Lecture 19: Invasive Pathogens

Question 1

List examples of invasive pathogens

Answer 1

1. Salamander plague
2. Invasive american bullfrog transmitting lethal fungus to amphibian host sp (alpine newt)
3. Crayfish plague – transmitted to native crayfish
4. Invasive gray squirrel have a virus that kills red squirrels
5. White nose syndrome and bats
6. Deformed wing virus in bees via varra mites

Question 2

DO human migrations promote invasion?

Answer 2

yep

L> i.e. colonialism sucks

Question 3

C. gattii?

Answer 3

tropical fungal pathogen

• casuses fatal infections of the lungs and CNS
• native range = Aus and Indonesia
• discovered in Canada
• c colonizes trees and soils, spores are airborne
• infects mammals and birds
• higher infections rtes in canada vs native range

Question 4

Zika virus?

Answer 4

• native to Africa
• antibodies in locals
  asian tiger mosquito is transmitting it
• brain deformities and head deformities

Question 5

Trend of global human infectious disease outbreaks?

Answer 5

• on the rise

Question 6

Explain the epidemiological triad?

Answer 6

• vector transmits disease to host
• environment mediates this transfer, may or may not be hospitable to the vector and may not provide the right host , may not make the host susceptible enough
• maybe not a good enough environment for the agent itself
  Ex: Peacock fish (ate up mesopredators that kept malaria mosquitos in check)

Question 7

West nile?

Answer 7

• birds are the primary reservoir for the virus
• also invests horses and humans
• probably brought to the americas via illegal exotic bird trade

Question 8

Asian tiger mosquito

Answer 8

• larvae brought to NA via tires from Japan

- vector of yellow fever, dengue fever, encephalitis etc

Question 9

African mosquito

Answer 9

• vector for malaria

- introduced to Brazil by French ships coming from Africa

Question 10

Zoonoses?

Answer 10

• diseases and infections of vertebrate animals that can be transmitted to humans

Question 11

Zoonotic spillover in Africa?

Answer 11

• loss of forest cover and consumption of bushmeat drive contact between humans and wild hosts, leading to infections

Question 12

Bushmeat?

Answer 12

• bushmeat : meat of wild animals captured in forested areas are brought to urban areas for sale – carrying viruses from wild otherwise not encountered by us

Question 13

Forest fragmentation ?

Answer 13

increases edge of contact between human s and wild reservoirs of new pathogens

Question 14

Discuss the influ virus

Answer 14

• outermsmbrane is covered with enzymes N and H
• these help the virus attach to, and break into and out of host cells
• different types of H and N and different viruses have different combinations of them
  ex: H1N2

Question 15

What do H and N antigens do to hosts?

Answer 15

• trigger immune response (antibodies)
• a persons immunity to these reduces prob of infection and severity of the disease
• immunity to one HN combination confers little to no protection against a diff combo
  SOOOOO
  mutations in viruses can create strains that infect large numbers

Question 16

List two ways viruses can evolve

Answer 16

1. Antigenic drift

2. Antigenic shift

Question 17

Antigenic drift?

Answer 17

• genetic reassortment
• the whole HN combo changes
• large pieces of genome are exchanged between different viruses attacking THE SAME CELL
• produces novel flu strains distinct from all previous strains -> potentially pandemic
  *pigs = mixing vessel for Influenza (bird virus and human viruses can mix and undergo drift) then infect a human
  L> further mixing can occur when people are infected with a human virus and a bird virus

Question 18

Why do many strains of influenza type A originate from China ?

Answer 18

• SE Asia

- due to intense agricultural activity among a dense human population

Question 19

Issue with prairie dogs?

Answer 19

• monkeypox virus
• related to small pox but not as deadly
• endemic to Africa
• first discovered in monkeys
• first case in NA with people in 2003

***prairie dogs could be sitting in a warehouse with many animals, stressful situation, biologically damaged species may spread disease WHICH can then spread to us

Question 20

SARS?

Answer 20

severe acute respiratory syndrome

• caused by coronavirus similar to cold virus
• jumped from the civet cat which was kept as pets, to humans

** bats are natural reservoirs of SARS like coronaviruses – probs passed them to civet cat

Question 21

Paramoeba invadens?

Answer 21

• pathogenic amoeba caused mass mortalities of sea urchins
• non indigenous and periodically introduced by movements of warm water
• outbreaks occur in warm years

Question 22

Issues with aquaculture?

Answer 22

• crowded = easy transmission
• introduced stock = worldwide dispersal of pathogens
• escapees transmit to wild populations
• excess nutrients promotes microbial growth
• overuse of antibiotics stimulates selection for supersets

Question 23

Infectious Salmon Anaemia (ISA) virus?

Answer 23

• similar to flue
• can mutate and evolve
• causes hemorrhages in kidney and spleen and death
• no cure for infected fish
• fish seen in Norwegian fish farms
• now spread to NB Canada

Question 24

Trout ulcer disease?

Answer 24

• bacterial infection of salmon and trout
• ruptures blood vessels
• kills
• introduced to GL before 1900 possible with brown trout stock from Germany

Question 25

Emerging threat: Pfiesteria piscicida

Answer 25

• toxic dinoflagellate
• lesions in fish
• can hurt mammals
• native to mid atlantic coast
• recently in Norway

Question 26

Oysters?

Answer 26

-global trade of larvae and adults worldwide
- carry many pathogens
-

Question 27

Paralytic Shellfish Poisoning is rising??

Answer 27

1. more outbreaks being identified by increased awareness and detection efforts
2. Coastal waters are increasingly used for aquaculture greater nutrient loading and transfer of infected shellfish
3. Coastal eutrophication is increasing the frequency of toxic algal blooms
4. Increased transfers of dinoflagellates by ships

**Forms cysts on shellfish by the toxic dinoflagellate