Video 8.4: Isolation and quarantine and contact tracing

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Do curso por The University of Hong Kong

Epidemics

23 ratings

The University of Hong Kong

Epidemics

23 ratings

“If history is our guide, we can assume that the battle between the intellect and will of the human species and the extraordinary adaptability of microbes will be never-ending.” (1) Despite all the remarkable technological breakthroughs that we have made over the past few decades, the threat from infectious diseases has significantly accelerated. In this course, we will learn why this is the case by looking at the fundamental scientific principles underlying epidemics and the public health actions behind their prevention and control in the 21st century. This course covers the following four topics: 1. Origins of novel pathogens; 2. Analysis of the spread of infectious diseases; 3. Medical and public health countermeasures to prevent and control epidemics; 4. Panel discussions involving leading public health experts with deep frontline experiences to share their views on risk communication, crisis management, ethics and public trust in the context of infectious disease control. In addition to the original introductory sessions on epidemics, we revamped the course by adding: - new panel discussions with world-leading experts; and - supplementary modules on next generation informatics for combating epidemics. -------------------------------------------------------- (1) Fauci AS, Touchette NA, Folkers GK. Emerging Infectious Diseases: a 10-Year Perspective from the National Institute of Allergy and Infectious Diseases. Emerg Infect Dis 2005 Apr; 11(4):519-25. What you'll learn - Demonstrate knowledge of the origins, spread and control of infectious disease epidemics - Demonstrate understanding of the importance of effective communication about epidemics - Demonstrate understanding of key contemporary issues relating to epidemics from a global perspective

Na lição

Theme Three: Control (Non-pharmaceutical intervention (NPI))

Theme Three Summary

Week 8 Introduction1:42

Week 8.1: Non-pharmaceutical interventions overview and John Snow4:34

Week 8.2: Control of Cholera8:37

Week 8.3: Hygiene and other personal interventions6:23

Video 8.4: Isolation and quarantine and contact tracing6:02

Video 8.5: School closure7:49

Video 8.6: International measures including travel restrictions and entry screening4:40

Video 8.7: Zoonoses - market closure6:18

Conheça os instrutores

Gabriel M. Leung (HKU)
Dean
Li Ka Shing Faculty of Medicine
Joseph T. Wu (HKU)
Associate Professor
Li Ka Shing Faculty of Medicine
Kwok-Yung Yuen (HKU)
Professor
Li Ka Shing Faculty of Medicine
Tommy Lam (HKU)
Assistant Professor
Li Ka Shing Faculty of Medicine
Maria Huachen Zhu (HKU)
Associate Professor
Li Ka Shing Faculty of Medicine
Guan Yi (HKU)
Chair Professor
Li Ka Shing Faculty of Medicine
Benjamin Cowling (HKU)
Professor
Li Ka Shing Faculty of Medicine
Thomas Abraham (HKU)
Associate Professor
Journalism and Media Studies Centre
Mark Jit (LSHTM)
Professor
Department of Infectious Disease Epidemiology
Malik Peiris (HKU)
Chair Professor
Li Ka Shing Faculty of Medicine
Marc Lipsitch (Harvard)
Professor
Department of Epidemiology

Non-pharmaceutical interventions, sometimes

abbreviated as NPIs, are actions, apart from

getting vaccinated and taking medicine, that people

and communities can take to help slow the spread

of infectious diseases and control epidemics.

In this third part, I'm going to talk about

isolation, quarantine, and contact tracing.

The objectives of this session are:

to define and distinguish isolation and quarantine;

to describe considerations for implementation

and duration of isolation, contact tracing, and quarantine;

and to discuss the difference between

quarantine and public health observation.

Isolation and quarantine are some of the earliest

recorded interventions to control infections, going back to

biblical times, more than two and a half thousand years ago.

The basic idea of isolation is to reduce the chance

of transmission from an infected person

to other patients, health care staff, or visitors.

