1. Emerging & Re-emerging
Infectious Diseases- Microbial
health hazards
Paper-203
Dr. Sneha Gang

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

3. Infectious Disease- Trends
 Receded in Western countries 20th
century
 Urban sanitation, improved housing, personal
hygiene, antisepsis (the practice of using
antiseptics) & vaccination
 Antibiotics further suppressed morbidity &
mortality
 Note: Morbidity refers to the unhealthy state of an individual,
while mortality refers to the state of being mortal.
 Both concepts can be applied at the individual level or across a population.
 For example, a morbidity rate looks at the incidence of a disease across
a population and/or geographic location during a single year.
 Mortality rate is the rate of death in a population.

4. ??
AIDSAIDS
Avian InfluenzaAvian Influenza
EbolaEbola
MarburgMarburg
CholeraCholera
Rift Valley FeverRift Valley Fever
TyphoidTyphoid
TuberculosisTuberculosis
LeptospirosisLeptospirosis
MalariaMalaria
ChikungunyaChikungunya
DengueDengue
JEJE
Antimicrobial resistanceAntimicrobial resistance
UPUP
Guinea worm Smallpox
Yaws
Poliomyelitis
Measles
Leprosy
Neonatal tetanus
DOWNDOWN
Infectious Diseases: A World in TransitionInfectious Diseases: A World in Transition

5. Definition
 Emerging infectious disease
 Emerging infectious diseases are diseases of infectious origin whose
incidence in humans has increased within the recent past or threatens
to increase in the near future.
 These also include those infections that appear in new geographic
areas or increase abruptly.
 The new infectious diseases and those which are re-emerging after a
period of quiescence are also grouped under emerging infectious
diseases.
OR
Newly identified & previously unknown infectious agents that cause public
health problems either locally or internationally

6. 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

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

8. Factors Contributing To
Emergence
2. HOST
 Human demographic change (inhabiting new
areas)
 Human behaviour (sexual & drug use)
 Human susceptibility to infection
(Immunosuppression)
 Poverty & social inequality
 Changes in lifestyle that promote unhealthy and
risk prone behavior patterns affecting food
habits and sexual practices.

9. Factors Contributing To
Emergence
3. ENVIRONMENT
 Climate & changing ecosystems
 Economic development & Land use (urbanization,
deforestation)
 Technology & industry (food processing & handling)
 Environmental sanitation characterized by unsafe water
supply , improper disposal of solid and liquid waste, poor
hygienic practices and congested living conditions all
contribute to emergence of infection

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

11. Transmission of Infectious Agent
from
1. 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)

12. 2. Climate & Environmental
Changes
 Deforestation forces animals into closer human
contact- increased possibility for agents to breach
species barrier between animals & humans
 El Nino (This refers to times when waters of the tropical eastern Pacific are
colder than normal and trade winds blow more strongly than usual)- Triggers
natural disasters & related outbreaks of infectious
diseases (Malaria, Cholera)
 Global warming- spread of Malaria, Dengue,
Leishmaniasis, Filariasis

13. 3. 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

14. 4. 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

15. 5. 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

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

17. CONTD.
• Loss of effectiveness:
• Community-acquired (TB,
Pneumococcal) &
Hospital-acquired (Enterococcal,
Staphylococcal
 Antiviral (HIV), Antiprotozoal (Malaria),
Antifungal

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

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

20. Examples of recent emerging
diseases
Source: NATURE; Vol 430; July 2004;
www.nature.com/nature

21. •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

22. CONTD.
 Zoonoses- 1,415 microbes are infectious for
human
Of these, 868 (61%) considered zoonotic
(A zoonotic disease is a disease that can be passed between
animals and humans. Zoonotic diseases can be caused by viruses,
bacteria, parasites, and fungi.)
70% of newly recognized pathogens are
zoonoses (A zoonosis is any disease or infection that is naturally
transmissible from vertebrate animals to humans. Animals thus play an
essential role in maintaining zoonotic infections in nature. Zoonoses may be
bacterial, viral, or parasitic, or may involve unconventional agents.)

