biological hazards

1. Biological HazardsBiological Hazards

2. BIOLOGICAL HAZARDS:BIOLOGICAL HAZARDS:
DISEASE IN DEVELOPED ANDDISEASE IN DEVELOPED AND
DEVELOPING COUNTRIESDEVELOPING COUNTRIES
 Infectious diseaseInfectious disease - caused by pathogen- caused by pathogen
such as bacterium, virus, or parasitesuch as bacterium, virus, or parasite
 TransmissibleTransmissible (contagious, communicable)(contagious, communicable)
diseasedisease – can spread from person to person– can spread from person to person
 Nontransmissible diseaseNontransmissible disease – not caused by– not caused by
living organisms, cannot spread from oneliving organisms, cannot spread from one
person to another (ex: cardiovascular, asthma,person to another (ex: cardiovascular, asthma,
malnutrition)malnutrition)

3. Infectious DiseasesInfectious Diseases
 Pathways for infectious disease in humansPathways for infectious disease in humans
 More likely in areas disturbed by humansMore likely in areas disturbed by humans

4. Infectious DiseasesInfectious Diseases
 BioterrorismBioterrorism – deliberate release of– deliberate release of
disease-causing bacteria or virus into air,disease-causing bacteria or virus into air,
water or food supplywater or food supply

5. Infectious DiseasesInfectious Diseases
 EpidemicEpidemic – large-scale outbreak of– large-scale outbreak of
infectious disease in a country or areainfectious disease in a country or area
 PandemicPandemic – global epidemic – ex: AIDS– global epidemic – ex: AIDS

6. Infectious DiseasesInfectious Diseases
 WHO estimatesWHO estimates
that each year thethat each year the
world’s sevenworld’s seven
deadliest infectionsdeadliest infections
kill 10 millionkill 10 million
people – most ofpeople – most of
them poor in less-them poor in less-
developeddeveloped
countriescountries

7. Case Study: Genetic Resistance toCase Study: Genetic Resistance to
AntibioticsAntibiotics
 Rapidly producing infectious bacteria areRapidly producing infectious bacteria are
becoming genetically resistant to widely usedbecoming genetically resistant to widely used
antibioticsantibiotics (chemicals that kill bacteria):(chemicals that kill bacteria):

8. Case Study: Genetic Resistance toCase Study: Genetic Resistance to
AntibioticsAntibiotics
 Other factors causingOther factors causing antibiotic resistanceantibiotic resistance::

Spread of bacteria around globe by human travelSpread of bacteria around globe by human travel

Overuse of pesticides – produces pesticideOveruse of pesticides – produces pesticide
resistant insects that carry bacteriaresistant insects that carry bacteria

Overuse of antibioticsOveruse of antibiotics – ½ used for humans are– ½ used for humans are
unnecessary, overuse for livestock and poultryunnecessary, overuse for livestock and poultry

Overuse of antibacterial soaps, etc.Overuse of antibacterial soaps, etc.

9. Case Study: Genetic Resistance toCase Study: Genetic Resistance to
AntibioticsAntibiotics
 Ex:Ex: MRSAMRSA – methicillin-resistant– methicillin-resistant
staphylococcus aureus – bacteria resistant tostaphylococcus aureus – bacteria resistant to
most antibiotics – esp. problem in hospitalsmost antibiotics – esp. problem in hospitals

10. Case Study: The Growing GlobalCase Study: The Growing Global
Threat from TuberculosisThreat from Tuberculosis
 Tuberculosis (TB)Tuberculosis (TB) – highly infectious – kills– highly infectious – kills
1.4 million people per year1.4 million people per year
 Recent increases in TB are due to:Recent increases in TB are due to:

People do not know they are infectedPeople do not know they are infected

Lack of TB screening and control programs –Lack of TB screening and control programs –
esp. less-developed countries – expensiveesp. less-developed countries – expensive

Genetic resistance to the most effectiveGenetic resistance to the most effective
antibioticsantibiotics

Population growth, urbanization, air travelPopulation growth, urbanization, air travel

AIDS patients are highly susceptibleAIDS patients are highly susceptible

11. Case Study: The Growing GlobalCase Study: The Growing Global
Threat from TuberculosisThreat from Tuberculosis

12. Viral DiseasesViral Diseases
 World’s most widespread and dangerousWorld’s most widespread and dangerous
viruses:viruses: influenza (flu), HIV and hepatitis B –influenza (flu), HIV and hepatitis B –
kill many more people each year then otherskill many more people each year then others
 Newer, highly publicized viruses: West Nile,Newer, highly publicized viruses: West Nile,
SARS (severe acute respiratory syndrome),SARS (severe acute respiratory syndrome),
ZikaZika

