EESA10 Final Exam Lecture Notes (lecture 7-12) | Human Health and
Environment 2026 upcoming exam Tips (everything you need to know)
Lecture 7 Biological Hazards
INFECTIOUS DISEASE
Infectious disease is host-centered concept:
• Human body is a habitat and host to many organisms
• Associations that harm or bother us are infectious diseases; agents are pathogens
• Zoonosis- infectious disease transmissible to humans from other animals
TYPES OF PATHOGENS
• Worms: multicellular; parasitic
• Protozoa: unicellular; parasitic
• Bacteria: unicellular; most not parasitic
⟶ Aerobic vs anaerobic: or tolerate each other
⟶ Some form sores
• Viruses (not have cell): strand of DNA or RNA; parasitic
• Size compare: Protozoa>Bacteria>Virus
THE BODIES DEFENSE AGAINST PATHOGENS
• Immune system distinguishes “self” from “foreign” (because of the protein)
, ⟶ Active immunity- on first exposure to antigen body produces antibodies (forming
antigens to protect the host – immunity action)
• Vaccination (not 100% protect from the virus, but chance to infect has been reduced)
⟶ Antigen preparation-> active immunity
⟶ Antibody preparation-> passive immunity (vaccines protection)
• Herd immunity- practical protection (群体免疫)
⟶ If enough members of a group are immune, hard to maintain chain of infection
EVOLUTION OF STRATEGIES FOR MANAGING TRANSMISSION OF DISEASE
• Segregation of sick or exposed persons, two types as follow:
⟶ Isolation (isolation of sick): the separation of persons who have an infectious illness
⟶ Quarantine (include sick people and the surrounding environment): the separation
of persons who have been exposed to infectious agent
• Sanitation: misguided but beneficial (washing hands)
• Vaccination to prevent illness (no vaccine for everything)
• Antibiotics to treat illness (don’t kill virus, 100 years)
⟶ Populations of pathogens become resistant over time
⟶ Methicillin- resistant Staphylococcus aureus (MRSA)
⟶ Highly reproductive rate allows them to become genetically resistant quickly
, ⟶ Problem: Overuse of antibiotics (antibiotics in food additives to boost livestock)
• Pesticides to control vectors
THE TRANSMISSION OF INFECTIOUS DISEASES
• Transmission through closeness/ contact
⟶ Droplet transmission: coughing, sneezing (touching objects that sick people touched)
O Diphtheria, TB, pertussis; influenza, measles, mumps, rubella
⟶ Direct oral contact
O Strep, herpes simplex-1, infectious mononucleosis
⟶ Transmission by fomite (object or substance capable of carrying infectious
organisms)
O Skin cells, hair, clothing, bedding
• Airborne transmission in aerosols (eg: air circulation) -- distinct from droplet
transmission, airborne can travel longer distances
• Fecal oral transmission or diarrheal disease
⟶ Fecal-oral pathway: one person’s infectious diarrheal disease becomes next
person’s diseases of fecal origin
⟶ If sewage not well controlled, waterborne transmission dominates
⟶ Fecal-oral transmission also via soil and by hand-to-mouth transmission
⟶ Cholera, typhoid fever, dysentery; giardiasis, cryptosporidium (zoonoses); hepatitis
A, Norwalk virus and polio
• Non-fecal organisms also transmitted into water or soil
⟶ Guinea worm disease
⟶ Tetanus
• And via food (foodborne transmissions)
⟶ Housefly as mechanical vector
GLOBAL PATTERNS OF INFECTIOUS DISEASE MORTALITY
• Fast global spreading --- because of travelling
• 2008 is a regular year: not have very large pandemic around world
• Total: 12.3 million deaths in 2008, leading infectious causes of death:
⟶ Respiratory infections 29%
⟶ Diarrheal disease: 20%
⟶ HIV/AIDS: 14%
• Worldwide, 22% of all deaths in 2008:
⟶ Highest in Africa: 53%
⟶ Southeast Asia: 27%
⟶ Eastern Mediterranean: 25%
, INFECTIOUS DISEASE AS A CAUSE OF CANCER
• Infection can increase cancer risk
⟶ E.g chronic irritation → cell proliferation
• Known infectious causes of cancer account for 18% of cancers worldwide
⟶ Liver (hepatitis B and C viruses)
⟶ Cervix (human papilloma virus)
⟶ Stomach (helicobacter pylori bacterium)
• Higher percentage in lower income countries (developing countiries)
SOME IMPORTANT TYPES OF PATHOGENS
• Bacteria
⟶ Tuberculosis
⟶ Anthrax
⟶ Plague
• Viruses
⟶ Yellow Fever
⟶ HIV
⟶ Bird Flu
⟶ West Nile Virus
• Protozoa
⟶ Malaria
TUBERCULOSIS (bacteria)
• Tuberculosis (TB) is one of the world’s deadliest diseases:
