Zika virus, the new kid on the block. Euro Surveill. 2016; 21(23): pii=30255. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.23.30255
According to Tolstoy, happy families were all alike, whereas unhappy families were each unhappy in their individual ways. So it is with the emergence of new virus infections. Each new virus epidemic brings misery to affected human populations, in unique ways. In the last 15 years, we have experienced the emergence and spread of Severe Acute Respiratory Syndrome (SARS), H5N1 and H7N9 influenza A viruses, pandemic influenza A(H1N1), Middle Eastern Respiratory Syndrome (MERS) and Ebola virus disease, and most recently in 2015–16, Zika virus. The wider societal impact that such infectious disease events can cause has been amply demonstrated with Ebola virus in West Africa, which was responsible for over 11,000 deaths and has inhibited economic growth in this war-torn region of the world. Each of the viruses mentioned above occupies a different ecological niche, with diverse impact on the human population (magnitude of the epidemic, disease severity) as a result of transmission characteristics, host immune response and disease pathogenesis. Serious complications and deaths from Zika virus infection have not been common: most infections are asymptomatic or very mild, although there is an association with neurological complications such as Guillain–Barré syndrome. The key issue, however, is the impact of infection on pregnancy. For most emerging viruses, classical control measures of contact tracing and quarantine will eventually break chains of transmission between humans following zoonotic infection, when human-to-human transmission occurs and infectiousness is related to symptomatic illness. However, when infection is through a vector-borne route and sexual transmission can occur from a minimally symptomatic person, such as with Zika virus infection, additional population-based control measures must be undertaken. Vector control requires sustained and determined efforts to achieve a measurable impact and may involve a range of interventions at a personal level (e.g. avoidance, mosquito nets and insecticide) and at population level (e.g. breeding genetically resistant mosquitoes). Steering towards other rational interventions requires evidence from well-documented individual case studies.