By Dr. Mercola
In October 2015, Brazil experienced an unusual increase in the number of babies born with microcephaly, a neurological condition in which the baby's head size is much smaller than normal.
The increase was reportedly linked to Zika virus, a mosquito-borne disease that typically causes only mild symptoms or, in 1 out of 4 people affected, no symptoms at all.
The U.S. Centers for Disease Control and Prevention (CDC) released a report that out of the 250 pregnant women who had confirmed Zika infection in the U.S in 2016, only 24, or about 1 in 10, had a fetus or baby with Zika-related birth defects.1
The World Health Organization (WHO) wrote in 2016, however, that although Brazil reported an association between Zika virus infection and microcephaly (as well as the neurological disorder Guillain-Barré syndrome, or GBS), "for neither event was a causal link proven.2
Further, if Zika virus were in fact the cause of Brazil's surge in microcephaly, it would be expected that another surge would have occurred in 2016 as well, particularly during the country's prime mosquito season, the summer months of December, January and February.
However, as WHO's Christopher Dye told NPR, "We apparently saw a lot of cases of Zika virus in 2016. But there was no microcephaly." He further described the difference in microcephaly rates between 2015 and 2016 as "spectacular."3
Why Wasn't There a Surge of Microcephaly Cases in Brazil in 2016?
Since the Zika virus has spread throughout Brazil, but extremely high rates of microcephaly have not, officials are now being forced to admit that something else is likely at play.
Writing in The New England Journal of Medicine, a group of doctors and Ph.D.s from the Brazilian ministry of health, the Oswaldo Cruz Foundation, the Pan American Health Organization, and the World Health Organization, revealed a spike in both GBS and, about 23 weeks later, a spike in microcephaly.
The 2016 data revealed a similar spike in GBS but not in microcephaly. According to the authors:
"In view of the apparent resurgence of ZIKV infection and GBS early in 2016, we anticipated a further increase in cases of microcephaly later in the year. But such a resurgence did not happen."4
Officials expected more than 1,000 cases of microcephaly to occur in northeast Brazil in 2016, but only about 80 cases were reported. Three potential explanations were offered as for why.
1. 2016 Infections May Have Been Caused by a Different Virus
The authors suggested that, given the widespread Zika virus infection rates in 2015, herd immunity may have developed by 2016.
As such, there's a possibility the spike in GBS cases weren't due to Zika virus at all, but rather to another arbovirus transmitted by Aedes aegypti mosquitoes, such as chikungunya, a known cause of GBS.
" … [S]ome chikungunya infections were evidently misclassified as ZIKV [Zika virus] infection in Pernambuco [Brazil] in 2016," the authors wrote.5
This theory, which the authors described as the most plausible, suggests that both Zika virus and chikungunya may lead to spikes in GBS, but only Zika leads to spikes in microcephaly. If that's the case, the question still remains, what happened to Zika virus in 2016?
The researchers suggest that it's a case of misdiagnosis, meaning there weren't actually that many cases of Zika virus infection in 2016 after all. Not all experts agree with this assessment, however.
Dr. Albert Ko, an epidemiologist at Yale School of Public Health, told NPR, "Misdiagnosis is a reasonable hypothesis. But it's not clear that this explanation accounts for the whole story."6
2. Zika Virus Alone Does Not Cause Microcephaly
The authors suggested that Zika virus infection during pregnancy may be:
"[A] necessary but not a sufficient condition for the development of microcephaly in newborn infants — in other words, the presence of some other unknown cofactor that is not essential for GBS is required."7
What might this unknown cofactor be? It's a question that's been asked before, because when the cases first began and were reportedly linked to Zika virus, health officials believed they'd see a wave of birth defects across Brazil, but that didn't happen.8
Instead, nearly 90 percent of the 2015 microcephaly cases in Brazil occurred in the Northeast. Most of the women who gave birth to babies with microcephaly were poor and lived in small cities or on the outskirts of big cities.
In addition, the outbreak occurred in a largely poverty-stricken agricultural area of Brazil that uses large amounts of banned pesticides.
The current authors said they'd ruled out the use of insecticides as a cofactor, but there are still the issues of lack of sanitation and widespread vitamin A and zinc deficiency, which sets the stage for an increase in poor health outcomes among newborn infants in that area.
Still, "The fact that there were few microcephaly cases the following year means that the co-factor would have been missing in 2016 — and that makes it less likely," the authors pointed out.9
Others, however, have suggested that dengue, another tropical disease spread by Aedes mosquitoes, may be involved, as prior exposure to a certain dengue variety may make exposure to another dengue variety (there are five in all) more severe.
Zika is closely related to dengue, so it's possible that "prior exposure to dengue may actually enhance or promote the risk of birth defects from Zika," Ko told NPR.10
3. Fear of Zika Virus Changed Pregnancy Outcomes
The authors also surmised that fear of the adverse effects of Zika virus may have led women to avoid pregnancy or increased the rate of abortions in 2016.
"However, since any changes in the number of live births would be small, this hypothesis cannot be the principal reason why few cases of microcephaly were reported in the northeast region in 2016."
If Dengue Is Involved, the Global Threat of Zika Is 'Less Dire'
Intriguing research published in the journal Science revealed that when engineered mice were exposed to dengue antibodies prior to being exposed to Zika virus, it led to increased deaths and symptoms.11
When the mice were exposed without receiving dengue antibodies, only 10 percent died. However, in mice with the antibodies, 80 percent died within eight days of exposure to Zika virus.
