December 10, 2018

Hydatid Disease: Man Has Gotten This Disease Since the Domestication of Dogs

Recently, Prof. Dr. P. R. Torgerson, PhD, VetMB, DipECVPH, Professor of Veterinary Epidemiology Vetsuisse Faculty, published an article titled, “Frequency Distributions of Helminths of Wolves in Kazakhstan.”

The Summary reads as follows:

Summary of “Frequency distributions of helminths of wolves in Kazakhstan.”

Between 2001 and 2008 a total of 41 wolves (Canis lupus) were necropsied in southern Kazakhstan and their intestinal parasite fauna evaluated. Of these animals 8 (19.5%) were infected with Echinococcus granulosus, 15 (36%) with Taenia spp, 13 (31.7%) with Dypilidium caninum, 5 (12.2%) with Mesocestoides lineatus, 15 (36.6%) with Toxocara canis, 16 (39%) with Toxascaris leonina, 8 (19.5%) with Trichuris vulpis, 9 (22%) with Macracanthorhynchus catulinus and 1 (2.4%) with Moniliformis moniliformis. All parasites had an aggregated distribution which followed a zero inflated or hurdle model. Although a small convenience sample of wolves, the results indicate a high prevalence of infection with E. granulosus. The mean abundance (1275 E. granulosus per wolf) was high with individual infected wolves carrying intensities of several thousand parasites. As wolves are common in Kazakhstan they may act as an important host in the transmission of this zoonotic parasite. The wolves were sampled from an area of Kazakhstan where there is a high prevalence of hydatid cysts in livestock and where echinococcosis has been observed in wild ungulates.

Affiliation

Kazakh State Veterinary Research Institute, Almaty, Kazakhstan.
Journal Details

This article was published in the following journal.

Name: Veterinary parasitology
ISSN: 1873-2550
Pages: 348-51
Links

PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21962968
DOI: http://dx.doi.org/10.1016/j.vetpar.2011.09.004

Will Graves, author of “Wolves in Russia: Anxiety Through the Ages” and co-author of a new book soon to be released about wolves in the United States, having read Dr. Torgerson’s article, sent him an email seeking more information.

He wrote:

I am not a biologist but would like to exchange ideas with you about wolves. I am interested in Echinococcus granulosus and Neospora caninum.

Dr. Togerson replied to Will Graves, Torgerson says:

Dear Mr Graves
Thank you for your interest in our article. However I know little about wolves, other than there are lots of them in Kazakhstan. The primary interest was really in the parasites – especially Echinococcus granulosus. E. granulosus is a very serious zoonosis and in rural areas of Kazakhstan infects about 20% of dogs. It then transmits to people through close contact with dogs causing hydatid disease which is a large cystic lesion in your liver of lungs. The parasite naturally circulates between sheep and dogs. However the parasite almost certainly originated in wild life, probably circulating between wolves and wild ungulates. Man has been getting this disease ever since dogs were domesticated. I work with several scientists in Kazakhstan and the material for the manuscript was supplied by local hunters. In many areas wolves are considered a pest and a danger to livestock, especially as there are so many in Kazakhstan. (emboldening added)

Scientists that have knowledge of Echinococcus granulosus, i.e. Dr. Delane Kritsky, Dr. Valerius Geist, among others, have been trying to educate the public about where the real risk to humans comes from contracting human hydatid disease. Here we have Dr. Torgerson, in a region of the world where historically wolves have always been present, telling us that, “Man has been getting this disease ever since dogs were domesticated.”

The threat comes from free ranging dogs in rural settings that come in contact with the E.G. eggs through multiple sources. The dogs bring those eggs home with them running the risk of humans ingesting the tiny eggs.

But there exist some alarming figures that need to be shared. Dr. Torgerson says that of the 41 wolves he tested, 19.5%, or 8 of the wolves, tested positive for Echinococcus granulosus. As a result, Dr. Torgerson says that about 20% of domestic dogs become infected. Those numbers are startling enough. However, consider these numbers from Idaho.

