Does Zika Virus Cause Microcephaly – Applying the Bradford Hill Viewpoints

This study included more recent evidence compared to the previous one. The Bradford-Hill Viewpoints are used in public health to determine causation of diseases.11 Systematic application of the viewpoints can assist with analysing a possible causal relationship. Additional studies to assess the risk of microcephaly in affected pregnant mothers are ongoing.12 In this study we applied the Bradford-Hill viewpoints to investigate the association between Zika virus and Microcephaly. Method Using the Bradford Hills nine viewpoints we analysed data from a 2013 outbreak in French Polynesia and the 2015 Brazilian outbreak to establish a causal link between Zika virus and microcephaly. We searched major databases including PubMed, Medline and Embase from 2000 onwards using search words, such as Zika virus, Microcephaly and Flavivirus. We also searched news reports and grey literature for information on the outbreaks. We examined historical studies and previous data and also we compared historical rates of microcephaly prior to the Zika virus outbreak. Available data and studies were used to determine whether each of the nine Bradford Hill viewpoints were fulfilled. For strength of association, we sought studies which calculated measures of association for Zika virus and microcephaly. Where the calculation was not done, but suitable data available, we calculated a measure of association. We utilised data from a prospective cohort study conducted in Brazil “Zika virus infection in...
Source: PLOS Currents Outbreaks - Category: Epidemiology Authors: Source Type: research