23. Emerging Zoonoses: Human-
animal interface
Marburg virus
Hantavirus Pulmonary Syndrome
Ebola virus
Borrelia burgdorferi: Lyme
Deer tick (Ixodes
scapularis)
Mostomys rodent: Lassa fever
Avian influenza virus
Bats: Nipah virus

24. SARS: The First Emerging Infectious
Disease Of The 21st Century
SARS Cases
19 February to 5 July 2003
China (5326)
Singapore (206)
Hong Kong (1755)
Viet Nam (63)
Europe:
10 countries (38)
Thailand (9)
Brazil (3)
Malaysia (5)
South Africa (
Canada (243)
USA (72)
Colombia (1)
Kuwait (1)
South Africa (1)
Korea Rep. (3)
Macao (1)
Philippines (14)
Indonesia (2)
Mongolia (9)
India (3)
Australia (5)
New Zealand (1)
Taiwan (698)
Mongolia (9)
Russian Fed. (1)
Total: 8,439 cases, 812 deaths,
30 countries in 7-8 months
Source: www.who.int.csr/sars
No infectious disease has spread so fast and far as SARS did in 2003

25. Lesson learnt from SARS
 An infectious disease in one country is a
threat to all
 Important role of air travel in
international spread
 Tremendous negative economic impact
on trade, travel and tourism, estimated
loss of $ 30 to $150 billion

26. CONTD.
 High level commitment is crucial for
rapid containment
 WHO can play a critical role in
catalyzing international cooperation and
support
 Global partnerships & rapid sharing of
data/information enhances
preparedness and response

27. Highly Pathogenic Avian Influenza
(H5N1)
 Since Nov 2003, avian influenza H5N1 in birds
affected 60 countries across Asia, Europe,
Middle-East & Africa
 >220 million birds killed by AI virus or culled to
prevent further spread
 Majority of human H5N1 infection due to direct
contact with birds infected with virus

28. Avian Influenza/bird flu:
 A Viral disease of Domestic and Wild
Birds characterized by the full range of
responses from almost no signs of the
disease to very high mortality; caused
by several subtypes of the type A strain
of the influenza virus.
 The incubation period is also highly
variable, and ranges from a few days to
a week (3 to 7 days).

29. Aetiology of Avian Influenza
 Influenzavirus A genus of the Orthomyxoviridae
family.
 They are enveloped, negative stranded RNA
viruses.
 Influenza A viruses can be divided into 15
Haemagglutinin (H) antigens. 9 Neuraminidase (N)
antigens.
 Extreme antigenic variability brought about by
genetic reassortment in host cells.

30. Aetiology of Avian Influenza
 NOTE:
 Negative strand RNA viruses have a unique mechanism of replication.
 Their genome is a single strand RNA that has to be transcribed as soon
as the virus enters the host in order to carry out viral replication.
 As a result, a viral-specific RNA polymerase is packaged in the virion
and is ready for transcription after virus entry.
 This novel replication mechanism dictates the assembly and RNA
synthesis of negative strand RNA viruses.
 In recent years, many discoveries have been made with regard to the
entry, replication and assembly of this class of viruses.

31. Influenza A virus host range
is polygenic
α2-3Gal
α2-6Gal
α2-3Gal
α2-6Gal
α2-3Gal
α2-6Gal
(Perez, 2006)

32. H5N1 virus
electron micrograph of avian influenza H5N1 viruselectron micrograph of avian influenza H5N1 virus

33. Avian Influenza
Host Range
•Exotic BirdsExotic Birds •Domestic PoultryDomestic Poultry

34. Avian Influenza
Peri-domestic species
Occasional isolations
of avian influenza virus
from starlings and
house sparrows (in
contact with infected
poultry)
Replication of some
avian influenza virus in
these species
(experimental)

35. 2006 Avian Influenza
Natural Reservoirs of
Influenza A Viruses
Wild aquatic birds
Majority are represented
by two Orders:
1. Anseriformes (ducks,
geese, and swans)

36. 2006 Avian Influenza
Natural Reservoirs of
Influenza A Viruses
2.Charadriiformes (gulls,
terns, and shorebirds)
Usually show no
clinical disease

37. Avian Influenza
How are these viruses transmitted
and maintained in these species?
Transmission: Fecal/Oral route
Heavy fecal shedding by infected ducks
Long term persistence in water
Isolation of AIVs from surface water
Maintenance: Bird to bird
Persistence in environment

