Risk factors for transmission of Ebola or Marburg virus disease
This review concludes that transmission of filovirus is unlikely except through close contact, especially in the most severe stages of direct illness, but more data are needed and risk factors specific to urban environments may need to be determined.
This systematic review searched for all published evidence which identified and/or quantified the risk factors for community acquisition of filovirus, including Ebola, infection. Papers were also included where opinion (anecdotal observation) was expressed even if the evidence was not of the usual epidemiological standard. 55 articles were chosen for full text review, and 31 articles were included about any African filovirus in the final review, for which data extraction was undertaken. It is summarized narratively with partial meta-analysis.
Information was used from disease studies from 1987 to 2015, with accounts related to Ebola virus were overwhelmingly anecdotal. Data extracted included numerical odds, risk or prevalence ratios for a variety of filovirus disease transition but these cover all filovirus infections together rather than the individual virus infections. There was no evidence in the studies found that risk factors for human-to-human transmission differ between EVD and Marburg.
Specific conclusions relating to Ebola virus disease are that unsafe needle-sharing practices in a vaccination programme were specifically blamed for rapid disease spread in 1976, and that children (unlike other reports on filovirus) are not confirmed as less frequently infected or with greater chances of survival. One confirmed case with no direct contact was noted, where a person slept in a blanket previously used by his brother, who had recently died of EVD.