8.15 - Pathogens And Infectious Diseases

Question 1

Pathogens and Vectors

Answer 1

Pathogens:
- A living organism (virus, bacteria, fungus, protist, worm) that causes an infectious disease
Infectious diseases are capable of being spread or transmitted (HIV, ebola, Covid-19); noninfectious diseases are not transmissible (heart disease, asthma, cancer, diabetes)
- Pathogens adapt and evolve to take advantage of humans as hosts for their reproduction and spread (Covid-19 is a SARS-associated coronavirus that evolved to become especially effective at surviving and reproducing in humans)

Vectors:
- A living organism (rat, mosquito) that carry and transmit infectious pathogens to other organisms
- Climate change is shifting equatorial climate zones north and south away from the equator; this brings warmer temperatures to subtropical and temperate regions
- Warmer temperatures allow pathogens and their vectors (mosquitos) to spread north & south to parts of the world previously too cold
- Many pathogenic bacteria and viruses survive and replicate better in warmer weather

Question 2

Infectious Disease and Development

Answer 2

• less developed, poorer countries typically have higher rates of infectious disease
• Less sanitary waste disposal; pathogens can reproduce in open waste areas where children may play or animals may scavenge & pass to humans
• Less access to healthcare facilities and antibiotic medications to treat infectious diseases cause by bacteria & other pathogens
• Lack of treatment/filtration for drinking water & sewage treatment exposes people to bacterial and viral pathogens in water, often from human waste
• Tropical climates & more open-air living can expose people to vectors like mosquitoes; less money for vector eradication (spraying mosquito breeding grounds)

Question 3

Plague

Answer 3

• Bacterial (pathogen) infection transmitted by fleas (vector) that attach to mice & rats (vectors as well)
• Transmitted by flea bite, rodent contact or contaminated human fluids
• Aka “bubonic” or “black” plague; modern antibiotics are highly effective against it, but some isolated instances still occur

Question 4

Tuberculosis (TB)

Answer 4

• Bacterial infection that targets the lungs
• Transmitted by breathing bacteria from body fluids (resp. droplets) of an infected person, which can linger in air for hours
• Causes night sweats, fever, coughing blood; treatable in developed nations with access to powerful antibiotics
• Leading cause of death by disease in the developing world ~ 9 million cases per year and 2 million deaths (for comparison ~ 2.8 million global deaths from Covid-19)

Question 5

Malaria

Answer 5

• parasitic protist (pathogen) infection caused by bite from infected mosquitoes (vector)
• Most common in sub-Saharan Africa (& other tropical regions of Middle East, Asia, South & Central America; recurring flu-like symptoms; kills mostly children under 5
• Can be combated with insecticide spraying that kills mosquitoes; US eradicated in 1951

Question 6

West Nile

Answer 6

• Virus (pathogen) infection caused by bite from infected mosquitoes (vector)
• Birds are the main host, but the virus can be transmitted to humans by mosquitoes that bite infected birds and then bite humans
• Causes brain information that can be fatal

Question 7

Zika Virus

Answer 7

• Virus infection caused by bite from infected mosquitoes and sexual contact
• Causes babies to be born with abnormally small heads and damaged brains; can be passed from mother to infant
• No known treatment currently, so prevention is focused on eliminating mosquito populations

Question 8

SARS (Severe Acute Respiratory Syndrome)

Answer 8

• Coronavirus infection caused by respiratory droplets infected person
• Primarily transmitted by touching or inhaling fluids from an infected person
• Causes a form of pneumonia
• Initial outbreak was in Southeast Asia
• SARS-CoV-2 is the virus that causes the disease COVID-19

Question 9

MERS (Middle East Respiratory Syndrome)

Answer 9

• Virus (pathogen) respiratory infection transmitted from animals to humans
• Originated on Arabian Peninsula

Question 10

Cholera

Answer 10

• Bacterial (pathogen) infection caused by drinking infected water
• Can be introduced by water contaminated with human feces or undercooked seafood
• Vomiting, muscle cramps and diarrhea; can cause severe dehydration