38. 2006
Clinical Signs
 Incubation period 3-5 days
 Severe depression
 Decreased food and water
consumption
 Drastic decline in egg production
 Many birds affected
 Dehydration
 Huddling
 Subcutaneous swelling of the
head and neck area
 Nasal and oral cavity discharge
•Ruffled feathers
•Swollen, cyanotic (blue) combs
and wattles
•Conjunctivitis with respiratory
signs

39. Note swollen head, and discharges.
Wattle is cyanotic and necrotic.
Huddling
Ruffled
feathers
Respiratory Symptoms

40. Classification
 Influenza viruses are
subtyped according to
surface glycoproteins:
hemagglutininhemagglutinin (HA) and
neuraminidaseneuraminidase (NA)
 Currently, there are 16
hemagglutinins (H1 to H16) and 9
neuraminidases (N1 to N9)

144 possible sub-types

HemagglutininHemagglutinin attaches the virus
to the surface of the host cell so
the virus can replicate

NeuraminidaseNeuraminidase lets the newly
replicated viruses out of the cell to
infect more cells
http://micro.magnet.fsu.edu/cells/viruses/influenzavirus.html

41. What are the types of Avian Influenza in
domestic poultry?
 Low pathogenic avian influenza (LPAI)
 mild or no clinical signs
 low to moderate mortality
 However, the low pathogeniclow pathogenic H5 and H7H5 and H7 strains arestrains are
capable of mutating under field conditions into highlycapable of mutating under field conditions into highly
pathogenic strainspathogenic strains
 Highly pathogenic avian influenza (HPAI)
 sudden onset
 severe clinical signs
 high mortality

42. Low Pathogenic AI
Highly
Pathogenic AI

43. How long can AI virus survive?
 AI virus is shed in feces
for 7 to 14 days after
infection
 AI virus can survive in
manure for up to 105
days especially with high
moisture and low
temperature
 1 gram of contaminated
manure can infect 1
million birds
 1 gram of manure will
cover the surface of a
dime

44. What is the incubation period?
 Usually 3 to 7
days
 Depends on:
 strain of virus
 dose of inoculum
 age and immune
status of bird
 management and
environmental
factors

45. How does AI virus spread?
 Exposure of poultry to migratory
waterfowl (any bird that spends
much of its life on or around a
river or lake)
Exposure of commercial poultry to
AI-infected backyard, gamebird, or
hobby flocks

46. How does AI virus spread?
 Contact with AI-infected live bird markets
Dr. S. Trock Dr. S. Trock

47. How does AI virus spread?
 Bird to bird contact (through feces)
 Aerosol droplets

48. How does AI virus spread?
 Manure, equipment, vehicles, egg flats, crates,
contaminated shoes and clothing

49. How does AI virus spread?
•Wildlife vectors/scavengers
Photos courtesy of G. Malone
University of Delaware

50. How do humans get infected with H7N9?
 Mainly through direct contact
with infected poultry
 When people sell or
slaughter and consume
infected birds
 Exposure during slaughter,
defeathering, butchering,
and preparation of poultry
for cooking
 So far, evidence suggests
that the source of H7N9 virus
is poultry and live bird
markets and the most likely
route of transmission from
poultry to humans
www.terradaily.com
www.cnn.com

51. Why should we be concerned about
H7N9?
 H7N9 has not been previously reported in
humans
 No background or pre-existing immunity
 H7N9 is more easily transmissible from
poultry to humans than H5N1
 However, unlike H5N1 infections, poultry
infected with H7N9 appear healthy

52. How do AI viruses change or mutate?
 Antigenic DriftAntigenic Drift
 Occurs through small changes in the virus that happen
continually over time
 Produces new virus strains that may not be recognized by
antibodies to earlier influenza strains
 Antigenic ShiftAntigenic Shift
 An abrupt, major change in influenza A viruses, resulting in
a new influenza virus that can infect humans (one that has
not been seen in humans for many years)

