Oral History Program Malcolm McDonald Interviewed by Carmen Anderson 14 July 1972 Oral History Program Weber State University Stewart Library Ogden, Utah Malcolm McDonald Interviewed by Carmen Anderson 14 July 1972 Copyright © 2012 by Weber State University, Stewart Library Mission Statement The Oral History Program of the Stewart Library was created to preserve the institutional history of Weber State University and the Davis, Ogden and Weber County communities. By conducting carefully researched, recorded, and transcribed interviews, the Oral History Program creates archival oral histories intended for the widest possible use. Interviews are conducted with the goal of eliciting from each participant a full and accurate account of events. The interviews are transcribed, edited for accuracy and clarity, and reviewed by the interviewees (as available), who are encouraged to augment or correct their spoken words. 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These oral history assignments were created to help Weber State students learn the value and importance of recording public history and to benefit the expansion of the Weber State oral history collections. ____________________________________ Oral history is a method of collecting historical information through recorded interviews between a narrator with firsthand knowledge of historically significant events and a well-informed interviewer, with the goal of preserving substantive additions to the historical record. Because it is primary material, oral history is not intended to present the final, verified, or complete narrative of events. It is a spoken account. 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It is recommended that this oral history be cited as follows: Malcolm McDonald, an oral history by Carmen Anderson, 14 July 2012, WSU Stewart Library Oral History Program, Archives, Stewart Library, Weber State University, Ogden, UT. iii Dr. Wayne Jensen and Dr. Malcolm McDonald Abstract: This is an oral history interview with Dr. Malcolm McDonald, conducted by Carmen Anderson on July 14, 1972 at the Bear River Research Station near Brigham City, Utah. Dr. McDonald is a parasitologist or wildlife research biologist with a specialization in parasitology in the laboratory. He has spent fifteen years working on and studying the parasites of watefowl and the effects of these parasites on animal and human populations. In this interview, Dr. McDonald discusses a major part of his work which was compiling a bibliography of helminths of waterfowl and the worm parasites of waterfowl. CA: Dr. McDonald, would you please tell us a little bit about yourself and how you became interested in your present work? MM: First, I might give my title here. I am a parasitologist or wildlife research biologist with a specializing in parasitology at the laboratory. I've been interested in natural history and wildlife all my life. I started as a bird watcher when I was about ten years old and I have continued with this very intense interest ever since then. I became interested in parasites during college work and was rather fascinated with parasites in wild animals, particularly birds. I obtained a Ph.D. in wildlife management—the study and management of wild animals in natural surroundings—at the University of Michigan. Then I taught college for about ten years. I was teaching in the east, at Schenectady Union College, and took a leave of absence to teach at the University of Nevada in wildlife courses. This was the first time I had been out in the west. I liked the west so well that I quit my job and stayed out here. At that time, this opening came at Bear River Research 1 Laboratory, working as a parasitologist to work with waterfowl. I applied for the job and obtained it. I've been here fifteen years now, working on and studying the parasites of waterfowl. The major concern is with the effect of parasites on waterfowl and on waterfowl populations. This is a long-term goal and, of course, requires a great deal of study on parasites as well as a great deal of knowledge on the parasites of waterfowl. I've found that parasites of waterfowl are not well known and before I could work on their effects I had to find out what parasites were present and try to obtain data on the numbers of individuals and numbers of species of parasites in waterfowl. I'm still working on this. I have obtained comparatively little information on the effects of parasites on populations. I like to feel that I'm an ecologist working on the ecology of parasites. This, of course, is the basis of a degree in wildlife management. The actual studies I've been carrying on are taxonomic, that is the identification and classification of parasites. It is really preliminary to the major problem with which I'm supposed to be working. I started out by looking at as many different waterfowl as possible, going through them collecting the parasites and then identifying these. This hasn't been done in this country. There has been a great deal of work done on parasites of waterfowl. Most of it, however, was by individuals concerned with a particular group or particular species of parasite, working on the biology of the life cycle and the effects of a single parasite. Usually they have looked at a hundred or so individual birds in order to look for that parasite but they paid no attention to other 2 parasites present. So most of the data—most of the papers that are available—deal with only a single line or small group of parasites. I'm interested in the total parasitism, the joint effect of parasites and am collecting data on all parasites present in birds. This has not been done previously. Since I started, there have been several students that have taken up aspects of this, mostly under my influence or suggestion or encouragement. There are now several papers