State animal health officials, northeast New Mexico ranchers and hunting guides remain watchful of domestic animal herds and wildlife just east of the Sangre de Cristo Mountains after an unexpected and so far unexplained kill off of about 100 elk that happened in the area some 10 days ago.

"So far this remains a mystery," reports Dr. Kerry Mower, animal health specialist for the New Mexico Department of Game & Fish. "We have been getting back a number of tests, have walked the area in question and even conducted an aerial survey in an effort to determine the actual cause of death for these elk, but so far nothing has turned up."

Mower said after careful examination he has ruled out any type of human involvement. The animals were not shot and in speaking with property owners and other residents in the area, no indication of mischief or reason to suspect human involvement has surfaced.

All the elk were found dead within a small area on a ranch near Las Vegas, New Mexico, Sept. 27. The following day plant samples were collected from a wide area of the region and toxicologists have ruled out plant poisoning.

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The animals were discovered in a remote region by a hunting guide employed by the owners of the property, which is located in the heart of elk and deer hunting country. It is a popular area where gun and archery hunting is common on the property and on surrounding ranches every year between September and January.

Mower said intense weather this time of year is common in this area of the state and while there were no clear signs of adverse weather related to the incident, investigators did look at the possibility.

New Mexico ranks as the leading U.S. state for the most human deaths by lightning strikes with 1.88 deaths per every million people. Officials checking with agencies that keep tab on the environmental and weather information for the area indicated no lighting strikes observed in the immediate area in recent weeks. Other weather related concerns include flash flood drowning, but this was also ruled out.

"We did a fly over the area in search of other sick or dead animals of any kind and this did not turn up anything either. We also looked for any chance of exposure to toxic chemicals. There are no industrialized operations or even large farms near the area so we eliminated the chance of fertilizer, pesticide or heavy metal contamination. This area is fairly remote," Mower added.

Other tests inconclusive as well

While early water tests indicate a normal presence of bacteria in samples collected from the area, bacteria levels were not considered a major issue, and Mower says the state is still awaiting toxicology reports from out of state on the possibility of disease involvement.

"There has been some talk of epizootic hemorrhagic disease, and it is too early to rule that out completely," he added, but if animal disease or sickness was related to the incident, he is surprised that other sick, dying or dead animals have not been found at this point.

"Epizootic Hemorrhagic Disease (EHD) is not uncommon and we certainly are anxious to get final results back on tests for this and other types of pathogen involvement, but at the moment about all we can say is these deaths are a bit of a mystery. But we continue to follow every trail and hope we may soon discover the cause and nature of the incident," Mower said.

While EHD poses no serious concern to human health, it can be transferred from cervidae to cattle herds and has caused mass deaths of animals in the past, most notably across the Midwest. But officials say ranchers and wildlife officials are well aware of the dangers of the disease and are being watchful and have seen no indications of an occurrence or outbreak of the disease in the region. The tell-tale signs of the disease, such as lesions, erosions or hemorrhages around the lips and in the mouth, did not appear to be prominent in animals discovered dead at the site.

Among the cervidae, EHD is most severe in white-tailed deer. In this species, the morbidity and mortality rates may be as high as 90 percent. Severity of the disease varies from year to year. It also varies with the geographic location. In the U.S. Southeast, most cases are mild and mortality rates are low. In the Midwest and Northeast, EHD typically recurs each year, but can vary from a few scattered cases to severe epizootics with high mortality rates.

"Without the results of the tests that have not yet come back, I suspect we are most probably talking about an incident that involves some type of environmental condition of unknown type or variety," Mower said.

Meanwhile, he says hunters have been ringing the phones for updates and landowners across the region remain on the watch, but he believes there is no food or human safety issues related to the incident and that the hunting season is getting underway as usual. He says any meat harvested from the hunt should be free of any problems that would harm humans.

Also of interest:

New Mexico elk deaths raise warning

Definitive deer study targets rural property owners

Concerns over Chronic Wasting Disease in cervids prompts rule change