According to Steve Alder of Idaho for Wildlife, in a recent email sent out, nearly 100% of recent necropsied wolves were infected with Echinococcus granulosus. If nearly 20% of infected wolf populations in Kazakhstan translates into about 20% of infected domestic dogs, what does this mean for Idaho?

This is a difficult thing to determine as certainly we don’t know the similarities in geography and population demographics of wolves and humans between Idaho and Kazakhstan. Nor do we know what kind of veterinary care exists between the two populations.

It is often said in this country that Echinococcus granulosus has never been a problem. That may be true but does the United States, particularly the lower 48 states, where denser human populations are exposed to wolf populations, have any real history of wolves and humans sharing the landscape?

This is why information that comes to us from areas around the world where that history is long can be helpful to us…..if only we would listen closely and learn. Dr. Torgerson says that hydatid disease in humans has existed since the domestication of dogs and yet people in this country refuse to except that fact, even though there now are thousands of wolves roaming the forests in parts of this nation.

The sooner doctors, scientists and canine lovers recognize this disease, along with many others carried by the wolf, the sooner we can all learn how best to protect ourselves, our children, pets and livestock. What’s wrong with that?

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Hydatid Cyst Transmission and Growth

Hydatid Cyst Transmission and Growth
February 22, 2013
Author: Clayton H. Dethlefsen
Chairman and Executive Director
Western Predator Control Association

ISSUE: Can Hydatid Cysts cause the development of Hydatid Disease without the Transmission of E.g. Tapeworm Eggs through their expulsion in the fecal discharge of Canines?
 
DISCUSSION:

Key Point: Transmission from Hydatid Cysts that directly creates a new Cyst happens.  The only question is how this happens.
 
Ungulates with multiple Cyst including humans generally get them when Cyst that they already have burst or seep causing the Protoscolices (Hydatid Sand and/or the Cyst Fluid) to migrate to new location within the body.  Mostly these new cysts grow within the same body cavity or the same or immediately adjacent vital organs.

Hydatid Fluid contains tapeworm larva that have heads with connected tails that look much the same as swimming frog pollywogs. This fluid is often referred to as Hydatid Sand, which, if it gets into the circulation or respiratory system, can flow its way to new ungulate body locations.  Also, new cyst can form, if the initial Cyst was in the eye, in the eye socket, and if the initial Cyst was in bone marrow, new Cysts (because of the bone’s structure) are habitually confined to the bone’s cavity. Also, Cysts form in the tracheal and bronchial tubes, particularly where the Trachea branches into the Bronchi, or at a subcutaneous location if Sand from a burst or leaking cyst moves to these locations.
 
A good number of multiple cysts have developed from leakage of cystic fluid during surgical procedures including Puncture, Aspiration, Irrigation and Reaspiration (PAIR) and/or biopsy procedures used to determine if in fact a cyst is an Echinococcus granulosus (E.g.) product.  Most medical research on children and operations on these patients have been done in their brain cavity where PAIR and biopsy processes are extremely restricted. When secondary Cysts do form adjacent to vital organs or in adjacent brain locations, including those that form post operation, they cause a resurgence of nearly identical patient symptoms and problems. However, if the Sand migrates to other body locations the symptoms are usually somewhat different, as is their medical impact.

(Keep in mind that symptoms of Hydatid Cyst involvement are numerous, dependent on their location, and are similar to other vital organ maladies and/or infections such as tumors or bacterial infections which cause physical pressure increases and/or the destruction/decaying of organ tissue in circulation, respirations, digestion, etc. systems.)
 
The question of whether a person can get a cyst or cysts from puncturing them while field dressing game or butchering domestic animals comes up frequently.  In considering this we have to understand that viable (infectious) Hydatid Sand must get directly into a susceptible body cavity and/or vital organ, and the environment surrounding a cyst’s growth must nearly approximate the hermetically sealed or the surgical environment that is inherent with the formation of a new cyst, or a secondary cyst from an original leaking or bursting cyst.
 
