Background on Zika Virus

A Blog post by Elaine Faustman (WDS Scientific Committee member)

I’d like to start by providing a little background on Zika virus, as one critical step in risk assessment is hazard identification and characterization. Though Zika virus was first discovered in 1947 in Africa, the first large epidemic was not reported until 2007 in the Pacific Island of Yap (Al- Qahtani et al. 2016). Since then, outbreaks have been reported in French Polynesia (2013), and Brazil and surrounding countries (Chang et al. 2016). The first case of Zika virus in Brazil was reported in May of 2015. Currently, 30 countries in the Americas have reported active cases of Zika virus. Though Zika is usually transmitted through the bite of a mosquito from the Aedes genera (Aedes albopictus and Aedes aegypti), it can also be spread through sexual activities and intravenous infection, such as blood transfusions. For most healthy individuals, infection can lead to mild flu-like symptoms or even be asymptomatic. However, infection (both symptomatic and asymptomatic) during pregnancy can lead to irreparable birth defects that severely impair child development (Kleber de Oliveira et al. 2016).

The most common birth defect associated with Zika virus exposure during pregnancy is microcephaly (Rasmussen et al. 2016). The basic definition of microcephaly is 'the clinical finding of a small head compared with infants of the same sex and gestational age' (CDC 2016). Problematically, there is no universally accepted definition of microcephaly; thus, when tracking cases of microcephaly and Zika viruses across healthcare providers, provinces, states, countries, and regions, the criteria employed can be drastically different. Inconsistencies in data collection techniques frequently limit the ability of Public Health professionals to accurately identify and predict Zika-induced microcephaly cases. To add further complications, microcephaly is not unique to Zika infection, but can be caused by a number of environmental and viral exposures, such as toxicoplasmosis, rubella, cytomegalovirus, herpes, HIV, Syphilis, mercury, alcohol, radiation, as well as genetic and maternal health conditions including poorly controlled material diabetes and hyperphenylalaninemia (CDC 2016).

This fast spreading epidemic demonstrates the need for access to global databases tracking the spread of mosquito species, infections, and birth defects, both under current and future climate conditions. Next, I will describe databases and data sources relevant to tackling this multifaceted global health risk.