What: Shares of Intrexon (PGEN -2.07%), a developer of gene-based medicines, scorched higher by as much as 15% during Thursday's trading session thanks to growing fears over the spread of the Zika virus.

So what: The Zika virus is an arbovirus, meaning it's spread from insect to human, and not from human to human. The culprit is the Aedes Aegypti mosquito, which has been wreaking havoc in Brazil, and is now working its way up into Central and North America. The virus itself only winds up making one-in-five adults it infects ill, and the resulting symptoms if you are one of those five are usually mild (joint pain, fever, and rash).

The concern is the more than 20-fold increase in microcephaly cases in Brazil that happens to coincide with the spread of the Zika virus. Microcephaly is a rare condition where the brain fails to fully develop, resulting in a smaller head.

More infants than normal have presented with this condition in Brazil in recent months, which was the impetus behind Brazil's President, Dilma Rousseff, calling the disease a "real threat." Additional testing is underway to confirm if there's a link, but the Centers for Disease Control and Prevention has advised pregnant women not to travel to more than a dozen Zika virus hot zones.

Today, we also witnessed Florida's governor declaring a state of emergency in five counties where the Zika virus has been diagnosed.

Image source: Centers for Disease Control and Prevention. 

Now what: The reason Intrexon shares are shooting through the roof is due to its purchase last summer of Oxitec, which is a company working to eradicate a number of global diseases -- and one just so happens to be the Zika virus. Oxitec is working on modifying the genetic make-up of male mosquitos.

The idea here is that these mosquitos would pass along a gene that would cause future generations to die young before reaching the reproductive age. If successful, Oxitec's solution would dramatically decrease the Zika virus-carrying mosquito population. These genetically modified male mosquitos are being tested in Brazil, Panama, and the Cayman Islands at the moment.

While I can certainly see why investors are so excited, it's also important to keep things in perspective. To begin with, pandemic and epidemic solutions aren't always surefire winners for developing companies. We witnessed drug developers working on an Ebola cure shoot into the stratosphere, only to have cross-border cooperation work to contain the disease. We could see the same thing happen with the Zika virus.

By a similar token, we're also talking about a disease that's far less deadly than past pandemics. Ebola had a mortality rate of roughly 40%. By contrast, there have been just a handful of confirmed cases of microcephaly in Brazil with a Zika infection (and microcephaly isn't necessarily a death sentence). In other words, investors could be going a bit overboard with this move higher.

I would personally suggest paying attention to Intrexon's partnership with Ziopharm Oncology for CAR-T cancer therapies, because that's where the real value of Intrexon likely lies.