available which weren't available when I started. I still haven't published very much but I have accumulated a great deal of data in this regard. Waterfowl are widespread—found around the world. Even the same species, Mallard and Pintail, for example, are found throughout Europe and Asia as well as North America, and there is essentially no difference in the forms present. In fact, there are exchanges of Pintail birds flying back and forth between Siberia and North America. With the similarity of waterfowl, there is a similarity of parasites, so the study of parasites can't be done just in North America or the parasites of North America aren't just restricted to this continent. The same parasites are found pretty much throughout the world. In order to identify the parasites of this area, you must be able to study or have access to the literature of parasites in other parts of the world. As soon as I started to try to identify parasites, I found that this was necessary. There wasn't any compilation or any manual or grouping of material necessary for identification so I got involved in trying to run down the references on parasites—the references of parasites in other countries or in other languages. For several years, a major part of my work was compiling a bibliography of helminthes of waterfowl, which are the worm parasites of 3 waterfowl. I compiled information about these parasites from the world literature, confining myself to helminthes of waterfowl. The total field of parasitology is simply too big for any one person to cover. There is a man with the Fish and Wildlife Service at the Patuxent Laboratory in Maryland working on the blood parasites of waterfowl, the blood protozoa of malaria, and similar forms. Since he is working on that phase of parasitology there in Maryland, there was no point in my duplicating his work and so I started working on the helminthes, which weren't being covered at that time. Getting back to the bibliography, I've compiled a bibliography of world literature on helminthes of waterfowl. This was published by the Fish and Wildlife Service several years ago, in about 1965, I believe. The catalog, which is a compilation or summary of all the information available about each one of these parasites, was also published. This runs to a couple of sizable publications spanning several hundred pages. There are something like 2,800 references on helminthes of waterfowl. There are something like 950 or a thousand different species of parasites reported from waterfowl. I am maintaining this interest in the compilation of world literature on helminthes of waterfowl. There is something like 125 to 150 articles per year coming out in this field. I try to get ahold of as many of those as possible to abstract the material and copy it down if there are parasites described. I've accumulated a copy of the descriptions of every parasite reported from waterfowl and have those available for my use. With the completion of the catalog and bibliography, I've gone back to identification, the original reason for working on this literature. I've identified all the nematodes that I've collected so far. 4 There is something like 35 different species of nematodes obtained from waterfowl here at this station. At the present time, I'm working on the cestodes, the tapeworms of the waterfowl, trying to identify them. I've identified some 30 different forms. I have about 30 or 40 unknown forms that are distinct but for which I do not yet have a name. Some of these are new species, some of them are simply forms for which the origin descriptions are not adequate so that I can’t, as yet, be sure which species I have. Most of those will be identified before too long, I hope. The other groups that I'm working with, the other groups of helminthes, include the flukes or trematodes, of which I have identified 20 or 25. I haven't really started doing any work on the trematodes. The leeches involve a couple of species. Then acanthocephala, the thorny-headed worms, involve perhaps 15 or so different species. I've looked at about 400 different individual birds collecting parasites, from which I've been trying to identify parasites. At the present time, I’m carrying on a study of several hundred additional birds for other data, getting the parasites from them but collecting them for specific information rather than just as part of a general survey of the parasites of waterfowl. The general survey involved the first 400 birds I spoke of. Besides the survey and identification of parasites of waterfowl, the other study that I'm carrying on is a study of the relationship of species and numbers of parasites in regard to age of the waterfowl. Taking Mallards and Gadwalls as particular species for this study, I've collected these forms at all ages from the first week of life to adults. I am working out graphs showing the changes in the parasites during the life of the bird, changes in number of parasites, changes in variety of parasites. Each bird l look at 5 I go through from stem to stern or from mouth to anus, cutting open every organ in the bird. Slitting open the complete length of the intestine, the lungs, the trachea, the esophagus, kidney, ureters, the oviducts in the female, the body cavity, the organs of the bird are examined for parasites. This includes the nasal passages, in some cases the brain, blood vessels, heart. The ordinary bird has from 5 to perhaps 23 or 24 different kinds of parasites within it. Usually it runs between 5 and 10 different kinds. In two or three birds I've found none. Usually, there are 5 to 10 individual worms. Sometimes there are up to 50 to 100 thousand. Getting this complete data and analyzing it will provide a great deal of information on what can be expected in a normal bird, what can be found in a normal bird and what can be expected or what