As news of rising Zika infections strike fear and anxiety among Americans, savvy investors see opportunity. Many are quietly plunking down cash into companies that are offering products to prevent, diagnose and, in some cases, wipe out the virus. But investors should scrutinize valuations and risks carefully as some companies offer potentially bigger windfalls than others.

Spectrum Brands Holdings (SPB) - Get Report , which makes mosquito repellent sprays, is among those that could potentially benefit from the viral outbreak. With Americans slathering on bug-spray whenever they go outdoors and retailers scrambling to meet the surge in demand, there's little doubt bug-spray makers will cash in. However, experts say this product represents such a small part of Spectrum's total revenue that even if its bug-spray sales rose ten-fold, it wouldn't lift the company's earnings per share much. "No one product accounts for more than 2% of the company's revenue," said one analyst, who did not wish to be named.

Still, the company has benefited "from heightened consumer awareness of the Zika virus," said Bill Schmitz, a research analyst at Deutsche Bank, in a note. Indeed, Spectrum's shares recently surged to a 52-week high of $133.47 from their low of $87.65 set in January. But they could still go higher: Schmitz has a 12-month price target on the stock of $140.

One of the biggest potential beneficiaries of the Zika scare is Intrexon Corp. (XON) - Get Report , whose Oxitec unit makes genetically modified mosquitoes that could kill off the mosquitoes that carry the Zika virus. The modified insects have been successful in trials done in Piracicaba, Brazil in the past year. "They've had a 90%-plus efficacy in the first six to nine months of eradication," said Ryan MacDonald, a senior analyst at Wunderlich Securities. Plans are now in the works to conduct an FDA-related trial in the Florida Keys.

Once the trial is over and the company gets Food and Drug Administration approval, MacDonald estimates the mosquito program could add $1.8 billion to the company's revenue line.

However, some feisty Florida Keys residents are trying to derail the company's plan. They don't want genetically modified mosquitoes unleashed in their community. The FDA trial has now been put on hold until after a November referendum on the issue.

Analysts believe the community concerns are overblown. They note that chemicals currently being sprayed in Miami pose a far bigger risk.

"Chemical sprays are far more dangerous to humans and to the general environment than these mosquitoes," said Keith Markey, science director at Griffin Securities.

Despite the delays, analysts see huge potential gains once the program does get the FDA's blessing.

Intrexon's shares recently traded at $25.45, but MacDonald has a 12-month price target on the stock of $50. Other analysts are even more bullish, with Markey's price target at $55 and Shrader's at $57.

Several other companies - Roche Holding (RHHBY) , Luminex (LMNX) - Get Report , Quest Diagnostics (DGX) - Get Report , and Hologic Inc. (HOLX) - Get Report - are also on investors' radars. The companies recently received special FDA "emergency use" approval for their Zika diagnostic tests, which can now be used to detect the virus in the blood supply or in people. And since the FDA last week recommended all blood centers in the U.S. start screening for the Zika virus, demand for the tests should pop.

The stocks have ticked up on the news. However, in some cases, a surge in Zika test kit sales won't move the needle much on the company's overall earnings. At Roche, for example, the diagnostic division represents less than 20% of the company's total revenue, analysts said.

Other potential beneficiaries of the Zika outbreak are OraSure Technologies (OSUR) - Get Report and Inovio Pharmaceuticals (INO) - Get Report , which are both developing products.

OraSure received $16.6 million in federal funding to develop a rapid Zika antibody test, similar to ones it currently has for HIV, HCV, and Ebola. Karen Koski, a director and senior analyst at BTIG, expects the test, once developed, to bring in far more cash than its Ebola test kit, which generated $2.3 million in revenue in fiscal 2015.

"Ebola kind of came and went relatively quickly in the developed world," because it was easy to see when someone was infected, said Koski. "Whereas most people with Zika are asymptomatic, where the only way to really know is to test people."

However, Koski believes much of the upside is already priced into the OraSure's stock. "The stock has run up a lot recently," she said.

Analysts are bullish on Inovio for its work on a Zika vaccine. "Inovio has the early lead in the Zika vaccine race," said Thomas Shrader, an analyst at Stifel, in a note. The shares recently traded at $9.45, but Shrader has a 12-month price target on the stock of $13.

As of August 24, the Centers for Disease Control and Prevention had reported 2,517 confirmed cases of the Zika virus in the U.S., with 548 affecting pregnant women. Most infections came from travelers, except for Florida, where 29 cases involved people being bitten by local mosquitoes, which created a public panic. More than 9,000 other cases have been reported in U.S. territories, such as Puerto Rico and the U.S. Virgin Islands, the CDC said. There is currently no cure.

The virus poses the biggest threat to pregnant women as it has been linked to microcephaly, which is a birth defect that causes babies to be born with unusually small heads and possible developmental problems.

This article is commentary by an independent contributor. At the time of publication, the author held TK positions in the stocks mentioned.