Relationship between airborne detection of influenza A virus and the number of infected pigs

Abstract

Influenza A virus infects a wide range of species including both birds and mammals (including humans). One of the key routes by which the virus can infect populations of animals is by aerosol transmission. This study explored the relationship between number of infected pigs and the probability of detecting influenza virus RNA in bioaerosols through the course of an acute infection. Bioaerosols were collected using a cyclonic collector in two groups of 7 week-old pigs that were experimentally infected by exposure with a contact infected pig (seeder pig). After contact exposure, individual pig nasal swab samples were collected daily and air samples were collected three times per day for 8 days. All samples were tested for influenza by real-time reverse transcriptase (RRT)-PCR targeting the influenza virus matrix gene. All pigs' nasal swabs became influenza virus RRT-PCR positive upon exposure to the infected seeder pig. Airborne influenza was detected in 28/43 (65%) air samples. The temporal dynamics of influenza virus detection in air samples was in close agreement with the nasal shedding pattern in the infected pigs. First detection of positive bioaerosols happened at 1 day post contact (DPC). Positive bioaerosols were consistently detected between 3 and 6 DPC, a time when most pigs were also shedding virus in nasal secretions. Overall, the odds of detecting a positive air sample increased 2.2 times for every additional nasal swab positive pig in the group. In summary, there was a strong relationship between the number of pigs shedding influenza virus in nasal secretions and the generation of bioaerosols during the course of an acute infection.

Determination of Infective Dose of H9N2 Avian Influenza Virus in Different Routes: Aerosol, Intranasal, and Gastrointestinal

“…Influenza virus aerosols could generate during the course of an acute infection to pigs and temporal dynamics of this virus was closely associated with nasal shedding of infected pigs [19]. Influenza viruses could transmit in mammals and humans by aerosols, and healthcare professionals were easily infected within 1.829 m away from patients who released airborne influenza virus into the air by breathing, coughing and sneezing [5,6,20].…”

Influence of microclimate conditions on the cumulative exposure of nursery pigs to swine influenza A viruses

“…Results of another field study showed that confined places are more likely to increase aerosol transmission. In contrast, no viral particles were identified outside of the barn, which was attributed to the distribution of particles in a more open space (Corzo, Culhane, et al., ; Corzo, Romagosa, et al., ); however, no association was made with microclimate findings.…”

“…Previous studies conducted under experimental conditions in mechanically controlled ventilated building showed that the detection of influenza in aerosol was associated to the number of animal shedding at a specific point in time (Corzo, Culhane, et al., ; Corzo, Romagosa, et al., ), although no attempt was made to correlate this finding to the microclimate conditions. Results of another field study showed that confined places are more likely to increase aerosol transmission.…”

Asociación entre la seropositividad al virus de influenza porcina (VIP) y las características de las granjas tecnificadas porcícolas en Colombia

“…Se ha estimado matemáticamente que el riesgo de transmisión de las partículas en suspensión se eleva exponencialmente con el aumento del número de cerdos que comparten el mismo espacio 23 . Dado que las partículas en suspensión pueden llevar agentes infecciosos, la probabilidad de transmisión por el aire de patógenos entre los cerdos infectados y susceptibles aumenta en los galpones que albergan un gran número de cerdos 2 , que a su vez puede aumentar la propagación de la enfermedad por el contacto de los hocicos de los animales.…”