Abuja - Health officials in Nigeria have called for calm after dozens of suspected cases of monkeypox were reported in seven states across the south of the country.Thirty-one suspected cases of the viral disease have been identified since the first was reported in Bayelsa State on September 22, according to the Nigeria Centre for Disease Control (NCDC).States affected include Lagos, whose mega-city capital of about 20 million people is sub-Saharan Africa's largest.The national coordinator of the NCDC, Chikwe Ihekweazu, said in a statement on Monday that samples had been sent to laboratories and that so far no case had been confirmed.It is "unlikely" that many of the suspected cases are monkeypox, he added, but investigations are necessary."Nigerians are advised to remain calm, avoid self-medication and report any suspected case to the nearest health facility," he said. The NCDC has set up an emergency operation centre to help states control and limit any outbreak. Affected patients were all "improving" at medical facilities, Ihekweazu added.According to the World Health Organisation, monkeypox is a rare disease that occurs mainly in remote areas of central and west Africa near tropical rainforests.Symptoms are similar to those found in human smallpox patients but much less severe, and the disease has a low fatality rate.The symptoms include aches, body pain and fever as well as a bumpy localised rash on the skin.The WHO said the virus is transmitted from monkeys, African squirrels and other wild animals. Human-to-human transmission is also possible but the chances of catching it are slim.In September, at least 10 people in the Central African Republic died in a monkeypox outbreak. There have also been fatalities in the Democratic Republic of Congo.Nigeria has issued public health messages calling on people to wash hands frequently and avoid eating bushmeat.