Emerging infectious diseases and re-emerging diseases are newly identified and previously unknown infections which cause public health problems either locally or internationally. The optimism that many infectious diseases were no longer a threat to man and other animals has proved to be false with the emerging and re-emerging of many diseases over the last decades. Infectious diseases such as SARS, HIV/AIDS, influenzas and other mosquito-borne diseases such as lassa fevers etc have become more serious global health problems than in the past. Several factors such as the biology, ecology, genetic mechanisms, population explosion in many urban areas, global travels and altered human behaviours have been proposed as factors responsible for this

1. Re-emerging infectious
diseases (RIDs)

2. Presentation outline
• Introduction
• Important Terminologies
• Describe the factors contributing to the re-emergence of
infectious diseases
• Control & Prevention of Infectious Diseases
• challenges to the control and prevention of emerging and re-
emerging infectious diseases
• Conclusion
• References

3. Introduction
• In developing countries where much of the population lives
in conditions of extreme poverty, infectious diseases remain
the leading cause of death
• In the U.S., prevention and control of infectious diseases
have been so successful in the past half century that many
people view infectious diseases as either a thing of the past
or minor illnesses easily treated and cured

4. Important Terminologies
• Emerging infectious disease- An infectious disease that has
newly appeared in a population or that has been known for
some time but is rapidly increasing in incidence or
geographic range.
• Re-emerging infectious disease- diseases that once were
major health problems globally or in a particular country,
and then declined dramatically, but are again becoming
public health problems for a significant proportion of the
population.

5. Important Terminologies
• Infectious diseases- are caused by pathogenic
microorganisms, such as bacteria, viruses, parasites or fungi;
the diseases can be spread, directly or indirectly, from one
person to another.
• Zoonotic diseases- are infectious diseases of animals that can
cause disease when transmitted to humans.

6. Examples of emerging infectious diseases
• Ebola virus (first outbreaks in 1976 and the discovery of the virus
in 1977)
• HIV/AIDS (virus first isolated in 1983)
• Hepatitis C Influenza A(H5N1) virus
• Severe Acute Respiratory Syndrome (SARS)
• Swine Flu Influenza A (H1N1)

7. 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/ Dengue Hemorrhagic Fever- Over past 40 years, 20-fold increase
to nearly 0.5 million (between1990-98)

8. Factors contributing to the re-emergence of
infectious diseases
• There are many factors contribute to infectious disease
emergence, these are;
• Agent factors
• Host factors
• Environmental factors

9. Factors contributing to the re- emergence of
infectious diseases`-
Agent Factors
• Evolution of pathogenic infectious agents (microbial
adaptation & change)
• Development of resistance to drugs
• Resistance of vectors to pesticides

10. Factors contributing to the re-emergence of
infectious diseases
Host Factors
• Human demographic change (inhabiting new areas)
• Human behaviour:
• Human susceptibility to infection (Immunosuppression)
• Poverty & social inequality

11. Factors involved in the emergence of
infectious diseases cont’d
Environmental factors
• Climate & changing ecosystems
• Economic development & Land use (urbanization,
deforestation)
• Technology & industry (food processing & handling)

12. Control & Prevention of Infectious Diseases
• Controlling the reservoir
• Interrupting the transmission
• Protecting the susceptible host
• Surveillance at national, regional, global level

13. Challenges to Control and Prevention of
emerging and re-emerging Disease
• Lack of political commitment to the enforcement of public health laws
• The effectiveness in treating common bacterial infections is diminishing
• Limitations in both surveillance and the availability of appropriate
diagnostic tests
• Lack of collaboration between the human health and animal health

14. Conclusion
• Since we live in a global village, we cannot afford to be complacent
about the tremendous economic, social and public health burden
of these diseases.
• Effective surveillance is the key to their early diagnosis and
containment.
• There is a need to develop epidemiology improved diagnostic
facilities, a strong public health structure, epidemic preparedness
and rapid response.

15. References
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