We have positive medical records with photographs that show cysts occurring in human eyes, bone marrow and from external injection in subcutaneous tissue. We also know that cysts form internally in the vital organs and at the juncture of the trachea and bronchial transition. The cysts that occur at these non-normal locations form as a result of unusual circumstances, which generally do not include free movement of E.g. Eggs or Hydatid Sand through the normal process, i.e. the ungulate’s circulation system.
 
In the cases of Eye Cysts, Trachea and Bronchial Cysts and Subcutaneous Cysts, Cyst formation, normal and non-normal, has had only limited medical evaluation; therefore, no absolutely definitive formation-origin or cause has been confirmed. But several doctors and/or medical researchers believe that it is feasible that cysts in these locations can and do start with the direct-to-the-site, as opposed to by the normal circulatory system, introduction of E. g Eggs and/or Hydatid Sand from external sources and by external means.
 
The circulation system in the eye cavity where eye-cyst growth starts is primarily at the end of the circulation system, where very tiny capillaries distribute blood, and where the eye socket is warm and well lubricated. This fact and the fact that normal cyst formation is nearly always in the nearest and most easily accessible vital organ (fed by large veins and arteries) makes it highly improbable that eye cysts, for example, would be sourced through the ungulates digestive system with subsequent movement by blood-flow through capillaries. It is therefore more possible that initial and secondary eye cysts, as well as, subcutaneous, some bone marrow (reference broken bones) and bronchial and trachea cysts can and do occur as a result of more direct contact with and movement by outside physical transmission means.
 
Further, the normal development and passage of E.g. eggs (at this point they have developed into oncospheres) directs that they in sequence attach/seat themselves in major vital organs such as Liver, Kidney, Lungs and Heart, and as often in the case of children in the child’s Brain, and not further down the very constricted recesses of the circulation corridor. It is therefore most reasonable to conclude that cysts in the eye socket, bone marrow, and in subcutaneous tissue, as well as at the junction of the trachea and bronchi come by way of other transmission means.
 
From confirming medical data, specifically patient records and medical research, we find, conclusively, that cysts can develop and have developed from seeping or burst cysts, particularly when multiple cysts are found, and specifically without the introduction of new E.g. eggs (oncospheres). What is not clear, particularly with cyst that form from surgical procedures (where the body cavity is open to an external atmosphere) is how long Hydatid Sand will maintain a viable-infectious protoscolices loading or allow secondary cysts to grow after the patient’s surgery has concluded and the patient’s surgical site is closed.
 
During surgical procedures (a very sterile process in a maintained-sterile external environment) it is confirmed that Sand/Protoscolices exposure, because of the normal length of a surgical procedure, has been and is many hours. Hence it is reasonable and logical to conclude that (in the near-term) time of exposure of Hydatid Sand to an external environment seems to have little degradation or death effect which would prevent the formation of secondary cysts from Hydatid Sand.
 
Taking all this factually based information and using the “Reasonable Person” method of assessment, it is logical to assert that both primary and secondary Hydatid Cysts can form in ungulates if Hydatid Fluid flows, is inhaled/ingested or is injected from an external source (Elk, Deer, domestic sheep, cattle, etc.) into a human. Of course this Hydatid Fluid needs to move into open human and other ungulate orifices (mouths, bleeding cuts, nose, eye sockets, etc.) from where Hydatid fluid movement continues into susceptible body nodes through normal respiratory and/or bodily flow processes. Although rare, this action can and does happen.

It has been medically determined and medically reported that cysts can form in the respiratory system at and near the junction of the trachea and bronchial connection, in subcutaneous tissue through injection and direct contact with an open wound, and in a very wetted eye cavity. It is also a medical fact the E.g. eggs and subsequently oncospheres survive the passage through the hostile digestive environment in ungulates and that scolices/protoscolices are unharmed in the hostile canine and human digestive, circulatory, respiratory systems. If these conclusions were not factual the E.g. life cycle would have terminated centuries ago.
 
It has also been established that human hands, insects such as coprophagic flies and wasps, and wind are transporters of E.g. eggs from one point to another, and that ingestion, injection and inhalation are all primary means by which E.g. is transmitted. Thus, open access to Hydatid Sand with viable protoscolices from a burst or seeping cyst can also be transmitted by these means, and can henceforth be inhaled, ingested and/or injected into an ungulate with the result being the formation of new and/or secondary Hydatid Cyst.

