Swine flu refers to a type of influenza virus that primarily circulates among pig populations. While adapted to pigs, these viruses can occasionally cross the species barrier and infect humans. Understanding these viruses is important for public health, as some strains can cause illness.
What Swine Flu Is
Swine flu is caused by influenza A viruses, known for their ability to infect various animal species. Specific subtypes like H1N1, H1N2, H3N1, H3N2, and H2N3, are endemic in pigs worldwide. These viruses are zoonotic, meaning they originate in animals and can be transmitted to humans. Transmission from pigs to humans is generally rare and does not always lead to human illness.
A notable example of a swine-origin influenza A virus impacting humans was the 2009 H1N1 pandemic. This strain was a novel reassortant virus, containing genetic segments from swine, avian, and human influenza viruses. The World Health Organization (WHO) declared it a pandemic in 2009, leading to an estimated 284,400 deaths globally before it was declared over in August 2010. The H1N1 strain from this pandemic subsequently became one of the strains that cause seasonal flu in humans.
Swine Flu’s Presence in 2024
As of 2024, human cases of swine-origin influenza viruses continue to be monitored by public health organizations. These cases are generally sporadic and localized, rather than widespread outbreaks. For example, in February 2024, two human cases of swine-origin influenza A(H1N1)v were reported worldwide, one each from Brazil and Spain.
In March 2024, the United States reported its first human infection of the year with an influenza A(H1N2) variant (v) virus in a child from Pennsylvania who had direct contact with pigs. This case resulted in hospitalization, and the patient has since recovered. Public health investigations did not identify person-to-person transmission. Overall, since 2005, there have been 48 human cases of A(H1N1)v and 52 human cases of A(H1N2)v reported globally.
Protecting Against Swine Flu
The symptoms of swine flu in humans are often similar to seasonal influenza. These include fever, cough, sore throat, body aches, headache, chills, tiredness, and weakness. Some individuals may also experience diarrhea or vomiting, which is more common in children. Symptoms typically appear three to five days after exposure to the virus.
Swine flu viruses, like other influenza viruses, transmit primarily through respiratory droplets released when an infected person coughs, sneezes, breathes, or talks. The virus can also enter the body if a person touches a contaminated surface and then touches their eyes, nose, or mouth. To prevent the spread of swine flu, good hygiene practices are recommended. This includes frequent handwashing with soap and water for at least 20 seconds, or using an alcohol-based hand sanitizer with at least 60% alcohol when soap and water are unavailable. Individuals should also cover coughs and sneezes with a tissue or their elbow, avoid touching their face, and clean and disinfect frequently touched surfaces regularly.
If experiencing flu-like symptoms, stay home to avoid close contact with others. If medical care is needed, contact a healthcare provider by phone before visiting a clinic or hospital. For those at higher risk of complications or experiencing emergency symptoms like trouble breathing, chest pain, or ongoing dizziness, immediate medical attention is necessary.