In 2025, Nigeria confronted multiple disease outbreaks, exposing persistent weaknesses in infectious-disease control, immunisation uptake, sanitation, and health surveillance.
A mix of viral and bacterial diseases continued to threaten lives across several states throughout the year.
Health authorities battled emerging threats while struggling to contain long-standing endemic infections.
Lassa fever
Lassa fever, a viral haemorrhagic infection, remained one of the deadliest outbreaks in Nigeria in 2025.
According to the Nigeria Centre for Disease Control and Prevention, as of December 7, 2025, the country recorded 1,069 confirmed cases across 21 states with 195 deaths.
This gave a case fatality rate of about 18.2 per cent, which was significantly higher than previous years.
Ondo, Edo, Bauchi, and Taraba were among the worst-hit states as surveillance efforts tracked spread across several local government areas.
The outbreak again highlighted Lassa fever’s endemic nature, driven by rodent exposure and challenges with early diagnosis and treatment.
Diphtheria
Nigeria continued to record the highest number of diphtheria cases in the African region, and 2025 followed the same trend.
The World Health Organisation stated that from January to November 2, more than 12,150 suspected cases and 8,587 confirmed cases led to 884 deaths.
Confirmed infections were recorded in 30 states and 240 local government areas, with children and adolescents the most affected, especially in poorly immunised communities.
Authorities rolled out reactive vaccination in priority states such as Imo, Kaduna, and Lagos, although gaps in information and vaccine availability persisted.
Mpox
Despite a decline in global attention after the 2022 outbreak, Nigeria still recorded mpox transmission in 2025.
WHO data showed that as of October 18, 2025, the country had reported 389 confirmed cases and six deaths across 35 states and the Federal Capital Territory.
Although fatalities were lower than those recorded for diphtheria and Lassa fever, continued spread reinforced the need for stronger community awareness.
Cholera
Cholera, a water-borne diarrhoeal illness, also remained a significant concern in 2025.
Between January and September 14, Nigeria recorded 10,353 suspected cases and 244 deaths across 37 states.
Children under five were the most affected, followed by those aged five to 14 years across both genders.
Widespread flooding, poor sanitation, and lack of access to clean water fuelled transmission in vulnerable communities.
The United Nations Children’s Fund noted that cholera remained endemic in Nigeria and that the country carried the second-highest burden in West and Central Africa.
Polio
Although wild poliovirus was declared eliminated in August 2020, Nigeria continued to record circulating vaccine-derived poliovirus type 2 cases in 2025.
These outbreaks arise when weakened vaccine virus mutates and spreads in under-immunised populations.
Dozens of cVDPV2 cases were reported across multiple states in 2025.
By October, 66 cases had been documented in 12 states, reflecting a gradual reduction compared with previous years and suggesting some improvement in vaccination and surveillance.
Why 2025 followed a recurring pattern
The World Health Organisation linked recurring outbreaks to weak routine immunisation, which left millions, particularly children, exposed to preventable illnesses such as diphtheria.
Late health-seeking behaviour and poor access to early diagnosis worsened outcomes for diseases like Lassa fever.
Poor water and sanitation infrastructure, combined with seasonal flooding, created ideal conditions for cholera outbreaks.
Overwhelmed health facilities, limited essential medicines, and weak surveillance further slowed early detection and timely response.
