GENERAL ARTICLES

War on the Parasite

In the "New Bug Building" at Ste. Anne de Bellevue, scientists are handing a drubbing to an age-old enemy of Man

H. G. COCHRANE March 15 1940
GENERAL ARTICLES

War on the Parasite

In the "New Bug Building" at Ste. Anne de Bellevue, scientists are handing a drubbing to an age-old enemy of Man

H. G. COCHRANE March 15 1940

War on the Parasite

H. G. COCHRANE

In the "New Bug Building" at Ste. Anne de Bellevue, scientists are handing a drubbing to an age-old enemy of Man

WHAT should we feed an orphaned sleigh-dog puppy? Is it safe to eat that rabbit the Smiths sent us? Should baby be allowed to play with a cat? Where did I get this “swimmer’s itch”? What is killing off all the sheep this year? Should we murder our parrot?

These are just samples of the thousands of questions for which answers are being sought and found at the new Institute of Parasitology at Ste Anne de Bellevue, Quebec. This Institute—housed in a building familiarly known as the “New Bug Building,” which is the latest addition to the group clustered around beautiful Macdonald College campus—was inaugurated in 1932. While it is a department of McGill University, it is directed by a joint committee of the National Research Council and McGill University, with representatives of the Departments of Agriculture of Quebec, Ontario and the Dominion, and the Imperial Bureau of Agricultural Parasitology.

The only institute of its kind in Canada, and the only Animal Parasitology Institute in the world, its main objective is research, and more research.' Its secondary function is education—lectures, films, short courses for veterinarians, post-graduate degrees. It comes under McGill for discipline, under the McGill and Research Council joint committee for administration, under McGill and the Research Council for pay and rations.

Were you to visit the Institute without a guide, you would have difficulty in making up your mind whether you were in a pet shop, a sheep barn, a chemistry laboratory, a butcher shop, an aquarium, or a greenhouse. Here, a staff of scientists and internes—men in white—are variously engaged in peering through microscopes, feeding sheep, filing records in the reference library, performing post-mortems on test animals, developing photographs, helping with the birth of a family of guinea pigs—with everything as immaculate as in a hospital. But it is a hospital for forestalling disease rather than for curing it.

Here, Dr. T. W. Cameron, Director of the Institute, a keen, shrewd, analytic Scotsman of Edinburgh University, a scientist with boundless imagination yet with his feet firmly on the ground, may be found from dawn to dark, while lighted windows at late hours testify to the keen interest of all the staff in their work.

The Greeks had a name for social “hangers-on” who surrounded the rich men of the period. They called them “Parasites,” meaning—“those who dine at another’s table.” And so the term and its meaning have passed to those pests which exist at the expense of other animal life. Parasitic worms have been known from earliest times, yet when “bacteria” were discovered, a good many scientists almost forgot about parasites in their headlong zeal for tracking down bacteria, that is, germs of vegetable origin carried in the air, in water, and in food. Greater attention is now being paid to this other great cause of disease— parasites, such as worms and insects.

Losses due to parasites in Canada are far greater than those due to bacteria, and they are increasing steadily. It is because the need for research in this field is so urgent, that %his institute was established to investigate the parasitic diseases of animals and to assist in bringing them under control.

Livestock Losses Cut

AS AN instance, in 1936 studies were commenced to - determine ways of cutting down the tremendous losses to Eastern Canadian sheep breeders due to stomach worms in sheep. While the infection carried in pastures does not survive the rigorous winter climate, for complete control of infection it would be necessary to carry out a thorough treatment of the breeding stock in the spring.

“Here is one of our latest achievements.” said Dr. Cameron, producing a box filled with large white pellets half the size of hen’s eggs and about the consistency of

putty. “These are the result of almost three years of experimenting on how to prevent stomach worms in sheep.

“We first tried the drug phenothiazine, mixed in varied proportions in the animal’s drinking water, later with the feed. But these methods have not proved totally effective, depending for results, as they do, on the animal’s thirst or appetite. Next, the drug was administered in the form of a hard pellet, which generally proved to be insoluble in the stomach. Finally these pills were evolved, and at last we had the answer.” Replying to a question as to what this meant in hard money to the sheep industry, Dr. Cameron continued:

“While these pills are not yet produced commercially, their widespread use, when available, can easily result in doubling the sheep population of Eastern Canada. This w’ould mean an additional national income of close to a million dollars annually for wool alone, and a welcome addition to our scanty wool supply in these days of furious war-knitting activity. On top of this, at least another million dollars a year would be saved on sausage casings that now must be imported from foreign countries. This saving would follow destruction of the parasites which now perforate the interior mechanisms of our Canadian sheep, rendering them useless for this purpose.”

Then take the research carried out for prevention of “warbles.” These are hard lumps found under the skins of cattle, lumps formed by maggots which grow from eggs laid by flies on the skin. This was one of the earliest subjects of research at the Institute.

