It has now been close to three months since the Brazilian government announced an outbreak of the Zika virus. In that time, Canadians have become witness to a rather new form of epidemiology in which the public learns details almost as soon as public health officials. While this reveals the importance of real-time updates to keep the public informed, there is a drawback in providing such information.
Normally, when an outbreak or epidemic is found, the first order of business is to confirm a situation is actually happening. Once that is confirmed, the next step is to identify the cause. In the case of Zika virus, both these steps happened without much concern. Unfortunately, the rest of the epidemiological investigation has been anything but a matter of routine.
The reason stems from our rather rudimentary understanding of the Zika virus. While we have known about its existence for decades, only a few studies on its effect on humans have ever been conducted. Unlike other epidemic-causing agents such as Ebola, dengue, and pandemic influenza, the amount of information regarding the infectious process is limited at best. We know it is mosquito-borne, causes a systemic infection that lasts usually a week, and then usually disappears from the body with no secondary effects.
But there may be secondary symptoms, such as Guillain-Barré syndrome, infection of the male genital tract, and the most severe outcome, microcephaly. But these are not concrete links; no one has proven the virus actually causes these conditions. At the moment, making that definitive link with the virus is almost impossible. We can infer from studies from the past and work done on other viruses, such as dengue virus, West Nile Virus, and a closely related cousin, Chikungunya virus. But until actual studies are performed and results attained, questions form without any valid answers.
It's at this point when alternative explanations can enter the picture and muddy the waters even further. Although looking outside the box may be helpful in some cases, there needs to be some actual evidence to suggest the theory may be valid. The problem is, in a real-time world, sometimes evidence plays second fiddle to the potential for public curiosity and at times associated outcries.
One such jump to a causative conclusion deals with genetically modified mosquitoes. Back in January, the company Oxitec announced it was expanding a nine-month project in Brazilian city of Piracicaba. The company has designed a genetically modified mosquito to control populations. The mosquito is unable to reproduce and as such, populations diminish. Despite the success in lowering the insect population by over 80%, the nature of the mosquito did not sit well with some people. For them, the new strain was the reason for the epidemic.
Yet, these mosquitoes are not the cause. The genetic changes are specifically designed to act only on larvae. There would be no impact on Zika-infected adults. This alone could quell concerns. This theory also has a problem in terms of mathematics. The successful lowering of the mosquito population would have the opposite effect on Zika, there would be fewer cases, not more due to the massive drop in population.The final issue deals with area. The mosquitoes were released in an region of the country in which only 5,000 people lived. This outbreak has spread across the Americas and as such, cannot be blamed on this small region or the mosquitoes.
Another recent theory focuses on an alternative cause to microcephaly. For some, the virus is not the cause; it's a pesticide. Officially, the name of the chemical is pyriproxyfen. The chemical has been around for decades and is considered to be a good choice for mosquito control as it inhibits the growth of larvae so they cannot thrive. This latter point is where the theory is derived as a deforming effect on insect babies could possibly lead to similar effects on human ones.
"When it comes to questions from Zika, the best advice is to have patience."
However, this is not the case. The chemical has been tested numerous times by the United States Environmental Protection Agency, the Food and Agriculture Organization of the United Nations, and the World Health Organization. In all cases, the actual amounts needed to cause any signs of toxicity are up to hundreds of times greater than anything used in practice.
But this isn't the only reason. In animal studies using extremely high concentrations, no effects on fetal brains has ever been found. If the chemical was indeed causing troubles, the effects would most likely be in the limbs, not the brain. With this information in place, it becomes relatively easy to find this theory has no merit.
Developing theories in a time of concern is needed and many play the "What If..." game to find answers to outstanding questions. It is, after all, one of the tenets of research. But it is just as important to ensure a hypothesis isn't simply proffered because it seems right, or it happens to fit within an unrelated debate. Both theories presented here can be ruled out using information readily available in the public domain. Yet they continue to thrive.
When it comes to questions from Zika, the best advice is to have patience. Researchers around the world are working hard to find the answers. In the coming weeks, some will be revealed while others may still take months or a year. In the meantime, government and public health officials are offering the best advice they can with the information they have. For your own health, both physical and psychological, it's best to listen to them rather than to allow unfounded theories to increase concern and worry.
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