may be found in sick birds. About a third of the birds I've inspected are normally healthy, presumably healthy, free-flying birds in good condition. About a third of the birds I've looked at have been ill for some particular reason, brought in, and sent to us for examination. There are also birds we've picked up out in the field which are sick or in poor shape. A special disease which we are working with here is botulism. About a third of the birds I've looked at have been specifically ill with botulism. The botulism affects the birds in such a way that they are more or less normal except for the botulism. It's not an illness in the ordinary sense of the infectious disease which may affect the health of the bird. Botulism causes the death of the bird or causes it to stop feeding for a few days. About one-third of the birds are botulism birds, one-third with other diseases, and one-third normal. 6 A study being carried on at the present time is a study of the relationship between botulism and parasites, to see if botulism birds perhaps might be susceptible to botulism because they have unusual parasites or unusual numbers or species of parasites. I don't really think there is any relationship but a brief study that I made indicated that there might be. Comparing how parasitism is modified or changed depending upon the age of the bird and the particular season of the year, sex of the bird, there are some differences between the males and the females. There are also changes from one year to the next. Some years the parasites are abundant, other years such parasites may be absent. A comparison of parasitism in birds involves a great deal of study of the characters of the bird and is rather difficult to make. In making comparison between botulism and normal birds, I'm trying to do it on a matched pair basis, obtaining two birds with all the same characteristics except that one has botulism and the other has not. There were birds of the same age, same sex, taken the same season of the same year, and with the same physical condition except that one of them came down with botulism. We originally compared 15 or 16. They were not perfect pairs. They were, in most cases, not collected the same year, which was a bad feature of the comparison. Of the 16 pairs, something like 10 of the botulism birds showed more parasitism than the non-botulism birds. With this to go on, I set up a detailed study to see whether this is the general case. We are picking specifically collected birds for this purpose. I'm trying to obtain data on 50 such matched pairs. This involves examining some 300 or so additional birds. This 7 has not been completed. I've done about half of these and half of them are still waiting in the deep freeze for me to continue. It takes a full day to examine a single bird. Sometimes, with a bird that is very heavily parasitized, it will take 2 or even 3 days to examine a single bird in order to obtain the type of data I get on total numbers of parasite species. I think 24 is my maximum—24 individual species present in a single bird. This involves counting or obtaining, in cases where they run into the thousand, obtaining counts on sample portions of the total in order to come up with a figure. This comparison takes a long time. It's not only a comparison of the individual birds, but it involves a comparison of particular species to see whether there are certain species which are prone to characteristics of botulism birds and not present in others. I can conceive of parasites, for example, causing a breakdown in the mucosa of the intestine permitting toxin, botulinum toxin, to penetrate and be absorbed more easily through the intestine so that certain birds with certain parasites might be susceptible to botulism while others are not. As I said, I don't really think this happens but it is conceivable and I'm carrying on this study as a part of the general studies. CA: Do these parasites affect humans? MM: That's the first thing people want to know when they hear about the number of parasites in birds. Then they get disturbed about what they might do when they want to eat them. In the first place, most of these parasites are in the intestines or in the alimentary canal, so they are in a part of the bird that is thrown away. If the bird is 8 adequately cleaned, there is no contact with the parasites at all anyway. The other thing is that these are in the birds. Humans are mammals and there is comparatively little exchange of parasites between birds and mammals. The parasite, in order to survive in an animal, has to be adjusted to the chemistry of that animal. It's got all sorts of adaptations to resist the defenses of the animal—chemical and serological defenses. The adaptations of this sort apply to the particular host or particular group of hosts that the parasite normally occurs in. This is a specialized resistance which doesn't apply to other animals which may eat the same parasite. Ordinarily bird parasites could not survive in mammals. They are adjusted to the conditions of the bird, the chemistry and serology of the bird, and that means that they cannot withstand the different chemistry of mammals. There are a few parasites which are found in both birds and mammals, however. In those cases, the life cycle enters in so that the mammal cannot be affected unless he takes in the parasite the same way the bird does. There is, for example, a kind of cestode quite common in geese. This cestode has an intermediate host, a small micro-crustacean living free in the water which takes in the eggs of parasite and holds the parasite as a larva within its body. When this micro-crustacean is swallowed by a goose, then the larva is released by the intestinal juices and attaches itself to the intestine of the goose and grows up to form a large tapeworm. This has occurred in