1. “Emerging and Re-emerging humans disease     Abdul Aziz Djamal Dept of Microbiology Andalas University

2. Emerging Disease
Newly identified and previously unknown infectious agent that cause public health problem locally or globally

3. Re-emerging Infectious Disease
Infectious disease that have been known for sometime and had fallen to such a low level and no longer consider as a public health problem and now showing upward trend in prevalence or incidence globally

4. Examples of Emerging and Re-Emerging Infectious Disease: past 10 years
A Fauci, NIAID/NIH, 2005

5. Major and minor killers: global impact viewed on a ‘Richter’ (logarithmic) scale7
Tobacco
HIV
Infant/child ARI & diarrhoeal dis
Malaria
HBV + HCV 6
Road accidents
Measles
Non-
HIV tuberculosis
RSV, Rota virus
10,000-fold difference in impact
Influenza 5
Dengue
Viruses
Hospital infection
H Papilloma v 4
Suicide
West Nile virus 3
SARS
Ebola
Polio 2
Hanta virus
vCJD 1
Weiss & McMichael, 2004
Log 1

6. Outline of Talk Microbes, infectious diseases: recent trends
Infectious diseases as result of major changes in human ecology and environmental – historical transitions; current conditions
Examples of infectious disease risks
Travel, trade
Land use, agriculture
Intensive animal husbandry
Climate variability, climate change
Needed: a more ecological perspective

7. Receding – then Resurging?
1950s-60s: Infectious diseases apparently receding in developed countries
Antibiotics and vaccines
Pesticides to control mosquitoes
Improved surveillance and control measures – internationally coordinated
Early 1970s: Authorities proclaimed end of infectious disease era. Premature!
>30 new or newly-discovered human IDs over past 30 yrs
We overlooked the ecological/evolutionary dimensions

8. Avian ’flu, H5N1 Mad Cow Disease (BSE)  vCJD
Nipah viral encephalitis, Malaysia ( )
Previous ’flu epidemics ( , ’57, ’68)
                                                                                       
Choi Young-Soo/Associated Press - Yonhap
South Korean health workers disinfecting a chicken farm north of Seoul last week. Though 140 million birds have died or been killed as a preventive measure in Asia, the risks of wide human infection are not known.
South Korean health workers disinfecting a chicken farm in April, Though several hundred million birds have died or been killed as a preventive measure in Asia, the human epidemic risk remains unknown.

9. Human-Microbe Transitions over the Millennia
Pre-historic: hunter-gatherers disperse into distant new environments 1. Local agrarianism/herding: 5-10,000 yrs ago 2. Trans-continental: 1,000-3,000 yrs ago 3. Inter-continental: From c AD 4. Today, global: Fourth historical transition
Successive increases in SCALE

10. Factors in Emerging/Re-emerging Infectious Diseases
Microbial adaptation and change
Human susceptibility to infection
ageing, HIV, IV drugs, transplantation, transfusion
Population growth and density
Urbanization, crowding – social and sexual relations
Globalization of travel and trade
Live animal markets
Intensified livestock production
Misuse of antibiotics (humans & domestic animals)
Changes to ecosystems (deforestation, biodiversity loss)
Global climate change

11. Zoonotic Sources: Land-use, Livestock, Wild-life
Clearing forests for agriculture
Viral haemorrhagic fevers in South America: peasant-farmers
Guanarito, Sabia, Kunjin, etc.
Eating infected animals
New variant Creutzfeldt Jacob disease (from BSE)
Cultivation of infected animals
Nipah viral encephalitis (pig farms in Malaysia)
West Nile virus (goose “fois gras” farms in Ramala, Israel)
Collection and trade of wild game
HIV (bush meat: primates)
Ebola (bush meat?)
SARS (civet cat?)

12. Incidence of BSE in UK, 1987-99 (c.180K cases)
1988/9 bans: Sale of nervous tissue and offal for human consumption
Eating cattle >30 months old
Mammalian products in ruminant feed
BUT: no ban on feed for swine or poultry
Human vCJD (end 2003) cases: UK-117, France-6, Ireland-1, Italy-1

13. Nipah Viral Encephalitis, in Malaysia
01/97 Farm worker hospitalized with viral encephalitis (VE).
10/97 First death (pig-farm worker) from VE.
02/ farm workers develop VE.
11/98 Health Minister declares it ‘Japanese Encephalitis’  mosquito
control and vaccine program. But outbreak spreads.
1-2/99 Pig farmers begin ‘fire sales’ of pigs. Outbreak recedes a little.
02/99 Laboratories receive first samples of infected human
tissue. “New” virus? Mass pig culling begins. Villagers flee.
03/99 Virus isolated and identified with reagents used to characterize Hendra virus (a recently-identified horse virus, from Queensland).
04/99 ‘Nipah virus’ discovery announced. Culling continues.
05/99 WHO declares outbreak over (265 cases, 40% fatal).
02/00 Last death. Fruit bats (flying foxes) deemed the likely reservoir.

