CMAAO
CORONA FACTS and MYTH BUSTER 102 Super Spreader
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
916: 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 disproportionate 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. Infact
the primary case 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. uper
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 superspreader. 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 superspreading
event.
Medical history is replete with stories of
superspreading 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.
1. China first case looks like was a super spreader
2. The cases in Diamond Princess ship was a case of
super spreader focal outbreak
3. 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.
4. Iran
outbreak is possibly from a super spreader
Possibilities of finding super spreaders
1. Person
with lower respiratory corona illness
2. Person
with coronas pneumonia
3. Critically
ill or terminal corona infected patients
4. Immunocompromised
persons with corona infection
5. Person
who have not suffered from any other corona illness in past with non-virulent
strains
6. Rapidly
developing corona illness with very short incubation period
7. Direct
exposure to a super spreader compared to secondary or tertiary cases
8. Co-infection with another pathogen
9. Delayed identification and hospital admission
of a super spreader
Summary
1. Low
grade transmission: Through a spreader
2. High
grade transmission: through a super spreader, usually will end up with
community spread.
No comments:
Post a Comment