By Lindy Browning | Contributing Writer. Rocky Mountain Voice
As if there aren’t enough controversies around the consequences of wolf reintroduction in Colorado — impacts to livestock growers, impacts to deer, elk and other ungulate herds — there is another danger that has gone mostly unspoken by wildlife officials.
This danger is to humans, predominantly children, transferred to them by their beloved pets, after being exposed to the parasite. Echinococcus granulosus is a parasitic tapeworm that transfers to deer, domestic cattle, domestic sheep, elk and moose, along with domestic cattle, sheep, domestic pets and humans.
Interestingly, infestations of the parasites are relatively benign to wolves, but for the ungulates wild and domestic, and pets, the risk of transfer to humans increases.
Although CPW knows about the parasite infestation called Echinococcus granulosus, as verified by emails obtained by the Colorado Conservation Alliance (CCA), they have not openly discussed the actual danger to ungulates, livestock, domestic dogs and humans.
In emails in March 2020, between Reid DeWalt, Brian Dreher, David Klute, Eric Odell, Jeff Ver-Steeg and Mary Wood, all of whom are Colorado Parks & Wildlife and Department of Natural Resources staff, and Jeff Goncalves of CPW, who forwarded a lab report to the aforementioned individuals confirming that the parasite was in fact present in Grand County, where wolves were predating on livestock.
Josh Dilly of CPW also forwarded the necropsy report for a moose that was infested with the parasite and euthanized because of her poor body condition in Grand County in 2017. Wolves had already migrated into Colorado at that time.
The report reads that a female moose had been staying in and around a resident’s yard off and on for a month. CPW was called as the resident was concerned for the moose. When CPW arrived, they noted that the moose was in very poor body condition, drooling and had one eye that was cloudy and swollen. CPW shot the moose and took her for necropsy. The diagnosis listed in the report was Hydatid Disease. She tested negative for Chronic Wasting Disease.
In 2019, Veterinarian Dr. Carrie Schmidt authored two separate pathology reports on beef cattle that had died as a result of Hydatid Disease in Colorado.
Veterinarian Dr. Jenifer Chatfield said in a report to Colorado Cattlemen’s Association, “Translocation of wildlife is rarely a good idea and typically results in negative outcomes for the wildlife. Public health consequences can be significant and are frequently cited as the basis to prohibit the public from relocating or translocating native wildlife.”
Continuing the report, she said, “Human Hydatid disease is a parasitic disease that affects an estimated two to three million people and results in an annual monetary loss of over $750 million worldwide. The only treatment for human Hydatid disease is surgery to remove the cysts from the affected organ(s) or aspirate and inject chemicals, as traditional anti-parasitic drugs are largely ineffective against the encysted parasite.”
As it pertains to human health, Schmidt said, “Treatment is difficult, costly and risky. Canids, such as wolves, dogs and coyotes, are the only definitive hosts producing the infective stage of the parasite in their feces. In order to most effectively prevent human infection is to remove the definitive hosts from the area.”
Most people are not going to give up their pets.
“If one is interested in preventing this awful disease in Colorado families, the solution is fairly straight-forward: eliminate the introduced definitive hosts. Given the financial burden generated by human infections and potential economic losses to livestock producers, prudence would dictate that any translocated wolves from a Hydatid endemic region be avoided,” the report summarized.
According to information from a CDC report issued in 2024, “A person who is infected with the parasite will develop symptoms, usually involving the liver or the lungs, but can also be found in other organs of the body. Because the cysts are slow-growing, infection with CE may not produce any symptoms for many years. Pain or discomfort in the upper abdominal region or chest, nausea, vomiting, or coughing may occur as a result of the growing cysts. Rupture of cyst fluid can lead to allergic reactions or even death. If humans need treatment for the parasite, surgery followed by a medication regimen may be required.”
“Until recently, surgery was the only option for treatment of CE. However, now medication and a modified surgical procedure (aspiration) are increasingly used and can replace the need for surgical removal of the hydatid cysts. Even so, surgery may be necessary in certain circumstances. After surgery, medication may be needed to keep the cyst from growing back,” reads the CDC report .
According to Oregon Fish and Wildlife (OFW), wolves are known to be infected with Echinococcus granulosus, a parasitic tapeworm that can infect wolves and other canine species. It’s also known as Cystic Hydatid Disease.
According to Western Predator Control Association, Veterinarian Dr. Rodney E. Evans, wrote in a letter to a Colorado Judicial Panel, ”Praziquantel, an anti-parasitic medication, only kills the adult tapeworms and it is questionable how many adults can be killed with the allowable doses for canines.”
W. Evan Secori and Susan Montgomery wrote in a 2015 paper that “Praziquantel is only effective against adult parasites and a single treatment may not kill all the worms.”
“Since wolves are constantly eating hydatid cysts and sub-adult stages along with adult stages, they are, under normal conditions, carrying hundreds of thousands of adults along with millions of sub-adult stages of tapeworms. Praziquantel kills some of the adults, leaving some adults to hatch in addition to millions of sub-adults maturing all the time within the digestive tract,” Evans concluded.
In Evans’ final written words he says, “The wolf reintroduction into Colorado has, as it did in Idaho, polarized the people. Those that want the wolves want them whatever it costs. They don’t want to know about the tapeworm. The polarization is the reason we don’t reveal the identity of the person infected by the tapeworm. The family fears for their safety. Polarization is why we got a bomb threat against a town meeting. We had to get the word out about the tapeworm the wolves were carrying.”
When people read the information from the veterinarians, scientists and CDC, many of them believe that, once again, CPW senior staff employees have deliberately lied.