humans, but it can only occur in humans if they swallowed the same micro-crustacean and their resistance was not very good. Under modern conditions, drinking purified treated water, we're not 9 likely to swallow this micro-crustacean containing this parasite. In most cases, even if that happened, your body resistance would destroy the parasite and it wouldn't be able to attach itself. There are only a very few parasites which are even able to attack mammals and most of those have a life cycle such that you do not come in contact with them. If you ate ordinary pond snails, there are one or two parasites that would be able to attach or attack the mammalian host. There is a common fluke which is found in muskrats, for example, as well as waterfowl, and this has been found in humans in a few cases. However, for the humans to become infected they must eat aquatic snails. This, of course, does not happen very often in this area. In certain parts of the world, Indonesia, for example, this fluke is fairly frequent in humans because they have entirely different dietary habits than we have and do eat uncooked raw snails. Talking about the life cycle of the parasites brings out the reason why there are so many parasites in these ducks and geese. The difficulty for a parasite is to get into a new host—to get from one host to another. The eggs are released by one host then they must successfully invade another host. Usually this is done by some sort of intermediate host by a complicated life cycle. In some cases, they go through two or three hosts before they can mature and produce more eggs. The transfer from host to host or the survival of the eggs requires moist conditions. If the eggs dry up, they usually die or, if it is trying to transfer from one host to another in the larval stage, it may die by drying up. In situations in water, this drying up is much less likely to happen. So we find that there are many more parasites in 10 aquatic animals than there are in terrestrial animals. In water, there is a much greater variety and a much greater number of parasites so waterfowl carry many more parasites than do terrestrial birds. Another thing is the type of food habits. Most of these parasites require an intermediate host—this intermediate host is an animal of some sort, a crustacean, a snail, an insect, or some other animal. A bird which eats only plant material gets much fewer parasites than a bird which eats animal material. The waterfowl eating a great variety of almost anything which comes to hand for food pick up many more parasites than they would if they were much more restricted. The waterfowl which have a restricted diet, fish-eating birds for example, like the merganser and birds with similar diets, have fewer parasites, than do the birds which eat a greater variety of food. There are a number of parasites that use fish as an intermediate host. All of the parasites which use snails, micro-crustaceans, or insects and so forth are not picked up by the fish-eating birds. The number of types of parasites are comparatively few in the fish-eating birds. I mentioned the restriction in chemistry and adjustment to serology and so forth between birds and mammals. Even bird parasites are usually restricted to particular types of birds—either to a particular order or in many cases to a particular group of birds within the order. In the waterfowl, for example, we have two major groups of waterfowl. The geese and swans on one hand and all the ducks on the other. The geese and swans belong to a particular tribe, the anserine, within the waterfowl family. We find that the parasites of waterfowl are divided similarly between the geese and 11 swans on one hand and the ducks on the other. In many cases, a genus will be found throughout the waterfowl but it’s present as different species. Some genera of parasites will be divided into a number of species present in waterfowl with particular species being confined to particular groups. The gizzard worms, for example, genus amidostomum or epomidiostomum nematodes, present under the gizzard lining of waterfowl are genera with a number of species present. One species is found in geese and swans, one species in swans only, and one species is found only in ducks. There are actually a number of tribes of ducks, different tribes, and you find certain parasites which are confined to particular tribes. For example, we have the Ruddy Duck, in this area, which is of the tribe oxybutynin, the stiff-tailed ducks. We have only the one species in North America of that tribe. Similar birds are found throughout the world in Asia, Europe, Australia, and so forth, of other species. There is one of the same tribe down in the West Indies. The Ruddy Duck has gizzard worms but when we look at the particular species present we find that the Ruddy Duck has only gizzard worms of the genus epomidiostomum. These are the species E, uncinatum. The genus amidostomum, the commonest gizzard worms of waterfowl are not found in Ruddy Ducks. For some reason or other, they apparently don't survive. I'm sure the Ruddy Duck picks up the larva but for some reason they don't survive in the Ruddy Duck. The species of epomidiostomum that I just mentioned is found in all sorts of ducks. It's not restricted just to the Ruddy Duck. However, the other ducks have only one or two per individual. I think my studies show an average of 1.3 worms per individual duck. In the Ruddy Duck, the average is eighteen to twenty worms per 12 Ruddy Duck. This species, while it is found in all varieties of ducks seems to be typical and characteristic only of the Ruddy Duck and is fully adjusted as a parasite of the Ruddy and just survives, not much more than that, in the other birds. A successful parasite doesn't cause any damage to the host and becomes adapted, adjusted to the chemistry of the host