Introduction to emerging and re-emerging infectious diseases - PowerPoint Presentation

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Introduction to emerging and re-emerging infectious diseases

DOREEN SITALI

SCHOOL OF PUBLIC HEALTH

DEPT. OF HEALTH PROMOTION AND EDUCATION

Introduction

Global eradication of smallpox in 1977 and discovery of antibiotics led to optimism and complacency that infectious diseases as public health problems could be eradicated or eliminated

Complacency led to fatal consequences; infectious diseases are leading cause of death globally today. About 17 million people die from infectious diseases annually

Session objectives

Define key terms

Identify common drivers of emerging and remerging infectious diseases

Discuss the impact of EIs

Identify measures to mitigate EIs

What are emerging and re-emerging infectious diseases?

EIs

- newly identified /unknown infections which cause public health problems locally or globally

Term includes infections spreading to new geographic areas and those diseases that were responding to antibiotics but are now resistant

Not always possible to know if these diseases are new in humans, or whether were present but unrecognized throughout the years

EIs thought to be due to a closer contact of man with their reservoirs in nature, with a successful «jump» of the infectious agent from animal to man across the species barrier

Examples of EIs

HIV infection which causes AIDS, with its sequelae of human suffering and economic burden

Ebola hemorrhagic fever with a potential for international spread

Other examples of new or newly detected infectious diseases of global concern include a new form of cholera

hepatitis C and hepatitis E

Legionnaires’ disease, and Lyme disease,

dengue fever, West Nile virus, and the Zika virus.

COVID

Re-emerging infectious diseases

infections that have appeared after significant decline in their incidence

often reappear in epidemic proportions.

Tuberculosis increasing worldwide due in part to its close association with HIV infection

cholera re-introduced into countries and continents where it had previously disappeared, and where it can spread because water and sanitation systems have deteriorated

dengue or «breakbone» fever has started to occur in urban areas where mosquito control has broken down.

Reemerging diseases include

M

alaria, Tuberculosis, Cholera, Pertussis, Influenza, Pneumococcal disease, and gonorrhea.

Ebola , Marburg

Crimean

congo

haemorrhagic

fever

Lassa fever

MERS, SARS

Nipah

, Rift valley fever

Covid

Why are these diseases emerging?

Emergence is multifactorial in origin:

Rapid population growth – uncontrolled urbanization- crowded cities- unhygienic conditions that provide breeding ground for pathogens

intense international travel and growing trade and tourism

Migration and displacement of people due to war, strife or disasters

Agricultural practices

changes in handling and processing of large quantities of food;

and increased exposure of humans to disease vectors and reservoirs in nature.

Mutations that lead to new strains; and drug resistance;

Resistance of vectors to pesticides

Most significant factor: deteriorating public health infrastructure which is unable to cope with population demands, and the emergence of resistance to antibiotics linked to their increased misuse.

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, ‐ B. anthracis, C. botulinum toxin, F.

tularensis

, Y. pestis, Variola virus, Viral

haemorrhagic

fever viruses

Likeliest route‐ aerosol dissemination

During first half of the 20th century deaths from infectious diseases declined because of improved hygiene and nutrition. This trend was strengthened with the advent of vaccines and antibiotics during the 1940s and culminated in the late 1970s in the eradication of one infectious disease, smallpox. Because at that time infectious diseases appeared to be a decreasing threat, funds for their control were channeled to other problems, experts on infectious disease retired or left the field and students turned to more rewarding subjects than viruses and bacteria - the infrastructure for communicable disease control began to crumble.

Emerging and re-emerging infections reflect the constant struggle of microorganisms to survive.

Transmission of Infectious Agent from Animals to Humans‐ ZOONOTIC diseases

>2/3rd emerging infections originate from animals‐ wild & domestic

e.g

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)

Impact of EIs

Economic

Social

Public health

PRIORITY AREAS FOR ACTION

1.

STRENGHTHENING NATIONAL CAPACITIES

Create early warning systems and rapid response mechanisms

Strengthen epidemiological laboratory and systems

Early action for prevention and control

2.

Intersectoral collaboration

Constant dialogue about the health implications of projects in other ministries

Close collaboration between health and other ministries

Intercountry collaboration

Rapid flow of disease surveillance between countries

The global response

Since 1992 alarm over emerging and re-emerging diseases resulted in a number of national and international initiatives to restore and improve surveillance and control of communicable diseases. Member States of WHO expressed their concern in a resolution of the World Health Assembly in 1995, urging all Member States to strengthen surveillance for infectious diseases in order to promptly detect re-emerging diseases and identify new infectious diseases. The WHA recognized that the success of this resolution depends on ability to obtain information on infectious diseases and willingness to communicate information nationally and internationally.

The World Health Organization warned in its 2007 report that infectious diseases are emerging at a rate that has not been seen before. Since the 1970s, about 40 infectious diseases have been discovered, including SARS, Ebola, Avian flu, and Swine flu

Surveillance and Response 

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

Applied Research 

Infrastructure and Training 

Prevention and Control

Conclusion

Infectious diseases will continue to dominated disease scenarios in most countries.

The most sustainable way to deal with them is through early detection and rapid response.