Mpox (Monkeypox Virus) For the latest information and guidance on Mpox, click here. Mpox is a rare, but potentially serious, viral illness which belongs to the orthopoxvirus family. Infection typically begins with flu-like symptoms and swelling of the lymph nodes and progresses to a rash on the face and body. A United States case involving a Massachusetts resident was reported on May 18, 2022. Since that time, every state, including Rhode Island, has also reported cases to CDC.