Herpesviridae - Alphaherpesvirinae - Porcine Herpesvirus 1

Question 1

What does PHV-1 cause?

Answer 1

Psuedorabies, Aujeszky disease, Mad itch

Question 2

What species are the hosts of PHV-1?

Answer 2

Pigs

Secondary hosts include horses, cattle, sheep, goats, dogs, cats

Question 3

Can humans contract PHV-1?

Answer 3

No, they are refractory

Question 4

What species act as reservoirs?

Answer 4

Pigs

Rodents – transmit from farm to farm

Question 5

How is PHV-1 transmitted?

Answer 5

Saliva, nasal discharges, and milk of infected pigs through licking, biting, aerosol, ingestion of contaminated carcass, water, and feed.

Question 6

Can the virus be transmitted in urine or feces

Answer 6

NO

Question 7

How do dogs and cats get infected with PHV-1?

Answer 7

Ingestion of infected pig meat or bite of infected rodent

Question 8

How are cattle infected with PHV-1?

Answer 8

Direct contact with infected pigs through the oral and nasal routes

Question 9

Where is the primary site of viral replication?

Answer 9

Upper respiratory tract

Question 10

Where else can the virus be located?

Answer 10

CNS via axons of cranial nerves

Preference for neurons of the pons and medulla

Question 11

What lesions can occur in the CNS due to PHV-1?

Answer 11

Ganglioneuritis
Nonsuppurative meningoencephalitis
Perivascular cuffing

Question 12

What are the clinical signs of pseudorabies in pigs?

Answer 12

Non-immune piglets: 100% mortality
Non-immune pregnant sows: 50% abortion rate
Older piglets, growers, and adult pigs: <2% mortality rate

Question 13

What are the clinical signs of pseudorabies in pigs?

Answer 13

Generalized febrile response, anorexia, weight loss

Pruritus is rare in pigs

Question 14

What is a common clinical sign of pseudorabies in secondary hosts?

Answer 14

Pruritus

Question 15

What are the clinical signs of pseudorabies in non-immune piglets?

Answer 15

CNS disease

Incoordination of hindlimbs, tremors, paddling

Question 16

What are the clinical signs of pseudorabies in weaned pigs?

Answer 16

Reduced CNS signs.
Increase in respiratory signs.
Listlessness, depression, sneezing, coughing, moderate fever, vomiting
Incoordination, muscle spasm, circling, convulsions
Headpressing!

Question 17

What are the clinical signs of pseudorabies in non-immune pregnant sows?

Answer 17

Infection before 30th day – death and resorption of embryo.
Infection in late pregnancy – mummified, stillborn, weak, or normal piglets
Up to 20% of sows aborting are infertile on next breeding

Question 18

What gross findings would you find in a necropsy?

Answer 18

Often absent or minimal but you may see:
Serous to fibrinous rhinitis 
Necrotic tonsillitis
Liver and spleen have yellow-white necrotic foci (2-3mm)
Necrotic placentitis and endometritis

Question 19

What is pseudorabies in cows called?

Answer 19

Mad itch

Question 20

What are the clinical signs of mad itch?

Answer 20

Intense pruritus causing frenzy– self trauma
Progressive CNS signs, paralysis, ataxia
Death from respiratory failure
Profuse salivation

Question 21

What are the clinical signs in dogs?

Answer 21

Pruritus with self-mutilation
Paralysis of jaws and pharynx
Salivation
Plaintive howling
Dogs do not attack-- unlike rabies

Question 22

What are the clinical signs in cats?

Answer 22

Often not observed because disease is so rapid

Question 23

How is PHV-1 diagnosed?

Answer 23

History and clinical signs
Histopathology- intranuclear inclusion bodies
Serology
PCR

Question 24

When should the PHV-1 vaccine be used?

Answer 24

In enzootic areas to reduce swine losses.

Vaccination does not prevent infection but alleviates clinical signs.

Question 25

What types of PHV-1 vaccines are there?

Answer 25

Recombinant DNA
Deletion-mutant
Live-attenuated
Inactivated

Question 26

What is deleted from the pseudorabies vaccines?

Answer 26

Thymidine kinase and glycoprotein gene