Transcript Document

Chapter 17
New Infectious threats
A. Definitions
infection, pathogen, epidemic, pandemic
B. Diseases
Factors affecting how diseases spread:
Host susceptibility/pathogen virulence
Herd Immunity
Weather
Route of transmission
Direct contact, Food, Water, others…
C. Specific problems
Bioterrorism
Anthrax, Small pox, ?
STD’s
bacterial, viral
Antibiotic resistance
Niche
role, position and function
in the community
Community
organisms living with and
interacting with each other
Niche
normal bacteria living with (in) us
prevent cavities
help digestive system
prevent “bad guys”
from growing
New Infectious Threats
Infection:
organism finds a place to grow
within another species, causing
it harm
New Infectious Threats
Pathogen:
organism infects
and
causes a disease
(parasite)
Measles
Chicken pox
Disease is there, but at
a low,constant rate
Endemic
SARS
Disease is becoming
more frequent and
spreading
Epidemic
AIDS
Disease is becoming
more frequent and
spreading worldwide
Pandemic
Name some pathogens:
virus
bacteria
protist
bacteria
fungus
animal
HIV (AIDS; 16)
TB (tuberculosis; 17)
Plasmodium (malaria; 7)
E. coli (food poisoning)
Candida (yeast infection)
Worms (tapeworms, etc.)
fig. 17-1
Pathogens - characteristics
enter host
species specific
adhere and replicate
binding molecules
escape immune system
change proteins (antigenic drift)
exit the host
transmission methods
Pathogens - how they spread
Host / pathogen
Herd immunity
Weather
Routes of transmission
Pathogens - how they spread
Host / pathogen
Susceptible host
Virulent pathogen
(can cause disease)
Pathogens - how they spread
Herd immunity
Proportion of non-susceptible
people in a population
Increase herd immunity via
vaccination programs
Polio and measles
Pathogens - how they spread
Weather
Flooding
Draught
Climate change
Pathogens - how they spread
Routes of transmission
Physical contact
Vectors
Food / water
Used needles
Size of the epidemic (pandemic)
Increase in population size
Increase in travel
int. departures
1950
2000
-
5,000,000
- 200,000,000
Bioterrorism
Intentional transmission of disease
13th century Europe
Bubonic plague
October 2001
Anthrax in mail
23 deaths, $$$$
Kill bacteria
drying
freezing
heating
(endo)spores
resist
killing
fig. 17-2
Smallpox
3/10 die
India and China
1000 BC
Europe
700 AD
Central America
1520
Aztec Indians
Smallpox
Smallpox
People who lived through infections
were protected from future infections
Expose people to dried crusts
most were protected, some died
Dairy workers exposed to cowpox
were protected
Smallpox
Edward Jenner (MD) exposed an boy
(James Phipps, 8 years old) to cowpox
Later he was exposed to smallpox
He did not get smallpox
vacca (L. cow)
vaccination,vaccine
Smallpox
Vaccine developed to give life-long
immunity
Spread by close contact
No other host
Eradication - proposed in 1958
began in 1967
Smallpox
Last case
Ali Maalin
Somolia 1977
eradicated (gone since 1979)
(WHO declared world free of smallpox)
Cultures kept in US, Russia
Vaccinations discontinuedlosing herd immunity
Should we vaccinate people for it?
STD’s
sexually transmitted diseases
Transferred via body fluids
Viral
Bacterial
Protists
AIDS, genital herpes, HPV
syphylis, gonorrhea, Chlamydia
trichomoniasis
Figure 17.3
Prognosis
(forecast)
AIDS
Syphilis (untreated)
Others:
death
Sterility, paralysis, chronic pain,
severe disease in newborns,
arthritis…
Chlamydia
3,000,000 cases/year (US)
1984
1997
3.2/100,000
207/100,000
Most carriers are asymptomatic
PID
pelvic inflammatory disease
Figure 17.4
Gonorrhea
62,000,000 cases/year (world)
If untreated (asymptomatic):
Scar tissue (infertility)
Spread to brain, heart
Passed to baby (blindness)
Syphilis
12,000,000 cases/year (world)
Often mis-diagnosed
Passed to newborn
Viral STD’s
Genital warts
HPV
Also causes cervical cancer
Viral STD’s
Genital warts
Herpes
HPV
HSV
herpes simplex virus
type 1
type 2
cold sores
genital herpes
20% of US adolescents/adults
Viral STD’s
Genital warts
Herpes
HPV
HSV
herpes simplex virus
type 1
type 2
cold sores
genital herpes
More susceptible to HIV infection
CDC
“Genital herpes is a sexually transmitted disease
(STD) caused by the herpes simplex viruses type
1 (HSV-1) and type 2 (HSV-2). Most genital
herpes is caused by HSV-2”
“Nationwide [USA], at least 45 million people
ages 12 and older, or one out of five adolescents
and adults, have had genital HSV infection.”
