Saturday, July 9, 2016

The Zika puzzle: Why are there so few cases of microcephaly in Colombia?

The meme goes on about Zika and birth defects.

Did you know Zika has affected tens of thousands outside of Brazil?

there is a similar outbreak in Colombia. According to the CDC, the highlands where my son lives is less likely to be affected.

But that outbreak has caused some to question the link between Zika and microcephaly.

and now some are wondering if the insecticide might be behind the huge number of cases in Brazil:

Recently, the New England Journal of Medicine published the preliminary results of a large study of pregnant Colombian women infected with Zika. Of the nearly 12,000 pregnant women with clinical symptoms of Zika infections until March 28, no cases of microcephaly were reported as of May 2. At the same time, four cases of Zika and microcepy symptomless for Zika infections and therefore not included in the study itself....

The NECSI report analyzes the data and shows that the four cases of Zika and microcephaly that have been observed till April 28 are just what would be expected due to the background rate -- of the 60,000 pregnancies about 20,000 births would already be expected. The expected microcephaly rate for countries with no reported infections of 2-in-10,000 births gives exactly four cases. The study also notes that until April 28 there has been a total of about 50 microcephaly cases in Colombia, of which only four have been connected with Zika.

 The four cases are expected for the coincidence of Zika and microcephaly in the same pregnancies even if Zika is not the cause.

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. 

Pyriproxyfen is an analogue for insect juvenile hormone which is cross reactive with retinoic acid, which is known to cause microcephaly. A physicians group in Brazil and Argentina, the Swedish Toxicology Sciences Research Center, and NECSI have called for further studies of the potential link between pyriproxyfen and microcephaly. 

Has this been noted elsewhere?

Time reports 12000 cases in Colombia, but laments at the end of their article:

The study authors note that in 2010, over half of all pregnancies in Colombia were unintended and less than half of sexually active women reported using a condom the last time they had sex, though 61% said they used contraception in general.
This shows the meme being pushed: the idea that sex without babies is the goal, and that if you don't delberately plan a kid, it's "unintended"

Ah, but for many people (including most people in the USA before the pill and the sexual revolution), babies just happened. You accepted the kid as part of life, and often behind this was the idea that there was a plan behind things, a karma, the will of God behind all things good and bad.

Yes,  Zika is a major public health worry, (albeit not as serious as Dengue, which is not being pushed with the hysteria of the Zika outbreak) but why does my paranoid mind think it's more about contraception than babies?

this is especially true if earlier outbreaks suggested only one percent of pregnant women who got the virus had a microcephalic baby.

update: more links to the original articles.

NEJM has several articles on it but the review article is HERE discussing the epidemiological studies that made them suspect the Zika virus, but notes why doctors were not as quick to blame the virus as the MSM:

This cautious approach toward ascribing Zika virus as a cause of birth defects is not surprising, given that the last time an infectious pathogen (rubella virus) caused an epidemic of congenital defects was more than 50 years ago, no flavivirus has ever been shown definitively to cause birth defects in humans,4 and no reports of adverse pregnancy or birth outcomes were noted during previous outbreaks of Zika virus disease in the Pacific Islands.
a;ctually, the outbreak in the Pacific Islands was too small to be significant, but in that epidemic the rate of microcephaly in infected women was one percent, which is small but higher than baseline.

Link for the NEJM preliminary report from doctors in Colombia.

Preliminary surveillance data in Colombia suggest that maternal infection with the Zika virus during the third trimester of pregnancy is not linked to structural abnormalities in the fetus. However, the monitoring of the effect of ZVD on pregnant women in Colombia is ongoing.
Translation: A lot of the moms who got Zika in early pregnancy haven't delivered yet, so data is lacking, but if you got Zika later in pregnancy you and your baby probably will do okay.

I should note that I've read anecdotal cases of Zika encephalitis in newborns causing the brain to shrink.

the NECSI report is here.

The strongest evidence is in favor of Zika, through the observation of Zika virus in neural tissue, though a key piece of evidence is missing in the expected rise of cases in other locations, specifically Colombia. Evaluation of the potential role of pyriproxifen is difficult due to the limited number and nature of available studies, which should be revisited as they include some evidence for neurodevelopmental toxicity. The possibility of DPT immunizations of pregnant women as a factor is largely ruled out by an increase in immunization in countries in which microcephaly cases are not being reported. There is no direct evidence for GM mosquitoes as a cause. If there is a dramatic increase in cases of microcephaly in Columbia in the next three months, the case for Zika will be dramatically strengthened, and the case for pyriproxyfen and GM mosquitoes will be essentially ruled out. On the other hand if the cases do not materialize, Zika will essentially be ruled out and pyriproxyfen would become the strongest case with GM mosquitoes a speculative alternative along with other environmental toxins.

their report on pyriproxyfen toxicity is here. 

summary: It's action and metabolite is similar to another chemical that can cause microcephaly, the toxicity studies claimed it was safe but did show problems, and the chemical was overused in Brazil, i.e. giving moms a higher dosage than elsewhere:

Finally, the pyriproxyfen use in Brazil is unprecedented—it has never before been applied to a water supply on such a scale. Claims that it is not being used in Recife, the epicenter of microcephaly cases, do not distinguish the metropolitan area of Recife, where it is widely used, and the municipality, where it is not. Given this combination of information we strongly recommend that the use of pyriproxyfen in Brazil be suspended pending further investigation.

No comments:

Post a Comment