Week 7

Question 1

What are emerging infectious diseases?

Answer 1

Diseases which are being found in new areas, new species or new populations

Question 2

What are re-emerging infectious diseases?

Answer 2

Those being re-discovered in an area or species

Question 3

What percentage of emerging diseases are zoonotic?

Answer 3

75%

Question 4

What percentage of all human diseases are zoonotic?

Answer 4

60%

Question 5

What are the 4 main emerging infectious disease charcteristics?

Answer 5

Pathogen type
Transmission type
Drug resistance
Transmission mode

Question 6

What is the main trend for pathogen type 1940 to 2000?

Answer 6

Overal increase (drop from 80s compared to 90s)
Bacteria or rickettsiae have increase the most and are the largest group
Viruses or prions always second largest group

Question 7

What is the main trend for transmission origin 1940 to 2000?

Answer 7

Zoonotic - wildlife always largest expect in 80s when non-zoonotic took over
Zoonotic - nonwildlife always the largest

Question 8

What is the main trend for drug resistance 1940 to 2000?

Answer 8

Overal increase in EID
Overal larger percentage increase in reistant EIDs
Both had a decrease in the 90s

Question 9

What is the main trend for transmission mode 1940 to 2000?

Answer 9

Non vector born always been the largest group
Vector born increased in the 90s even though overall EIDs decreased

Question 10

Where do most Zoonotic pathogens come from?

Answer 10

Places where biodiveristy is greatest
Europe is slighly odd just lot of explorers and scientists

Question 11

Where do most zoonotic from non-wildlife come from?

Answer 11

Contact with lifestock

Question 12

Where do most drug resistance pathogens come from?

Answer 12

Major farm areas and areas with higher populations
Greater antibiotic use

Question 13

Where do most vector born pathogens come from?

Answer 13

Warm, populated areas particually along rivers

Question 14

What is driving the increase in EIDs?

Answer 14

Anthropogenic and demographic changes

Question 15

When was agriculture invented and how did that increase crowd infections?

Answer 15

Around 10,000 years ago
Led to denser populations and settlements and closer contact with live stock
Led to surge in ‘crowd infections’

Question 16

When did measles emerge?

Answer 16

Around 7,000 years ago likely emerge form rindepest of cattle
Become exclusively human pathegon when human population density

Question 17

When did smallpox first emerge?

Answer 17

Around 4,000 years ago, likely form camelpox (closest phylogenetic relative)

Question 18

When did diseases start to spread through long distance trade?

Answer 18

Around 1,500 years ago
Large eurasian empires become commercial and start to have more global influence

Question 19

What was the Plague of Athens happen?

Answer 19

430 BC likely caused by typhus due to the peloponnesian war

Question 20

What was the plague of Justinian?

Answer 20

541 to 549 believed to be from Yersinia pestis

Question 21

What are common factors in all these pathogen outbreaks?

Answer 21

Role of vectors, extended travel, non-human stowaways and contact with native populations

Question 22

Why did diseases become more global starting around 500 years ago?

Answer 22

Human travel increases and the world gets smaller
Travel expands geographically, exploration goes global bringing colonisation

Question 23

How did pathogens get a major spread due to european colonisation?

Answer 23

Outbreaks of pathogens like smallpox, syphilis, tuberculosis and measles travelled with European crews to remote oceanic islands and the New world exposing immunologically naive populations

Question 24

What factors in present day which is causing an increase in global infections?

Answer 24

Urbanisation and globalisation (Quick travel with more densely populated areas)
Changing agriculture, global travel, transport hubs

Question 25

How have Humans responded to the outbreak of illnesses?

Answer 25

Surveillance effort has increased with many new pathogens being detected now that wouldnt have been in the past

Question 26

What is worrying about novel pathogens?

Answer 26

Emerging with increasing frequency

Question 27

What are crytosporidium?

Answer 27

Zoonotic protozoan parasites with wide range of hosts and global distrubution

Question 28

What is the cryptosporidium parvum?

Answer 28

Main cause of human cryptosporidiosis
A protozoan

Question 29

What is the life cycle of cryptosporidiosis?

Answer 29

1 - Sporulated oocysts are excreted by in the faeces of an infected host
2 - Contaminated water (drinking or recreational) or food (e.g raw milk) are ingested
3 - If host is suitable, excystation occurs where the sporozoites are released and they invade the epithelial cells (usually of intestines and multiply before being excreted and the cycle continued

Question 30

What animal are C. parvum outbreaks most linked to?

Answer 30

Cattle, particually calves

Question 31

What percentage of children have cryptosporidiosis infection?

Answer 31

25%

Question 32

What is the timespan of a cryptosporidiosis infection?

Answer 32

7 day incubation
Immunocompetent individuals symptoms pass within 2 weeks but worse for immunocompromised

Question 33

What is the overwiew of Trypanosoma?

Answer 33

Zoonotic protozoan parasites e.g T. cruzi causes Chagas disease

Question 34

What is trypanosomiasis?

Answer 34

African sleeping sickness

Question 35

What causes trypanosomiasis?

Answer 35

Trypanosoma brucei gamibense (over 95% of reported cases) (protist)

Question 36

What is the life cycle of trypanosomiasis?

Answer 36

Infected tsetse fly bites a person/animal and injects trypomastigotes which travel to lymphatic system and blood stream
Inside the host the trypomastigotes change form and travel throughout body
Protozoa multiple in the blood and body fluids and circulate the body

Question 37

What is a pathogen reservoir?

Answer 37

A place where a pathogen normally occurs eg an animal or environmental (soil)

Question 38

What can makes animal/human resovoirs harder to control?

Answer 38

They are not always symptomatic (seen in Typhoid Mary case)

Question 39

What is the portal of exit?

Answer 39

The route by which a pathogen exits a host, often closely linked with site of action of the pathogen

Question 40

What is the portal of entry?

Answer 40

The route by which a pathogen enters a host, it must have a route to the target cell/tissue

Question 41

In pathoegns what is the link between portal of entry and exit?

Answer 41

In pathogens they are often the same

Question 42

What is the exception for the link between portal of entry and exit?

Answer 42

Pathogens transmitted via the faecal-oral route

Question 43

What can be a portal of entry?

Answer 43

Any way in which the body’s first lines of defence are breached eg break in skin or damage to mucus membrane

Question 44

What are the 5 ways for zoonotic diseases are transmitted?

Answer 44

Airborne - transfer of viruses
Vectors - transmitting from infected agents
Close proximity to animals - Faecal oral transfer/ animal body fluid in cuts
Direct contact with animals - bites from infected animals
Food-borne - consuming infected meat or milk