53. Mutation and Reassortment 1
Reassortant
HUMAN- AVIAN
virus
AVIAN
virus
1. Mutation
2. Reassortment
HUMAN
virus

54. Mutation and Reassortment 2
Reassortant
HUMAN- AVIAN
virus
AVIAN
virus
1. Mutation
2. Reassortment
HUMAN
virus

55. Can H7N9 spread from person to person?
 The spread of infection in
birds increases the
opportunities for direct
infection of humans
 Humans concurrently infected
with human and avian
influenza strains could serve
as a “mixing vesselmixing vessel” for the
emergence of a novel subtype
with sufficient humans genes
that can be transmitted from
person to person
 However, the virus has notthe virus has not
yet developed the ability toyet developed the ability to
pass easily from human topass easily from human to
humanhuman
Avian flu Human flu
Novel flu subtype

56. Diseases cycle

58. Avian Influenza Infections in Humans
 1997: Hong Kong
(HPAI H5N1)
 Infected chickens and
humans
 18 sick (6 died)
 Spread primarily from
birds to humans
 Person-to-person
infection noted but rare
 1.5 million chickens
destroyed
yaleglobal online

59. Avian Influenza Infections in Humans
 2003: China and Hong Kong (HPAI
H5N1)
 Occurred among members of a Hong Kong family that had
traveled to China
 1 person recovered, another died
 Another family member in China died
 Origin unknown

60. Avian Influenza Infections in Humans
 2013: China (H7N9)
 126 cases (24 deaths) as of 29 April 2013
ecdc.europa.eu

61. Pandemics are rare but deadlyPandemics are rare but deadly
• 1918-19 Spanish Flu (H1N1)
• 20-50 million infected worldwide
• >500,000 deaths U.S.
• 1957-58 Asian Flu (H2N2)
• 70,000 deaths U.S.
• 1968-69 Hong Kong Flu (H3N2)
• 50,000 deaths U.S.
• 2009-2010 Swine Flu (H1N1)
• 60 million infected worldwide
• 18,000 deaths

62. Can another pandemic happen again?
 Only when three
conditions have been
met:
1. a new influenza virus
subtype emerges
2. it infects humans,
causing serious illness
3.3. it spreads easily andit spreads easily and
sustainably amongsustainably among
humans*humans*
**has not yet occurred withhas not yet occurred with
H7N9 or H5N1H7N9 or H5N1
http://en.wikipedia.org/wiki/File:Spanish_flu_victims_burial_Nort
h_River_Labrador_1918.JPG

63. What can we do to prevent AI in humans?
 Practice normal hygienic
precautions
 Wash hands with soap and
water for 15-20 seconds
 Cover your mouth when you
cough or sneeze
 Get vaccinated for
seasonal flu
 Stay home and rest if you
have the flu
 Practice “social
distancing” if there is a flu
outbreak
 Avoid live bird markets

64. Questions?

66. Highly Pathogenic Avian Influenza
(H5N1)
 What is the name of the bird flu?
 There are 16 different avian flu types.
The H5N1 strain is the one that causes the
most concern, because it is the most virulent;
the deadliest.
 Fortunately, humans do not become easily
infected with the H5N1 virus strain.
 However, some highly pathogenic strains have
caused severe respiratory diseases in humans

67. Highly Pathogenic Avian Influenza
(H5N1)
 Where was Bird Flu First Discovered?
 Influenza A/H5N1, a severe strain of bird flu,
was first found to infect humans during poultry
outbreaks in Hong Kong in 1997.
 Eighteen humans were infected and six died.
A mass culling of all poultry in Hong
Kong may have prevented a human A/H5N1
pandemic (global epidemic) at that time.

68. Highly Pathogenic Avian Influenza
(H5N1)
 What does the H and N stand for in flu?
 Influenza A viruses are divided into subtypes
based on two proteins on the surface of the
virus: the hemagglutinin (H) and the
neuraminidase (N).
 There are 18 different hemagglutinin subtypes
and 11 different neuraminidase subtypes.

69. Highly Pathogenic Avian Influenza
(H5N1)
 Neuraminidase enzymes are glycoside
hydrolase enzymes (EC 3.2.1.18) that cleave
the glycosidic linkages of neuraminic acids.
 Viral neuraminidase is a type
of neuraminidase found on the surface of
influenza viruses that enables the virus to be
released from the host cell.
 Neuraminidases are enzymes that cleave
sialic acid groups from glycoproteins and are
required for influenza virus replication.

