Population Health for Health Professionals

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Population HealthforHealth Professionals
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EMERGING INFECTIOUS DISEASES

• PART 1

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Purpose

• The purpose of this module is to provide an
  exposure to some of the emerging diseases that
  will affect the health of the public and to
  examine the challenges and opportunities they
  pose to the public health system

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At the completion of this module you will be able
to

• Describe the causes and contributing factors
  which lead to the emergence of infectious
  diseases.
• Describe the latest emerging infections which
  have the potential to threaten people living in
  the United States.
• Describe some of the measures that can be used to
  control and contain these diseases

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What Are EmergingInfectious Diseases?

• These are human illnesses caused by
  microorganisms or their poisonous byproducts and
  having the potential for occurring in epidemic
  numbers.

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Why are we concerned about Emerging Infectious
Diseases?

• These diseases
• Pose a threat to all persons regardless of age,
  sex, lifestyle, ethnic background, or
  socioeconomic status
• Cause suffering and death
• Impose a financial burden on society

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• Over the past century, infectious diseases have
  decreased as a cause of death in this country
• Improved sanitation, vaccination and antibiotics
  have played a large part in this decrease and are
  responsible to the increase in the lifespan of
  our residents
• However, in the past twenty years the incidence
  of emerging infectious diseases has increased

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FACTORS RELATED TO THE EMERGENCE OF INFECTIOUS
DISEASES

• Factors studied Examples
• 1. Biological----------Genes, microbes,
  medicines, vaccines, blood and organ transplants,
  rapid microbial adaptation and resistance to
  antibiotics
• 2. Behavior----------Sports, nutrition,
  sexuality, tobacco, alcohol, international travel
• 3. Environment physical--------Air, water,
  toxins, radiation, pollution, noise, agricultural
  development, climate change, technology
• 4. Environment social ---------Housing,
  education, employment, and working conditions
• 5. Environment human rights-------Discrimination
  , war, torture, physical and mental abuse, lack
  of access to health care, prevention and health
  education
• 6. Breakdown of traditional basic public health
  infrastructure

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• An existing organism given the selective
  advantage by such things as a changing
  environmental condition and given the opportunity
  can infect a new host population
• An organism can re-emerge in a drug resistant form

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• In the US, about 25 of physician visits are
  attributed to infectious diseases
• In 1993, direct and indirect costs were estimated
  to be more than 120 billion. Today, these costs
  are substantially more

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Economic and Social Impact of Some Infectious
Diseases
Economic and Societal Impact of Some Infectious
Diseases
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How Are Infectious Diseases Acquired?

• Inhalation
• Ingestion
• Food, water, soil
• Percutaneous inoculation
• Absorption from mucous membranes
• Exposure to blood and body fluids

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CDCs Target Areas

• Antimicrobial resistance
• Foodborne and waterborne diseases
• Vectorborne and zoonotic diseases
• Diseases transmitted through blood transfusions
  or blood products
• Chronic diseases caused by infectious agents

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CDCs Target Areas (cont.)

• Vaccine development and use
• Diseases of persons with impaired host defenses
• Diseases of pregnant women and newborns
• Diseases of travelers, immigrants, and refugees

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CONTROL MEASURES

• Water treatment
• Vector control
• Rodent reduction
• Vaccination
• Antibiotics

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ROLE OF PUBLIC HEALTH

• Surveillance and early response (detect,
  investigate, initiate action and monitor)
• Assessment of health status, risks, and services
  available to a community
• Development of health policy
• Assurance of quality services (discourage
  inappropriate use of antibiotics)
• Laboratory identification

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ROLE OF PUBLIC HEALTH (CONT.)

• Rapid communication with medical providers and
  hospitals
• Communication with the media
• Public and health care provider education (role
  in transmission, modification of lifestyle to
  avoid disease, etc.)
• Environmental assessment and remediation, e.g.
  food inspection, water supply inspection, vector
  control)

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EMERGING INFECTIOUS DISEASES

• PART 2

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New EmergingInfectious Diseases

• The following diseases have recently emerged
  as public health concerns and will be discussed
  more fully in the slides that follow
• Atypical Influenza
• Severe Acute Respiratory Syndrome (SARS)
• West Nile encephalitis (WNV)
• Monkey Pox
• Ebola
• Hantavirus

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INFLUENZA and ATYPICAL INFLUENZA
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Influenza USA annual stats

• 10-20 of population contract influenza annually
• 36,000 die (excess mortality), more than 90 are
  65 and older
• 226,000 hospitalizations (2004 data)
• 38 million missed school days, 70 million missed
  work days
• 1-3 Billion in direct costs

R. Ball, MD, MPH
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Worldwide 3 to 5 million people are infected with
influenza each year with 250,000 to 500,000 deaths
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Major Influenza Pandemics of the Twentieth Century
Excess US Mortality
Major Years
Subtype
17-18 H1N1 550,000 57-58 H2N2
70,000 68-69 H3N2 36,000 NEXT ? H5N1
(Avian) ?
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Influenza Surface Proteins
Neuraminidase (N)
Hemagglutinin (H)
RNA (highly mutagenic)
M2 protein (only on type A)
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The Usual Human Influenza A Strains within the
Last Century
Major influenza surface antigens Hemagglutinin
Neuraminidase
Asian Flu
Hong Kong Flu
1920
1957
1968
1977
2003
Thanks to Eric Brenner, MD for slide.
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The Wider Family of Influenza Critters
15H x 9N? 135 potential HN combinations H5N1
already spreading in SE Asia (mortality 1 in 2)
inefficient person-person transmission USA is
developing a limited vaccination program vs. A/
H5N1 Avian Flu
H5N1

Slide by Eric Brenner, MD R. Ball, MD, MPH
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Emergence of New Influenza A Virus Subtypes in
Humans
Thanks to JJ Gibson, MD for graph.
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Is this virus actively reassorting its genes to
achieve a unique combination of virulence
and communicability?
Thanks to Eric Brenner, MD for slide.
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• Avian influenza A (H5N1) that infects poultry is
  a concern due to the potential for spread of an
  influenza A variant to humans, and the
  eventuality of human to human transmission, and a
  pandemic of atypical influenza.
• Recent reports from several Asian countries that
  are experiencing Asian flu outbreaks in flocks
  of chickens indicate that humans have been
  infected who live or work in close proximity to
  those flocks of chickens

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Avian Influenza may well be the pandemic in
waiting
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• Even if an epidemic is not deliberately caused by
  an altered strain of influenza virus, an epidemic
  or pandemic originating from natural origins will
  more than likely occur

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If Pandemic Influenza Came Today...

• Up to 200 million people infected
• Up to 50 million people requiring care
• Up to 2 million hospitalizations
• Between 100,000 and 500,000 deaths
• just in the USA

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THE INFLUENZA CLOCK IS TICKING, WE JUST DONT
KNOW WHAT TIME IT IS

• Ed Marcuse, MD and past chairman, The National
  Vaccine Advisory Committee

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• SARS (SEVERE ACUTE
• RESPIRATORY SYNDROME)

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A Novel Virus SARS
NEJM May 15, 2003
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SARS-BASIC FACTS

• SARS is an illness which can vary in severity and
  is caused by a Corona virus most likely of animal
  origin, e. g. civet
• The disease is spread by large respiratory
  droplets from sneezing and coughing within a
  radius of 6 to 8 feet.
• Incubation period-3 to 10 days
• It can survive on surfaces up to 3 days but is
  easily killed by standard disinfectants

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SARS Summary Points - 1

• In retrospect epidemic started November 2002 in
  Southern China
• WHO issues Global Alert March 2002
• February 2003 very infectious patient infects
  many guests at Metropole Hotel in Hong Kong who
  in turn spread SARS to their own countries
• World attention remained focused on SARS until
  global surveillance shows all chains of
  transmission interrupted July 2003

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MMWR March 28, 2003 / Vol. 52 / No. 12
Hong Kong Metropole Hotel index case. Example of
a super-spreader.
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Is there a small subset of SARS patients who
account for a disproportionate share of
transmission? MMWR May 9, 2003 / Vol. 52 / No. 18
- I
Patients No 1, 6, 35, 130127 seemed to be
hypertransmitters
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SARS news www.cnn.com
ThursdayMay 15,2003
R. Ball, MD, MPH
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WHO consensus document on the epidemiology of
SARS Selected conclusions

• The report found no evidence that SARS is an
  airborne disease
• Health Care Workers were at special risk,
  especially those involved with aerosol-generating
  procedures
• The risk of transmission is greatest around day
  10 of the illness
• Children were rarely affected by SARS
• The implications of the events at the Metropole
  Hotel are not yet fully understood

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The Return of SARS--2004

• SARS reoccurred in China in 2004
• There were nine cases
• WHO issued a Global Health Advisory
• The outbreak was contained 5/18/04, but WHO
  advised continued vigilance

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The return of SARS - 2004 Summary Comments

• SARS improved the ability of public health to
  conduct surveillance, investigate, and establish
  control measures for an infectious respiratory
  disease with (then) apparently pandemic potential
• How extraordinary to have lived through the first
  global outbreak which was managed in real-time by
  means of public health measures, the Internet,
  and teleconferencing calls (e.g. between WHO,
  CDC, Hong-Kong, Singapore, Toronto, etc.)

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The return of SARS - 2004 Summary Comments

• How extraordinary to have lived through the first
  global outbreak which was managed in real-time by
  means of public health measures, the Internet,
  and teleconferencing calls (e.g. between WHO,
  CDC, Hong-Kong, Singapore, Toronto, etc.)