⟶ 1/3 of worlds population Is infected with TB
Environment 2026 upcoming exam Tips (everything you need to know)
Lecture 7 Biological Hazards
INFECTIOUS DISEASE
Infectious disease is host-centered concept:
• Human body is a habitat and host to many organisms
• Associations that harm or bother us are infectious diseases; agents are pathogens
• Zoonosis- infectious disease transmissible to humans from other animals
TYPES OF PATHOGENS
• Worms: multicellular; parasitic
• Protozoa: unicellular; parasitic
• Bacteria: unicellular; most not parasitic
⟶ Aerobic vs anaerobic: or tolerate each other
⟶ Some form sores
• Viruses (not have cell): strand of DNA or RNA; parasitic
• Size compare: Protozoa>Bacteria>Virus
THE BODIES DEFENSE AGAINST PATHOGENS
• Immune system distinguishes “self” from “foreign” (because of the protein)
, ⟶ Active immunity- on first exposure to antigen body produces antibodies (forming
antigens to protect the host – immunity action)
• Vaccination (not 100% protect from the virus, but chance to infect has been reduced)
⟶ Antigen preparation-> active immunity
⟶ Antibody preparation-> passive immunity (vaccines protection)
• Herd immunity- practical protection (群体免疫)
⟶ If enough members of a group are immune, hard to maintain chain of infection
EVOLUTION OF STRATEGIES FOR MANAGING TRANSMISSION OF DISEASE
• Segregation of sick or exposed persons, two types as follow:
⟶ Isolation (isolation of sick): the separation of persons who have an infectious illness
⟶ Quarantine (include sick people and the surrounding environment): the separation
of persons who have been exposed to infectious agent
• Sanitation: misguided but beneficial (washing hands)
• Vaccination to prevent illness (no vaccine for everything)
• Antibiotics to treat illness (don’t kill virus, 100 years)
⟶ Populations of pathogens become resistant over time
⟶ Methicillin- resistant Staphylococcus aureus (MRSA)
⟶ Highly reproductive rate allows them to become genetically resistant quickly
, ⟶ Problem: Overuse of antibiotics (antibiotics in food additives to boost livestock)
• Pesticides to control vectors
THE TRANSMISSION OF INFECTIOUS DISEASES
• Transmission through closeness/ contact
⟶ Droplet transmission: coughing, sneezing (touching objects that sick people touched)
O Diphtheria, TB, pertussis; influenza, measles, mumps, rubella
⟶ Direct oral contact
O Strep, herpes simplex-1, infectious mononucleosis
⟶ Transmission by fomite (object or substance capable of carrying infectious
organisms)
O Skin cells, hair, clothing, bedding
• Airborne transmission in aerosols (eg: air circulation) -- distinct from droplet
transmission, airborne can travel longer distances
• Fecal oral transmission or diarrheal disease
⟶ Fecal-oral pathway: one person’s infectious diarrheal disease becomes next
person’s diseases of fecal origin
⟶ If sewage not well controlled, waterborne transmission dominates
⟶ Fecal-oral transmission also via soil and by hand-to-mouth transmission
⟶ Cholera, typhoid fever, dysentery; giardiasis, cryptosporidium (zoonoses); hepatitis
A, Norwalk virus and polio
• Non-fecal organisms also transmitted into water or soil
⟶ Guinea worm disease
⟶ Tetanus
• And via food (foodborne transmissions)
⟶ Housefly as mechanical vector
GLOBAL PATTERNS OF INFECTIOUS DISEASE MORTALITY
• Fast global spreading --- because of travelling
• 2008 is a regular year: not have very large pandemic around world
• Total: 12.3 million deaths in 2008, leading infectious causes of death:
⟶ Respiratory infections 29%
⟶ Diarrheal disease: 20%
⟶ HIV/AIDS: 14%
• Worldwide, 22% of all deaths in 2008:
⟶ Highest in Africa: 53%
⟶ Southeast Asia: 27%
⟶ Eastern Mediterranean: 25%
, INFECTIOUS DISEASE AS A CAUSE OF CANCER
• Infection can increase cancer risk
⟶ E.g chronic irritation → cell proliferation
• Known infectious causes of cancer account for 18% of cancers worldwide
⟶ Liver (hepatitis B and C viruses)
⟶ Cervix (human papilloma virus)
⟶ Stomach (helicobacter pylori bacterium)
• Higher percentage in lower income countries (developing countiries)
SOME IMPORTANT TYPES OF PATHOGENS
• Bacteria
⟶ Tuberculosis
⟶ Anthrax
⟶ Plague
• Viruses
⟶ Yellow Fever
⟶ HIV
⟶ Bird Flu
⟶ West Nile Virus
• Protozoa
⟶ Malaria
TUBERCULOSIS (bacteria)
• Tuberculosis (TB) is one of the world’s deadliest diseases:
⟶ 1/3 of worlds population Is infected with TB
