Animal reservoir for swine influenza virus is?
**Core Concept**
The swine influenza virus is a zoonotic pathogen that primarily infects pigs, but can also be transmitted to humans. The virus is a subtype of the influenza A virus, which is characterized by its ability to infect multiple animal species, including pigs, birds, and humans.
**Why the Correct Answer is Right**
The correct answer is a pig, as pigs are the primary animal reservoir for the swine influenza virus. This is because pigs can be infected with both avian and human influenza viruses, allowing for the generation of new, reassorted viruses that can be transmitted to humans. The pig's respiratory tract is a suitable environment for the replication and transmission of the virus, making them an ideal host.
**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable.
**Option B:** While humans can be infected with swine influenza virus, they are not the primary reservoir.
**Option C:** Birds are not the primary reservoir for swine influenza virus, although they can be infected with avian influenza viruses that can be transmitted to pigs.
**Clinical Pearl / High-Yield Fact**
Pigs are considered an "influenza mixing vessel" due to their ability to be infected with multiple influenza viruses, leading to the generation of new, reassorted viruses that can be transmitted to humans.
**Correct Answer: C. Pigs.**