13. Viral DiseasesViral Diseases
 Influenza virusInfluenza virus – biggest killer virus– biggest killer virus
worldwideworldwide
• Pigs, chickens, ducks and geese – majorPigs, chickens, ducks and geese – major
reservoirs – virus can move from one speciesreservoirs – virus can move from one species
to another, mutate and exchange geneticto another, mutate and exchange genetic
material with other virusesmaterial with other viruses
• Kills 2% - usually young, old, weak or sickKills 2% - usually young, old, weak or sick
• Pandemics – 1918, 1957, 1968Pandemics – 1918, 1957, 1968
• 1918 – Spanish flu – killed 80% = 20-50 million1918 – Spanish flu – killed 80% = 20-50 million
• 1997 – H5N1 – bird flu1997 – H5N1 – bird flu

14. Case Study: The Global HIV/AIDSCase Study: The Global HIV/AIDS
EpidemicEpidemic
 According to the World Health OrganizationAccording to the World Health Organization
(WHO), since start of epidemic through(WHO), since start of epidemic through
2015 – 70 million people worldwide (1.22015 – 70 million people worldwide (1.2
million in U.S.) were infected with HIV, 35million in U.S.) were infected with HIV, 35
million died (660,000 in U.S.)million died (660,000 in U.S.)
 No vaccine for HIVNo vaccine for HIV
 Drugs help many people live longer, butDrugs help many people live longer, but
many can’t afford themmany can’t afford them

15. Case Study: The Global HIV/AIDSCase Study: The Global HIV/AIDS
EpidemicEpidemic
 AIDS – reduced the lifeAIDS – reduced the life
expectancy of sub-expectancy of sub-
Saharan Africa from 62Saharan Africa from 62
to 47 years – 40 yearsto 47 years – 40 years
in the seven countriesin the seven countries
most severely affectedmost severely affected
Projected age structureProjected age structure
of Botswana's populationof Botswana's population
in 2020in 2020

17. Case Study: The Global HIV/AIDSCase Study: The Global HIV/AIDS
EpidemicEpidemic
 Virus itself is not deadly – cripples theVirus itself is not deadly – cripples the
immune system, leaving body susceptible toimmune system, leaving body susceptible to
infections (ex: Kaposi’s sarcoma)infections (ex: Kaposi’s sarcoma)

18. Case Study:Case Study:
Malaria – Death by MosquitoMalaria – Death by Mosquito
 Malaria killsMalaria kills
655,000 to 1.2655,000 to 1.2
million peoplemillion people
per yearper year
 ProtozoanProtozoan
parasite spreadparasite spread
by mosquitoesby mosquitoes

19. Case Study:Case Study:
Malaria – Death by MosquitoMalaria – Death by Mosquito
 Economists – spending $2-3 billion onEconomists – spending $2-3 billion on
malaria treatment may save more than 1malaria treatment may save more than 1
million lives per yearmillion lives per year
 Possible spread because of climate changePossible spread because of climate change
Figure 18-6Figure 18-6

20.  Draining wetlands and insecticides (DDT)Draining wetlands and insecticides (DDT)
kills mosquitoes – but results in habitat losskills mosquitoes – but results in habitat loss
and insecticide resistanceand insecticide resistance

Low concentrations of DDT sprayed in housesLow concentrations of DDT sprayed in houses
helps, but DDT being phased outhelps, but DDT being phased out

Cost vs benefit?Cost vs benefit?
 Antimalarial drugs – but parasite is resistantAntimalarial drugs – but parasite is resistant
 Other options: screens, bed nets, biologicalOther options: screens, bed nets, biological
control (ex: tilapia)control (ex: tilapia)
Case Study:Case Study:
Malaria – Death by MosquitoMalaria – Death by Mosquito

22. Ecological Medicine andEcological Medicine and
Infectious DiseasesInfectious Diseases
 Infectious diseases moving at increasing ratesInfectious diseases moving at increasing rates
from one animal species to another (includingfrom one animal species to another (including
humans) – ex: avian flu, HIV, SARS, West Nilehumans) – ex: avian flu, HIV, SARS, West Nile
virus, Hantavirus, Lyme diseasevirus, Hantavirus, Lyme disease
 Due to: invasion of wildlife habitat, trade inDue to: invasion of wildlife habitat, trade in
wildlife, global trade, bushmeat, factory farmingwildlife, global trade, bushmeat, factory farming
 Ecological (or conservation) medicineEcological (or conservation) medicine ––
tracking down connections between wildlife andtracking down connections between wildlife and
humans to determine ways to slow and preventhumans to determine ways to slow and prevent
disease spreaddisease spread