Dr. Cameron pressed a button and sent to the library for a bulletin on the subject. To show what warbles cost the country, he explained. “Hides from animals infested with warbles bring anywhere from fifty cents to two dollars a hide less. By eliminating warbles, an average of, say, SI .50 per hide, saved on half of the million or more hides marketed in Canada each year, means at least another three quarters of a million dollars to the cattle industry. And then there is the saving due to a reduction of losses in milk production, losses in turn due to the annoyance caused dairy stock by the flies which hatch from the eggs. While these gadflies don't sting, they have a wicked buzz, and keep the cows on the move, often stampeding them.”

A perfect method of control for warbles has been evolved at the Institute, consisting of the swabbing two or

three times a year of infected stock with a mixture of derris root and soap.

“A thorough and widespread treatment of warbleinfected Canadian cattle with this remedy would eliminate warbles completely in a year’s time,” stated Dr. Cameron. “Britain and Denmark were pioneers in this work of fighting warbles, and their methods have been very successful. Losses in Denmark of twenty JXT cent were reduced, over a two-year period, to slightly over four per cent, and while the treatment is slightly different for Canadian conditions, the possibilities are greater, due to the more widespread infection in this country.”

Carriers

ILLIONS of ix?ople—perhaps sixty to seventy JXT 4VJ. cent of the world's population—carry parasites of one sort or another, though not to such a great extent in temperate climates such as Canada, as in the tropics. There, mosquito-borne malaria and flea-carried plague are the great killers, claiming hundreds of thousands of victims yearly. Every member of the animal kingdom carries some sort of parasite, some of them several species. We recall the well-known little rhyme:

“Big fleas, with little fleas on their backs to bite ’em, Little fleas with smaller fleas, and so ad infinitum!”

As a rule these parasites are not harmful to the carrier, but are only seeking a free ride and “board and keep” while they lay eggs to be passed along, to be hatched, and to do their harm elsewhere. Vet these products are so widely scattered that a very small percentage reach their objective. Another interesting thing about parasites is that they are all more or less “specific.” that is. they can develop only in a single species. For instance, a young sheep parasite would not develop if swallowed by a horse. And for these reasons, though every member of the animal kingdom is infested with parasites, every member fortunately does not have parasitic diseases.

The whole trouble started away back in prehistoric times when man first captured animals and confined them for domestic use. In their wild state, they had scattered

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War on the Parasite

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parasite eggs thinly over a wide area. Confined, they spread the same number of parasites thickly over a much smaller one, with increased chances of reaching their carrier or “host.”

With the years, pastures became smaller and permanent, and parasites thicker. Modern methods of transports, too, spread the old species more rapidly and introduced new species.. Their spread today is the more insidious because so few people are aware of it. A farmer may see evidences of worms in his livestock; we may be bitten by insects, but the millions of smaller parasites, and the trillions of their eggs, we never see !

Horses are all infested with parasites; cattle, less seriously so. But it is among sheep, swine and poultry that the greatest losses to stockmen occur, and the smaller the area they are confined in, the greater the degree of infestation. Zoos are ideal breeding places for parasites, especially where overcrowding exists, and if the strictest sanitation is not practiced. Ranches for foxes and other fur-bearing animals are miniature zoos, and many a fox farm has gone into liquidation on account of hookworms, lungworms and other {jests.

Among fish, too, many species are heavily parasitized and quite a number of both human and animal worms are transferred from carrier to carriel by fish. We need not have inhibitions about eating fish, as cooking destroys the effects; yet, alive, fish are always helping in circulating parasites.

Infected Wild Life

CANADA and the United States, with their many national parks and game preserves, are both carrying out a system of segregation. More animals per acre results in more parasites. Artificial protection, closed seasons, and extermination of predatory animals and birds, too, has resulted in other species multiplying faster, resulting again in more parasites. With the spread of agriculture, drainage reduces the water area available for use of ducks and other wild fowl, overcrowding of lakes and marshes is the result, and parasites increase. Birds are forced to seek new kinds of food, and thus may acquire new and more injurious forms of parasites.

Two years ago, in Western Canada, there was formed an organization called “Ducks Unlimited,” financed largely by wealthy United States sportsmen. The organization’s objectives is to arrest the serious depletion of bird population that has occurred in the North and Northwest over the past dry decade. To this end. more water areas are being provided through the creation of reservoirs, and diseases of ducks, and means of preventing them, are being studied.

Scientists can tell us how to kill many of these parasites with drugs, but that is not a permanent cure, and the drugs, too, are often poisonous to the carrier. The obvious course is to prevent parasites from entering the bodies of the carriers at all, to find out all the stages in their cycle of development and to destroy them at some one of those stages. Liver flukes, for example, must carry out part of their development outside of a sheep, in the form of a snail, and destroying these snails—not a difficult matter—will exterminate the disease.

