Health seeking behavior after the 2013–16 Ebola epidemic: Lassa fever as a metric of persistent changes in Kenema District,Sierra Leone

BackgroundThe West African Ebola epidemic of 2013–2016 killed nearly 4,000 Sierra Leoneans and devastated health infrastructure across West Africa. Changes in health seeking behavior (HSB) during the outbreak resulted in dramatic underreporting and substantial declines in hospital presentations to public health facilities, resulting in an estimated tens of thousands of additional maternal, infant, and adult deaths per year. Sierra Leone’s Kenema District, a major Ebola hotspot, is also endemic for Lassa fever (LF), another often-fatal hemorrhagic disease. Here we assess the impact of the West African Ebola epidemic on health seeking behaviors with respect to presentations to the Kenema Government Hospital (KGH) Lassa Ward, which serves as the primary health care referral center for suspected Lassa fever cases in the Eastern Province of Sierra Leone.Methodology/Principal findingsPresentation frequencies for suspected Lassa fever presenting to KGH or one of its referral centers from 2011–2019 were analyzed to consider the potential impact of the West African Ebola epidemic on presentation patterns. There was a significant decline in suspected LF cases presenting to KGH following the epidemic, and a lower percentage of subjects were admitted to the KGH Lassa Ward following the epidemic. To assess general HSB, a questionnaire was developed and administered to 200 residents from 8 villages in Kenema District. Among 194 completed interviews, 151 (78%) of respondents stated they felt hospitals were safer post-epidemic with no significant differences noted among subjects according to religious background, age, gender, or education. However, 37 (19%) subjects reported decreased attendance at hospitals since the epidemic, which suggests that trust in the healthcare system has not fully rebounded. Cost was identified as a major deterrent to seeking healthcare.Conclusions/SignificanceAnalysis of patient demographic data suggests that fewer individuals sought care for Lassa fever and other febrile illnesses in Kenema District after the West African Ebola epidemic. Re-establishing trust in health care services will require efforts beyond rebuilding infrastructure and require concerted efforts to rebuild the trust of local residents who may be wary of seeking healthcare post epidemic.     

Comparative Study between CalTOX and Soil Screening Levels Modeling Approaches

A comparison was made between two different approaches to environmental modeling and risk assessment, specifically the one-medium approach of the USEPA Soil Screening Levels (SSL) and the multimedia approach in the CalEPA (CalTOX). Eleven priority pollutants were selected to represent different classes of chemicals as per their toxicity, physical and chemical properties, and persistence in the environment. Benzene, dioxin, PCB, B(a)P, chlo-rdane, chloroform, and TCE represent carcinogens, while xylene, toluene, phenol, chlordane, pyrene, TCE, and chloroform represent noncarcinogens. The highly volatile contaminants, including benzene, chloroform, xylene, toluene, and TCE, were selected to compare the volatilization from soil and the significance of inhalation pathways of the two models. The contaminants with strong sorption to soil and dust particles (dioxin, B(a)P, PCB, and chlordane) exhibited a preferential soil ingestion pathway. In contrast with CalTOX, inhalation was not considered as the dominant pathway for all the volatile contaminants in SSL. Furthermore, the risk assessment component of CalTOX accounts for multiple pathways as a consequence of its multimedia representation. Because the two models were based on different approaches, it is expected that the results would be different. For example, the results of the SSL were more conservative compared with CalTOX for all 11 chemicals. This observation still holds when considering the total risk from CalTOX vs. the risk based on the dominant pathway in SSL. Finally, the cancer slope factors and references doses were not the same for all the chemicals used in this study and resulted in different risk estimates.     

Boosting understanding of Lassa Fever virus epidemiology: Field testing a novel assay to identify past Lassa Fever virus infection in blood and oral fluids of survivors and unexposed controls in Sierra Leone

BackgroundDespite identification 50 years ago, the true burden of Lassa Fever (LF) across Africa remains undefined for reasons including research focus on hospitalised patients, lack of validated field-feasible tools which reliably identify past infection, and the fact that all assays require blood samples making large-scale surveys difficult. Designated a priority pathogen of epidemic potential requiring urgent research by the World Health Organisation, a better understanding of LF sero-epidemiology is essential to developing and evaluating new interventions including vaccines. We describe the first field testing of a novel species-neutral Double Antigen Binding Assay (DABA) designed to detect antibodies to LF in plasma and oral fluid.Methodology/Principal findingsPaired plasma and oral fluid were collected in Sierra Leone from survivors discharged from Kenema Government Hospital Lassa Fever Unit between 1980 and 2018, and from controls recruited in Freetown in 2019. Epidemiological sensitivity and specificity of the DABA measured against historical diagnosis in survivors and self-declared non-exposed controls was 81.7% (95% CI 70.7%– 89.9%) and 83.3% (72.7%- 91.1%) respectively in plasma, and 71.8% (60.0%– 81.9%) and 83.3% (72.7%– 91.1%) respectively in oral fluid. Antibodies were identified in people infected up to 15 years and, in one case, 40 years previously. Participants found oral fluid collection easy and painless with 80% happy to give an oral fluid sample regularly.Conclusions/SignificanceGiven the difficulties of assay validation in a resource-limited setting, including unexpected exposures and diagnostics of varying accuracy, the new assay performed well in both plasma and oral fluid. Sensitivity and specificity are expected to be higher when case/control ascertainment is more definitive and further work is planned to investigate this. Even at the performance levels achieved, the species-neutral DABA has the potential to facilitate the large-scale seroprevalence surveys needed to underpin essential developments in LF control, as well as support zoonotic investigations.