Prevalence and outcome of Lassa fever among hospitalized patients in Ebonyi State, Nigeria, 2018-2019

Predictors of Lassa fever diagnosis in suspected cases reporting to health facilities in Nigeria

Lassa fever (LF) remains endemic in Nigeria with the country reporting the highest incidence and mortality globally. Recent national data suggests increasing incidence and expanding geographic spread. Predictors of LF case positivity in Nigeria have been sparsely studied. We thus sought to determine the sociodemographic and clinical determinants of LF positivity amongst suspected cases presenting to health facilities from 2018 to 2021. A secondary analysis of the national LF surveillance data between January 2018 and December 2021. Socio-demographic and clinical data of 20,027 suspected LF cases were analysed using frequencies and Chi-square statistics with significant p-value set at p < 0.05. The outcome variable was LF case status (positive or negative). Predictors of LF case positivity were assessed using multiple logistic regression models with 95% confidence intervals (CI). Case positivity rate (CPR) for the four years was 15.8% with higher odds of positivity among age group 40-49 years (aOR = 1.40; 95% CI 1.21-1.62), males (aOR = 1.11; 95% CI 1.03-1.20), those with formal education (aOR = 1.33; 95% CI 1.13-1.56), artisans (aOR = 1.70; 95% CI 1.28-2.27), religious leaders (aOR = 1.62; 95% CI 1.04-2.52), farmers (aOR = 1.48; 95% CI 1.21-1.81), and symptomatic individuals (aOR = 2.36; 95% CI 2.09-2.68). Being a health worker (aOR = 0.69; 95% CI 0.53-0.91), a teacher (aOR = 0.69; 95% CI 0.53-0.89) and cases reporting in the 3rd quarter (aOR = 0.79; 95% CI 0.69-0.92) had lower odds. In a sex-disaggregated analysis, female farmers had higher odds of positivity (aOR = 2.43; 95% CI 1.76-3.38; p < 0.001) than male farmers (aOR = 1.52; 95% CI 1.19-1.96; p < 0.01). Fever (aOR = 2.39; 95% CI 2.00-2.84) and gastrointestinal (GI) symptoms (aOR = 2.15; 95% CI 1.94-2.37) had the highest odds among symptoms. Combination of fever and GI symptoms (aOR = 2.15; 95% CI 1.50-3.10), fever and neurological symptoms (aOR = 6.37; 95% CI 1.49-27.16), fever and musculo-skeletal symptoms (aOR = 2.95; 95% CI 1.37-6.33), fever and cardiopulmonary symptoms (aOR = 1.81; 95% CI 1.24-2.64), and cardiopulmonary and general symptoms (aOR = 1.50; 95% CI 1.19-1.89) were also predictive. Cumulative LF CPR appears high with clearly identified predictors. Targeted interventions with heightened index of suspicion for sociodemographic categories predictive of LF in suspected cases are recommended. Ethnographic and further epidemiological studies could aid better understanding of these associations.

Contemporary and emerging pharmacotherapeutic agents for the treatment of Lassa viral haemorrhagic fever disease

This review was designed to discuss the emerging and current pharmacotherapeutic agents for the treatment of Lassa viral haemorrhagic fever disease (LVHFD), also known as Lassa fever (LF). Original peer-reviewed articles that investigated LF were identified using the Medline Entrez-PubMed search. Information was also sourced from printed textbooks and reports by recognized health professional bodies such as the WHO, CDC, the Nigerian Federal Ministry of Health and the United Nations Children's Fund (UNICEF). A total of 103 articles were reviewed and 78 were found to contain information relevant to the study. LF remains an endemic disease of public health concern in the West Africa region, and in the rest of the world as cases have been imported into non-endemic regions as well. Currently, there are no approved vaccines or therapeutics for the treatment of Lassa mammarenavirus (LASV) infection. There are, however, off-label therapeutics being used (ribavirin and convalescent plasma) whose efficacy is suboptimal. Research is still ongoing on possible therapeutic options and drug repurposing of therapeutic agents currently in use for other clinical conditions. Considered therapeutic options include favipiravir, taribavirin, Arevirumab-3 and experimental drugs such as losmapimod, adamantyl diphenyl piperazine 3.3, Arbidol (umifenovir) and decanoyl-RRLL-chloromethyl ketone (dec-RRLL-CMK). Current treatments for LF are limited, hence the institution of mitigating measures to prevent infection is of utmost importance and should be prioritized, especially in endemic regions. Heightened searches for other therapeutic options with greater efficacy and lower toxicity are still ongoing, as well as for vaccines as the absence of these classifies the disease as a priority disease of high public health impact.

Pathology and Pathogenesis of Lassa Fever: Novel Immunohistochemical Findings in Fatal Cases and Clinico-pathologic Correlation

BACKGROUND

Lassa fever is a zoonotic, acute viral illness first identified in Nigeria in 1969. An estimate shows that the "at risk" seronegative population (in Sierra Leone, Guinea, and Nigeria) may be as high as 59 million, with an annual incidence of all illnesses of three million, and fatalities up to 67,000, demonstrating the serious impact of the disease on the region and global health.

METHODS

Histopathologic evaluation, immunohistochemical assay, and electron microscopic examination were performed on postmortem tissue samples from 12 confirmed Lassa fever cases.

RESULTS

Lassa fever virus antigens and viral particles were observed in multiple organ systems and cells, including cells in the mononuclear phagocytic system and other specialized cells where it had not been described previously.

CONCLUSIONS

The immunolocalization of Lassa fever virus antigens in fatal cases provides novel insightful information with clinical and pathogenetic implications. The extensive involvement of the mononuclear phagocytic system, including tissue macrophages and endothelial cells suggests participation of inflammatory mediators from this lineage with the resulting vascular dilatation and increasing permeability. Other findings indicate the pathogenesis of LF is multifactorial and additional studies are needed.

Early onset of neurological features differentiates two outbreaks of Lassa fever in Ebonyi state, Nigeria during 2017-2018

Lassa fever (LF) is an acute viral haemorrhagic illness with various non-specific clinical manifestations. Neurological symptoms are rare at the early stage of the disease, but may be seen in late stages, in severely ill patients.The aim of this study was to describe the epidemiological evolution, socio-demographic profiles, clinical characteristics, and outcomes of patients seen during two Lassa fever outbreaks in Ebonyi State, between December 2017 and December 2018. Routinely collected clinical data from all patients admitted to the Virology Centre of the hospital during the period were analysed retrospectively. Out of a total of 83 cases, 70(84.3%) were RT-PCR confirmed while 13 (15.7%) were probable cases. Sixty-nine (83.1%) patients were seen in outbreak 1 of whom 53.6% were urban residents, while 19%, 15%, and 10% were farmers, students and health workers respectively. There were 14 (16.8%) patients, seen in second outbreak with 92.9% rural residents. There were differences in clinical symptoms, signs and laboratory findings between the two outbreaks. The case fatality rates were 29.9% in outbreak 1 and 85.7% for outbreak 2. Neurological features and abnormal laboratory test results were associated with higher mortality rate, seen in outbreak 2. This study revealed significant differences between the two outbreaks. Of particular concern was the higher case fatality during the outbreak 2 which may be from a more virulent strain of the Lassa virus. This has important public health implications and further molecular studies are needed to better define its characteristics.