71. Dr. KANUPRIYA CHATURVEDI
Novel Swine origin Influenza A
(H1N1)
 Swine flu causes respiratory disease in pigs –
high level of illness, low death rates
 Pigs can get infected by human, avian and
swine influenza virus
 Occasional human swine infection reported
 In US from December 2005 to February 2009,
12 cases of human infection with swine flu
reported

72. Swine Flu
Influenza A (H1N1)
 March 18 2009 – ILI outbreak reported in
Mexico
 April 15th
CDC identifies H1N1 (swine flu)
 April 25th
WHO declares public health
emergency
 April 27th
Pandemic alert raised to phase 4
 April 29th
Pandemic alert raised to phase 5
 NOTE- A pandemic is the worldwide spread of a
new disease

73. Dr. KANUPRIYA CHATURVEDI
Influenza A (H1N1)
 By May 5th
more than 1000 cases confirmed in 21
countries
 Screening at airports for flu like symptoms
(especially passengers coming from affected area)
 Schools closed in many states in USA
 May 16th
India reports first confirmed case
 Stockpiling of antiviral drugs and preparations to
make a new effective vaccine

74. Dr. KANUPRIYA CHATURVEDI
74

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

76. Dr. KANUPRIYA CHATURVEDI
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)

77. Dr. KANUPRIYA CHATURVEDI

78. Dr. KANUPRIYA CHATURVEDI
Bioterrorism
 Possible deliberate release of infectious
agents by dissident individuals or terrorist
groups
 Biological agents are attractive instruments
of terror- easy to produce, mass casualties,
difficult to detect, widespread panic & civil
disruption

79. Dr. KANUPRIYA CHATURVEDI
CONTD.
 Highest potential- B. anthracis, C.
botulinum toxin, F. tularensis, Y. pestis,
Variola virus, Viral haemorrhagic fever
viruses
 Likeliest route- aerosol dissemination

80. Dr. KANUPRIYA CHATURVEDI
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

81. Dr. KANUPRIYA CHATURVEDI
National surveillance:
current situation
 Independent vertical control
programmes
 Surveillance gaps for important
diseases
 Limited capacity in field epidemiology,
laboratory diagnostic testing, rapid field
investigations
 Inappropriate case definitions

82. Dr. KANUPRIYA CHATURVEDI
CONTD.
 Delays in reporting, poor analysis of
data and information at all levels
 No feedback to periphery
 Insufficient preparedness to control
epidemics
 No evaluation

83. Dr. KANUPRIYA CHATURVEDI
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

84. Dr. KANUPRIYA CHATURVEDI
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

85. Dr. KANUPRIYA CHATURVEDI
Sharing Outbreak-related InformationSharing Outbreak-related Information
• with Public Health Professionalswith Public Health Professionals
• with Publicwith Public
• with Public Health Professionalswith Public Health Professionals
• with Publicwith Public

86. Dr. KANUPRIYA CHATURVEDI
Solutions
 Internet-based information technologies
Improve disease reporting
Facilitate emergency communications &
Dissemination of information
 Human Genome Project
Role of human genetics in disease susceptibility,
progression & host response

87. Dr. KANUPRIYA CHATURVEDI
Solutions
 Microbial genetics
Methods for disease detection, control & preventio
 Improved diagnostic techniques & new vaccines
 Geographic Imaging Systems
Monitor environmental changes that influence
disease emergence & transmission

88. Dr. KANUPRIYA CHATURVEDI
Key tasks - carried out by whom?
National
Regional
Global
Synergy

89. Dr. KANUPRIYA CHATURVEDI
What skills are needed?
Multiple expertise neededMultiple expertise needed !
Infectious
diseases
Epidemio-
logy
Public
Health
International
field
experience
Information
management
Laboratory
Telecom. &
Informatics

90. Dr. KANUPRIYA CHATURVEDI
Global Disease Intelligence:
A world on the alert
CollectionCollection
VerificationVerification DistributionDistribution
ResponseResponse

91. Dr. KANUPRIYA CHATURVEDI
The Best Defense (Multi-
factorial)
 Coordinated, well-prepared, well-
equipped PH systems
 Partnerships- clinicians, laboritarians
& PH agencies
 Improved methods for detection &
surveillance

92. Dr. KANUPRIYA CHATURVEDI
CONTD.
 Effective preventive & therapeutic
technologies
 Strengthened response capacity
 Political commitment & adequate
resources to address underlying socio-
economic factors
 International collaboration &
communication