Cytomegalovirus (CMV) is a common virus that belongs to the herpes family of viruses.
It's spread through bodily fluids, such as saliva and urine, and can be passed on through close contact with young children, such as when changing nappies.
CMV can also be passed on through kissing, having sex, or receiving an infected organ during an organ transplant.
Most cases of CMV don't cause symptoms. If you do have symptoms, they're often similar to flu or glandular fever, and include a high temperature (fever), sore throat and swollen glands.