Isolation is typically used for serious infections,

and takes place in special hospital facilities such as

negative pressure rooms, where access

to the patient can be tightly controlled.

For less serious diseases, such as measles

and chickenpox, cases can be isolated at home.

For isolation to be most effective, it should be done while

the case is infectious, i.e. during the infectious period.

Therefore isolation is most effective as a public health

measure when cases can be rapidly identified and diagnosed.

Control of the SARS epidemic in 2003 coincided

with shortening in the median time to admission

and isolation of cases, along with effective

infection control procedures in hospitals.

Quarantine refers to the detention of exposed

and potentially infected persons for close observation

until it is apparent that they have not been infected.

Persons who show signs of infection during

quarantine will typically be moved to isolation.

In Europe in the 14th century, an epidemic of Black Death

wiped out 30% of the population, and many cities

took measures to prevent introduction of the disease.

The word "quarantine" is derived from the Italian word

for 40, since some cities required visitors to stay

for 40 days in an enclosed location, such as an island,

before being allowed into the city.

In order for quarantine to be effective,

potentially exposed persons must be observed

for the duration of the potential incubation period.

In the case of SARS, the mean incubation period

was around five days, and a quarantine period of 14 days

would capture more than 95% of incubations.

In the case of Ebola virus, the mean incubation period

is 11 days, and 95% of infections

lead to symptoms within 21 days.

It is important to be clear on the difference

between isolation and quarantine.

Isolation is used for infectious individuals

who are typically symptomatic, while quarantine

is used for persons who have been exposed

and might be infected, but are not thought to be infectious.

Both isolation and quarantine aim to prevent

infectious individuals from spreading infection to others.

Now, in order to identify persons who have been

exposed to infection, and therefore should be quarantined,

it is often necessary to do contact tracing.

The number and type of contacts to be traced depends

on the mode in which infection occurs.

For respiratory viruses such as SARS, the most important

people to identify are those who have had prolonged

close contact, such as family members, classmates,

or work colleagues, and health care workers

that came into contact with the case.

In some cases it can be difficult to identify contacts,

and instead much broader criteria are used.

For example, in Hong Kong, an outbreak of SARS

in a residential apartment block in 2003

led to quarantine of all residents for two weeks.

While in 2009, identification of an imported case

of H1N1 in a tourist led to a seven-day quarantine

of the entire hotel he was staying at.

Contact tracing is usually done by public health

officials but in some emergencies it

may be necessary to involve others.

For example, in the SARS epidemic in 2003,

contact tracing in Hong Kong was done by police force,

while in Singapore it was done by the military.

In some diseases which are less serious or

which have longer incubation periods, quarantine can be

impractical, and instead those people who are exposed

and potentially infected are kept under public health

observation but allowed to stay at home

or even to go about their daily activities rather than

being placed in a quarantine facility.

Public health observation would typically involve

regular visits or telephone calls to check

whether the person had developed any symptoms.

Thinking about the current epidemic of Ebola virus disease

in West Africa, the most effective tools to control

the epidemic are isolation of the ill, and quarantine

or observation of exposed persons.

And one of the factors contributing to the scale

of the epidemic has been the lack of

resources to trace and observe contacts,

and to rapidly isolate cases in some areas.

Public health monitoring of exposed persons

and isolation of cases has been able to halt

Ebola virus disease outbreaks in Nigeria

and Senegal during the current outbreak,

and prior Ebola outbreaks in Congo and Uganda.

Another contributing factor to the scale of the current

outbreak is the limited capacity for infection control

in health care settings, leading to infection

and in many cases the death of health care workers.

One additional factor which may be controversial

is the idea that quarantine policies earlier

in the epidemic contributed to the speed

of geographic spread of Ebola virus disease in Liberia.

The argument goes like this--

faced with the prospect of being confined for three weeks

with other potentially infected persons, some exposed people

fled affected areas rather than complying with quarantine.

In this case, medical observation rather than

strict quarantine may be more acceptable,

and consequently more effective.

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