14. Travel and Trade: examples
Aedes albopictus mosquito eggs in shipments of used tyres  dengue fever
Long-distance travel; wild animal trade
HIV/AIDS
West Nile Virus (New York City, 1999)
SARS, 2003

15. SARS Severe Acute Respiratory Syndrome
   
A genetic model for the Coronavirus family.
(Photo: J Oxford, Retroscreen Virology Ltd)

16. Key wildlife trade routes in SE Asia and China
Vietnam
Cambodia
Lao PDR
China

17. Environmental Changes
Land use, forest clearance
Biodiversity losses, extinctions
Dams, irrigation
Climate change

18. Density of An. darlingi (malaria vector) in Peruvian Amazon
An. Darlingi abundance (log scale)
No. of survey sites = 2433
Village
(deforested)
Farm
Secondary
growth
Forest
Patz et al, 2003

19. Lyme Disease: Influences of Habitat Fragmentation & Biodiversity Loss
High Lyme
Disease risk
Woodland suburban
housing (NE USA)
High tick density
and high tick infection
prevalence  infected deer
Complex life-
cycle of tick
Many competent
reservoir species  less dilution by incompetent reservoir species
Expanding mouse
populations
Less diversity of vertebrate
predators and viral hosts
Poor inter-species regulation
Forest fragmentation, hunting (wolves, passenger pigeons)
Adapted from: R. Ostfeld

20. Climate Change and Infectious Disease
Some recent changes in ID patterns may reflect the influence of climate change (debate continues)
Tick-borne encephalitis (north spread in Sweden)
Cholera in Bangladesh (strengthening relationship with El Niño events)
Malaria ascent in east African highlands
Time-trends in incidence of (reported) food poisoning, esp. Salmonellosis

21. Dengue Fever: Estimated geographic region suitable for maintenance of Ae. aegypti, under alternative climate scenarios for 2050
Risk region under medium
emissions scenario, 2050
Darwin
Katherine
Cairns
Mackay
Rockhampton
Townsville
Port Headland
Broome .
Carnarvon .
Darwin .
Katherine . . .
Cairns
Broome .
Townsville .
Port Headland
Mackay .
Current risk region for dengue
Rockhampton
Darwin
Katherine
Cairns
Mackay
Rockhampton
Townsville
Port Headland
Broome .
Carnarvon
Risk region under high
emissions scenario, 2050 .
Brisbane
NCEPH/CSIRO/BoM/UnivOtago, 2003

22. MALARIA IN ZIMBABWE, UNDER CLIMATE CHANGE
Baseline
Source: Kris Ebi

23. Baseline
Source: Kris Ebi

24. Baseline
Source: Kris Ebi

25. Summary
Humans, domestic animals and wildlife are inextricably linked by epidemiology of infectious diseases (IDs).
IDs will continue to emerge, re-emerge and spread.
Human-induced environmental changes, inter-species contacts, altered social conditions, demography and medical technology affect microbes’ opportunities.
Also:
New research, technology and collaborative networks will also elucidate role of infection in diverse, mostly chronic, diseases of unknown cause

26. CHRONIC DISEASE: Examples
INFECTIOUS CAUSES OF
CHRONIC DISEASE: Examples
Disease
Cervical cancer
Chronic hepatitis, liver cancer
Lyme disease (arthritis)
Whipple’s disease
Bladder cancer
Stomach cancer
Peptic ulcer disease
Atherosclerosis (CHD)
Diabetes mellitus, type 1
Multiple sclerosis
Inflammatory bowel disease
Cause
Human papilloma virus
Hepatitis B and C viruses
Borrelia burgdorferi
Tropheryma whippelii
Schistosoma haematobium
Helicobacter pylori
Chlamydiae pneumoniae
Enteroviruses (esp. Coxsackie)
Epstein-Barr v, herpes vv?
Mycobacterium avium sub-spp.
Paratuberculosis, Yersinia

27. Conclusion I: Understanding what promotes human-microbe contacts
Intensified modification/exploitation of natural environments and food production.
Disturbance of natural ecosystems and their various internal biotic controls.
Poverty, crowding, social disorder, mobility and political instability.

28. Conclusion II: Microbes as Co-Habitants
Microbes’ interest is in survival and reproduction. They have no malign intent; morally neutral! Their evolution-based drive to survive is as strong as ours (and draws on much longer experience).

29. That’s all, folks

30. Cyclone Sid: Precursor to 1998 Japanese Encephalitis incursion?
Air 100 m altitude
Backwards trajectory analysis of JE
27 Dec 1997: Tropical Cyclone Sid