Population HealthPopulation Healthforfor

Health ProfessionalsHealth Professionals

EMERGING INFECTIOUS EMERGING INFECTIOUS DISEASESDISEASES

PART 1

PurposePurpose

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

At the completion of this At the completion of this module you will be able tomodule 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

What Are EmergingWhat Are EmergingInfectious Diseases?Infectious Diseases?

These are human illnesses caused by microorganisms or their

poisonous byproducts and having the potential for occurring in

epidemic numbers.

Why are we concerned about Why are we concerned about Emerging Infectious DiseasesEmerging 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

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

FACTORS RELATED TO THE EMERGENCE OF FACTORS RELATED TO THE EMERGENCE OF INFECTIOUS DISEASESINFECTIOUS 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

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

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

Economic and Social Impact of Economic and Social Impact of Some Infectious Diseases Some Infectious Diseases

Economic and Societal Impact of Economic and Societal Impact of Some Infectious DiseasesSome Infectious Diseases

How Are Infectious How Are Infectious Diseases Acquired?Diseases Acquired?

Inhalation Ingestion

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

CDC’s Target AreasCDC’s 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

CDC’s Target Areas (cont.)CDC’s 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

CONTROL MEASURESCONTROL MEASURES

Water treatment Vector control Rodent reduction Vaccination Antibiotics

ROLE OF PUBLIC HEALTHROLE 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

ROLE OF PUBLIC HEALTH ROLE OF PUBLIC HEALTH (CONT.)(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)

EMERGING INFECTIOUS EMERGING INFECTIOUS DISEASESDISEASES

PART 2

New EmergingNew EmergingInfectious DiseasesInfectious 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

INFLUENZA and ATYPICAL INFLUENZA and ATYPICAL INFLUENZAINFLUENZA

Influenza: PandemicInfluenza: Pandemic--inin--waitingwaiting

R. Ball, MD, MPH

Influenza ward 1917Influenza ward 1917--18182020--40 m. deaths globally40 m. deaths globally~ 0.5 m. deaths in USA~ 0.5 m. deaths in USA

When (not if)When (not if)will it happen will it happen

again ?again ?R. Ball, MD, MPH

CDC. MMWR Vol. 51 (No. RRCDC. MMWR Vol. 51 (No. RR--3)3)44--1212--02 02 www.www.cdccdc..govgov//mmwrmmwr

R. Ball, MD, MPH

Influenza: USA annual statsInfluenza: 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

Worldwide 3 to 5 million people Worldwide 3 to 5 million people are infected with influenza each are infected with influenza each

year with 250,000 to 500,000 year with 250,000 to 500,000 deathsdeaths

Major Influenza PandemicsMajor Influenza Pandemicsof the Twentieth Centuryof the Twentieth Century

Major Influenza PandemicsMajor Influenza Pandemicsof the Twentieth Centuryof the Twentieth Century

Major YearsMajor Years SubtypeSubtypeExcess USMortality

Excess USMortality

’17-’18 H1N1 550,000

’57-’58 H2N2 70,000

’68-69 H3N2 36,000

NEXT ? H5N1 (Avian) ?

Neuraminidase (N)

Hemagglutinin (H)

RNA(highly mutagenic)

M2 protein(only on type A)

Influenza Surface ProteinsInfluenza Surface Proteins

H1N1 H2N2 H3N2

The Usual Human Influenza A The Usual Human Influenza A Strains within the Last CenturyStrains within the Last Century

Asian Flu Hong Kong Flu

1920 1957 1968 1977 2003

Major influenza surface antigens:

HemagglutininNeuraminidase

Thanks to Eric Brenner, MD for slide.

N1 N2 N4 N5 N6 N7 N8 N9H1 H1N1 H1N2H2 H2 N1 H2N2H3 H3N1 H3N2H4H5H6H7H8H9H10H11H12H13H14H15

The Wider Family of Influenza The Wider Family of Influenza CrittersCritters15H x 9N15H x 9N 135 potential HN 135 potential HN

combinationscombinations

*H5N1 already spreading in SE Asia (mortality 1 in 2); *H5N1 already spreading in SE Asia (mortality 1 in 2); inefficient person-person transmission; USA is developing inefficient person-person transmission; USA is developing a limited vaccination program vs. A/ H5N1 “Avian Flu”a limited vaccination program vs. A/ H5N1 “Avian Flu”

*H5N1*H5N1

**

Slide by Eric Brenner, MD & R. Ball, MD, MPH

Emergence of New Influenza A Virus Subtypes in HumansEmergence of New Influenza A Virus Subtypes in Humans

Thanks to JJ Gibson, MD for graph.

