Friday, 8 April 2016

Describing the brain anomalies in some infants born with microcephaly

In a new study by Hazin and colleagues, 7 of 23 (30.4%) infants with congenital microcephaly were found to have IgM antibodies (which indicate recent infection) in their cerebrospinal fluid. Dr. Ana van der Linden, one of the original doctors who brought the world's attention to a reportedly higher-than-normal number of microcephaly diagnoses, is a co-author of this study.

No antibodies were detected in the cerebrospinal fluid of any of the 23 infants that identified the following diseases or infections:

  • toxoplasmosis (disease due to infection with Toxoplasma gondii)
  • syphilis (disease caused by infection with Treponema pallidum)
  • Varicella Zoster virus
  • Parvovirus B19
  • Human immunodeficiency virus
  • Rubella virus
  • Cytomegalovirus
  • Herpes simplex
No antibody testing was described for Dengue virus or for Chikungunya virus and no antibody testing was reported from the mums of these infants.

No PCR testing was reported at all.

The authors note that - perhaps at a reviewer or Editors request...

"Our findings are nonspecific and may be 
seen in other congenital viral infections."

However, the authors extrapolate from those 7 ZIKV IgM positive results to all 23 infants throughout their publication. 
  • The title broadly defines an association 
  • The first sentence of the results describes the compatibility of the unproven association between prior undescribed ZIKV-like disease and congenital microcephaly
  • The Letter wraps up by stating that ZIKV is associated with a disruption in brain development rather than its destruction

This Letter doesn't leave any doubt for the reader, in my opinion, that detection of antibody in the cerebrospinal fluid is enough to prove causality of the described brain anomalies. Which of course is simply untrue.

It may well turn out that this association is solid as a rock. Of course, we all know by now that there is a "scientific consensus" already stating this is a proven association. Nevertheless, the data in this study don't prove anything. They are descriptions of something that has already happened. Not explanations of how it happened. Not what caused it to happen.

I don't understand why this Letter, essentially a detailed description of congenitally acquired brain anomalies of which there have been other descriptions, has only now been published. Yes, the NEJM is a journal that will give it greater oxygen...among those who read the NEJM...but the NEJM isn't the only journal that science media can access for the latest science and medical research. Is it the only journal that Doctors,the WHO and medical researchers read? I really hope not. Was it the slow pace of publication? This issue has been attributed to NEJM and could mean that these were new observations when originally received.[2] I can't find when the letter was first submitted so it's hard to know the answer there. Is there novel information in here that would be beneficial to spread widely via a platform like NEJM? Not that I can see.


So, welcome to the literature of Zika'ville

References...

  1. Computed Tomographic Findings in Microcephaly Associated with Zika Virus
    http://www.nejm.org/doi/pdf/10.1056/NEJMc1603617
  2. https://www.bostonglobe.com/metro/2016/04/05/new-england-journal-medicine-increasingly-targeted-critics/9H3JFKzTNJpCsOQqIUNXJP/story.html