The researchers noted that prior infection with dengue could be responsible for the severe disease manifestations associated with recent Zika outbreaks, and also "highlights the need to exert great caution when designing flavivirus vaccines."12 Further, NPR reported:13
"Ko is working on epidemiological studies in northeast Brazil, right now, to see whether …[this] is the case [in people]. If the dengue theory turns out to be true, it could mean the global threat of Zika for pregnant women is less dire than scientists originally thought."
Another potential cofactor worth considering is vaccination during pregnancy. In October 2014 the Brazilian government mandated that all pregnant women receive the pertussis-containing Tdap (tetanus, diphtheria and pertussis) vaccine, effective as of 2015.
The fact that birth defects began rising toward the end of 2015 seems more suspicious in light of this mandate — especially when you consider that pertussis vaccine has previously been linked to brain inflammation and brain damage in infants, and the safety of administering Tdap to pregnant women has never been proven.
In regard to microcephaly in particular, vitamin A deficiency has been linked to an increased risk,14 and zinc is known to play an important role in the structure and function of the brain.15
Even the U.S. Centers for Disease Control and Prevention (CDC) lists malnutrition and exposure to toxic chemicals as two of the three known risk factors for microcephaly. The third is certain infections during pregnancy, including rubella, cytomegalovirus, toxoplasmosis, and others.16
Researchers have also noted that microcephaly may follow "an apparent autosomal recessive pattern" and may be the result of a recessed gene.17
Zika: Another Example of Overblown Fear-Mongering?
In the U.S., mosquito season is viewed as more of an itchy nuisance than a health threat, but that has changed recently, at least perceptually, amidst fears of Zika virus.
The fear-mongering has continued, even as experts said they expect Zika to go the way of other tropical diseases spread by mosquitoes, such as dengue fever and chikungunya, in the U.S. with perhaps small clusters of outbreaks in southern states and little activity elsewhere.
We've seen a string of these over-hyped virus scares in recent years, from the bird and swine flu "pandemics" to Ebola — all of which died down as suddenly as they emerged, without causing the predicted widespread catastrophic damage in the real world.
Meanwhile, pharmaceutical companies are racing to develop the first Zika vaccine, while the U.S. House of Representatives passed a $1.1 billion Zika funding bill. A rider inserted into the bill would allow pesticides to be sprayed over ditches, streams and other waterways protected by the Clean Water Act for a period of 180 days, with no permit required.
Critics argued the bill has nothing to do with combating Zika and, instead, has been on the table for years, with the majority pushing for its passage "under whatever name" was convenient at the time.
Biotech company Oxitec has also created and is seeking to release genetically engineered (GE) mosquitoes in the U.S. to fight Zika. But, as Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, told USA Today, the GE mosquitoes have not been shown to reduce rates of diseases such as Zika (nor is Zika virus widespread in the U.S.).18
The GE mosquitoes may also prove to be too expensive for areas that are plagued with mosquito-borne diseases. Environmental red flags have also been raised. The potential exists for these foreign genes, which hop from one place to another, to infect human blood by finding entry through skin lesions or inhaled dust.
Such transmission could potentially wreak havoc with the human genome by creating "insertion mutations" and other unpredictable types of DNA damage.19
Sensible Solutions to Avoiding Mosquito Bites
Many experts agree that the threat of an epidemic outbreak of Zika virus on continental U.S. soil is virtually nonexistent and may be overblown elsewhere as well. So you needn't go dousing your backyard (or yourself) in chemicals in an attempt to stay safe from the Zika virus (whose connection to birth defects is still being explored).
If, however, mosquitoes are bothersome for you, there are some steps you can take to encourage them to live elsewhere. Draining standing water, including pet bowls, gutters, garbage and recycling bins, spare tires, bird baths, children's toys and so on, is important. This is where mosquitoes breed, so if you eliminate standing water you'll eliminate many mosquitoes.
Planting marigolds around your yard also works as a bug repellent because the flowers give off a fragrance that bugs do not like. This is a great way to ward off mosquitoes without using chemical insecticides. A simple house fan could also help keep mosquitoes at bay if you're having a get-together in your backyard or, for a longer-term solution, try installing a bat house (bats are voracious consumers of insects, especially mosquitoes).
It's best to avoid using bug zappers in your yard, as these may actually attract more mosquitoes while killing beneficial insects. Insect foggers designed to clear insects out of your backyard should also be avoided, as they require the use of strong, potentially harmful, pesticides and don't offer lasting protection.
Even those clip-on repellents and fans that are widely sold are best avoided, as they contain even more toxic ingredients than repellents that can be applied to your skin, and they pose an inhalation hazard.20
Some experts also recommend supplementing with one vitamin B1 tablet a day from April through October, and then adding 100 mg of B1 to a B-100 Complex daily during the mosquito season to make you less attractive to mosquitoes. Regularly consuming garlic may also help protect against mosquito bites, as may the following natural insect repellants:
- Cinnamon leaf oil (one study found it was more effective at killing mosquitoes than DEET21)
- Clear liquid vanilla extract mixed with olive oil
- Wash with citronella soap, and then put some 100 percent pure citronella essential oil on your skin. Java citronella is considered the highest quality citronella on the market
- Catnip oil (according to one study, this oil is 10 times more effective than DEET22)