Beyond The Rodents: Lassa’s Human Cost

For many Nigerians, the dry season brings more than dusty winds and rising temperatures, it also heralds the return of Lassa fever. From rural villages to overcrowded towns, the disease continues to spread through contaminated food, leaving families and health workers grappling with its deadly consequences. PATIENCE IVIE IHEJIRIKA reports.

With the onset of the dry season each year comes the resurgence of a familiar public health threat. Lassa fever, a rodent-borne viral disease, continues to claim lives, strain healthcare facilities, and reveal deep weaknesses in Nigeria’s disease surveillance and prevention systems.

First identified in 1969 in the town of Lassa in Borno State, the disease continues to pose a significant public health challenge in Nigeria. The country still battles seasonal outbreaks that typically peak between November and April, affecting communities across several states.

Lassa fever is an acute viral haemorrhagic illness caused by the Lassa virus, a member of the arenavirus family. The disease is endemic in parts of West Africa, including Nigeria, Sierra Leone, Liberia, Guinea, Benin, Ghana, Mali and Togo.

According to the World Health Organisation (WHO), the virus is primarily transmitted to humans through food or household items contaminated by the urine or faeces of infected Mastomys rats, commonly known as multimammate rats.  Human-to-human transmission can also occur through contact with bodily fluids such as blood, urine, or faeces, particularly in healthcare settings with weak infection control practices.

WHO said about 80 per cent of people infected with the virus show mild or no symptoms, which can include fever, weakness, sore throat, cough, and headaches. However, in roughly 20 per cent of cases, the illness becomes severe and potentially fatal.

The global health body further explained that patients with severe infections may experience persistent vomiting, diarrhoea, chest pain, abdominal pain, breathing difficulties, bleeding from the eyes, nose or mouth, confusion, and seizures.

In Nigeria, despite decades of response efforts, the country continues to record significant outbreaks each year, underscoring persistent challenges in prevention, early detection, and effective disease control.

The country has recorded hundreds of deaths from Lassa fever in recent years, with a handful of states consistently accounting for the majority of infections, according to epidemiological data.

Recent data from the Nigeria Centre for Disease Control and Prevention (NCDC) showed an increase in infections, with 82 confirmed cases and 20 deaths recorded between February 9th  and 15th (one week) this year.

The Nigeria Centre for Disease Control and Prevention (NCDC) said the figure represents an increase from the 74 cases recorded in the previous week, signalling sustained transmission across several high-burden states.

According to the epidemiological report, 84 per cent of all confirmed cases in 2026 have come from just four states: Bauchi 33 per cent,  Ondo  22 per cent,  Taraba 19 per cent  and Edo 10 per cent The remaining 16 per cent of cases were spread across 12 other states, including Ebonyi, the Federal Capital Territory (FCT), Kogi, Kebbi, Kaduna and Benue.

Cumulatively, as of February 15, 2026,  the country has recorded 75 deaths, representing a Case Fatality Rate (CFR) of 23 per cent, which is higher than the 19.7 per cent recorded during the same period in 2025.  In total, 14 states have reported at least one confirmed case across 58 local government areas this year.

LEADERSHIP Weekend recall that in 2025, Nigeria recorded 1,069 confirmed cases and 195 deaths as of week 49, representing a case fatality rate of 18.2 per cent, higher than the 16.5 per cent recorded during the same period in 2024.

In 2024, the country reported 1,309 confirmed cases out of 10,098 suspected infections, resulting in 214 deaths and CFR of 16.3 per cent, slightly lower than the 17.9 per cent recorded in 2023.

Data showed that Ondo State accounted for 31 per cent of the confirmed cases in 2024, followed by Edo State with 22 per cent and Bauchi State with 19 per cent. Together, the three states made up 72 per cent of infections, while the remaining 28 per cent were spread across 25 other states. In total, 28 states reported at least one confirmed case across 139 local government areas during the year.

In 2023, Nigeria recorded 1,270 confirmed cases from 9,155 suspected infections, with 227 deaths and a CFR of 17.9 per cent. During that year, Ondo State accounted for 34 per cent of confirmed cases, while Edo State contributed 27 per cent and Bauchi State 15 per cent, bringing the combined total of the three states to 76 per cent of national infections.

Similarly, in 2022, the country documented 1,055 confirmed cases out of 8,128 suspected infections, with 184 deaths and a CFR of 17.4 per cent. Again, Ondo State, Edo State and Bauchi State dominated the outbreak, accounting for 72 per cent of confirmed cases nationwide. One healthcare worker was infected during that year.

Earlier in 2021, Nigeria recorded 510 confirmed cases from 4,654 suspected infections and 102 deaths, with a higher CFR of 20 per cent. Edo State had the highest share of cases at 42 per cent, followed by Ondo State with 34 per cent and Bauchi State with eight per cent.

Public health advocates said that the recurring concentration of cases in these states highlights persistent environmental and public health challenges that continue to drive the spread of the disease in affected communities.

Public health expert, Dr. Ozy Okonokhua explained that rodent infestations remain a major driver of outbreaks.

“Rodents, the primary carriers of Lassa fever, thrive in dirty and unhygienic environments. Maintaining clean surroundings and properly covering food are essential steps in breaking the chain of transmission,” he said.

Many rural communities, where the disease often hits hardest, store grains and food items in ways that leave them exposed to rodents.

“Many rural residents dry their grains in the open, leaving them exposed to rodent contamination. Without practical alternatives for food preservation, awareness alone will not suffice,” Okonokhua added.

He also expressed concern that most public awareness campaigns are concentrated in urban areas, leaving rural populations who are often at higher risk poorly informed.

Meanwhile, the Director-General of NCDC, Dr. Jide Idris, has urged Nigerians to adopt preventive measures such as blocking holes that allow rodents into homes, storing food in sealed containers, and disposing waste properly.

“Cover your waste bins and dispose of waste properly. Safely store food items such as rice, garri, beans, and maize in well-covered containers. Communities should also set up dump sites far from residential areas to reduce rodent infestations,” he advised.

However, one of the major challenges in controlling Lassa fever is the difficulty in diagnosing it early. The disease shares many symptoms with other common illnesses such as malaria, typhoid fever, and yellow fever, making clinical detection difficult without laboratory confirmation.

Delayed diagnosis often leads to late treatment, which significantly increases the risk of death. Infectious disease specialists said the antiviral drug Ribavirin can improve survival chances when administered early in the course of the illness, but its effectiveness declines sharply once the disease progresses.

While prevention remains the primary strategy, researchers are also working to develop long-term solutions, including vaccines.

The Institute of Human Virology Nigeria (IHVN) has intensified research on Lassa fever and other viral threats through its International Research Centre of Excellence.

According to the institute’s Executive Director, Prof. Alash’le Abimiku, scientists are collaborating with international partners to test candidate vaccines that could eventually protect populations in endemic regions.

“Lassa virus remains problematic for Nigeria. We are currently working with partners on the potential testing of candidate vaccines, with the hope that in a few years we can identify a vaccine that is effective against Lassa,” she said.

Nigeria is also participating in global studies supported by the Coalition for Epidemic Preparedness Innovations (CEPI), which aims to accelerate vaccine development for emerging infectious diseases.

Despite ongoing interventions by health authorities, Nigeria’s battle against Lassa fever seem far from over.

For millions of Nigerians living in vulnerable communities, the fight against Lassa fever is not just a seasonal concern. It is a reminder that without stronger health systems, improved sanitation, and greater public awareness, a preventable disease can continue to claim lives year after year.