Predicting the combined effects of case isolation, safe funeral practices, and contact tracing during Ebola virus disease outbreaks

Abstract

Background The recent outbreaks of Ebola virus disease (EVD) in Uganda and the Marburg virus disease (MVD) in Ghana reflect a persisting threat of Filoviridae to the global health community. Characteristic of Filoviridae are not just their high case fatality rates, but also that corpses are highly contagious and prone to cause infections in the absence of appropriate precautions. Vaccines against the most virulent Ebolavirus species, the Zaire ebolavirus (ZEBOV) are approved. However, there exists no approved vaccine or treatment against the Sudan ebolavirus (SUDV) which causes the current outbreak of EVD. Hence, the control of the outbreak relies on case isolation, safe funeral practices, and contact tracing. So far, the effectiveness of these control measures was studied only separately by epidemiological models, while the impact of their interaction is unclear. Methods and findings To sustain decision making in public health-emergency management, we introduce a predictive model to study the interaction of case isolation, safe funeral practices, and contact tracing. The model is a complex extension of an SEIR-type model, and serves as an epidemic preparedness tool. The model considers different phases of the EVD infections, the possibility of infections being treated in isolation (if appropriately diagnosed), in hospital (if not properly diagnosed), or at home (if the infected do not present to hospital for whatever reason). It is assumed that the corpses of those who died in isolation are buried with proper safety measures, while those who die outside isolation might be buried unsafely, such that transmission can occur during the funeral. Furthermore, the contacts of individuals in isolation will be traced. Based on parameter estimates from the scientific literature, the model suggests that proper diagnosis and hence isolation of cases has the highest impact in reducing the size of the outbreak. However, the combination of case isolation and safe funeral practices alone are insufficient to fully contain the epidemic under plausible parameters. This changes if these measures are combined with contact tracing. In addition, shortening the time to successfully trace back contacts contribute substantially to contain the outbreak. Conclusions In the absence of an approved vaccine and treatment, EVD management by proper and fast diagnostics in combination with epidemic awareness are fundamental. Awareness will particularly facilitate contact tracing and safe funeral practices. Moreover, proper and fast diagnostics are a major determinant of case isolation. The model introduced here is not just applicable to EVD, but also to other viral hemorrhagic fevers such as the MVD or the Lassa fever.

The Outbreak of Marburg Virus in Tanzania: An Emerging Global Health Threat

“…A critical component of a successful response was an effective surveillance system, which involves early detection through active case finding and investigation to allocate resources to respond to outbreaks effectively [10,14,15,16]. Another important lesson is the importance of effective infection prevention and control measures, which includes contact tracing to identify exposed individuals, isolation of infected individuals, appropriate treatment, and the effective use of personal protective equipment such as face masks, eye protection such as goggles and face shields, gloves and gowns by healthcare workers and other individuals who are at high risk of exposure to viruses, including safe burials [17]. Next, international cooperation is critical in responding to viral outbreaks that cross borders and involves sharing information and best practices, coordinating response efforts, and providing financial and technical support to affected countries; while research can help to improve our understanding of the disease and develop effective treatments and vaccines [18,19].…”

A mathematical model to assess the effectiveness of test-trace-isolate-and-quarantine under limited capacities

“…One such approach is to introduce additional compartments in the model to account for individuals who will be traced or confirmed as positive in the future. Those individuals then reside in these compartments until they are successfully quarantined or isolated [ 35 , 36 ]. Another approach is presented in [ 32 ] where expressions for the probability that individuals had recent contact with an infectious individual are derived.…”

Dynamical analysis for a stochastic Ebola virus epidemic model with age-structured effect

“…It also highlights that the high infection rate of the Ebola virus is closely linked to local customs, sanitary conditions, and conflicts [7] .…”