"I'll tell you--but you may not understand," Kennon said.

"I'll take a chance."

Kennon grinned. "All right, you asked for it. The parasite that's doing the damage is a flatworm, a trematode called Hepatodirus hominis. As I've told Blalok, it's a tricky thing. Like all trematodes it has a three-stage life cycle, but unlike every other fluke, its life cycle is not fixed to definite intermediate hosts. Depending upon where it is, the fluke adapts. It still must pa.s.s through its life cycle, but its intermediate host need not be one species of snail, fish, or copepod.

Any cold-blooded host will do. What you have here is a Kardonian variant which has adapted to some particular intermediate host on this world.

Until now, its final host was either man or Varl. Now we have a third, the Lani. And apparently they are the most susceptible of the three.

It never kills Varl. And humans, while they're more susceptible, only occasionally succ.u.mb, but the Lani appear to be the most susceptible of all. I've never seen an infestation like those Lani had. Their livers were literally crawling with flukes." Kennon paused and looked at Jordan. "You following me?" he asked.

"Slowly and poorly," Jordan said. "You're a.s.suming too much knowledge on my part."

Kennon chuckled. "You can't say I didn't warn you."

"Well--I'm really interested in only one thing--how do you break the parasite up in business?"

"There's only one sure way--and that's to break the life cycle. The technique is thousands of years old, but it's just as good today as it was then."

"Good--then let's do it."

"To make a varrit stew," Kennon said, "one must first catch the varrit."

"Huh?"

"We have to learn the beastie's life cycle before we can break it, and like I said, it adapts. Its intermediate host can be any one of a hundred cold-blooded animals."

"Is there no place else where it can be attacked?"

"Sure, in the body of the final host, or on its final encysting place.

But that won't eliminate the bug."

"Why not?"

"It'll still survive in its infective form and enough Lani will get subacute dosage to propagate it until the time is right for another epizootic. We have to kill its intermediate host--or hosts if it has more than one. That will keep it from growing and will ultimately eradicate it."

Judson scratched his head. "It sounds complicated."

"It is. It's so complicated that once the fluke becomes well established it's virtually impossible to eradicate."

"And you think it can be done here?"

"We can give it the old college try. But it's going to take some detective work."

"Where do we start?"

"With Bay Ten. We look it over real well. Then we check the diet and habits of the Lani. Then we check each individual Lani. Then we check the life cycle of the parasite. Somewhere along the line if we're lucky we'll find a weak point that can be attacked."

"That's a big order," Blalok said.

"It can't be helped. That's the way it is. Of course, we're lucky that we're on an isolated land ma.s.s. That gives us an advantage. We should be able to clean this up."

"How long do you think it will take?"

"It depends on how well the fluke is established. Six months at the minimum--and I wouldn't care to guess at the maximum. However, I hope the minimum will be time enough."

"So do I," Blalok said.

"Well," Kennon said, "let's get on with it."

"I hope it won't interrupt our program," Jordan said.

"Of course it will interrupt it," Kennon replied. "It can't help it. Get the idea in your head that you're facing something here that can cripple you--maybe abort your whole operation. You have a choice--interrupt now or abort later. And half measures won't work. To eradicate this pest requires an all-out effort."

"But I can't see why we can't merely bypa.s.s Bay Ten--" Jordan said.

"Take my word for it," Kennon said. "You can't. There's no accurate way of telling how far this spreads until the death losses occur. Our tests for fluke infestation aren't that good. We have to work thoroughly and carefully. We can't be b.u.t.ting heads over this--either we all co-operate or this whole operation will blow up in our faces.

"Look at the record. Six months ago you ended a year with no deaths from disease. Five months ago Old Doc and two Lani were ill. Four months ago one of the two Lani was dead and Old Doc was too ill to be effective.

Three months ago Old Doc and the other Lani were dead, and before the end of the month two more followed them. Two months ago six died, last month eight, and so far this month you've lost four and you have over two weeks to go. Up to now they've all been from here, but two this month were at other stations. In six months if nothing is done, we'll be having losses there unless we're lucky. And the losses will keep on increasing. Apparently you don't know what it is to live with parasites--so let me tell you. It isn't pleasant!"

Blalok shrugged. "You needn't get hot about it," he said. "After all, you're the Doc--and we'll co-operate."

Jordan nodded. "We will," he said. "All the way."

CHAPTER X

There is a special providence that looks over recent veterinary graduates, Kennon reflected as he checked the monthly reports from the Stations. Since the time he had laid down the law to Judson and Blalok, he had had no trouble from the production staff. And for the past four months there had been no further trouble with Hepatodirus. That unwanted visitor had apparently been evicted. At that, they had been lucky. The parasite had been concentrated at Hillside Station and had failed to establish itself in the training area. The intermediate host, it had turned out, was a small amphibian that was susceptible to commercial insecticide. It had been no trouble to eradicate. Systemic treatment and cooking of all food had cleaned up the infective cercaria and individual infections, and after six months of intensive search, quarantine, and investigation, Kennon was morally certain that the disease had been eradicated. The last four reports confirmed his belief.

He sighed as he leaned back in his chair. Blalok was at last convinced that his ideas were right. The hospital was operating as a hospital should, with a staff of twelve Lani kept busy checking the full wards.

Actually, it was working better than it should, since stationmasters all over the island were now shipping in sick animals rather than treating them or requesting outpatient service.

"Hi, Doc," Blalok said as he pushed the door open and looked into the office. "You doing anything?"

"Not at the moment," Kennon said. "Something troubling you?"

"No--just thought I'd drop in for a moment and congratulate you."

"For what?"

"For surviving the first year."

"That won't be for two months yet."

Blalok shook his head. "This is Kardon," he said. "There's only three hundred and two days in our year, ten thirty-day months and two special days at the year's end."

Kennon shrugged. "My contract is Galactic Standard. I still have two months to go. But how come the ten-month year? Most other planets have twelve, regardless of the number of days."

"Old Alexander liked thirty-day months."