Transcript Epidemiology of Emerging Infectious Diseases: Global Threats to

Epidemiology of Emerging Infectious
Diseases: An Examination of Global
Threats From a Public Health
Education Perspective
Dr. B. McKinley Thomas
Assistant Professor of Education
Department of Kinesiology and Health Science
Augusta State University
Email: [email protected]
About the Author
Dr. B. McKinley Thomas is a public health educator in
the Department of Kinesiology and Health Science at
Augusta State University, Georgia, USA. He
graduated with a Doctorate of Education in 1995
from the University of Tennessee. Post doctorate
work was completed with the University of South
Carolina, School of Public Health, Eastern Carolina
HIV Prevention Collaboration. The authors research
interest include HIV/AIDS, trend analysis of mortality
/ morbidity data, and the global impact of suicide
among elderly females.
Performance Tasks
define emerging infectious diseases.
 list infectious agents that pose a major threat
to public health.
 discuss the etiology of emerging infectious
diseases.
 acknowledge CDC’s response to emerging
infectious diseases.
 generate ideas regarding future trends and
issues.
 locate internet resources in the area of
infectious disease control.

Public Health Issues / Concerns
International
relations
 Political
collaboration
 Nuclearization
 Food shortages
 Equity
 Life expectancy
 Data Validity

Violence
 Reproduction and
birth control
 Chronic diseases
 Warfare
 Mortality / Morbidity
 Injury

Infectious Disease

1900 - Leading
Causes of Death
– Tuberculosis
– Pneumonia and
–
–
–
–
–
–
–
–
Influenza
Heart Disease
Diarrhea / Enteritis
Cerebrovascular
Disease
Nephritis / Nephrosis
Unintended Injury
Cancer
Diphtheria
Typhoid Fever

1992 - Leading
Causes of Death
– Heart Disease
– Cancer
– Cerebrovascular
–
–
–
–
–
–
–
Disease
COPD
Unintended Injury
Pneumonia / Influenza
Diabetes Mellitus
HIV/AIDS
Suicide
Homicide / Legal
Intervention
Emerging Infectious Diseases (EID)
Defined
 Defined
to include diseases with rates
of incidence that have increased within
the last two years or those with the
potential of increasing in the future
Institute of Medicine, 1992
Pathogenic Microbes Identified as Threats
to Humans Since 1973
1973 - Rotavirus
 1977 - Ebola virus
 1977 - Legionella
pneumophila
 1980 - HTLV 1
 1981 -Toxin-producing
Staphylococcus aureus
 1982 - Escherichia coli
O157:H7
 1982 - Borrelia
burgdorferi

1983 - HIV
 1983 - Helicobacter
pylori
 1989 - Hepatitis C
 1992 - Vibrio cholerae
O139
 1993 - Hantavirus
 1994 - Cryptosporidium
 1996 - nvCJD
 1997 - HVN1

CIA, 2000
Examples of Problem Scope




1981
– The emergence of HIV/AIDS
1994
– More than 200,000 cases of Dengue reported in
Latin America and a 140% increase (over 1990)
of diphtheria in the same region.
1995
– Reports a four-fold increase in cholera levels over
1990 estimates.
Estimated, 25% of all U.S. Doctor visits each year
due to complications associated with infectious
diseases.
Cholera


Vibrio cholerae
Sub-Saharan Africa
affected
– Democratic
Republic of Congo
– Uganda
– Rwanda
– Burundi
– Tanzania
– Kenya
– Sierra Leone
– Cameroon


Over a 3 month period in
1997 outbreaks in Kenya
& Tanzania, over 400
killed
Cases reported in 2000
– Federated States of
Micronesia
 954 cases / 9 deaths
– Somalia
 2,232 cases / 230
deaths
– Madagascar
 15,173 cases / 860
deaths
Dengue




Most important mosquito-borne disease, worldwide
Aedes aegypti
Affected regions
– Indian Subcontinent
– Southeast Asia
– Southern China
– Central and South America
– Caribbean
– Mexico
– Africa
Symptoms similar to those of influenza
Diarrheal Diseases


Organisms most frequently associated with diarrhea
in young children / estimated percentage of cases
seen at health centers in the developing countries
– Rotavirus - 15-25%
– Enterotoxigenic Escherichia coli - 10-20%
– Shigella - 5-15%
– Salmonella (non-typhoid) - 1-5%
– Campylobacter jejuni - 10-15%
– Cryptosporidium - 5-15% (PAHO, 2000)
Oral rehydration therapy (ORT) is one way of
combating diseases within this classification
Diphtheria
Corynebacterium diphtheriae
 Good example of how political issues can
influence the reemergence of a disease
– [See following graph]
 Very contagious and potentially lifethreatening
 Large epidemics in the Soviet Republics,
Algeria, China, and Ecuador.

Source: Morbidity and Mortality Weekly Report. (1996). August 16, 1996 / 45(32);693-697
Escherichia coli O157:H7
Food-borne
 First recognized as a cause of illness in 1982 during
an outbreak of severe bloody diarrhea
 Annually
– 73,000 cases
– 61 deaths
 Primarily transmitted via ingestion of meat that has
not been properly cooked
 Person-to-person, contaminated drinking water,
consumption of contaminated plant products (CDC,

20006)
Ebola
Filovirus
 Fifteen global outbreaks since 1967 Breman, van

der Groen, Peters, & Haymann (1997)

