A hantavirus outbreak aboard a luxury cruise ship that has left three people dead is veering into the fringe.

Online, a growing number of social media users are floating ivermectin as a possible treatment for the rare infectious disease, which can cause life-threatening heart and lung complications.

Yes, you read that right — the antiparasitic drug used in livestock that became a pandemic-era flashpoint after being touted by media figures, politicians and even some doctors as a Covid cure is back in the spotlight.

“Hantavirus is a RNA virus, and ivermectin should work against it,” Dr. Mary Talley Bowden, a Houston-based, board-certified ear, nose and throat (ENT) specialist, posted on X Wednesday. She also teased that she would soon be selling it directly to Texans, “no prescription needed.”

Her comments were amplified by former Rep. Marjorie Taylor Greene, who previously promoted the drug as an alternative Covid treatment.

In a quote of Bowden’s post, the former Georgia Republican wrote: “I actually texted her today and asked what can we treat hantavirus with. I’m so glad she posted it. Ivermectin.”

Greene also suggested that vitamin D and zinc may also be effective against hantavirus, adding: “Those of us who refused to lockdown, mask up, and get vaxxed took the good ole horse paste and also developed natural immunity.”

The one-time congressional firebrand and Bowden aren’t alone. On X, a growing mix of users — from doctors to internet personalities — have been pushing ivermectin as possible hantavirus treatments.

But infectious disease experts say there’s no scientific evidence to support the claims.

“There’s no data to show that ivermectin could help treat the virus,” Dr. Suraj Saggar, chief of infectious disease at Holy Name Medical Center in Teaneck, NJ, told The Post.

The ivermectin theory

Hantaviruses are RNA viruses, which follow a specific blueprint for replicating themselves. Bowen argued that ivermectin can stop RNA viruses from getting into cells, slow down how they multiply and damage the virus itself.

But Dr. Steven Quay, a physician-scientist and biotech entrepreneur, poured cold water on the claim.

“Ivermectin is primarily an anti-parasitic drug, not a proven broad antiviral,” he said. Though some lab studies have suggested there might be antiviral effects under artificial conditions, that doesn’t “automatically translate into effective human treatment.”

It would be a “leap,” he said — that’s “not scientifically justified”

Experts say the bigger issue is that ivermectin was designed to target parasites — not viruses.

“Do not bet your lungs on a theory.”

Dr. Steven Quay

“Ivermectin binds to specific nerve and muscle signal receptors in parasites which paralyze and kill them,” said Dr. Bruce Hirsch, an attending physician in the division of infectious diseases at Northwell Health.

“Ivermectin does not impact receptors in the human body,” he continued. “Hantaviruses have no nerves or muscles of course and ivermectin does not impact viruses at all.”

Asked to expand on her comments, Bowden said: “To my knowledge, no one has studied ivermectin as a treatment for hantavirus.”

“Ivermectin has multiple anti-viral and anti-inflammatory properties that could potentially work against hantavirus,” she continued.

What are hantaviruses?

They are a family of viruses that humans primarily contract by inhaling particles from infected rodent droppings, urine or nesting materials.

But health officials believe the outbreak aboard the MV Hondius was caused by the much rarer Andes strain, which is unique because it can spread from person to person and carries a mortality rate of roughly 40%, according to the World Health Organization.

As of Wednesday evening, three passengers had died and several others had fallen ill.

In the US, hantavirus infections are rare, averaging about 30 cases a year over the last two decades, according to Quay, the CEO of Atossa Therapeutics.

It can trigger two severe diseases.

The first, hantavirus cardiopulmonary syndrome (HCPS), is the more common form seen in the US. It typically begins with flu-like symptoms before rapidly progressing to breathing trouble. In severe cases, fluid builds up in the lungs, leading to potentially fatal heart and lung complications.

The second, hemorrhagic fever with renal syndrome (HFRS), is more common in Europe and Asia and primarily attacks the kidneys.

What actually works to treat hantavirus?

Researchers have previously studied whether the antiviral medication ribavirin could help treat HCPS, but human studies have not shown a significant benefit.

“If even ribavirin, a real antiviral with hantavirus-related data, has not proven useful for the pulmonary form, ivermectin is several steps further away from evidence,” Quay said.

Instead, Quay, Hirsch and Saggar said treatment generally centers on supportive care — helping patients survive the virus while the body fights it off.

“Some cases require a massive amount of extra fluids,” Hirsch said. “Patients sometimes need the support of ventilators and even temporary heart-lung machines to get through the worst of it.”

For patients with HFRS, dialysis is sometimes used, and ribavirin may be administered intravenously if the illness is caught early enough to prevent death.

Asked what he would tell someone considering ivermectin to prevent or treat hantavirus, Quay put it bluntly: “Do not bet your lungs on a theory.”

“Hantavirus can move from flu-like symptoms to respiratory failure with frightening speed,” he warned. “The treatment that saves lives is not a pill from the internet; it is early medical evaluation, hospital monitoring, oxygen, ICU-level support and rapid escalation if breathing or blood pressure deteriorate.

“Ivermectin has no credible evidence for hantavirus prevention or treatment, and using it may delay the care that actually matters.”

As for claims that vitamin D and zinc may also help with hantavirus, Hirsch said they don’t work against the virus itself, though they can be supplemented if levels are low as part of general nutritional support during the acute infection.

Is ivermectin dangerous?

In a statement to The Post, Bowden called ivermectin “incredibly safe.”

“I’ve used it in thousands of patients and believe it should be available over the counter,” she said.

Quay noted that ivermectin is generally well tolerated when prescribed at approved doses for parasitic infections, but problems can arise when people self-medicate, take veterinary formulations or consume high doses.

“Reported toxicities include nausea, vomiting, diarrhea, low blood pressure, dizziness, confusion, hallucinations, seizures, coma, and in severe cases serious neurologic injury,” Quay said.

As of Thursday, at least six Americans from the hantavirus-infected cruise ship had returned home to four states and were being monitored for symptoms.

None currently show signs of infection, but their return has still fueled fears that the virus could spread in the US. Public health experts, however, say the overall risk remains low.

“This is not something anyone should worry about,” Quay said.