Som e C onfirm ed Instances of A vian Som e C onfirm ed Instances of A vian Influenza Infecting H um ans since 1997 (*)Influenza Infecting H um ans since 1997 (*)

Y ear V iru s L ocatio n1997 H5N1 Ho ng Ko ng1999 H9N2 Ho ng Ko ng2002 H7N2 Virgin ia2003 H5N1 Ho ng Ko ng2003 H7N7 Nether lan d s2003 H9N2 Ho ng Ko ng2003 H7N2 New Yo rk2004 H5N1 T hailand , Vie tnam2004 H7N3 Can ad a

(*) For details see: ww w.cdc.gov/flu /avian/gen -in fo/avian-flu -hum ans.htm

Sum m ary tally:H 5N1: 3

H 7N2: 2H 7N3: 1H 7N7: 1

H 9N2: 2

Thanks to Eric Brenner, MD for slide.

Is this virus activelyIs this virus activelyreassorting its genesreassorting its genesto achieve a uniqueto achieve a uniquecombination ofcombination ofvirulence andvirulence andcommunicability?communicability?

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

Avian Influenza may well be Avian Influenza may well be the pandemic in waitingthe pandemic in waiting

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

If Pandemic Influenza Came Today...If Pandemic Influenza Came Today...If Pandemic Influenza Came Today...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

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

““THE INFLUENZA CLOCK IS TICKING, WE THE INFLUENZA CLOCK IS TICKING, WE JUST DON’T KNOW WHAT TIME IT IS”JUST DON’T KNOW WHAT TIME IT IS”

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

SARS (SEVERE ACUTE

RESPIRATORY SYNDROME)

A Novel Virus: SARSA Novel Virus: SARS

NEJM May 15, NEJM May 15, 20032003

SARS-BASIC FACTSSARS-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

SARS: Summary Points - 1SARS: 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

MMWR March 28, 2003 / Vol. 52 / No. 12

Hong Kong Metropole Hotel index case. Example of a “super-spreader”.

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, 130&127 seemed to be “hypertransmitters”

R. Ball, MD, MPH

ThursdayThursdayMay 15,May 15,

20032003

SARS news: www.cnn.comSARS news: www.cnn.com

WHO consensus document on the WHO consensus document on the epidemiology of SARS : epidemiology of SARS :

Selected conclusionsSelected 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

The Return of SARS--2004The 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

The return of SARS - 2004The return of SARS - 2004 Summary CommentsSummary 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.)

The return of SARS - 2004The return of SARS - 2004 Summary CommentsSummary 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.)

R. Ball, MD, MPH

SARS “over its peak” ?SARS “over its peak” ?

June 5 & 19,June 5 & 19,20032003

R. Ball, MD, MPH

http://www.gao.gov/new.items/d031058t.pdfhttp://www.gao.gov/new.items/d031058t.pdf

www.gao.govwww.gao.gov

SARS: we’re “unprepared”SARS: we’re “unprepared”

WEST NILE VIRUSWEST NILE VIRUS

FACTS ABOUT WNVFACTS 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

FACTS ABOUT WNVFACTS 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%

West Nile Virus:West Nile Virus:a novelty becoming endemica novelty becoming endemic

West Nile Virus:US 2003-CDCWest Nile Virus:US 2003-CDC

MONKEY POXMONKEY 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

MONKEY POXMONKEY 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

A NewA NewInfectious Infectious

DiseaseDiseaseOutbreakOutbreak

NEJM 350:4, 1-22-04NEJM 350:4, 1-22-04

The next two diseases, Ebola The next two diseases, Ebola and Hantaviral pulmonary and Hantaviral pulmonary disease, are caused by a disease, are caused by a

group of similar viruses. They group of similar viruses. They are generally classified as are generally classified as

Hantaviral diseases.Hantaviral diseases.

EBOLAEBOLA 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

SUDAN 2004: 20 cases and 5 deaths

Outbreak coming under control now…

HANTAVIRUS PULMONARY HANTAVIRUS PULMONARY SYNDROMESYNDROME

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

EBOLAEBOLA

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

HANTAVIRUS PULMONARY HANTAVIRUS PULMONARY SYNDROME (CONT.)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

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.

YOUR ROLE IN DETECTION YOUR ROLE IN DETECTION OF EMERGING INFECTIONSOF EMERGING INFECTIONS

Participate in surveillance activities in your clinical setting

Know your resources and who to call for consultation

Report to local health department

Note to the readerNote 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”

or

Proceed with the modules on Bioterrorism

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

Describe how various components of the environment affect the public’s 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

At the completion of modules titled “Bioterrorism - At the completion of modules titled “Bioterrorism - South Carolina at Risk” and “Bioterrorism - South South Carolina at Risk” and “Bioterrorism - South

Carolina Responds”, you should be able to: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