Check out the Cloudy Media Blog for a good discussion about the Zika Virus and it’s Uber transit pal, the Mosquito. Consider why some people are raising the alarm and others are trying to reassure us that it’s not the end of the world if you do contract Zika.
For most people Zika is not all that harmful. the symptoms are often described as similar to a mild case of the flu. But, like rubella, the major risk may be to women who contract the disease while pregnant. It has been found that a rise in microcephaly cases in Brazil has coincided with a rise in Zika cases (increasing since April 2015). However, whether there is a causal link between the virus and the birth defect has been more difficult to demonstrate. Correlation is not Causation, otherwise the link between sunburns and the dramatic rise in ice cream sales seen every summer might make us consider shuttering the Dairy Queen to prevent skin cancer.
So, why think there is a link between Zika and Microcephaly? The immediate reason is the spike in Zika cases just before the spike in microcephaly.
Why doubt the connection? One reason is that Brazil is not the only country seeing a spike in Zika infections. In fact, Columbia has many more confirmed cases of Zika than Brazil (however it is estimated that Brazil may have a larger population of unconfirmed cases) but has not yet seen the spike in microcephaly (or at least I haven’t been able to find good data on it). So, shouldn’t Zika be causing birth defects in children regardless of where they live?
To answer this question, some have decided to look directly at the brains of children born (or fetuses not born) with microcephaly to see if there is any evidence of the virus there. In work performed by the CDC, four of four cases were positive by RT-PCR (a technique looking for virus-specific RNA), and sequence analysis provided further evidence of Zika virus infection, revealing highest identities with Zika virus strains isolated from Brazil during 2015. Workers in San Paulo, Brazil found that the mothers of 23 of 29 infants (79.3%) with microcephaly reported signs of Zika virus infection. The majority of these reported that the symptoms occurred during the first trimester of the pregnancy.