Emerging arboviruses

Question 1

How could an emerging infectious disease arise?

Answer 1

-New infection (evolution of existing)
-Re emerging of known infections
-

Question 2

What is an EID?

Answer 2

Has increased over last 20 years and could increase in near future

Question 3

What contributes to a vector borne EID?

Answer 3

• Climate change
• Economic change
• Public health issues
• Poverty
• Change in water supplies
• Change in human susceptibility
• Change in vectoral competency

Question 4

What are reasons why elimination programmes to get rid of vector borne diseases may have failed?

Answer 4

• Diversion of financial support (no longer became profitable)
• Loss of public health infrastructure (e.g. closing down of emergency treatment centres for ebola)
• Reliance on quick fixes such as drugs and insecticides.

Question 5

Three examples of arbovirus vectors

Answer 5

Mosquitoes, ticks, sandflies

Question 6

What is the genome size for the most medically important arboviruses?

Answer 6

11-12 kilo bases

Question 7

What type of RNA virus is the bunyaviridae family? How is it translated into proteins?

Answer 7

Is a negative sense RNA virus so must form a positive strand before being translated.

Question 8

What type of RNA virus is the flavivirus family? How is it translated into proteins?

Answer 8

Positive sense RNA. Can be directly translated into proteins by the host ribosome.

Question 9

What is the extrinsic incubation period?

Answer 9

Time taken by an organism to complete its development in the intermediate host

Question 10

Describe the structure of flaviviruses. Example?

Answer 10

Enveloped, single strand RNA. Zika.

Question 11

What proportion of the world is at risk of dengue?

Answer 11

1/3

Question 12

What is the leading cause of morbidity and mortality in the tropics and subtropics?

Answer 12

Dengue

Question 13

When did dengue emerge as a worldwide problem?

Answer 13

1950s

Question 14

What are the serotypes of dengue?

Answer 14

DENV1-4

Question 15

How many people are affected per year with dengue?

Answer 15

400 m

Question 16

How has dengue increased in incidence from 1950 to 2013?

Answer 16

<1000 cases per year 1950, >3m cases per year 2013.

Question 17

Where is mainly endemic for YFV and how many cases and deaths are there?

Answer 17

Mainly in Africa.
60,000 deaths/year
200,000 cases

Question 18

How is yellow fever prevented?

Answer 18

Live attenuated vaccine.

Question 19

When was the most recent YFV outbreak?

Answer 19

2016, shortfall in vaccine supply to deal with outbreak

Question 20

Where else is YFV currently emerging and why?

Answer 20

China, previously absent in asia. Due to aegypti vector presence and large pop exchange between endemic African regions and china

Question 21

Where have recent outbreaks of zika occurred post 2007?

Answer 21

South America, Asia, Pacific islands

Question 22

Why is zika importnat?

Answer 22

Sexual transmission, microcephaly, following spread of CHIKV and DENV into southern USA.

Question 23

Which mosquito transmits jap enceph?

Answer 23

Culex tritaeniorhynchus

Question 24

What are the zoonotic reservoirs of jap enceph?

Answer 24

Pigs, cattle egrets, pond herrings

Question 25

HOw many countries are endemic for jap enceph? How many people are at risk?

Answer 25

24

3 billion

Question 26

When did outbreaks of west nile virus occur and where?

Answer 26

Europe and America in late 1990s

Question 27

How has west nile virus been maintained (enzoonotically)?

Answer 27

Cycle between mosquitoes and susceptible birds.

Question 28

Describe epidemiology of usutu virus.

Answer 28

Similar to west nile. Outbreaks in Europe (cases in Italy, Spain, serological evidence in UK) and America.

Question 29

What are the two encephalitis viruses?

Answer 29

St louis, la crosse.

Question 30

How is st louis encephalitis maintained?

Answer 30

cycle betwen culex pipiens and birds

Question 31

How is la crosse ncephalitis maintained?

Answer 31

Aedes mosquito and vertebrate cycle e.g. chipmunks and squirrels also vertical transmission between mosquito and eggs.

Question 32

Where is endemic for tick borne encephalitis? What is the main vector. What are the main hosts.

Answer 32

Europe, soviet union, Asia. Hard tick. Rodents mainly, humans are accidental hosts.

Question 33

WHere was powassan isolated and where are cases reported? What might be a zoonotic reservoir?

Answer 33

Canada and Russia. Deer.

Question 34

What are alpha viruses?

Answer 34

Positive sense ssRNA virus. Enveloped.

Question 35

Where were outbreaks of CHIKV and also where are they now?

Answer 35

Africa, Asia, Europe, India, Pacific islands, also now most of america

Question 36

WHich recent event may have caused widespread CHIKV?

Answer 36

Mutation in glycoprotein 1 (at residue 266) which allows A albopictus to transmit.

Question 37

What is the vector for mayaro and in which people does it commonly occur?

Answer 37

Haemogoggus and in people in contact with humid tropical forests.

Question 38

What are thought to be the primary vectors for o’nyong’nyong in East Africa?

Answer 38

Anopheles fenestus and gambiae

Question 39

Where is semliki forest virus found? What are the hosts? What does it cause?

Answer 39

Africa, asia, southern europe.

Wide range-rodents, domestic animals and primates

Lethal encephalitis in rodents, mainly asymptomatic in humans

Question 40

Which mosquito spp involved in zoonotic cycle for equine enceph? Waht are the types?

Answer 40

Culex. Eastern and western and venezuelan viruses

Question 41

Give two examples of bunyaviruses. How are they thought to be spreaD?

Answer 41

Crimean congo haemorrhagic fever and rift valley fever. Ticks and mosq respectively.

Question 42

Whats the vector for oropouche?

Answer 42

Midges

Question 43

Why may climate change increase arboviral transmission?

Answer 43

Decreases extrinsic incubaiton period. Increased precipitation increased mosquito range.