Major human outbreaks
– Sub-Saharan Africa
 Kikwit
 Zaire
 Sudan
 Gabon
Ebola Virus and the Global Community
Year
Location
Cases
Fatality
67
Germany
2
Unsure
76
Sudan
280
53
76
Zaire
318
90
77
Zaire
1
100
79
Sudan
34
65
89
U.S.
4
65
95
Zaire
393
79
Source: Benini, A. A, & Bradford, 2000
Hantavirus
Also known as...
– Sin Nombre virus (responsible for most hantaviral
infections in the U.S.) Wells, et al, (1997)
– Convict Creek virus
– Muerto Canyon virus
 First recognized in 1993
– Four corners region of the U.S.
– Has been identified in the U.S. from CA to FL
 Mortality rate, 50%
 Associated disease
– Hantavirus pulmonary syndrome (HPS)

Helicobacter pylori
Bacterium
 Believed to be the etiologic agent in
– 90% of duodenal ulcers
– 80% of gastric ulcers
 Discovered as culprit in 1982
 Large portion of world population infected
 Related chronic disease
– Gastric cancer

Listeriosis




Listeria monocytogenes
Common among individuals who work with animals
Causes spontaneous abortion and stillbirth in
domestic animals
Primarily affects
– Pregnant women
– Newborns
– Elderly
– Immuno compromised adults (Canadian Institute of
Public Health Inspectors, 2000)
Malaria
Due to Plasmodium parasite transmitted by the 
Anopheles mosquito
 300 million infected each year
 Regions
– Asia
– Africa
– South / Central Americas
 >1 million deaths annually
– Mostly infants and children (National Institutes of Health,

2000)
Tuberculosis


Chronic bacterial infection
Principal infectious cause of death worldwide
– Three million deaths annually
– One-third of world population infected with M.

Tuberculosis (OSHA, 2000)
Outbreak locations
– Jails / prisons
– Hospitals
– Nursing homes
– Homeless shelters
Tuberculosis
Estimated 15 million Americans with latent
infections
 Minorities affected disproportionately [as is
the case with many other infectious diseases]
– 54% active M. Tuberculosis cases (1995)
reported among African American and
Hispanic populations
– An additional 17.5% among Asians
 In some U.S. sectors, morbidity rates surpass
those of poorest countries

Cases of M. Tuberculosis by Year of
Diagnosis, 1953-1999
90,000
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
19
53
19
55
19
57
19
59
19
61
19
63
19
65
19
67
19
69
19
71
19
73
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
0
Source: Centers for Disease Control and Prevention, 20001
West Nile Encephalitis
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Mosquito-borne infection
Outbreaks evident in Egypt, Asia, Israel, South
Africa, parts of Europe and Australia
No recorded cases in the U.S. prior to 1999
Culex pipiens mosquito (the common house
mosquito) associated with West Nile virus
Transmission: Bird ---> mosquito ---> human
– American crows most commonly infected, yet
confirmed in other species (State of New York, Department
of Health, 2000)
– May also infect other mammals such as horses
– 62 cases 7 deaths
Institute of Medicine
Demographic shifts
 Advances in technology / industry
 Economic development and change in land
use patterns
 Travel / commerce
 Microbial adaptation / change
 Breakdown of the public health infrastructure

Drug Resistance


Drug Resistance
– Gonorrhea, malaria, childhood ear infections
– Resistance is a factor in most nosocomial
infections
– More effective medications are needed
 In some U.S. clinics, 30% of cases of
gonorrhea resistant to penicillin or tetracycline
or both
– MDR-TB
Inappropriate use of antibiotics is a salient factor in
drug resistance
Infectious Diseases and Chronic Diseases

Emerging evidence that a substantial proportion of
human cancers are caused by infectious diseases
(~15%) (Valerie Beal, Speaker, 2nd International Conference on
Emerging Infectious Diseases)
– 1911 - Rous Sarcoma
– 1932 - Shope Skin Tumor
– 1960 - Feline Leukemia
– 1978 - HPV, Skin Cancer
– 1981 - HBV, Liver Cancer
– 1981 - EBV, non Hodgkin's Lymphoma
– 1983 - HPV, Cervical Cancer
CDC’s Response to EIDs
 Goal
I: Surveillance and Response
 Goal II: Applied Research
 Goal III: Infrastructure and Training
 Goal IV: Prevention and Control
Suggestions for Enhanced Public Health
Public health education
 Continued collaborative efforts on the part of
the international community
 Government funding for biomedical and
educational efforts
 Recognition of infectious diseases that pose
the greatest risk to public health
 As usual, more research is needed...

Conclusions




Emerging infectious diseases are omnipotent and will
continue to command attention.
– EID’s are most deleterious in 1) developing
nations and 2) among children, the elderly,
females, and those with weakened immune
systems
EID’s are controllable!
It is the responsibility of the global community to
continue to develop / refine public health
infrastructures to deal with burgeoning crises.
Initiatives must be developed in order to overcome
social, religions, and regional barriers to prevention
and control.
Useful Documents on the World Wide Web
Emerging Infectious Diseases
– http://www.cdc.gov/ncidod/EID/index.htm
 HIV/AIDS Education / Prevention Slide Set
– http://www.cdc.gov/hiv/graphics.htm
 Morbidity and Mortality Weekly Report
(MMWR)
– http://www2.cdc.gov/mmwr/
 Preventing Emerging Infectious Diseases: A
Strategy for the 21st Century
– http://www.cdc.gov/ncidod/emergplan/p
lan98.pdf

Useful Sites on the World Wide Web
Alliance for the Prudent Use of Antibiotics
– http://www.healthsci.tufts.edu/apua/apu
a.html
 Centers for Disease Control and Prevention
– http://www.cdc.gov
 International Trachoma Institute
– http://www.trachoma.org/
 ProMed Email
– http://www.promed.org/
 World Health Organization
– http://www.who.ch
