Ugochukwu Timothy Eze emphazies the imperative for Nigeria to develop a vaccine for Lassa fever as soon as possible
Lassa fever is among the group of diseases called the viral haemorrhagic fevers because they are caused by viruses and produce fever and bleeding (especially in the late stage) in persons infected. It was first identified in Nigeria in Lassa Town, Borno State among missionary nurses working in a mission hospital in the town. Since then, Nigeria has experienced several outbreaks of Lassa Fever which usually occur only during the dry seasons between November and March. However, in the recent past, that seasonal pattern has changed as we now have all year round transmission with peaks during the dry season.
Also, earlier outbreaks in Nigeria were confined to the North-Central Nigeria with sporadic cases reported in other regions of Nigeria. But in the mid 90s, Edo State began to witness major outbreaks of Lassa Fever and has since become the major hotbed of Lassa Fever in Nigeria. Currently, Edo, Ondo and Ebonyi States are the three leading states in terms of annual number of cases of Lassa Fever recorded in Nigeria. Another important trend to note is the increasing number of cases of Lassa recorded in each successive year since 2016. In fact, in 2018, Nigeria witnessed what was called then the largest outbreak of Lassa Fever in the world in terms of the number of cases, deaths and the states involved. However, the 2019 outbreak surpassed that of the preceding year.
The epidemiologists were asking why the large outbreaks were occurring. Could it be that new strains of the virus were driving the large outbreaks or what has changed about the environment or the hosts of the virus? A gene sequencing study of the virus published in 2019 provided insights. It showed that nothing has changed about the virus; the same strains driving the outbreaks in 2018 were the same strains that have caused the outbreaks in the past. It also showed that majority of the cases resulted from rodent to human transmissions with a few human to human transmissions. Therefore, majority of the Lassa Fever transmissions occur within the communities.
Since the virus has not changed, why are we witnessing an increasing number of cases and geographical spread over the past four years? The Director General of the Nigeria Centre for Disease Control (NCDC) gave likely reasons for the observed trend saying that they have become victims of their own success. The NCDC under his leadership has invested so much in strengthening capacity for the detection of diseases of public health importance across the country. Also, it has supported the increase in the number of laboratories for the diagnosis of Lassa Fever across different states in Nigeria. Furthermore, it has supported the increase in the number of designated treatment centres for Lassa fever to three. The NCDC has also supported states to increase the awareness of Lassa Fever and where people can seek help when Lassa Fever is suspected. All these Lassa fever related investments may have led to increased awareness of Lassa Fever and the increased reporting of Lassa Fever over these years. It was worthy to note that though the number of cases have been showing upward trend, the number of deaths due to the disease have been on steady decline.
In 2020, we are witnessing another spike in the number of cases of Lassa Fever and the number of states involved. Nigerians are worried if the agencies responsible for preventing and controlling such outbreaks are doing enough in the face of the rising cases. It is worthy to note that in 2015, Nigeria has only one treatment and diagnostic centre for Lassa situated in Irrhua, in Edo State. But through the leadership provided by the NCDC we currently have three designated treatment centres for Lassa Fever and five laboratory networks for diagnosis of Lassa Fever. Also, many teaching hospitals, federal medical centres and state specialist hospitals have been supported by NCDC to receive specialised training in Lassa fever care and have also established their own dedicated units for the treatment of Lassa fever.
Subsequently, the death rate from Lassa fever has been on steady decline. However, most people are concerned with the upward trend in the number of cases each consecutive year since 2016. But the right question to ask will be what factors are driving the rodent to human transmission at the community level? These factors may not be entirely known for now, however, many scientific evidence have shown a link between certain practices within communities and the disease. They include agricultural practices such as bush burning, processing and drying of food substances in the open where rodents get easy access to them: nutritional practices such as consumption of rodents as protein source and poor environmental health practices such as poor housing, poor storage of food items, poor cooking of foods and poor environmental sanitation.
Risk communication messages prioritizing communities mainly affected by Lassa Fever have been carried out severally. It targets the earlier mentioned practices and trying to show people the link between them and Lassa Fever. However, some of these practices are rooted in the nutritional and economic survival of these communities as an agrarian economy. No matter the number of messages being shared, as long as it has to do with nutritional and economic survival, it may be difficult to change these practices.
Preventing Lassa Fever outbreaks will require providing very affordable alternatives to open air drying of food substances; alternative sources of protein for some local communities who depend on rodents for their proteins; good housing that will limit access of rodents to the houses and very affordable rodent proof food storage containers. Until we provide these alternatives which are beyond the health system, we may continue to witness increasing outbreaks of Lassa Fever in Nigeria unless a vaccine for Lassa fever is developed as soon as possible.
There are no easy solutions; it will require multiple approaches and multiple stakeholders working together. Governments at the state and local levels of the communities mostly affected by Lassa fever may need to involve the services of agricultural extension workers. These extension workers will have to engage community members to find alternatives to some nutritional and agricultural practices linked with Lassa fever. Rural electrification cannot be overemphasised; availability of electric energy may spur innovations within communities and provide alternatives to sun drying of food substances. Governments at local levels need to support farmers through subsidies including the clearing of their farmlands to discourage bush burning. Legislation against bush burning may be considered.
*Eze writes from the Department of Community Health,
Lagos University Teaching Hospital