enough to stay home :

Or they could involve infected people who shed an unusual amount of virus — a poorly studied factor that might be due to variations in the amount of virus in the aerosol droplets from a patient’s cough or the amount of infectious virus in feces.

No matter what the cause, public health measures, like avoiding crowds, and cough hygiene, can prevent a super spreading event :

Medical history is replete with stories of super spreading in outbreaks of parasitic disease, tuberculosis, measles and other illness. There is Mary Mallon, a cook better known as Typhoid Mary, who spread typhoid fever to more than 50 people in the early years of the twentieth century. She herself was not ill but was asymptomatic — silently infected with typhoid.

  • China first case looks like was a super spreader
  • The cases in Diamond Princess ship was a case of super spreader focal outbreak
  • The lady in South Korea cult church was a super spreader. There were 28 cases of the coronavirus in South Korea on Feb. 13. Four days had passed without a new confirmed infection. President Moon Jae-in predicted that the outbreak would “disappear before long,” while the prime minister assured people that it was OK not to wear surgical masks outdoors. They probably missed the super spreader possibility. The virus had been rapidly spreading at the time through a large, secretive church in Daegu, with the presence of a super spreader, where it has since mushroomed into the largest epidemic of the coronavirus outside China, with 1,766 cases, including 13 deaths. Now the president is facing a political backlash over his response as the number of cases continues to climb — 505 new infections on Thursday alone.
  • Iran outbreak is possibly from a super spreader
  • Possibilities of finding super spreaders :

  • A person with lower respiratory corona illness
  • A person with coronas pneumonia
  • Critically ill or terminal corona infected patients
  • Immunocompromised persons with corona infection
  • A person who has not suffered from any other corona illness in past with non-virulent strains
  • Rapidly developing corona illness with a very short incubation period
  • Direct exposure to a super spreader compared to secondary or tertiary cases
  • Co-infection with another pathogen
  • Delayed identification and hospital admission of a super spreader
  • Summary :

  • Low grade transmission: Through a spreader
  • High grade transmission: through a super spreader, usually will end up with community spread.
  • Virus ‘does not spread easily’ from contaminated surfaces or animals, revised CDC website state :

    The coronavirus primarily spreads from person to person and not easily from a contaminated surface.

    The revised guidance now states, in headline-size type, “The virus spreads easily between people.” It also notes that the coronavirus, which causes the disease covid-19, “is spreading very easily and sustainably between people.”

    The CDC made another key change to its website, clarifying what sources are not major risks. Under the new heading “The virus does not spread easily in other ways,” the agency explains that touching contaminated objects or surfaces does not appear to be a significant mode of transmission. The same is true for exposure to infected animals.

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