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New Report Questions Causal Link Between Zika and Microcephaly

Zika virus

The NECSI report suggests that consideration should be given to the “alternative that Zika is not the cause of microcephaly,” and that, based on the data in the Colombian study, there may be “no direct link between Zika and microcephaly except for random co-occurrence.”

A recent news article in Science Daily cites a “status report” by New England Complex Systems Institute (NECSI) of Cambridge, MA raising questions about the supposed causal link between the Zika virus and the birth defect known as microcephaly.1 2 According to the article:

Brazil’s microcephaly epidemic continues to pose a mystery—if Zika is the culprit, why are there no similar epidemics in other countries also hit hard by the virus? In Brazil, the microcephaly rate soared with more than 1,500 confirmed cases. But in Colombia, a recent study of nearly 12,000 pregnant women infected with Zika found zero microcephaly cases. If Zika is to blame for microcephaly, where are the missing cases?1

The Colombian study of 11,944 pregnant women referenced in the NECSI report was supported by the Colombian National Institute of Health and the U.S. Centers for Disease Control and Prevention (CDC) and published in The New England Journal of Medicine (NEJM) on June 15, 2016.3  The NECSI report notes that, of the 11,944 cases with “Zika symptoms being observed in clinical settings,” there were no cases of infants born with microcephaly.2

The Science Daily article asks the question, “Is it possible that more time is needed for births to give rise to the high numbers seen in Brazil?” But it points out that, according to the NECSI report, the numbers just “don’t add up.”1

The Zika and microcephaly cases that are not part of the study show that there are many more pregnancies affected by Zika without symptoms. Because there are four cases of microcephaly with Zika, and none in the study, there should be about four times as many cases of Zika that are unreported. This means there are at least 60,000 Zika-infected pregnancies in Colombia.1

According to the NECSI report, however, there have only been a total of 50 microcephaly cases reported in Colombia from August 2015 through the end of April 2016. Of those cases, only four of them were “connected” with Zika. Given the high number of Zika-infected pregnancies in Colombia, though, the four microcephaly cases may have simply been a coincidence.1 2

The NECSI report suggests that consideration should be given to the “alternative that Zika is not the cause of microcephaly,” and that, based on the data in the Colombian study, there may be “no direct link between Zika and microcephaly except for random co-occurrence.”2

In light of this evidence, NECSI says the cause of microcephaly in Brazil should be reconsidered. One possibility that has been raised is the pesticide pyriproxyfen, which is applied to drinking water in some parts of Brazil to kill the larvae of the mosquitos that transmit Zika.1

An article published by The Vaccine Reaction in February raised the issue of the pyriproxyfen cited in a report published by Médicos de Pueblos Fumigados (Physicians in the Crop-Sprayed Villages) of Argentina.4 

Médicos de Pueblos Fumigados, the Brazilian association of doctors and health researchers called the Asociación Brasileña de Salud Colectiva (Brazilian Association for Collective Health), the Swedish Toxicology Research Center, and NECSI have reportedly called for “further studies of the potential link between pyriproxyfen and microcephaly.”1  4

Note: NECSI describes itself as an “independent academic research and educational institution with students, postdoctoral fellows and faculty.” The organization maintains an “in-house research team, but also has “co-faculty, students and affiliates from MIT, Harvard, Brandeis and other universities nationally and internationally.”5


1 New doubts on Zika as cause of microcephaly. Science Daily June 24, 2016.
2 Bar-Yam Y, Evans D, Parens R, Morales AJ, Nijhout F. 
Is Zika the cause of Microcephaly? Status Report June 22, 2016. New England Complex Systems Institute.
Pacheco O,  Beltrán, M, Nelson CA, Valencia, D, Tolosa, N, Farr SL, Padilla AV, Tong VT, Cuevas EL, Espinosa-Bode A, Pardo L, Rico A, Reefhuis J, González M, Mercado M, Chaparro P, Martínez Duran M, Rao CY, Muñoz MM,, Powers AM, Cuéllar C, Helfand R, Huguett C, Jamieson DJ, Honein MA, Ospina Martínez ML. Zika Virus Disease in Colombia—Preliminary Report. The New England Journal of Medicine June 15, 2016.
Cáceres M. Pyriproxyfen Suspected of Causing Microcephaly in Brazil. The Vaccine Reaction Feb. 12, 2016.
About NECSI. NECSI.edu.

5 Responses to New Report Questions Causal Link Between Zika and Microcephaly

  1. James Lyons-Weiler Reply

    July 1, 2016 at 12:39 am

    I have it on good authority that (1) MC surge started in Brazil before Zika arrived; (2) the surge started a year after the mandated “Stork” pre-natal program (Data from the national heart study, http://www.who.int/bulletin/online_first/16-170639.pdf (3) that Brazil uses whole-cell pertussis to vaccinate the poor (who cannot afford the fee for the clinic), source: Dr. Waldely De Oliveira Dias pers comm to Dr. Lyons-Weiler). Add to that the new use of folic acid w/no MTHFR screening, and the larvicide, and expansion of the use of glyphosate in Brazil – a perfect storm.

  2. MARY FISHER Reply

    July 2, 2016 at 11:33 pm

    Neurology SEPT 15, 2009 (NOTE THE DATE)
    “Microcephaly may result from any insult that disturbs
    early brain growth…Annually, approximately 25,000
    infants in the United States will be diagnosed with
    #1. toxic pesticide,
    #2. toxic substance injected into the mother—
    ….(a street drug or a vaccine).
    #3. malnutrition of the mother
    #4. A physical blow.

  3. Rosech Reply

    July 3, 2016 at 4:32 pm

    Strange that Zika has been around for some 70 years and no problems. When we were in the Amazon Jungle, where the humidity is outrageous and all kinds of insects, NOT one child had a small head nor a sick brain. They eat right! To me this is definitely a charade to divert our attention from wanting to global America! As a health consultant, I have never seen this condition either. May I say I read an article where China/Russia/Brazil are getting together to forge a new currency, and this does not set well with the empty suit and others, so spreading the Zika rumor to stop and/or keep athletes from attending. Somehow, this rings much truer than the myth being pushed. Considering the CDC which is a horrible department, and WHO, both have been wrong several times and not to be trusted and always want MORE money.

  4. allan lieberman,MD Reply

    July 4, 2016 at 3:23 pm

    Congress is being pushed to provide 1.9billion for control of the Zika virus.But Congress wants to only allocate 1.1Billion. The agencies are taking advantage of the Zika virus spread to get more money.
    What is unfortunate is the facts as provided by the Brazilian and Argentinian Medical associations blame the epidemic on poverty of the people in the North East part of Brazil associated with the Larvicide. We now also learn that there was an epidemic of Pertusis in This area and several of the international health agencies strongly recommended that all the pregnant women should be vaccinated with the pertussis vaccine. Vaccines,pesticides and poor nutrition are known causes of microcephaly.
    This situation does not speak highly of our medical scientists. The facts indicate that the Zika virus is not the cause of the microcephaly.

  5. Nelson Rantz Reply

    August 3, 2016 at 5:12 am

    Establishing this causal relationship between Zika and fetal brain defects is an important step in driving additional prevention efforts, focusing research activities, and reinforcing the need for direct communication about the risks of Zika. While one important question about causality has been answered, many questions remain. Answering these will be the focus of ongoing research to help improve prevention efforts, which ultimately may help reduce the effects of Zika virus infection during pregnancy.

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