Cytomegalovirus (CMV) is a common and symptomless herpes virus that can cause serious harm to newborn babies and people with impaired immune systems like organ transplant and HIV patients, said experts here on Saturday. 

CMV belongs to the herpes virus family and can infect people of all ages. It spreads through body fluids and usually remains dormant, causing no symptoms or a mild illness characterised by fever, sore throat, fatigue or swollen glands.