polio

1. Emerging & Re-emerging
Infectious Diseases
Dr. JAYAKUMAR

2. Outline Of Presentation
 Definition of emerging & re-emerging diseases
 Factors contributing to emergence
 Examples
 Public health response

3. Definition
 Emerging infectious disease
Newly identified & previously unknown
infectious agents that cause public health
problems either locally or internationally

4. Definition
 Re-emerging infectious disease
Infectious agents that have been known for some
time, had fallen to such low levels that they were
no longer considered public health problems &
are now showing upward trends in incidence or
prevalence worldwide

5. Factors Contributing To
Emergence
AGENT
 Evolution of pathogenic infectious agents
(microbial adaptation & change)
 Development of resistance to drugs
 Resistance of vectors to pesticides

6. Factors Contributing To
Emergence
HOST
 Human demographic change (inhabiting new
areas)
 Human behaviour (sexual & drug use)
 Human susceptibility to infection
(Immunosuppression)
 Poverty & social inequality

7. Factors Contributing To
Emergence
ENVIRONMENT
 Climate & changing ecosystems
 Economic development & Land use
(urbanization, deforestation)
 Technology & industry (food processing &
handling)

8. CONTD.
 International travel & commerce
 Breakdown of public health measure
(war, unrest, overcrowding)
 Deterioration in surveillance systems
(lack of political will)

9. Transmission of Infectious Agent
from
Animals to Humans
 >2/3rd
emerging infections originate from animals-
wild & domestic
 Emerging Influenza infections in Humans
associated with Geese, Chickens & Pigs
 Animal displacement in search of food after
deforestation/ climate change (Lassa fever)
 Humans themselves penetrate/ modify
unpopulated regions- come closer to animal
reservoirs/ vectors (Yellow fever, Malaria)

10. Climate & Environmental
Changes
 Deforestation forces animals into closer human
contact- increased possibility for agents to breach
species barrier between animals & humans
 El Nino- Triggers natural disasters & related
outbreaks of infectious diseases (Malaria,
Cholera)
 Global warming- spread of Malaria, Dengue,
Leishmaniasis, Filariasis

11. Poverty, Neglect & Weakening of
Health Infrastructure
 Poor populations- major reservoir &
source of continued transmission
 Poverty- Malnutrition- Severe infectious
disease cycle
 Lack of funding, Poor prioritization of
health funds, Misplaced in curative rather
than preventive infrastructure, Failure to
develop adequate health delivery systems

12. Uncontrolled Urbanization &
Population Displacement
 Growth of densely populated cities- substandard
housing, unsafe water, poor sanitation,
overcrowding, indoor air pollution (>10%
preventable ill health)
 Problem of refugees & displaced persons
 Diarrhoeal & Intestinal parasitic diseases, ARI
Lyme disease (B. burgdorferi)- Changes in
ecology, increasing deer populations, suburban
migration of population

13. Human Behaviour
 Unsafe sexual practices (HIV, Gonorrhoea,
Syphilis)
 Changes in agricultural & food production
patterns- food-borne infectious agents (E. coli)
 Increased international travel (Influenza)
 Outdoor activity

14. Antimicrobial Drug Resistance
 Causes:
• Wrong prescribing practices
• non-adherence by patients
• Counterfeit drugs
• Use of anti-infective drugs in animals &
plants

15. Antimicrobial Drug Resistance
 Consequences
Prolonged hospital admissions
Higher death rates from infections
Requires more expensive, more toxic drugs
Higher health care costs

16. HUMAN
ANIMALS
ENVIRONMENT
VECTORS
Zoonosis
Population
Growth
Mega-cities
Migration
Exploitation
Pollution
Climate change
Vector
proliferation
Vector
resistance
Transmission
Antibiotics
Intensive farming
Food
production

17. Examples of Emerging
Infectious Diseases
 Hepatitis C- First identified in 1989
In mid 1990s estimated global prevalence
3%
 Hepatitis B- Identified several decades
earlier
Upward trend in all countries
Prevalence >90% in high-risk population

18. CONTD.
 Zoonoses- 1,415 microbes are
infectious for human
Of these, 868 (61%) considered
zoonotic
70% of newly recognized pathogens
are zoonoses

19. Pandemic HINI (Swine flu)
 Worldwide- 162,380 cases
1154 deaths
 India- 558 cases
1 death

20. Examples of Re-Emerging
Infectious Diseases
 Diphtheria- Early 1990s epidemic in Eastern
Europe(1980- 1% cases; 1994- 90% cases)
 Cholera- 100% increase worldwide in 1998
(new strain eltor, 0139)
 Human Plague- India (1994) after 15-30
years absence. Dengue/ DHF- Over past 40
years, 20-fold increase to nearly 0.5 million
(between 1990-98)

21. Key Tasks in Dealing with Emerging
Diseases
 Surveillance at national, regional, global level
 epidemiological,
 laboratory
 ecological
 anthropological
 Investigation and early control measures
 Implement prevention measures
 behavioural, political, environmental
 Monitoring, evaluation

22. Solutions
Public health surveillance & response systems
 Rapidly detect unusual, unexpected, unexplained
disease patterns
 Track & exchange information in real time
 Response effort that can quickly become global
 Contain transmission swiftly & decisively

23. GOARN
Global Outbreak Alert & Response Network
 Coordinated by WHO
 Mechanism for combating international
disease outbreaks
 Ensure rapid deployment of technical
assistance, contribute to long-term epidemic
preparedness & capacity building