emerging and re emerging diseases

1. Emerging & Re-emerging
Infectious Diseases
Dr .Mohamed Aboelmagd MD
Endemic and Infectious diseases Unit

2. Girolamo Frascatoro
Speaking About Syphilis
• “There will come yet other new and unusual ailments
in the course of time. And this disease will pass
away, but it later will be born again and be seen by
our descendants.”
• This quote was written 450 years ago.

3. Microbes and vectors swim in the evolutionary
stream, and they swim faster than we do.
Bacteria reproduce every 30 minutes. For them,
a millennium is compressed into a fortnight.
They are fleet afoot, and the pace of our
research must keep up with them, or they will
overtake us. Microbes were here on earth 2
billion years before humans arrived, learning
every trick for survival, and it is likely that they
will be here 2 billion years after we depart
(Krause 1998).

4. Impact of Infectious Diseases
• Infectious diseases has played a prominent role in world history.
– The Black Death in the Middle Ages killed 1/3 Europe’s
population.
– Measles destroyed the South American Aztec civilization.
– Smallpox destroyed indigenous peoples of North and South
America, facilitating the conquest of the New World.
"Triumph of Death" (Black Plague)
Painted in 1562

5. Definition
• Emerging infectious disease
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. Categories Of Emergence
1- Microorganisms that have not been known
previously and that cause new diseases (e.g.,
[SARS-CoV] , [MERS-CoV] and Zika virus.
2- Agents that have been known previously and
that cause new diseases (hantavirus in the U.S. in
1993 that caused respiratory distress instead of
kidney disease).

8. Categories Of Emergence
3- Microbes that have been known previously
to cause disease, but the incidence of disease
is noticeably increasing in a region (e.g.,
whooping cough caused by Bordetella
pertussis in the U.S.; diphtheria caused by
Corynebacterium diphtheriae in Russia)

9. Categories Of Emergence
4- New, and often more virulent, strains of a
known pathogen that cause disease (e.g.,
Vibrio cholerae O139 and epidemic diarrheal
disease; highly virulent Clostridium difficile
NAP1/027 and increased incidence of C.
difficile-associated disease in North America
and Europe).

10. Categories Of Emergence
5- Microbial pathogens that cause disease in a
new geographical location (e.g., West Nile
virus encephalitis in North America;
reintroduction of epidemic cholera in Haiti;
Chikungunya virus in the Caribbean; Ebola
virus in West Africa)

11. Categories Of Emergence
6- Microbes of animal origin that infect
humans (zoonoses).This includes animal-
associated microbes that are newly able to
infect humans (e.g., influenza virus from
birds or swine).

12. Categories Of Emergence
7- Microbial pathogens that have acquired
the ability to resist the effects of
antimicrobial agents (e.g., MDR-TB; MRSA;
VRSA; amantadine-resistant influenza A
virus ).

14. Factors Contributing To Emergence
A- AGENT
Microbial Adaptation and Change
• Increased antibiotic resistance with increased
use of antibiotics in humans and food animals (
VRSA, MRSA, multidrug-resistant
Salmonella,….)
• Increase virulence (Group A Strep, Shiga-toxin-
producing E. coli)
• Jumping species from animals to humans (avian
influenza)

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

16. Factors Contributing To Emergence
B- HOST
• Human demographic change (inhabiting new areas)
• Human behavior (Live-animal markets, Commercial
sex workers)
• Human susceptibility to infection

17. Human Demographics, Behavior, Vulnerability
• More people, more crowding
• Changing sexual mores (HIV, STDs)
• Injection drug use (HIV, Hepatitis C)
• Changing eating habits: out more
(foodborne infections)
• More populations with weakened immune
system: elderly, HIV/AIDS, cancer patients
and survivors, persons taking antibiotics
and other drugs

18. Factors Contributing To Emergence
C- ENVIRONMENT
• Climate & changing ecosystems
• Economic development & Land use
(urbanization, deforestation)
• Technology & industry (Transplantation, infected
blood products, food processing and water
distribution systems)

19. CONTD.
• International travel & commerce (SARS).
• Breakdown of public health measure (war,
overcrowding).
• Lack of political will ( Donors, health care
professionals, governments and civil
society).
• Intent to harm (Bioterrorism).
• Poverty and social inequality.