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SARS over its peak ?
June 5 19,2003
R. Ball, MD, MPH
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SARS were unprepared
www.gao.gov
http//www.gao.gov/new.items/d031058t.pdf
R. Ball, MD, MPH
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WEST NILE VIRUS
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FACTS ABOUT WNV

• West Nile Fever is a flu-like illness of sudden
  onset, caused by a subgroup of viruses called
  Flavoviruses
• Symptoms fever, sore throat, headache, malaise,
  arthralgia or myalgia. Rash is common.
• Complications meningitis or encephalitis
  (inflammation of the brain tissue or the
  covering of the brain) can occur. The disease is
  then named West Nile neuroinvasive disease
• Reservoir certain birds

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FACTS ABOUT WNV

• Incubation period usually 3 to 12 days
• Communicability no direct person to person
  transmission Mode of transmission the bite of an
  infected mosquito
• Prevention Mosquito eradication, mosquito
  repellents
• Treatment none specific
• Mortality rate 3 to 15

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West Nile Virus a novelty becoming endemic
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West Nile VirusUS 2003-CDC
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MONKEY POX

• Monkey pox, an Orthopox virus caused infection,
  closely resembles small pox clinically
• Recently transmitted to humans by prairie dogs
  infected by a Gambian giant rat imported from
  Africa
• Symptoms fever, rash, muscle aches, cough
• Mortality 1 to 10 in Africa, none in the US

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MONKEY POX

• Transmission person to person has occurred
• Treatment antibiotics, small pox vaccination if
  early in the course of the disease
• Prevention small pox vaccination is partially
  successful, public education about the dangers of
  illegally imported pets

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A New Infectious Disease Outbreak
NEJM 3504, 1-22-04
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The next two diseases, Ebola and Hantaviral
pulmonary disease, are caused by a group of
similar viruses. They are generally classified
as Hantaviral diseases.
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EBOLA

• Mode of transmission handling infected wild
  animals
• Incubation period 2 to 21 days
• Transmission may be spread person to person by
  contact with body secretions
• Treatment supportive
• Prevention caution in contact with infected
  monkeys

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SUDAN 2004 20 cases and 5 deaths Outbreak
coming under control now
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HANTAVIRUS PULMONARY SYNDROME

• Hantavirus pulmonary syndrome or hanta virus
  disease is caused by a Sin Nombre virus which has
  its reservoir in certain varieties of mice,
  principally the deer mouse.
• Infected rodents shed virus in urine, droppings
  and saliva. Humans become ill when breathing in
  dried aerosolized mouse excreta.
• Symptoms range from mild to severe. Fever,
  myalgias, gastrointestinal complaints, pneumonia
• Complications blood dyscrasias, respiratory
  failure and shock

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EBOLA

• This is a severe viral illness caused by the
  Ebola virus (Filoviridae family) with its
  reservoir in chimpanzees and gorillas
• Symptoms sudden onset of fever, myalgia,
  headache, followed by vomiting, diarrhea, and
  rash.
• Mortality from 50 to 90 in Africa
• Complications In severe forms, multiorgan
  failure occurs, primarily hemorrhagic and
  pulmonary complications

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HANTAVIRUS PULMONARY SYNDROME (CONT.)

• Mortality up to 50
• Incubation period a few days to six weeks
• Communicability no human to human transmission
• Treatment supportive
• Prevention rodent control, public education and
  caution

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• There are other infectious agents that will be
  the emerging infectious diseases of the future.
  We must be vigilante as a society and do our best
  to prevent their emergence by learning the
  lessons that the diseases we are dealing with
  today are teaching us.

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YOUR ROLE IN DETECTION OF EMERGING INFECTIONS

• Participate in surveillance activities in your
  clinical setting
• Know your resources and who to call for
  consultation
• Report to local health department

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Note to the reader

• Having just completed the module Emerging
  Infectious Diseases, you should proceed with
  either modules (5b) Environmental Impacts on
  Health or (5c) The Future of Health and Health
  Care
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• Proceed with the modules on Bioterrorism

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At the completion of modules 5(b c) you will be
able to

• Describe how various components of the
  environment affect the publics health
• Identify the roles and responsibilities of the
  health care provider in confronting health care
  threats related to the environment
• Discuss the health care needs of individuals and
  communities in the future
• Identify roles and responsibilities of different
  components of the public health system in
  confronting health challenges

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At the completion of modules titled Bioterrorism
- South Carolina at Risk and Bioterrorism -
South Carolina Responds, you should be able to

• Understand the concept of terrorism
• Understand how biological agents can be used as
  terrorist weapons
• Describe the characteristics of those biologic
  agents thought to be the choice of terrorists
• Understand the regional response to a
  bioterrorist act and the use of the unified
  incident/management command system
• Describe the role and responsibility of each
  responding agency
• Raise other issues that must be dealt with in
  planning a response to a bioterrorist act