Swine Influenza (SI)

Swine influenza (SI) is a respiratory ailment attributed to the swine influenza virus (SIV) and has yielded pronounced economic repercussions within the U.S. swine industry. Incidences of SI outbreaks are prevalent among pig populations, particularly in the winter season. SIV is responsible for inducing elevated morbidity rates within pig herds and sporadically traverses the species boundary to infect humans. Notably, in recent times, heightened consideration has been directed toward SI due to its capacity to precipitate both epidemics and pandemics.

Fig.1 Influenza A virus replication cycle.^1,2

Etiology

Swine influenza viruses (SIVs) belong to the Orthomyxoviridae family and the genus Influenzavirus A. SIVs are further classified into different subtypes based on the combination of their surface proteins: hemagglutinin (H) and neuraminidase (N). The most common subtypes in U.S. swine herds are H1N1, H3N2, and H1N2.

Cause and Effect

Swine influenza is spread primarily through close contact between pigs, but may also come from contaminated objects moving between infected and uninfected pigs. Pigs vaccinated against swine flu have also had sporadic cases. Co-infection with other pathogens further complicates the outbreak and may increase the severity of respiratory disease in swine.

Can Humans Get SI?

Swine flu viruses do not usually infect humans. However, there have been sporadic cases of human infection with swine influenza. Some cases are common among people who have had direct contact with pigs. An apparent swine flu outbreak in a Wisconsin hog herd in 1988 resulted in multiple human infections, although no community outbreak resulted, there was antibody evidence of the virus spread from patients to healthcare workers who had close contact with the patients. In 2009, a pig-derived H1N1 strain spread across the globe. It infects humans, pigs, poultry, and a small number of dogs, cats, and other animals.

Fig.2 Hosts and transmission routes of influenza A virus.^3.4

Signs and Symptoms of SI

Swine flu is mainly manifested as a respiratory disease in pigs. Clinical symptoms may vary in severity but typically include,

Severe cases can develop into pneumonia and even death. The clinical presentation of SI may resemble other respiratory disorders, so laboratory diagnosis is critical for accurate identification.

Diagnosis of SI

SI be diagnosed by clinical symptom discrimination, direct virus isolation, hemagglutination inhibition test, RT-PCR, ELISA, and other methods. Laboratory diagnosis plays a crucial role in confirming the diagnosis of SI cases and distinguishing them from other respiratory diseases.

BioVenic develops a variety of diagnostics for customers, including immunodiagnostics and molecular diagnostics to detect SIV or antibodies against SIV. These techniques allow the detection and identification of specific SIV subtypes involved in infection.

Treatment

There is currently no specific antiviral treatment for porcine SI. The treatment of bacterial secondary infection and fever in pigs can be accomplished with antibacterial agents and antipyretics based on clinical symptoms. Supportive care, including proper nutrition, hydration, and control of secondary bacterial infections, is crucial for managing affected animals. BioVenic provides appropriate supportive therapy solutions to alleviate clinical signs and reduce the impact of the disease.

Prevention and Control

• Vaccination of pig herds.
• Take good biosecurity practices.
• Promoting good hygiene practices among workers.
• Use proper ventilation.
• Surveillance and monitoring of new strains or recombinants of SIV.

Prevention and control strategies are critical to managing SI in pigs and reducing the risk of transmission to humans, and BioVenic develops effective control strategies for specific farm conditions. BioVenic can develop vaccines targeting specific subtypes of SIV to reduce the severity of the disease and limit its spread through vaccination. In addition to vaccination, strict biosecurity protocols should be implemented. These measures include controlled access to pig farms, proper hygiene practices, and the use of disinfectants.

Swine flu represents a significant challenge affecting both the swine industry and public health at large. As a pioneering veterinary diagnostics solution, BioVenic is committed to assisting the swine industry in effectively addressing swine influenza. Our comprehensive diagnostics methods and effective vaccine development services for the prevention and control of swine flu. If you're interested in forging a partnership with us, we invite you to initiate contact without hesitation.

References

1. Nuwarda, Rina Fajri, Abdulsalam Abdullah Alharbi, and Veysel Kayser. "An overview of influenza viruses and vaccines." Vaccines 9.9 (2021): 1032.
2. Image retrieved from Figure 2 "The life cycle of influenza A virus." Nuwarda, Rina Fajri, 2021, used under [CC BY 4.0] (https://creativecommons.org/licenses/by/4.0/), the image title was changed to "Influenza A virus replication cycle."
3. Lee, Chung-Young. "Exploring Potential Intermediates in the Cross-Species Transmission of Influenza A Virus to Humans." Viruses 16.7 (2024): 1129.
4. Image retrieved from Figure 1 "Cross-species transmission of influenza A virus."Lee, Chung-Young, 2024, used under [CC BY 4.0], the image title was changed to "Hosts and transmission routes of influenza A virus."