May 17th 2016
We were speculating on Colombia as a control group for microcephaly caused by Zika virus. 7 months later, we do not observe the same occurrence/prevalence for microcephaly than declared (without evidence) in NE Brazil. As of today less than 10 microcephalies has been recorded in Colombia. How explaining such a huge discrepancy between Brazil and Colombia?
- Lack of accurate reporting in Brazil leading to overestimation
- Possible non identified co-factors:
- Poverty, poor hygiene, Vitamin deficit/malnutrition
- Timeline of outbreaks: Dengue,Zika
During Zika summit hold in Paris, Institut Pasteur, there were some debate on the role and responsibility of immune system and microcephaly or Guillain-Barré Syndrome (GBS); We see emerging evidence for an autoimmune process as the main cause of central nervous system defects observed during Zika.
Brazil and Colombia have both naive population with regards immunization for Zika. It looks as if Dengue antibodies might react with Zika virus as an enhancement of the immune response on the CNS of fetus during the first quarter of pregnancy, affecting neural cells.
The immune response to the previous infection of dengue is potentially one of the mechanisms that can make you more susceptible to Zika. It’s definitely not been 100% proven yet, but there’s a lot of work going on to investigate it.
Recently, studies in mice are demonstrating that Zika virus is able to cross placenta barrier and to replicate, damaging the placenta by the way; same for the brain barrier.
These three reports provide conclusive evidence that Zika virus can cross the placenta and cause fetal defects in mice, and provide models to understand the biology and pathogenesis of infection.
But also more and more evidence to support the key role of immunity interacting with Zika virus like Dengue antibodies, leading to neural damages and explaining microcephaly acquired during Q1 of pregnancy.
Better knowledge of Zika virus and its interactions with other substances, antibodies or environments are key elements helping to understand the gaps between Colombia and Brazil. As said before, not sure Brazil will get the capability and willingness to review and validate the entire non tested cases recorded as Zika causing microcephalies. Home State Politics and Olympics Games will now take the lead…