Emerging infections

Emerging & Re-emerging Infectious Diseases

Dr .Mohamed Aboelmagd MDEndemic and Infectious diseases

Unit

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.

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).

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

Definition

• Emerging infectious disease

Newly identified & previously unknown infectious agents that cause public health problems either locally or internationally

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

Categories Of Emergence1- 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).

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)

Categories Of Emergence4- 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).


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)


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).


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 ).

Factors Contributing To EmergenceA- AGENTMicrobial 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)

Antimicrobial Drug Resistance

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

Factors Contributing To Emergence

B- HOST• Human demographic change (inhabiting new areas)

• Human behavior (Live-animal markets, Commercial sex workers)

• Human susceptibility to infection

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

Factors Contributing To EmergenceC- ENVIRONMENT

• Climate & changing ecosystems• Economic development & Land use

(urbanization, deforestation)• Technology & industry (Transplantation, infected

blood products, food processing and water distribution systems)

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.

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

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

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

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.

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)

Global examples of Emerging &Re emerging IDs

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

Transmission• Human Human • Zoonotic • Recent evidence of camel

to human transmission (Azhar et al, 2014)• Index patient and 3

friends had contact with camels

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)

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)

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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

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Outbreak Distribution — West Africa, July 8, 2015

Map includes total confirmed EVD cases reported to WHO

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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

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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

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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

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.

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

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.

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.

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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.

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.

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

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.

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.

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.

Global response strategy against Zika virus disease

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.

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)

RE-EMERGING INFECTIOUS DISEASES

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

CONTD.

• Highest potential- B. anthracis, C. botulinum toxin, F. tularensis, Y. pestis, Variola virus, Viral haemorrhagic fever viruses

• Likeliest route- aerosol dissemination

Prevention of Emerging Infectious Diseases Will Require Action in

Each of These Areas Surveillance and Response

Applied Research

Infrastructure and Training

Prevention and ControlCDC

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

Applied Research

• Integrate laboratory science and epidemiology to increase the effectiveness of public health practice.

CDC

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

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

Prevention and Control

CDC

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 EmergingInfectious Diseases: More to Do

Thank You

Emerging infections

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