Invasive Species by Joseph Wallace Page A

swollen, round, as if someone had surgically implanted an inverted bowl under her skin. Dead center in the swelling was a round black hole, perhaps a third of an inch across.
    Tumbu fly larva,
Sheila thought.
It must be a tumbu fly.
    Anyone who lived in tropical Africa for any length of time had encountered tumbu flies. The adults were innocuous, just one among a billion small winged creatures that infested the tropics. But they had a clever survival trick: They were parasites. And they used large mammals to host their young. Horses, cows, antelopes, and gazelles. Dogs.
    And humans.
    The eggs, laid on the ground or in wet laundry, would hatch into tiny larvae. As soon as one came into contact with a potential host, it would grab hold and then eat its way through the skin and into the flesh.
    It was a perfect home, the mammalian body. Warm, safe from predators, providing abundant food and moisture as the larva matured.
    The first sign of tumbu fly infection was usually a myiasis, a tumorlike swelling that indicated where the tunnel lay. A round opening in the skin, which the larva used as an airhole, confirmed the diagnosis.
    But tumbu fly myiases were tiny, since the larvae rarely exceeded a few centimeters in length. This swelling was different. Judging by the size of the swelling and the airhole, the larva within would have to be huge, a couple of inches long. The biggest Sheila had ever seen.
    As she watched, something wriggled just below the surface of her mother’s skin.
    â€œSheila?”
    She raised her eyes. Megan was staring at her curiously.
    â€œSheila, what’s wrong?”
    Sheila wet her lips, but still her voice was a croak when she spoke. “Mom,” she said, “why didn’t you tell me? You should have gone to the doctor days ago!”
    Megan blinked. “Tell you what?”
    Sheila ground her teeth so hard she could hear them. “This,” she said, pointing. “This!”
    Her mother’s gaze followed the direction of her finger. For a long moment she stared at her swollen belly, but when she lifted her head her face showed no comprehension.
    â€œI don’t know,” she said.
    Sheila felt a kind of cold fear spread outward from her heart. But she had to set it aside. There would be time for more questions later. She had a job to do.
    â€œWell,” she said, “let’s get this thing out of you. I’d guess you’ve got an allergic reaction going on there, too. I’ll put you on prophylactic antibiotics and an antihistamine. The swelling should go down fast once it’s out.”
    Talking to herself, that was what she was doing. Her mother was simply staring at her, as if she hadn’t understood a word. There was definitely something strange about her eyes.
    Sheila stood, stepped over to the supply cabinet, found two ampules of lidocaine hydrochloride. The first she injected near the airhole, to anesthetize the area.
    â€œDon’t.”
    Surprised, Sheila glanced up into her mother’s face. Megan had always been a stoic. Once, though gray-faced from the pain of a broken arm, she hadn’t protested as Sheila had rigged a field splint, nor during the long, bumpy ride to the hospital.
    â€œAlmost done,” Sheila said, trying but failing for the same light tone she used with her young patients. “Just sit still.”
    Megan said, “No. Please.
Sheila.
”
    Sheila wanted to put her hands over her ears. Without responding, she squirted the second dose of lidocaine through the airhole to calm down the larva. It was a lot easier to pull out a sleeping worm than a wriggling one.
    As the anesthetic sluiced into the burrow beneath the skin, she saw a flash of writhing white come to the surface of the airhole, then something black, and then white again.
    Her mother spoke no more. Nor did she make a sound when Sheila reached in with her sterilized thumb forceps, got hold of the larva, and slowly pulled it out of the