HSV-1 and HSV-2 can be found in and released from the
sores that the viruses cause, but they also are released
between outbreaks from skin that does not appear to be
broken or to have a sore. Generally, a person can only
get HSV-2 infection during sexual contact with someone
who has a genital HSV-2 infection. Transmission can
occur from an infected partner who does not have a
visible sore and may not know that he or she is infected.
HSV-1 can cause genital herpes, but it more commonly
causes infections of the mouth and lips, so-called “fever
blisters.” HSV-1 infection of the genitals can be caused
by oral-genital or genital-genital contact with a person
who has HSV-1 infection. Genital HSV-1 outbreaks recur
less regularly than genital HSV-2 outbreaks.
Viral STD’s
Genital warts
Herpes
AIDS
HPV
HSV
HIV
Good news/Bad news
“Abstinence or lifelong monogamy with an
uninfected partner will prevent STD’s”
BT3, pg. 625
Chlamydia
Gonorrhea
Syphilis
All caused by bacteria
All treatable with antibiotics
There aren’t any drugs to
eradicate viral STD’s
Chapter 17
New Infectious threats
A. Definitions
infection, pathogen, epidemic, pandemic
B. Diseases
Factors affecting how diseases spread:
Host susceptibility/pathogen virulence
Herd Immunity
Weather
Route of transmission
Direct contact, Food, Water, others…
C. Specific problems
Bioterrorism
Anthrax, Small pox, ?
STD’s
bacterial, viral
Antibiotic resistance
protozoan STD
Trichomonas vaginalis
Only one antibiotic works
Drug has bad side effects
Use of antibiotics
Kill or stop growth of bacteria
Put selective pressure
on populations
(natural selection)
Figure 17.6
Figure 17.5
Diseases can be transmitted via:
Sexual contact (body fluids)
Aerosol (coughing)
Tuberculosis (TB)
Mycobacterium tuberculosis
Resurgence in 1980’s and 1990’s
Infection in lungs, coughing will
put bacteria into the air
Tuberculosis (TB)
In Nigeria:
•300,000 cases/year
• 30,000 deaths/year
•Leading killer of people with HIV/AIDS
•Fairly economical to treat ($10)
Diseases can be transmitted via:
Sexual contact (body fluids)
Aerosol (coughing)
Foods
Food preparation/storage
Weak immunity - at risk
table 17-2
Figure 17.7
Diseases can be transmitted via:
Sexual contact (body fluids)
Aerosol (coughing)
Foods
Water
Cholera
Giardiasis
Legionaires…
Cholera
5 pandemics, before identified
Spread by “bad water”
Described by Koch (1886)
Specific to humans
Cause diarrhea
dehydration
death (25%)
clean water >1%
Figure 17.8
Giardiasis
Diseases can be transmitted via:
Sexual contact (body fluids)
Aerosol (coughing)
Foods
Water
Vectors
Carry from host to host
Malaria, Leishmaniasis
West Nile virus
Figure 17.9
Year(s)
cases
deaths
19992001
149
18
2002
2003
2004
2005
2006
4,156
9,862
2,539
3,000
4028
284
264
100
119
135
11/28/06
Factors to control disease
biological
social
economic
population size
population health
vector distribution
complicated
Chapter 17
New Infectious threats
A. Definitions
infection, pathogen, epidemic, pandemic
B. Diseases
Factors affecting how diseases spread:
Host susceptibility/pathogen virulence
Herd Immunity
Weather
Route of transmission
Direct contact, Food, Water, others…
C. Specific problems
Bioterrorism
Anthrax, Small pox, ?
STD’s
bacterial, viral
Antibiotic resistance