Detection of clusters and geographical hotspots for Lassa fever in Edo Central Senatorial District of Nigeria: a step into a Nation-wide mapping of Lassa fever
Creators: name: Chiedozie Ike
name: Asogun, Danny
Publisher: name: F1000Research
Year: 2016

description: Lassa fever is a viral hemorrhagic fever and a neglected tropical disease which was first discovered in Nigeria in 1969. The disease occurs mainly in West Africa with a few imported cases into Europe. The first reported outbreak was in a village called Lassa located in the North Eastern part of Nigeria followed by a nosocomial outbreak in a mission hospital in Jos, Nigeria. This initial report was restricted to only two states in Northern Nigeria. Both empirical and anecdotal reports since 1969 of the outbreaks of Lassa fever in Nigeria has shown that the outbreaks of the disease is progressively spreading across States in Nigeria with several hundreds of casualties and some times with a case fatality of more than 50%. Edo Central Senatorial district in Edo State located in the South southern part of Nigeria has been reporting outbreaks of the disease for more than a decade and hospital-based data shows that more cases of the disease has been reported in Edo State more than other States in Nigeria since the initial outbreak.<br><br>Unfortunately, not much has been done to determine the nature of spread and location of the disease hotspot geographically. Although, the disease is treatable using an antiviral drug ribavarin and there are presently more than two reference laboratories for its diagnostics and research in Nigeria with funding for both treatment and research. Yet, Community control has not been effective due to poor funding for health promotion campaign and for community-directed interventions. In order to allocate funding for both effective and efficient community sero-prevalence studies, health promotion campaigns and community directed interventions, determination of the nature of disease spread and location of its hot-spots becomes critical. This study was aimed at providing the baseline spatial data for the nation-wide mapping of Lassa fever in Nigeria.<br><br>The geographical coordinates of 213 traceable locations of the outbreak from 2008-2013 in the Edo Central Senatorial District of Edo State was determined using a Garmin GPS device and  GIS analyses of distribution of the outbreak in the study area was done using an ArcGIS 10.2 software. Determination of Clusters and Hotspots of the disease were done using two advanced geostatistical tools: Anselin Local Morans and Gertis-ord-Gi<sup>*</sup> statsitics. The results were represented as cluster output tables, cluster and Hotspot maps. An IDW interpolation technique was done to predict the location of the hotspots earlier identified.<br> Statistically significant (<i>p&lt;0.05</i>) clusters and hotspots of the disease were identified in Ihumudumu (an urban community in Ekpoma, Esan West Local Government Area of Edo State); a densely populated area where a major Tertiary Institution is located. There were other clusters of the disease identified in Irrua (a peri-urban community in Esan Central Local Government Area of Edo State). The Public health action recommended sequel to the identification of these sites of clustering and hotspots for the disease is for both Institutional, Governmental and International research and control partners in the control of Lassa fever and other Viral Hemorrhagic fevers to further determine the risk factor for the disease and conduct a sero-prevalence study at those locations. Also, a Nation-wide determination of clusters and hotspots of Lassa fever based on the findings from this study and using the same methods is highly recommended, especially as outbreaks are still occurring nationally and at a time when resources for disease control at the national level are highly prioritized. Stake holders in those identified communities are to partner with the Government together with International partners to ensure that effective control of Lassa fever at those determined sites are achieved while at the same time  offering support in preventing further spread of the disease from their locations to other disease-free communities. Health campaigns against Lassa fever by the media, Local health and school authorities, traditional rulers, Community and Environmental health staff should be intensified within and outside affected communities and where fund is available, training in disease tracking, mapping and effective real time reporting of Lassa fever to appropriate authorities for immediate action should be carried out both at the Local Government areas and at the State Level.<br>