Lagos, Jan 21 : Nigerian health authorities have issued an alert on the outbreak of diphtheria, a severe bacterial infection, in the country after some cases were reported in a few states. Ifedayo Adetifa, Director-General of the Nigeria Centre for Disease Control and Prevention (NCDC), said on Friday in a statement that the health agency has responded to reports of diphtheria cases in the southwestern state of Lagos and the northwestern state of Kano, and is monitoring the situation in Osun and Yobe states, where cases are now being picked up. Adetifa did not mention the total cases of diphtheria that have so far been reported in the four states, saying that in Kano alone, there have been 78 suspected cases of the highly contagious bacterial infection in 14 local government areas of the state. He added in addition to clinically suspected cases, there have been laboratory-confirmed cases, and the NCDC is working with state health authorities and other partners to improve surveillance and response to the outbreak in the affected states, Xinhua news agency reported. The NCDC Chief said people most at risk of contracting diphtheria are children and adults who have not received the pentavalent vaccine, people who live in a crowded environment, areas with poor sanitation, and healthcare workers, among others. Diphtheria is a serious bacterial infection caused by the Corynebacterium species bacterium that affects a person's nose, throat, and sometimes skin. The symptoms of diphtheria include fever, runny nose, sore throat, cough, red eyes and neck swelling; in severe cases, a thick grey or white patch appears on the tonsils and/or at the back of the throat, which is associated with difficulty breathing, the statement said. The NCDC also advised healthcare workers to maintain a high index of suspicion for diphtheria and advised individuals with signs and symptoms suggestive of diphtheria to isolate themselves and notify the state disease surveillance officers. /IANS