20. Climate & Environmental Changes
• Deforestation forces animals into closer human
contact- increased possibility for agents to breach
species barrier between animals & humans
• Global warming- spread of Malaria, Dengue,
Leishmaniasis, Filariasis

21. Uncontrolled Urbanization &
Population Displacement
• Growth of densely populated cities- substandard
housing, unsafe water, poor sanitation,
overcrowding, indoor air.
• Problem of refugees & displaced persons
• Changes in ecology, increasing deer populations,
suburban migration of population

22. 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

23. Breakdown of public health measures
• Decrease in cholorine in water supplies lead to rapid
spread of cholera in South America.
• Non functioning water plant in Wisconsin, USA lead
to outbreak of waterborne cryptosporidium.
• Inadequate vaccinations and Diphtheria in former
USSR independent countries.
• Discontinued mosquito control efforts and dengue
and malaria re-emergence.

24. 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)

27. Global examples of Emerging &Re emerging IDs

29. MERS-CoV
• Initially referred to as “novel” coronavirus
• First cases documented in spring 2012 (nurse &
university student)-Jordan
• All cases linked to the Middle East
• Severe morbidity and mortality

30. Transmission
• Human Human
• Zoonotic
• Recent evidence of camel
to human transmission
(Azhar et al, 2014)
• Index patient and 3
friends had contact
with camels

31. Epidemiology
• Human infections (May 2014)
• Median age 49 years
• 65% male
• 19% healthcare workers
• 62% severe disease (hospitalization)
• 5% mild illness
• 21% asymptomatic (case investigations)
• June 4, 2014: 815 cases and 313 deaths
(38% mortality)

34. Ebola Virus
 Prototype Viral Hemorrhagic Fever
Pathogen
 Filovirus: enveloped,
non-segmented, negative-
stranded RNA virus
 Severe disease with high
case fatality
 Absence of specific treatment
or vaccine
 2014 West Africa Ebola outbreak
caused by Zaire ebolavirus
species (five known Ebola virus
species)
34

35. Ebola Virus
 Zoonotic virus – bats the most likely reservoir,
although species unknown
 Spillover event from infected wild animals
(e.g., fruit bats, monkey, duiker) to humans,
followed by human-human transmission
35

36. Outbreak Distribution — West Africa, July 8, 2015
Map includes total confirmed EVD cases reported to WHO
36

37. Ebola Virus Transmission
 Virus present in high quantity in blood, body fluids, and excreta
of symptomatic EVD-infected patients
 Opportunities for human-to-human transmission
 Direct contact (through broken skin or unprotected mucous membranes) with
an EVD-infected patient’s blood or body fluids
 Sharps injury (with EVD-contaminated needle or other sharp)
 Direct contact with the corpse of a person who died of EVD
 Indirect contact with an EVD-infected patient’s blood or body fluids via a
contaminated object (soiled linens or used utensils)
 Possibly, contact with semen from a recovered male EVD patient
 Ebola can also be transmitted via contact with blood, fluids, or
meat of an infected animal
 Limited evidence that dogs become infected with Ebola virus
 No reports of dogs or cats becoming sick with or transmitting Ebola
37

38. Human-to-Human Transmission
 Infected persons are not contagious until onset of symptoms
 Possible that the virus can be transmitted through semen of a man
who has survived EVD. Risk considered to be very low, likely decreases
over time.
 Infectiousness of body fluids (e.g., viral load) increases as patient
becomes more ill
 Remains from deceased infected persons are highly infectious
 Human-to-human transmission of Ebola virus via inhalation
(aerosols) has not been demonstrated
38

39. 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

40. 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.

