Calicivirus is a group of viruses that can infect various animals, including humans. In humans, it is most commonly associated with the Norovirus, which causes gastroenteritis, leading to symptoms like vomiting and diarrhea. Caliciviruses are small, non-enveloped viruses that can spread easily, especially in crowded environments. In animals, caliciviruses can affect species such as cats, where the Feline Calicivirus can cause respiratory infections. These viruses are resilient and can survive on surfaces for extended periods, making hygiene important in preventing outbreaks. Vaccines are available for some animal calicivirus infections, but no specific treatment exists for human cases.