From Footnote to Headline– The Continuing Zika Story
The spread and impact of the Zika virus continue to garner daily news coverage. As scientists learn more about this once obscure disease, accurate information remains the first step toward avoiding tragedy. The process of understanding the present and potential dangers of Zika relate not only to this global health threat, but to any number of risks to individuals, families, businesses and communities. Instantaneous communication offers both a conduit for current knowledge and a torrent of speculation, misinformation and partial truths.
First, we know the path the virus has taken from its initial detection near the Zika River in Uganda, across the Pacific, and into South, Central and now North America. We know that the vast majority of Zika patients suffer relatively mild symptoms, then recover. We also know that a sudden and significant increase in instances of microcephaly has occurred in Brazil, a phenomenon preliminarily linked to contracting Zika while pregnant. This causal relationship is being aggressively investigated. It is only a matter of time before this link is confirmed or refuted.
We have discovered that the Zika virus remains in the blood of those infected for at least a week. We have also learned that Zika can be present in, and transmitted by, bodily fluids such as semen (not unlike many other viruses).
The Zika virus is conveyed by Aedes mosquitoes, such as A. aegypti and A. albopictus. Unlike mosquitoes native to North America, which come out in the evening, Aedes species are daytime-active. While these thrive in hot, wet climates, they can also be found in the United State from West Texas, throughout the South, and as far north as Connecticut. The North American lifestyle, including ubiquitous window screens and air conditioning, provides one barrier to Aedes mosquitoes. Women who are pregnant or may soon become pregnant should avoid travel to areas where Zika has been detected. Long sleeves and EPA-approved insecticides help limit exposure. Men who have recently traveled to a Zika area should use barrier protection (latex condom) during sex. There is no evidence of danger to a child conceived after the mother has recovered from the disease.
A casual search on Zika will also return myriad reports linking the increase in microcephaly cases to the use of the insecticide pyriproxyfen. This is a circumstantial association advanced by a group that regularly advocates against pesticide use. Pyriproxyfen is used all over the world, including in North American and Europe. No corresponding deformities have occurred. Australian pharmacology expert Dr. Ian Musgrave has stated “[t]he effect of pyriproxyfen on reproduction and fetal abnormalities is well studied in animals. In a variety of animal species even enormous quantities of pyriproxyfen do not cause the defects seen during the recent Zika outbreak. Pyriproxyfen is poorly absorbed by humans and rapidly broken down so even the minute amounts humans would be exposed to via water treatment would be reduced even further.”
It should also be noted that the accusatory accounts specifically address chemical giant Monsanto, a frequent target of some advocacy groups. Monsanto does not make pyriproxyfen.
The Brazilian city of Recife has the highest reported incidence of cases of microcephaly, but pyriproxyfen is not used in that region. The Brazilian health ministry has concluded “[u]nlike the relationship between the Zika virus and microcephaly, which has had its confirmation shown in tests that indicated the presence of the virus in samples of blood, tissue and amniotic fluid, the association between the use of pyriproxyfen and microcephaly has no scientific basis.”
Reducing disease carrying mosquito populations is a global challenge. The alternative in underdeveloped regions is Zika, dengue, malaria, and Yellow Fever, which inflict millions of deaths annually.
The power of the internet can complicate meeting this challenge. Coincidental factors can rapidly become widely accepted as related, complicating evidence-based actions and inflicting otherwise preventable damage. This phenomenon is not limited to the Zika outbreak, but can been seen in any number of circumstances. Timely and accurate information, critical analysis and awareness remain essential approaches to risk reduction.