#microcephaly and #zika in Brazil: towards a double blind test?

Following the second meeting of the WHO’s Emergency Committee on Zika, there are clearly growing evidences for recognizing link between Zika virus and neurological damages or fetal defects observed: here are now facts:

  • Zika virus is crossing placenta barrier;
  • Zika virus is capable to infect foetus;
  • Zika virus is crossing blood-brain barrier;
  • In vitro, brain cells are damaged by Zika virus;
  • Guillain-Barré syndrome, myelitis caused by Zika virus.
  • Microcephaly = 1% during Zika outbreak in French Polynesia
  • Microcephaly and Timetable: risk exposure = Q1

But where do we stand with regards microcephaly?

  • microcephaly in Americas located in NE Brazil;
  • microcephaly not always related to Zika virus;
  • other causes known for microcephaly worldwide:
    • viral (rubella), infectious (toxoplasmosis)
    • toxic (chemicals,pollutants)
    • malnutrition (Vit. defiency,alcohol,…)

Looking at the map of microcephaly in Brazil:

Brazil risk map mid march 2016

 How could we explain as of today that cases are concentrated in Northeast of Brazil? Scientists are talking about climate change and El Nino in that area; others point out that this area is the first South American location to be hit by Zika and that it is to early to observe microcephaly elsewhere.

I would like to encourage studies on the effects of some pesticides and larvicides to be tested in vitro by combining both Zika virus with pyriproxyfen (e.g). Recently, a report by NECSI refers to this larvicide used in 2014 as a larvicide and poured in the drinking water in the NE Brazil.

“These tests were performed by its producer Sumitomo Chemical. Testing is limited and inconclusive, but includes some evidence for neurodevelopmental toxicity (see below). Such tests should be made public so that they can be critiqued by the scientific community, not just by regulatory authorities whose public summaries are not adequate for evaluation [19, 20]. This is a quite general problem, as the inadequacy of neurodevelopmental toxicity testing has been identified as a global risk [17].”

 You migth be aware that the MSDS for pyriproxyfen is not fully completed with regards Toxicity for reproduction; nevertheless, WHO recommended it as a safe product to eradicate mosquitoes like, Aedes aegypti or albopictus (based on which tests?…). It is unclear today to evaluate possible conflict of interests when reviewing the role and responsibility of pyriproxyfen in microcephaly during zika outbreak in Brazil.

During the meeting held on Wednesday March 9th, it was mentioned that Vector control means, including use of pesticides and larvicides had poor effects on mosquito breeding.

Colombia has been quoted as a group of reference in order to compare with Brazil. Unfortunately, due to late arrival of zika in this country, we have to wait till end of Spring 2016 to know if there is or not a close relationship between Zika virus and microcephaly, knowing that Colombia did not use pyriproxyfen.


  1. Abnormal microcephaly rate recorded => Zika virus
  2. No microcephaly recorded: other cause to be explored but mostly larvicide (pyriproxyfen).

So Colombia might be considered as part of a double blind test for Zika virus and microcephaly. To be noticed on mid March 2016 is the decrease of numbers for Zika cases, mainly in North (Carthagena,Bolivar). No microcephaly so far reported but may be still too early…?


A good summary as a wishing list done by Ian McKay in his excellent Blog VDU

Taking into account the precautionary Principle, it might be of interest to recommend women of childbearing age or pregnant living in NE Brazil to drink mineral water provided for free by NGO or International autthorities (UN, WHO).

4 thoughts on “#microcephaly and #zika in Brazil: towards a double blind test?

  1. Pingback: The Mystery of #Microcephaly in Brazil :Questions unanswered. | The Ad Spread

    • There is no evidence for demonstrating use or bzn of the larvicide. But more importznt is to measure the number of microcephalies in Colombia/Brazil thrn trying to explzin how NE Brazil is recording >90% of national cases.
      In other words, Zika virus alone cannot explicite the outbreak; other risk factors are involved. Cross antibodies with Dengue virus are possibly playing a key role in the neuroligical defects/autoimmune diseases (GBS)


    • we don’t know.That remains one risk factor or co-factor for explaining microcephaly in NE Brazil. As you know Big Pharma has interests to control communication on this issue…


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