69. Swine influenza.

Question 1

Occurrence?

Answer 1

Orthomyxoviridae

• Swine influenza
• Acute febrile disease in swine with general & respiratory signs
• Pig = occasional host, the original host is always the bird!
• History, occurrence
• First descriptions together with the Spanish flu
• Originally in the USA, later worldwide
• Sporadic, more frequent in autumn & winter

Question 2

Causative agent?

Answer 2

Causative agent:

• H1N1, H3N2, rarely other serotypes (H1N2, H1N7 etc.)
• 2009, Mexico, USA: emergence of a novel strain ʹ multiple reassortment (related to swine H1N2 &
• H3N2, human & avian strains)

Question 3

Epizootiology?

Answer 3

Epizootiology

• Intro into the farm by infected animal
• Airborne transmission, swine of any age can get sick
• Quick spread in the herd
• High morbidity, low mortality
• Permanent carry
• pigs recovered should not be kept for breeding

Question 4

Pathogenesis?

Answer 4

Pathogenesis

• Entry: infection of upper resp tract epithelia
• Viremia
• Generalisation in lung on day 2-3, involvement of bronchi & alveoli
• Most serious signs on days 4-6
• W/out complications benign course
• Bacterial complications (H. parasuis, B. bronchiseptica, P. multocida, M. hyopneumoniae):
• catarrhal or croupous pneumonia

Question 5

Clinical signs?

Answer 5

Clinical signs

• Incubation: 1-3 days, many animals get sick
• Fever, loss of appetite, laying, laboured breathing, serous nasal discharge, coughing,sneezing
• Without complications quick recovery within 1 week

Question 6

Pathology?

Answer 6

Pathology:

• without complications mortality is rare,
• if die
• upper resp tract inflammations,
• lung oedema

Question 7

Diagnosis?

Answer 7

Diagnosis

• Episootiology data, signs
• Lab investigations ʹ nasal swab, lung: RT-PCR, virus isolation,
• serology (ELISA, HAI, VN, paired serum investigations)

Question 8

Differential diagnosis?

Answer 8

Differential diagnosis:

1. PRRS,
2. A. pleuropneumoniae (pleuropneumonia, haemorrhagic pneumonia),
3. mycoplasma-pneumonia (slower course, coughing)

Question 9

Treatment?

Answer 9

Treatment

• Resting, dust free environment
• AB against bacterial complications

Question 10

Control and Prevention?

Answer 10

Control & prevention

• Epizootiology measures
• Closed farming, separation of age groups
• Recovered gilts/boars should not be kept for breeding
• Immunisations:
• in endemic farms/areas (oil) adjuvated,
• inactivated, bivalent (H1N1, H3N2) vaccines;
• 3-4 weeks apart 2x, approx. ½-1-year protection