1. Global Health
Tom D. Y. Chin, MD, MPH

2. This lecture was given to the first year medical students at the University of Kansas School of Medicine in 2005

5. West Nile Virus
First isolated from the blood of a patient in Uganda in 1937.
The virus spread to Egypt, Middle East, Northern Mediterranean, Western Asia.
It was introduced in New York City in 1999, probably from Israel.
Since then, it has spread extensively throughout the United States.
It is spread by primarily mosquito bites

7. Life cycle of WNV
Life cycle of WNV

8. This knowledge has a direct impact on the practice of medicine and public health

10. Infectious Diseases Worldwide Size of the Problem
Biggest killers of children and young adults: >13 million deaths per year.
Particularly important in developing countries: average of 1 in 2 die of infectious disease.
In developing countries, the leading cause of deaths.
Developed countries, 3rd leading cause of deaths.

11. HIV/AIDS ACUTE RESPIRATORY INFECTIONS MALARIA MEASLES
DIARRHEAL DISEASES
TUBERCULOSIS

12. Disability-adjusted life years or years of health life lost

13. AIDS Pandemic
AIDS undoubtedly was one of the most devastating diseases emerged during the 20th century.
From 1981 to the end of 2004, 24.9 million people world-wide have succumbed to HIV infections.
The pandemic is expected to progress well into the 21th century.

14. HIV/AIDS AIDS is caused by a virus--human immunodeficiency virus.
Virus destroys the immune system. Thus termed acquired immunodeficiency syndrome or AIDS
AIDS represents complications of HIV infection when the immune system is sufficiently lowered.

15. Prevalence of HIV Infections End of 2004
Estimated 39.4 million people world-wide are living with HIV/AIDS.
2/3 of infected persons reside in Africa where the epidemic originated.
1/5 of those with HIV/AIDS are among people in Southeast Asia where the epidemic has been progressing rapidly. This area with the population of >2 billion may well be the future epicenter.

16. Global HIV/AIDS Epidemic
During the year million people became infected with HIV (incidence) million people died of AIDS

17. HIV/AIDS in U.S.
At the end of 2003, a total of 902, 223 cases of AIDS have been reported to the CDC, 505,801 (56%) have died.
About 1 million of U.S. residents are living with HIV/AIDS

19. Primary Modes of Transmission
Globally, unprotected sexual intercourse between men and women is the predominant mode of transmission. Ratio M:F 1:1.1
In Sub-Saharan Africa, the primary mode of transmission is by contact with sex workers. Ratio F:M 13:1
In China, Myanmar (Burma), parts of Europe, IV drug use is the principal mode.
Thus, prevention rests on determination of mode of transmission.

20. Prevalence of HIV
In some countries in Africa, such as Botswana, HIV prevalence among adults is as high as 25 to 35 percent, with a drastic decrease in life expectancy.
Even in the United States, HIV prevalence averages 25% among men having sex with men (MSM), with the rate as high as 48% in some ethnic groups
Thus, sexual transmission is most common.

21. Major Problems
Although drugs are available, and effective, for the treatment of AIDS, there are major deficiencies. Among them are inadequate distribution to developing countries (high cost), requiring prolonged treatment (not curative), adverse drug reactions, development of drug resistance.
Primary prevention such as use of condoms and needle exchange have been advocated, but with varying results
Vaccine for primary prevention not yet available. Therapeutic vaccine for treatment is being explored.

22. Emergence of Infections
New infectious disease agents continue to emerge in populations throughout the world.
More than 30 agents have emerged during the past two decades.
Infectious diseases may also reemerge after a period of quiescence, e.g. tbc
May appear in a new locality, WN encephalitis, monkey pox
An agent may undergo genetic changes (e.g. influenza).

24. Emergence of Influenza
An agent of great concern globally is influenza virus.
Influenza virus is known to cause epidemics as early as the 1500’s, and pandemics have been described as early as 1889.
The most extensive pandemic ever known is the pandemic of influenza of , which killed more 20 million people.

25. Ref Business Week, April 14, 2003

26. Discovery of Influenza Virus
First isolated from a pig in 1931 (swine flu)
Isolated from human in 1933

27. Characteristics of Influenza Virus
Types A, B, C
Diameter nm
Pleomorphic, spherical, filamentous particles
Single-stranded RNA
Segmented genome, 8 segments in A and B
Hemagglutinin and Neuraminidase on surface of virion

31. Mechanisms of Transmission of Influenza Viruses
Aquatic birds
Pigs
Humans

37. Coping with Emerging Infections
During the past several years, the public as well as health professionals are keenly aware of the potential of global spread of emerging infectious diseases, particularly SARS, avian influenza.
Agencies such as WHO, CDC, NIH as well as Global Health Council, World Bank, Global Forum for Health Research are taking up the challenges of global health. Millions of dollars have been appropriated to meet these challenges.

38. Preparing for the next pandemic Are we ready for the next influenza pandemic? Many epidemiologists and virologists feel another pandemic of influenza is inevitable; the question is when.

39. Bioterrorism
Similarly, use of biological agents to attack against civilian population is a likely possibility, the question is which agent; anthrax, smallpox, pneumonic plague?

40. Infectious Causes of Chronic Diseases
Helicobacter pylori: peptic ulcer
Hepatitis B & C: Hepatocellular ca
Human herpesvirus 8: Kaposi’s ca
Human papilllomavirus: cervical ca
Epstein-Barr virus: nasopharyngeal ca, Burkett’s lymphoma
Mycoplasma pneumoniae: coronary artery disease ?

41. suggested Reading
Anthony S. Fauci. Infectious diseases: Considerations for the 21st Century. Clinical Infectious Diseases. 2001:32: