From Fred Ezeh, Abuja
Dry season, the season of Lassa fever is here again, hence the need to reawaken the consciousness of the Federal Ministry of Health and its partners to their responsibilities of securing public health.
Nigeria is endemic to some diseases, notably, malaria, measles, cholera, yellow fever and Lassa fever. Majority of these diseases come with seasons and weather changes. This is not the case with COVID-19 pandemic. It took the world by surprise, crippling socio-economic activities, bringing down sophisticated health care system of developed countries.
In Nigeria, dry seasons are synonymous with Lassa fever. Many are infected including health care givers, with huge deaths annually. Lassa fever is an acute viral haemorrhagic illness caused by Lassa virus, a member of the arena virus family. The annual peak of human cases is usually observed during the dry season (December–April) following the reproduction cycle of the mastromy rats in the wet season (May–June).
Mode of transmission
Humans usually get infected with Lassa virus through exposure to food or household items contaminated with urine or faeces of infected mastomys (carrier rats). Evidently, the disease is endemic in the rodent population in parts of West Africa.
Lassa fever, aside Nigeria, is also endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, Togo and some other West African countries. Person-to-person infections and laboratory transmission can also occur, particularly in health care settings, in the absence of adequate infection prevention and control measures.
To this end, there is need for prompt diagnosis and treatment, which is essential for quick recovery. Medical records confirmed that overall case-fatality rate is one per cent. Nonetheless, among patients who are hospitalised with severe clinical presentation of Lassa fever, case-fatality is estimated at around 15 per cent, while early supportive care with rehydration and symptomatic treatment improves survival.
Surprisingly, about 80 per cent of people who become infected with Lassa virus display no known symptoms, thus aiding community transmission of the virus. However, one in five infections results in severe disease, particularly when the virus has affected several vital organs such as the liver, spleen and kidneys.
Previous experience
Epidemiology report for the 51st week of 2020 (December 14 to 20) as released by the Nigeria Centre for Disease Control (NCDC) indicated that number of new confirmed Lassa fever cases increased from five in week 50, 2020 to 12 cases in week 51. The cases were reported from Edo and Ondo states.
Cumulatively in 2020 (from week one to 51), the epidemiology report revealed that there were 6,668 suspected cases of Lassa fever, out of which 1,175 cases were confirmed with 242 deaths. Three states, Ondo, Edo and Ebonyi, account for the high number of deaths with 81,40 and 23 deaths, respectively.
In total for 2020, 27 states recorded at least one confirmed case of Lassa Fever across 130 Local Government Areas (LGAs). Of all confirmed cases, Ondo state had 36 per cent, Edo 32 per cent and Ebonyi states seven per cent, even as number of suspected cases significantly increased compared to reported cases for the same period in 2019.
Similarly, factsheet from the World Health Organization (WHO) revealed that 15 confirmed cases were reported among health care workers with one death among a confirmed case and one among a probable case.
However, there are fears that confirmed cases and casualties may rise due to the devastating effect of COVID-19, which has greatly taken the attention of the public health officials.
Risk assessment
WHO in its risk assessment maintained that Lassa fever is a viral haemorrhagic fever that could be transmitted to humans via contact with food or household items contaminated with rodent’s urine or faeces, while secondary human-to-human transmission could also occur through direct contact with the blood, secretions, organs or other body fluids of infected persons, especially in health care settings.
The organisation disclosed that about 80 per cent of persons infected with the Lassa virus are, most often, asymptomatic. But the illness manifests as a febrile illness of variable severity associated with multiple organ dysfunctions with or without hemorrhage in the remaining 20 per cent. WHO added that the overall regional and global risk is considered low due to minimal number of suspected cross-border transmission from Nigeria to neighbouring countries.
It admitted that Nigeria has developed capacity for managing Lassa fever outbreaks over time, but the current overall risk is considered moderate at national level, while capacities at sub-national levels remain suboptimal. It suggested that country’s capacity to detect and respond to Lassa fever outbreaks should be improved especially in areas of surveillance, laboratory, case management and coordination, as well as infection prevention and control.