CONCLUSION:

Fact–Humans get secondary Hydatid Cyst from internally located bursting and/or seeping Cysts.

Too, in the case of humans (hunters, butchers, etc.) it is not only feasible but it is truly possible for people to get Hydatid Cysts from an ungulate’s exposed Hydatid Cysts. This occurs when Hydatid Sand from a Cyst that has burst and/or is seeping comes into contacted with a human’s transmission means, and thereafter, this Hydatid Cyst Fluid (with viable Protoscolices) enters external body orifices. Transmission by hands or by having Sand surge or gush in some other manner into external orifices of the body are such means; hence, Cysts do not occur just from direct involvement with E.g. Eggs.

*Editor’s Note* – I presented this article to Dr. Delane Kritsky, noted parasitologist from Idaho State University. In particular I wanted clarification, once again, that hunters and trappers are not in danger of contracting hydatid disease simply by handling game animals that may have hydatid cysts. Here is Dr. Kritsky’s response:

Tom: It is true that if a cyst is ruptured within your body, it will result in new cysts developing. In addition, it is possible to inject material from a cyst from one host into a new host which will result in development of a cyst (or cysts) in the new host (This is often done to maintain E. granulosus and E. multilocularis in laboratory animals); injection is usually within the body cavity; this is one of the dangers associated with surgical removal of cysts — rupture and the release of the hydatid sand into the body cavity during surgery could result in new cyst development in the patient. However, there is no danger in becoming infected just by handling (or eating) a cyst that might have been present in a harvested animal. delane

 

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Human Hydatid Disease: A Warning to Trappers and Hunters

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

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Human Echinococcosis Mortality in the United States, 1990–2007

Abstract
Background

Despite the endemic nature of Echinococcus granulosus and Echinococcus multilocularis infection in regions of the United States (US), there is a lack of data on echinococcosis-related mortality. To measure echinococcosis-associated mortality in the US and assess possible racial/ethnic disparities, we reviewed national-death certificate data for an 18-year period.

Methodology/Principal Findings

Echinococcosis-associated deaths from 1990 through 2007 were identified from multiple-cause-coded death records and were combined with US census data to calculate mortality rates. A total of 41 echinococcosis-associated deaths occurred over the 18-year study period. Mortality rates were highest in males, Native Americans, Asians/Pacific Islanders, Hispanics and persons 75 years of age and older. Almost a quarter of fatal echinococcosis-related cases occurred in residents of California. Foreign-born persons accounted for the majority of echinococcosis-related deaths; however, both of the fatalities in Native Americans and almost half of the deaths in whites were among US-born individuals.

Conclusions/Significance

Although uncommon, echinococcosis-related deaths occur in the US. Clinicians should be aware of the diagnosis, particularly in foreign-born patients from Echinococcus endemic areas, and should consider tropical infectious disease consultation early.

Author Summary

Human echinococcosis is a parasitic disease that affects an estimated 2–3 million people and results in an annual monetary loss of over $750,000,000 worldwide. It results in the development of life threatening tissue cysts, primarily in the liver and lung, following accidental ingestion of eggs in infected dog, fox or wild canine feces. Echinococcus parasites have a complex, two-host lifecycle (such as in dogs and sheep) in which humans are an aberrant, dead-end host. The vast majority of cases of human echinococcosis occur outside of the United States (US); however, cases within the US do occur. In this study, the authors examined death certificate data of US residents from 1990–2007 in which echinococcosis was listed as one of the diagnoses at death. The analysis demonstrated 41 echinococcosis-related deaths over the 18-year study period with foreign-born persons accounting for the majority of the deaths. This study helps quantify echinococcosis deaths among US residents and adds further support to the importance of funding echinococcosis prevention research.

<<<Read the Complete Study at National Library of Medicine>>>

In addition, another study involving the presence of cystic echinococcosis in humans was undertaken in Turkey. You can find that information at Research Gate. (Note: You can access the entire study for free but requires a membership form.)

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