2. HORSES: Equine influenza (Influenzavirus A)

Question 1

disease

Answer 1

-equine influenza

-contagious disease of horses

Question 2

caused by

Answer 2

Influenzavirus A

Question 3

characterized by

Answer 3

acute respiratory disease

Question 4

agent

Answer 4

-agent: influenzavirus A

-family: Orthomyxoviridae

-RNA virus

-2 subtypes:

> H7N7 (equine virus 1)-more historical

> H3N8 (equine virus 2, INFLUENZA VIRUS A-EQ2)
=2 lineages:
=Eurasian and American
= Eurasian lineage uncommon
=American lineage: classical American lineage, Florida sublineage and South American sublineage
=Florida sub lineage WIDESPREAD!
Clade 1:predominant in North America
Clade 2: in EU

Question 5

Equine influenza viruses appear to

Answer 5

change more SLOWLY than human influenza A viruses or swine influenza viruses

Question 6

survives on

Answer 6

wet surfaces for 72h and dry surfaces for 48h

Question 7

susceptible to

Answer 7

wide variety of disinfectants

Question 8

HR

Answer 8

-horses and other Equidae

> disease may be more severe in donkeys and mules

> humans might be susceptible but there is no evidence of recent natural infections

Question 9

most common in

Answer 9

fall and winter

Question 10

more common in

Answer 10

-younger horses (yearlings, ages 2-3 years)

> RARE in FOALS(maternal immunity 3-6 months

Question 11

more severe cases seen in

Answer 11

pregnant mares close to parturition

Question 12

listed dz

Answer 12

yes

Question 13

morbidity

Answer 13

high: 60-90%

Question 14

mortality

Answer 14

low less than 1%

Question 15

distribution 2019

Answer 15

-usa
-sweden
-africa

Question 16

outbreaks 2019

Answer 16

-africa
-usa

Question 17

distribution 21/22

Answer 17

africa

Question 18

distribution 22/23

Answer 18

-norway
-uk
-usa

Question 19

distribution 23

Answer 19

-usa!!
-brazil
-sweden
-uk

Question 20

outbreaks 21/22

Answer 20

-South America
-africa

Question 21

outbreaks 2023

Answer 21

-usa
-africa

Question 22

transmission: excretion

Answer 22

-nasal discharge

> virus shedding 48h after exposure; shedding for 6-7 days

Question 23

transmission: ways

Answer 23

-direct contact (droplets)

-aerosols

-fomites

Question 24

transmission: route

Answer 24

-respiratory

> ocular?

Question 25

IP

Answer 25

1-3 days

Question 26

CS: ACUTE RESPIRATORY DISEASE

Answer 26

-begins with high fever -deep, dry, often paroxysmal cough; nasal discharge -other respiratory and non-specific signs

Question 27

CS: complications

Answer 27

-secondary bacterial infections >more rare: neurological signs, myocarditis

Question 28

CS: animals with partial immunity

Answer 28

-milder -atypical infection

Question 29

CS: young foal without maternal antibodies

Answer 29

SEVERE VIRAL PNEUMONIA

Question 30

recovery

Answer 30

-within 1-3 WEEKS >up to 6 months in severely affected animals

Question 31

PM

Answer 31

-lung consolidation and/or pneumonia -upper respiratory tract involvement alone in milder cases

Question 32

DDx

Answer 32

-equine herpesvirus 1 and 4 -equine viral arteritis -equine rhinoviruses -bacterial pneumonia or pleuropneumonia -other respiratory pathogens

Question 33

diagnosis: material

Answer 33

nasal swabs

Question 34

diagnosis: in the lab

Answer 34

-virus isolation -identification of viral nucleic acids (PCR) or antigens (ELISA) -serology (ELISA, hemagglutination inhibition)

Question 35

Tx

Answer 35

-supportive care and rest -ABs if secondary bacterial infections

Question 36

biosecurity measures

Answer 36

to minimize spread!

Question 37

vaccine?

Answer 37

YES -do not always prevent infections or virus shedding, but dz is usually milder and virus shedding may be decreased