The complete survey of parasites affecting all types of animals native to Canada, now being carried on by the Institute, is getting active support and co-operation from various governmental agencies, such as the Health of Animals Branch, the Parks Branch, the Northwest Territories Branch, the Mounted Police, the Department of Indian Affairs, and the

National Museum, as well as from many private individuals and corporations such as the Hudson’s Bay Company. As an instance, each year when the Hudson’s Bay Company’s icebreaker Nascopie sails for her summer voyage in Arctic waters, she carries scores of garbage cans, and a member of the Institute staff goes along to show the people of the North how to pickle carcasses of small wild animals with formaline solution. Pickled, in the garbage can containers, specimens are returned to Ste. Anne de Bellevue for examination and study.

Many medical men in the far North consider certain worms responsible for the numerous cases of acute appendicitis found there, in the past few years. Trachina worms—often found in undercooked pork and sometimes in Arctic foxes, polar bears and seals—hookworms, tapeworms, liver flukes, blood suckers, cysts and snails, all are patiently and carefully studied, and their life cycles traced out. From this study it may be determined which are of importance to animals and which to man, how sleigh dogs are affected, how “fur cycles” are caused, and what stage in each parasite’s development presents the

best opportunity for its extermination. Cages, tco, are taken north to bring back live specimens of the little lemmings, tiny furred rodents of the North that form the chief article of diet for the white foxes.

Experimental Animals

A SUCCESSFUL laboratory “followup” of these life cycles requires that a menagerie of test animals be kept at the Institute of Parasitology. For, while bacteria may be kept alive in test tubes and studied there, parasites will not live except in some form of carrier. And so there are kept on hand, at all times, hundreds of guinea pigs, mice, rats, muskrats, mink, rabbits, lemming, cats, pigeons, herons, ducks, crocodiles, many kinds of fish from local waters, goldfish, snails, as well as goats and sheep.

The few sheep kept there are unique, in that they are the only ones on the continent—probably in the whole world —which are absolutely free from parasites. Lambs everywhere are born entirely free of parasites, but quickly absorb them from the ewes’ udders or from the pens, bedding, or pasture. Institute sheep, from the moment they were born, have been reared under sanitary conditions, and are used for testing when it is necessary to observe the behavior of any certain type of parasite with which a sheep may be purposely contaminated, while no other species of pest is present in its body.

Two further species of test animals worthy of particular note are kept. One is the South American agouti, a creature the size of a big cat, with long legs, cloven hoofs, no tail, very much like a guinea pig, with similar characteristics and used

for much the same purpose. The other is a tiny, furry animal, halfway in size between a mouse and a rat, called a hamster. Dr. Cameron is very proud of these, for they are extremely rare. Balancing Horace, the daddy of them all, on the palm of his hand, he told us their history :

“Six years ago, in Syria, near Palestine, one pregnant female of this species was captured in a burrow twelve feet underground. Some of the progeny were obtained by Glasgow University, and from there we obtained one pair about a year ago. These have now multiplied until today we have over 300 at the Institute, and are supplying them to laboratories all over the continent. These little beasts are better than guinea pigs because they have no diseases of their own. They have been reared, like the sheep, in absolute sanitation. They are not a smelly animal like a guinea pig. They multiply much faster, about twelve to a litter and a litter every two months; they can breed between the ages of four and eighteen months. They are just as useful for tests as are guinea pigs, yet require only a third of the food.” Here is a sideline industry which, for a time, should help pay the Institute’s payrolls and bills!

To ensure sanitary forage, green feed— free from parasites—a large metal “fodder cabinet” was obtained from Britain, a presentation from Welwyn Metal Products Limited. In it, green feed is growm on trays two feet square, on each of which about nine pounds of corn, six or seven pounds of oats or barley, are spread. Water containing a nutrient mixture suitable for plant growth is sprayed on the grain; the trays are kept lighted, and

heated, with thermostatic control. About forty pounds of forage can be “harvested” per tray per week. From the cabinet the output is ample to keep all the Institute’s livestock in good health the winter through.

Co-operation through extramural experiments, and the obtaining of specimens, is being carried out through many agencies, both public and private, over all of Canada east of the Rockies. British Columbia has been neglected for the time being, due to that province’s climatic conditions. These being similar to Britain, it is found that practically all British Columbia parasitical life is of the temperate climate variety—as exists in the British Isles—and experiments made in Britain fit their case.

While the work of the Institute is mainly devoted to Canadian problems, it is not exclusively local in scope. Canada, with its tremendous area and great variations in climate—arctic, temperate, subtropical—is an ideal centre for Empire research, species of parasites from all three climatès being found.

As to the amount of economic loss annually to the Dominion of Canada through parasites, only a guess may be hazarded; but it would probably run to more than one hundred million dollars. One estimate of the losses due to warbles in cattle alone set the figure at around fifteen millions yearly.

But whatever the total figure, the Institute of Parasitology is coming to be a potent factor in reducing it, and the results w-ill be cumulative. More power to Dr. Cameron and his little staff of men in white!