Zika virus infection, transmission, associated neurological disorders and birth abnormalities: A review of progress in research, properties and knowledge gaps

Added May 11, 2017

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While there has been a lot of research into Zika in recent years, significant gaps in knowledge remain: the associations between Zika and foetal malformations, and Zika and  post-infection autoimmune disorders; there are uncertainties about transmission, and about viral  persistence. There are gaps in knowledge around vector control, and a significant need to identify vaccines and anti-viral medications.

This is a wide ranging review covering epidemiology, clinical presentation, zika-associated neurological syndromes, congenital microcephaly, Zika diagnosis and treatment, vector control and personal protection, promotion of research and development. The gaps in knowledge are highlighted.

The persistence of the virus in semen is unknown, and transmission from infected female to male has not been reported. Transplacental transmission can occur throughout pregnancy, transmission via breast milk has not yet been reported.While there is a strong association between pregnant women infected with Zika giving birth to babies with severe congenital abnormalities, few studies have laboratory confirmation of the Zika infection.

Diagnosis is only confirmed by the recognition of viral nucleic acid in serum. Antenatal diagnosis is still not reliable. No vaccine or therapeutic modality has yet been tested on humans.

Surveillance is vital for prioritising control interventions. Genetic modification of mosquitoes has been evaluated by WHO, but sustained implementation does not yet have epidemiological impact data. As the virus adapts and evolves more work is required.

The exact incidence of Zika in the Americas is still unclear since infection is so often asymptomatic or mild. Even the link between Zika and congenital abnormalities is unclear since this had not previously been described. This review does not include results from SciELO or LILACS, nor does it search ongoing trials registers. The search strategy is not included.