The case was recorded in the Ilesa East Local Government area of Osun State.
Osun State Government on Monday confirmed the first case of diphtheria disease in the state.
The case was recorded in the Ilesa East Local Government area of the state.
A middle-aged man whose identity could not be ascertained was discovered to have contracted the disease and is currently isolated at an undisclosed hospital.
The Nigeria Centre for Disease Control (NCDC) had earlier said it was monitoring the situation of diphtheria in Yobe and Osun States where it was picked up.
Olawale Rasheed, spokesperson to the state governor, confirmed the presence of the diphtheria disease in the state.
Mr Rasheed said the victim had been isolated and placed on treatment.
The governor's spokesperson said the government had also begun contract tracing and searching for others who might have been infected with the disease in other locations across the state.
He said the state government has also begun sensitisation programmes for residents on how to prevent the disease.
"What the state is doing to curtail the spread of Diphtheria in Osun State is community active case search and community sensitisation during the active case search, retroactive case search in health facilities in the affected LGA, contact tracing and follow up of the index case."
The governor's spokesperson added that the government was training health workers on how to treat diphtheria disease, distributing preventive materials to hospitals and sensitising residents of the state through radio jingles and other programmes.
He said the government was also carrying out: "Production and distribution of IEC materials. Training of Health workers on case definitions and Infection Prevention and Control of Diphtheria. Production and airing of jingle on prevention and Training of Health workers on sample collection of Diphtheria," he added.
Mr Rasheed advised parents to ensure their children are fully vaccinated.
"Diphtheria is a vaccine-preventable disease therefore, all parents and guidance to ensure their wards are fully vaccinated," he advised.
"Once anyone starts coughing or has a sore throat, consult your physician. There is nothing like an ordinary or normal cough. Eat fruits and Vegetables and stay hydrated. Avoid crowded environments and if it's necessary let us make use of our face masks."