“Everything is in place for the perfect storm of disease,” narrator Jeremy Renner says during the film. “And yet almost no one sees the dark clouds gathering.”

Are you scared yet? You should be.

The tiny bloodsuckers we often write off as pesky nuisances during the summer months are the deadliest animals in the world, killing roughly 750,000 people annually.

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The movie shows the human side of the worldwide problem, with the story of a Brazilian mother whose son has microcephaly after she contracted Zika while pregnant; an African boy suffering from malaria; a New York woman who’s permanently disabled after a bout of West Nile; and a husband and wife in Florida who have quarantined themselves in their house, in fear of Zika, after she became pregnant.

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Scarier, these awful stories may become more common for a number of reasons, one of which is globalization.

As Discovery Channel group President Rich Ross put it during a recent phone conversation, mosquitoes “have unrestricted air travel, and they don’t have to pay for luggage. They fly for free.”

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The insects — most of which are not deadly — can be stowaways on commercial flights or end up alongside exports leaving Africa for the United States. They’re a byproduct of international trade and the uptick in personal and professional air travel, and they don’t need much to survive.

As the movie explains, it took three centuries for dengue fever, yellow fever and malaria to make their way from Africa to the Americas and only an additional 16 years for three other mosquito-borne illnesses — West Nile, Zika and Chikungunya — to traverse the globe.

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“In rich countries, there’s almost a naivete about these things,” Bill Gates says during the film. “People are surprised if you have an infectious disease coming in to an area.”

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Globally, malaria is not a disease of the past — it still kills hundreds of thousands of people a year, mostly children. And new illnesses can spread quickly. Zika was only barely on the radar when Canadian director Su Rynard began working on the movie less than a year-and-a-half ago.

“It was kind of a footnote — nobody really knew about it, and in the course of this last year while making the film, it went from something people had never heard of to a crisis according to the World Health Organization,” said Rynard, who also made “The Messenger,” another documentary about the way humans are altering the natural world. “That speaks to the speed of change and it speaks to the future. I think that’s not a one-off — this is how things are going to go.”

Part of that speed is due to changing temperatures. Climate change is about more than a polar bear on an ice floe, Rynard said. It’s also about diseases ending up in places they’ve never been before. Deadly mosquitoes used to only live around the equator, but as temperatures rise around the world, the insects are able to survive farther north than they ever could.

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“Humans are driving many species to extinction, but we’re making the world a better place for the mosquito, so mosquitoes are actually on the rise,” Rynard said while in town for the AFI Docs film festival. “The way we live is really creating a problem for ourselves.”

It’s an important moment to consider the problem, as President Trump’s proposed budget will take money away from the Centers for Disease Control and Prevention and the National Institutes of Health, among other scientific agencies.

Former CDC director Tom Frieden has been critical of the potential cuts.

“If the president’s budget went through, it would endanger the lives of Americans,” he said before a recent screening of “Mosquito,” in which he appears. “We would basically have to pull back from the front lines of terrible organisms that we’re helping to keep in check.”

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Frieden believes that movies and pop culture can help people comprehend the magnitude of the danger. For example, after George W. Bush read John Barrie’s historical book “The Great Influenza,” about the deadly 1918 flu outbreak, the president made disease preparedness a priority. And movies like “The Hot Zone” and “Contagion” give some sense of the terrifying repercussions of a pandemic, even if the latter was “a little too optimistic about how quickly we’d get a vaccine out there,” according to Frieden.

“The real point is that public health is about public safety,” he said. Our country’s security depends on more than tanks and ammo.

Frieden does understand why people might get lackadaisical about mosquitoes and their potential to harm on a massive scale. For one thing, they’re tiny and they’re everywhere. It seems hopeless. It’s also difficult to do anything about the problem, which necessitates a multipronged approach that would entail work on a local level as well as the cooperation of countries around the world.

The key is to remember that, even though we can barely see mosquitoes, the threat is there.

“We live in this interconnected world and a disease anywhere is a disease everywhere,” Rynard said. “There’s no borders or walls we can put up to protect ourselves from disease.”