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.
Now, if you’ll excuse me, I have to get myself into a vector for the airport. Seriously, check out Cloudy Media.
March 21, 2016 at 9:54 pm
From what I’ve read part of the difference in rate of reported zika associated microcephaly in Brazil and Columbia is due to a difference in criteria. Brazil are using a very permissive set of criteria, Columbia a very strict set. I’m also not sure how complete the reporting is in either country. Reporting is a little hit and miss even in first world countries. I’m guessing it is much worse in impoverished regions of Brazil and Columbia. Columbia is an interesting case, as its constitution guarantees universal access to health care. But last time I looked less than two thirds of the population had any access, and that was very heavily skewed towards their three most populous cities.
There are some interesting studies coming from the data from the French Polynesian outbreak:
Click to access PIIS0140-6736%2816%2900562-6.pdf
The first finds a strong association between microcephaly and zika infection in the first trimester, but not the second and third trimesters.
The increased incidence of Guillain-Barré syndrome requiring intensive care, mentioned in the second paper, looks concerning. I suspect there is no allowance for the cost of this in regions currently suffering zika outbreaks
Meanwhile, the conspiracy theorists are having a ball. My favourite is that it is caused by vaccinations, because Big Pharma expect to make Big $PROFIT from introducing novel health care challenges into impoverished third world countries, though the mechanism for making said profit remains unknown.
Virology blog has an interesting look at zika, but the commentary is mostly depressing:
March 29, 2016 at 10:10 pm
I read the Lancet article on Zika and Microcephaly too. It looked to be a fairly reasonable paper and it’s quite consistent with other viruses or even environmental problems leading to developmental problems being most pronounced when exposure occurred in the first trimester. (I’m thinking of Rubella and Fetal Alcohol Syndrome immediately). The Guillain-Barré thing crops up much more than I would have expected – remember that it was a problem associated with the 1976 flu vaccine (at least here in the states because President Ford was trying to look like he was acting decisively and managed to jump the gun on a possible pandemic that never manifested). It’s not surprising that the anti-vax groups jump on things like Zika. It’s a health crisis, therefore it must be because of big pharma’s evil intentions. If they keep raising alarms over absolutely everything, I suppose one day they’ll luck into something like a broken clock giving the right time twice a day.Then we’re in for it!
It’s always a pleasure receiving your comments – keep em coming!