October 3rd 2016; updated on January 9th 2017
Early September, Minister of Health in Colombia declared end of Zika outbreak. With 78.000 suspected /7166 confirmed cases ; 21 microcephalies and 398 Guillain Barré Syndrome (GBS). It means prevalence for microcephaly estimated in a range of 2.7/10.000 to 29/10.000 at the time being. As of today we have 42 microcephalies recorded leading from 2.7/10.000 to 5.9/10.000 for the confirmed cases.
According to data, 7.9% microcephaly cases are linked/caused by Zika virus so far.
According to evidence based medecine, taking into account tested ZIKV + microcephaly cases, we get 17% of the entire microcephaly tested for ZIKV.
Question: if we all agree to say that Zika virus is involved in the immunological process leading to neural defect and microcephaly, we have to cope with other causes (83%) responsible for microcephalies. On a Global Health issue, it appears more and more obvious that studies are required to build a full picture of the root causes tree regarding microcephaly outbreak in South Americas. By comparing Brazil with Colombia, we might discover different paths to follow, especially by studying what happened in NE Brazil.
Colombia recorded a lot of GBS (>398) compared with microcephaly (>21). A interesting paper is just released in J.Autoimmun 2017 by Colombian researchers pointing out the role of Dengue antibodies. Socio-economics factors are also interfering in the process leading to neurological defects.
“All GBS patients were positive for IgG antibodies against both ZIKV and Dengue virus, and 69% were positive for Chikungunya virus.”
Some time ago, CDC and WHO have posted a statement on microcephaly caused by Zika virus. May be they jump the gun?
While we are observing an after-peak of Zika cases in Colombia and expecting no longer to reach 600.000 despite stats predictions, what is going on in Brazil and what do we know as of today about Zika virus and its pathogenesis?
What has been confirmed from In vitro studies?
- Zika virus crosses placenta barriers;
- Zika virus crosses blood-brain barrier;
- Zika virus can infect fetus;
- Zika virus has neurotropism;
- Zika virus is responsible for:
- Guillain-Barré Syndrome (GBS)
- Zika virus is linked with microcephaly during the Q1 of pregnancy.
When comparing Brazil/Colombia at the time being, meaning with some delay in the observance of microcephaly due to later spread of Zika virus in Colombia, on 61.393 suspected cases, 11.239 pregnant, zero microcephaly recorded so far in this cohorte but Colombia has identified 50 microcephalies, under investigation, of which only 7 under review for Zika virus while waiting for 25 (half of the cohorte) final results. We would be close to 2/10.000 prevalence or less with regards microcephaly related to Zika virus…more or less the historical prevalence of microcephaly in Brazil (26 times above in 2016).
Questions remaining without answer:
- Has Zika virus mutated since arrival in Americas/Brazil?
- Is there possible co-infection:
- with Dengue?
- with CMV, Rubella?
- Is there possible dual cause:
- with a chemical?
- with larvicide, pesticide?
- with Global Health issues (environment,Socio-economics)?
In a previous blog, we pointed out the choice of Colombia as a control group for the prevalence of microcephaly in link with Zika virus in order to answer the question about Zika virus as causative microcephaly.
So May we confirm, as WHO and CDC are delivering statement, that microcephaly is definitively related to Zika virus? More evidence required by answering questions.