41. 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

42. 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.

43. 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.

44. 44

46. Zika Virus
• GENERAL INFORMATION
• Zika virus disease is caused by a virus
transmitted by Aedes mosquitoes. Other
transmission modes are still under
investigation.
• People with Zika virus disease usually have a
mild fever, skin rash (exanthema), and
conjunctivitis. These symptoms normally last
for 2-7 days.

47. Zika Virus
• At present there is no specific treatment or
vaccine currently available. The best form of
prevention is protection against mosquito
bites.
• Zika virus is known to circulate in Africa, the
Americas, Asia, and the Pacific region. Zika
virus had only been known to cause sporadic
infections in humans until 2007, when an
outbreak in Micronesia infected 31 people.

48. Zika Virus
• EPIDEMIOLOGICAL UPDATE:
• From 2007 to 5 February 2016, Zika viral
transmission has been documented in a total
of 44 countries and territories.
• This includes 33 countries that reported
transmission in between 2015 and 2016

50. Zika Virus
• In 2015 and 2016, the geographical range of
Zika virus has been increasing steadily.
• The link to Zika virus was confirmed in April
2015. By October 2015, a single state in the
northeast of Brazil (Bahia)1, reported 56 318
suspected cases of Zika virus disease.
• Brazilian national authorities estimate that
between 497 593 and 1 482 701 cases of Zika
virus infection have occurred since the
outbreak began.

51. Zika Virus
• In October 2015, the Brazil Ministry of Health
reported an unusual increase in the number of
cases of microcephaly in the Northeast region
of Brazil. Between 2001 and 2014, an average
of 163 microcephaly cases has been recorded
nationwide per year.
• As of 30 January 2016, the Ministry of Health
reported 4 783 cases of microcephaly and/or
central nervous system (CNS) malformation
including 76 deaths.

52. Zika Virus
• In July 2015, Brazil reported the detection of
patients with neurological syndromes who
had recent history of Zika virus infection in the
state of Bahia. There were 76 patients with
neurological syndromes identified, of which
42 (55%) were confirmed as GBS. Among the
confirmed GBS, 26 (62%) had a history of
symptoms consistent with Zika virus infection.

53. Global response strategy against Zika virus disease

54. RECOMMENDATIONS FOLLOWING THE
EMERGENCY COMMITTEE MEETING
• Reducing populations of mosquitoes that
transmit Zika virus.
• Personal and household protection.
• Pregnant women and women planning to
become pregnant.
• Travel recommendations.

55. 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)

56. RE-EMERGING INFECTIOUS
DISEASES

58. 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

59. CONTD.
• Highest potential- B. anthracis, C.
botulinum toxin, F. tularensis, Y. pestis,
Variola virus, Viral haemorrhagic fever
viruses
• Likeliest route- aerosol dissemination

62. Prevention of Emerging Infectious
Diseases Will Require Action in
Each of These Areas
 Surveillance and Response
 Applied Research
 Infrastructure and Training
 Prevention and Control
CDC

63. Surveillance and
Response
Detect, investigate, and monitor emerging
pathogens, the diseases they cause, and the
factors influencing their emergence, and
respond to problems as they are identified.
CDC

65. Applied Research
• Integrate laboratory science and
epidemiology to increase the effectiveness of
public health practice.
CDC

67. Strengthen public health infrastructures to
support surveillance, response, and
research and to implement prevention and
control programs.
Provide the public health work force with
the knowledge and tools it needs.
Infrastructure and
Training
CDC

68. Ensure prompt implementation of
prevention strategies and enhance
communication of public health
information about emerging diseases.
Prevention and Control
CDC

69.  Enhance communication: locally, regionally, nationally, globally
 Increase global collaboration
 Share technical expertise and resources
 Provide training and infrastructure support globally
 Ensure political support
 Ensure judicious use of antibiotics
 Vaccines for all
Preventing Emerging
Infectious Diseases: More to Do