May 20, 2018

Human Hydatid Disease: A Warning to Trappers and Hunters

Print Friendly, PDF & Email

HYDATID DISEASE
(Echinococcosis)
By Dave Miller

The disease is the result of an infection caused by tapeworms of the family Taenidae. Of importance, is that the dormancy of this can be up to 50 years. It was previously most common in South & Central America, Middle East, China, and Western North America.

It has now arrived in the Northeast.

This is of equal importance to trappers and hunters alike in Maine and the rest of the Northeast.
Although, some of us in the trapping community have been aware of the disease for a number of years and I was planning to write an article on it eventually, I have moved up its importance. This is based on the fact that IF&W has done research on it and just made the fact that is here public. Some of us assumed it would get here in the near future, but was not aware it had already actually arrived. IF&W presented it publically during Lee Kantar’s recent February presentation of his annual report on moose and deer to the legislature’s IFW Committee. I think trappers along with hunters should have been made aware of it immediately upon its discovery in Maine, considering our possible expose to it.

There are three different forms of echinococcosis found in humans, each of which is caused by the larval stages of different species of the tape worm genus Echinococcus. They are cyctic echinococcosis (the most common), alveolar echinococcosis and the third is polycystic echinococcosis. We are concerned with the first one here caused by echinococcus granulsus.

The first article I have in reference to the disease is part of an Outdoorsman article published about 40 years ago. At that time most readers of the Outdoorsman were from Northwestern Canada and Alaska where the cysts were present in moose and caribou. That article included statistics on the number of reported human deaths resulting from the cysts over a 50 year period. It also addressed the decline in deaths, once outdoorsmen learned what precautions were needed to prevent humans from infection.

It has been reported that in Alaska alone, over 300 cases have been reported in humans since 1950 as a result of canines (primarily wolves) contaminating the landscape with billions of the worm eggs in their scat (feces). The invisible eggs are ingested by wild and domestic animals, and sometimes by humans. It is made airborne by kicking the scat or picking it up to see what the animal has been eating. It can also be spread by wind over large areas. The eggs are very hardy and survive through extreme temperatures and weather for very long periods. The egg hatches in the digestive system of the intermediate host, producing larva.

Once ingested this larvae develops from the egg stage, penetrates the intestinal walls, and moves into the capillary beds (liver, lungs & brain) where they develop into large cysts full of tiny tapeworm heads. It settles there and turns into a bladder-like structure called a hydatid cyst. The cysts eventually kill the infected animals (humans) unless diagnosed and removed surgically. After the death of the intermediate host, its body (animals) is consumed by carnivores suitable as its final host. In their intestines, the protoscolices (the inner layer of the cyst wall that buds and protrudes into the fluid sac) turns inside out, attach and give rise to adult tapeworms, completing its life cycle.

It is important that outdoorsmen (hunters & trappers in particular) know not to kick or touch the scat of canids. Also, the wearing of rubber gloves when field dressing game and/or while fur handling is of upmost importance to prevent infection from the blood and/or internal organs. It must be noted that the tapeworm affects many other mammals from your dog and horse to rodents. For those collecting and using the anis glands for scent making – be forewarned of the direct contact with the scat.

The announcement of a tiny tape worm who’s name most of us can’t pronounce, that had never been reported south of the U.S. and Canadian border is now infecting elk, deer, moose, and even humans is being rapidly spread cross thousands of square miles. It is believed this has resulted from the introduction of the Gray Wolf to our western mountains. The tape worm has been reported in elk, deer, and mountain goats over large areas out west.

Even Sweden and Finland have reported the westerly spread of the disease into their moose herds from from Russian wolves. The Russian wolf population is currently increasing dramatically to the point they are hiring hunters/trappers to reduce the wolf population.

There were plenty of warnings about the spread of this disease by experts. Despite this, various FWS and State Wildlife Departments ignored their warnings. A certain FWS biologist (I have a document that names him – but I won’t here) who was stationed in Alaska and was knowledgeable about the disease was assigned to head up the Northern Rocky Mountain Wolf Recovery Team. He chose not to address or evaluate the impact of wolf recovery on diseases and parasites in the 1993 Draft Environmental Impact Statement (DEIS) provided to the public.

This resulted in alarming a number of experts on pathogens and parasites. One individual (Will Graves) informed the FWS biologist with information including that in Russia wolves carried 50 types of worms & parasites, including Echinococcosis and others with various degrees of danger to both animals and humans. In Graves written testimony in 1993 to the FWS biologist he also cited the results of a 10 year Russia study in which a failure to kill most wolves by each spring resulted in up to 100% parasite infection rate of moose and wild boar with an infection incident of up to 30-40 per animal. Graves’s letter stated that despite the existence of foxes, raccoons and domestic dogs; wolves were always the basic/primary source of parasite infections in the moose and wild boar. He emphasized the toll it could take on domestic livestock, and along with other expert respondents, requested a detailed study on the potential impact wolves would have in regard to carrying, harboring and spreading disease.

In the final 414 page Gray Wolf EIS (FEIS) dated April 14, 1994 only one third of a page addressed Disease and Parasites to & from Wolves (chapter 5 page 55). It stated that “Most respondents who commented on this issue expressed concern about diseases and parasites introduced wolves could transfer to other animals in recovery areas”. Several other statements by the FWS biologist are as simplistic and ignored specific concerns. The FWS implied that Graves “facts” are only his opinion.

Several “other previously unrecognized parasites” in the states where wolves have been introduced have also been found. So our coyotes may well be bringing in new diseases into Maine and the Northeast region.

cyst

lungs1
Cysts found in the lungs of an elk

Share