Patient Zero sat on the edge of his hospital bed, a thin blanket wrapped around his body. His eyes were half-closed, red from crying, and focused on some distant point beyond the sterile white walls. 
In the observation room, Dr. Karen Westfield and her team watched the monitor with a mix of fascination and dread. Patient Zero – also known as Asher Kelley of Richland, OR – was the first victim of a new type of infection. And, if they did their jobs right, he’d also be the last.
“Look what it has already done to him,” Westfield muttered.
Once a robust college athlete, Asher now had a far more delicate frame. His once-muscular arms had slimmed to slender, graceful limbs. His jawline had rounded out, and his skin had developed a softer texture. But what had finally gotten Asher to seek medical attention were the changes to his chest. His pectoral muscles had softened and swelled, developing into small, pert breasts.
But that would only be the beginning.
Westfield glanced at her notes. “Four months ago, he was the epitome of masculinity.”
“Yes.” Dr. Morgan Price adjusted his glasses. “The Sacculina parasite has adapted to human physiology in ways we couldn’t have imagined. The patient was a frequent ocean swimmer. Maybe it invaded his body through a minor wound, then attached itself to the nervous system.”
Westfield reviewed Asher’s bloodwork again, shaking her head at the skewed hormone levels. His testosterone had plummeted while estrogen and progesterone soared. It was as if his body was undergoing a second puberty, but this time in the opposite direction.
“The parasite is essentially castrating him and inducing feminization,” Westfield said. “It’s hijacking his endocrine system, suppressing testosterone production and increasing estrogen levels.”
Price shook his head, “But to what purpose?”
“Ultimately? The same is true for all life on this planet. Reproduction. Male crabs infected with Sacculina become almost indistinguishable from females, even performing female mating behaviors to attract mates and releasing powerful female pheromones.”
Westfield nodded grimly. “And now it’s adapted to humans. God knows how many others Asher may have infected before his symptoms became apparent.”
She turned back to the observation window. “He lived in a remote area and didn’t report any sexual partners recently. But we can’t be sure.”
They watched helplessly over the next few weeks as Asher’s transformation progressed. His hips widened, his waist narrowed, and his voice rose in pitch. Facial hair fell out while his head hair grew longer and lusher.
But the most disturbing changes were behavioral. Asher became coy, almost flirtatious with the male doctors.
Dr. Westfield pored over the latest test results, her brow furrowed. “The parasite has infiltrated his brain chemistry. His serotonin and dopamine levels are through the roof. It’s... it’s making the feminization pleasurable for him. Addictive, even.”
She looked up at Price. “We need to keep all men away from her - him, I mean. The existence of human pheromones may be controversial, but we can’t take any chances.”
Price nodded solemnly. “With a body like that, Asher won’t need pheromones to attract a man. But I agree. We can’t risk further exposure until we understand the transmission vectors.” He paused, his expression troubled. “But Karen, if this parasite has already adapted to humans, and if it’s using pheromones and...and sexual attraction to spread...”
Westfield finished his thought, her voice low with horror. “Then we could be looking at a pandemic unlike anything we’ve ever seen.” She shook her head, trying to dispel the horrifying images that flooded her mind. “A sexually transmitted parasite that feminizes its male hosts, turning them into irresistible lures for further infection.”
Suddenly, an assistant barged into the observation room. “Doctors! They found another case.”
“Where?” Price snapped. “Oregon?”
The assistant shook his head and held up a tablet, his face pale. “No, not Oregon. New York City. A young man checked into a hospital this morning with the same symptoms as Asher.”
Dr. Westfield’s eyes widened in shock. “New York? But that’s on the other side of the country! How could it have spread so far, so fast?”
Price leaned over to study the tablet, his hands shaking slightly. “It says here that the patient recently returned from a spring break trip to Florida. He and his friends spent a week partying with college kids from all over the country.”
Dr. Westfield felt a chill run down her spine. “Florida. Spring break. Thousands of young people, all in close contact, engaging in...”
“Sexual activity,” Price finished, his voice grim. “The perfect breeding ground for a parasite like this.”
The assistant nodded, his face ashen. “There’s more. The patient mentioned that some friends had started showing similar symptoms. Fatigue, mood swings, changes in body shape. But they were all too embarrassed to seek medical attention.”
“Dear Christ,” Westfield said. “This is no longer a medical curiosity. Get the fucking White House on the line. We’re dealing with a potential national emergency.”
Price nodded, already reaching for his phone. “I’ll contact the CDC and Homeland Security. We need to track down everyone who might have been exposed and quarantine them.”
“And pray that it’s not too late,” Westfield added.
As the doctors scrambled to mobilize a response, Asher sat alone in his hospital room, staring at his reflection in the mirror. He ran his hands over his new breasts, marveling at their plump fullness, at the softness of his skin. A small, satisfied smile played across his full, pink lips, imagining all the men he couldn’t wait to meet once he got out of there.
Bill, the tech who brought his food, would do anything he asked, he was pretty sure. Even unlock the door.