Seashore finds elk with gut disease

02/04/2016

Five free-ranging tule elk in the Point Reyes National Seashore have tested positive for a lethal gut-wasting infection called Johne’s disease, the first positive results since the seashore began testing elk over a year and a half ago as part of its forthcoming ranch management plan. 

Johne’s disease infects both elk and cows, and can pass between the species, which are mingling more in recent years as two elk herds have grown and encroached on federal pastureland. 

For Ted McIsaac, president of the Point Reyes Seashore Ranchers Association, the positive tests appear to make one solution to the crisis some ranchers say they are facing—moving elk outside the seashore—impossible.

“Now we don’t know what [the park is] gonna do,” Mr. McIsaac said. “Well, we didn’t know what they were gonna do start with. It’s something we’ll have to deal with. It’s another avenue that they can’t use.”

Joe Hobbs, the elk and antelope coordinator at the California Department of Fish and Wildlife, said state policy forbids moving elk with Johne’s. But the policy does not prohibit moving uninfected elk in herds known to carry the disease. 

“We don’t want to create a problem somewhere else. But we look at everything in a totality,” he said. 

Mr. Hobbs said the state is still examining “all available options” for the seashore’s free-ranging elk to help inform the ranching plan. 

That plan will decide how to handle the free herds, which some ranchers say eat forage on lands they lease for cattle, a crucial resource for organic ranches that are required to pasture animals for a certain number of days to maintain that
status. 

A release of the plan’s draft environmental assessment, which will offer distinct management alternatives for elk issues and ranching practices, was previously expected this winter. It is now set for this fall, delayed due to the breadth and complexity of the plan, said the seashore’s superintendent, Cicely Muldoon.

Ultimately, the plan could ban elk from ranches or let them roam where they please—but both ranchers and wildlife advocates are concerned about the passage of the disease between the two species. 

“Given that elk populations have no significant predator control, exceed the [seashore’s] estimated carrying capacity for elk, are known to carry Johnes [sic] disease transmissible to cattle, and now reside within the Pastoral Zone in numbers high enough to have a serious detrimental economic impact on the ranches there, a means of first reducing and then controlling the [park’s] tule elk herd is an immediate necessity,” the rancher’s association wrote in its scoping comments on the plan. “As a first step, all elk should be immediately removed from the Pastoral Zone.”

Wildlife advocates, on the other hand, fear cattle give the disease to the elk. “Johnes [sic] Disease is a major issue….[I]t is a disease of confinement and occurs mainly in dairy herds. If this disease occurs among the elk, it was introduced to them by cattle,” Bruce Keegan, of the Committee for the Preservation of the Tule Elk, wrote in scoping comments.

Yet Ernie Spaletta, who with his wife, Nicola, runs a dairy on C Ranch, where one of the elk herds spends time, said his cattle do not have Johne’s. He was unsure when they last tested the cattle, but he said it is easy to know when animals have Johne’s. “You can tell,” he said. 

Johne’s disease, which typically spreads through manure, can kill its hosts. But infected animals often appear healthy since the bacteria typically lays low for two to 10 years. Animals showing symptoms of the disease, such as weight loss and diarrhea, are typically more contagious. 

It is more common in dairy cattle than in beef cattle because the former keep closer quarters. According to Dave Press, the wildlife biologist for the seashore, 68 percent of dairy cattle carry the disease nationwide, compared to only 8 percent of beef cattle. 

Since May 2014, the seashore has sent a testing center at the University of Wisconsin 517 fecal samples from the two free herds, one around Drakes Beach that spends time on C Ranch, and one that roams Limantour and Home Ranch. The testing program has already cost the seashore at least $25,000, according to Mr. Press.

(The state’s department of food and agriculture has a voluntary testing program for cattle, but ranches are not required to test for Johne’s, since it is not considered a public health risk.)

Of the 487 fecal samples tested so far, all had turned up negative until Tuesday, when the seashore received word that three tested positive from the Drakes Beach herd. (Thirty samples are still being processed.) 

Yet the disease is notoriously difficult to detect. “The bacteria that causes Johne’s is a very elusive bacteria,” Mr. Press said. “There are many testing methods, which all have potential to give false negative results.”

Necropsies are known to provide more accurate, if not definitive, results, and the testing center recommended them. So between last October and December, park staff collected 21 elk carcasses—15 from the Drakes Beach herd and six from the Limantour herd. 

One of those elk had died of natural causes, but the rest were killed for the cause. 

Two of 10 bull samples, all from the Drakes herd, turned up positive for Johne’s in tests conducted at the Wisconsin center. The same samples tested negative under a test at a lab at the University of California, Davis. The park is awaiting results from 11 animals. 

“It helps to illustrate the illusive nature of the bacteria and difficulty of testing,” Mr. Press said of the different
outcomes. 

It also complicates the prospect of moving animals. “The feedback we’ve received [from other agencies] is that when you’re moving animals around, between parks and reserves, there’s always a concern about unknowingly moving diseases…The results of our Johne’s program underscore that concern, since these are animals that we’ve probably sampled before, with many months of negative
results.”

The presence of Johne’s in the seashore dates to at least the 1970s. A study from 1979 found the disease in five of 10 seashore dairy herds, and positive tests have also turned up in elk in the Tomales Point enclosure. 

(Black-tailed deer in the seashore have not been tested, but Johne’s is known to occur in deer generally.)

When the park relocated a small group of elk from Tomales Point to Limantour in 1998 to create a free-ranging herd, the animals were kept in an enclosure for six months before being released.

Some of those elk tested positive for Johne’s at the time, but they were killed before the park let the rest loose. Given the inconclusive nature of testing, however, it’s possible that some infected elk were released.

The Wisconsin testing center has tissue samples from the animals that tested positive in the late ‘90s, so it may be possible for scientists to determine whether the strain found in the two recent bulls matches the old strain. 

“We’re interested to see if this bacterium has been present in elk since Tomales Point, and if it came through the relocation efforts and moved with the elk to Drakes Beach, or if they picked it up subsequently by spending time intermixing with beef and dairy cows,” Mr. Press said. “At this point, we don’t know.”

The seashore has not yet received word on whether those 17-year-old samples are intact enough to yield results.

Meanwhile, the park decided in December to cease testing the Limantour herd, following advice from the Wisconsin center. Mr. Press said the park may revisit that decision, given the positive tests from the Drakes herd and pending results from the dispatched Limantour elk. 

He said the park is not planning to dispatch any more animals.