National response
The NCDC is statutorily responsible for response against epidemics or other public health concerns alongside its partners. But there are fears that it might be overwhelmed because of the devastating effects of COVID-19 on manpower and the health care system.
In past years, NCDC responded to Lassa fever outbreaks through the activation of a National Emergency Operations Centre (NEOC) with an inter-disciplinary, multi-partner technical team to ensure a well-coordinated response and swift control of Lassa fever outbreaks in affected states. Confirmed cases were referred to designated treatment centres in the affected states following optimised standard of care protocols.
NCDC in its previous epidemiology reports confirmed that National Lassa fever multi-partner, multi-sectoral Technical Working Group (TWG), strongly engaged in the coordination of the response activities at all levels. It also confirmed a strong cross border collaboration with Benin Republic as regards the newly reported Lassa fever cases, as well as the implementation of targeted risk communication activities in most affected states
It, however, planned to continue community mobilisation of resources and manpower, in response to the fever, as well as the finalisation of Lassa fever five-year strategic plan. A senior NCDC officer who pleaded anonymity confirmed that guidelines for appropriate case management and infection prevention and control measures for 2020/2021 season have been disseminated to the different states, while surveillance activities have been enhanced in the affected states with enhanced active case finding in most endemic LGAs.
She added that an updated tool for detailed case investigation has also been provided and handed over to the investigation teams to ensure all relevant information is recorded. She equally confirmed that laboratories with capacity to test for Lassa fever infection in serum samples are currently operational across the country.
She charged health care workers to maintain a high index of suspicion for Lassa fever suspected cases and take adequate infection prevention and control measures during management of all patients in health care facilities.
NCDC also requested that states prioritise the resuscitation and training of Epidemic Preparedness and Response (EPR) Committee and Rapid Response Teams (RRT), intensify risk communication activities by airing radio jingles and other public awareness measures, and allocate a dedicated budget line for disease surveillance.
It asked states to designate isolation/treatment centres for clinical management of infectious disease cases, procure and preposition response commodities and medicines, as well as establish/strengthen state funded robust sample transporting system health facilities
NCDC directed that states intensify surveillance activities including active case search and contact tracing, provide comprehensive aftercare services for survivors and activate Emergency Operation Centres (EOCs) based on the protocol to declare an emergency
It urged state governments to fully support their respective epidemiology units and maximise the investments on the COVID-19 response to implement the activities. This, it said, is especially important to reduce the risk of spread of cases.
NCDC urged members of the public to take preventive measures to prevent Lassa fever disease including regular hand washing with soap and water, proper storage of food, ensuring clean environment to prevent breeding of rats among others.
WHO, expert’s advice
Just like COVID-19 and other epidemics, prevention of Lassa fever relies on promoting good hygiene to deny rodents’ access to homes. There are also effective measures that include storing grains and other foodstuffs in rodent-proof containers, disposing of garbage far from homes, maintaining clean households, among others.
Mastomys, an African genus of rodents are so abundant in endemic areas, hence the difficulty in completely eliminating them from the environment. Nevertheless, people should always be careful to avoid contact with blood and body fluids while caring for sick persons.
WHO suggested that in health-care settings, staff should always apply standard infection prevention and control precautions when caring for patients, regardless of their presumed diagnosis. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment to block splashes or other contact with infected materials and safe injection practices.
Health-care workers caring for patients with suspected or confirmed Lassa fever should strictly apply extra infection control measures to prevent contact with the patient’s blood, body fluids and contaminated surfaces or materials such as clothing and bedding.
When in close contact, within one metre, of patients with Lassa fever, health care workers should wear face protection, which could be a face shield or a medical mask and goggles, a clean, non-sterile long-sleeved gown, and sterile gloves for some procedures.