Zika virus: ask questions....

The World Health Organization WHO) finally opened up the AskZika hashtag a week ago. Sadly, it has not been staffed to the extent that #AskEbola was, so little interaction is happening at this stage. 

Nevertheless, here are the first questions I asked...

Hi @WHO
Is 80% "asymptomatic #Zika" based on Yap island household study or something more recent?
How robust is the figure? #AskZika

— Ian M Mackay, PhD (@MackayIM) April 15, 2016

Hi @WHO,
s there *any* evidence for/against mild or subclinical #Zika cases having any viraemia? #AskZika

— Ian M Mackay, PhD (@MackayIM) April 15, 2016

Is there any correlation between *symptomatic* #Zika virus disease and pre-existing #Dengue virus antibodies? #AskZika

— Ian M Mackay, PhD (@MackayIM) April 14, 2016

Are there current investigations into animal reservoirs for #ZikaVirus in the Americas?#AskZika#Zika

— Ian M Mackay, PhD (@MackayIM) April 13, 2016

Are there yet any confirmations of which mosquito species (single and plural) carry #ZikaVirus in the Americas? #AskZika#Zika

— Ian M Mackay, PhD (@MackayIM) April 13, 2016

.@MackayIM because people get infected early in life and are then immune?

— Ian Goodfellow (@igoodfel) April 13, 2016

Thanks to Ian for reminding me of this likely reason to address the last question - I had a caffeine-free moment when asking this one! 

Because Zika virus has been ticking along for over 60 years - that we know of - in African countries - the population of affected areas will already have some degree of immunity by due to constant exposures, which the current thinking says are unnoticed 80% of the time. My Yap island question above highlights my doubt about that figure though. 

But Ian's response made me think - do we know that an asymptomatic or mild Zika virus infection of a women produces enough immunity, and/or immunity of the right kind, to ensure that if she becomes infected by Zika virus a second time and she is pregnant, she could not deliver a child with central nervous system disease? We don't. Presumably, even with a population that has "seen" more Zika virus circulating, there would still be cases of adult women being infected for the first time and, if Zika virus is the cause, microcephaly resulting. Perhaps this has simply been lost in the background health issues though. Or perhaps something special, different or more complex is happening in Brazil that goes beyond Zika virus infection+pregnant woman=rare microcephaly case.

Congenital Zika syndrome is not reliably distinguished from other infective, toxic, or genetic causes of congenital anomalies, although others say the anomalies attributed to Zika virus infection outside the central nervous system are distinctive. This disagreement alone highlights how many questions this outbreak has raised and how few answers we've received. 

Do you have questions about all this? Pose them to the #AskZika channel. Maybe we'll get some answers soon. We may at least get the scientific consensus of some answers, if that is satisfying enough for you.