so that the host doesn't cause any damage to the parasite. A fully successful parasite is very common and very abundant and does very little damage. This epomidiostomum is a fully adjusted parasite for the Ruddy Duck. The amidostomum, for some reason or other, doesn't survive in the Ruddy Duck. There are many such cases of co-specificity restrictions to particular orders such as anseriformes, waterfowl, or families. In this case the waterfowl, there are only two families. One of which scarcely amounts to anything—it's a family of three species down in South America. The order anseriformes essentially means the family anatidae—the waterfowl. Then, as I said, within the waterfowl you have the geese and swans on one hand and the ducks on the other. I found one parasite in waterfowl which is of intense interest to me. It doesn't seem to have any effect on waterfowl at all. I've seen no indication of a pathogenic or a disease effect at all. From a biological or zoological stand point, I think this is one of the most important discoveries I've made in my studies. This is a protozoan parasite—a parasite of a single-celled animal called protozoa. It is present in the gall bladder and the bile ducts of the liver, primarily in the cell lining of the gall bladder. We find it by scraping the lining of the gall bladder and looking at the scrapings under the compound microscope. We find the cysts of this particular protozoan present in the scrapings. The first time I found this it was so abundant 13 that small groups of cells were floating free in the bile of the gall bladder. I always split open the gall bladder looking for certain flukes and I noticed these little plaques under the dissection scope and mounted some of them to see what they were. I found two such infections this way and then finally started looking at every bird using scrapings and found quite a few additional infections. It seems to be present in something like 10 percent of all the ducks as a normal parasite not causing any damage. This parasite is so interesting because this belongs to an entire group of parasites—an order, or according to some individuals, a sub-class of protozoa which are found only in cold blooded animals. That is in fish, reptiles, some amphibians, primarily in fish. All of the textbooks state that this group of protozoa is confined to the cold blooded vertebrates and they have never been found in birds or mammals. Now, here I have a species present in ten percent of the ducks belonging to this group and it's in the normal habitat, the gall bladder. In the particular genus this belongs to, there are something like ninety species described. Of these, maybe two are present in frogs. Two have been described from turtles and the other eighty-six are present in fish. Almost all of them are in the gall bladder of fish. Besides that ninety, we have one more present in birds. This is really almost earth-shaking in its implications to have such a group present in birds. Whether I'm the first one to ever look in the gall bladder of birds for this parasite, I don't know. I can't imagine that somebody wouldn't have seen it before if it is as common as my figures indicate. Perhaps nobody expected it in birds, so nobody looked for it there. I know there have been some studies for similar parasites without ever finding any so, as I said, over the years the statement has 14 developed that it simply isn't present. I have at least one and probably more new species of cestodes—tapeworms—present in waterfowl and have to work up a description on them, write up a paper describing it and reporting it so other people can look for it. As I mentioned earlier, the necessity of studying literature worldwide and of trying to find out about parasites reported elsewhere in an attempt to identify the parasites I find. One nematode, for example, that is very common in diving birds, a kind of gizzard worm was first reported, described from a diving duck in India. At the time, I found it in ducks in this area it had not been reported elsewhere, except in this discovery in India. In the last few years, it has been found to be widespread in European and Asian diving ducks. There has been one other researcher who has reported it from North America. I find that it is almost universal in diving ducks. In order to identify it, I had to go back to this paper which came from India. Another parasite I found in the gizzard lining of swans was a parasite first reported from Elder Ducks in Siberia and described in a Russian journal. It's been reported two or three times now in Europe but not reported from North America. I've found it in several swans and have a paper on nematodes of waterfowl in which this record in swans in North America will be reported. There are a number of similar occurrences of parasites described and reported from other countries. This survey of the literature, of course, requires knowledge of foreign languages. Like anybody getting a Ph.D, I was forced to become familiar and be able to utilize French and German. In this work, I have had to read quite a few papers written in these two languages. Most of the parasitological work at this time, 15 parasitological in wildlife at least, is being done in Russia. The Russians are systematically studying the parasites of all species of wildlife present in Russia, all the way from Europe across to the Pacific Coast and are reporting on these parasites. They have looked at thousands of waterfowl collecting the parasites from them, identifying them, describing any new forms and reporting them in the literature. In order to be familiar with this Russian work, I had to study Russian and did this as part of the work here as I regularly use Russian sources in some cases purchasing books from Russia or through the libraries using Russian journals. In the last few years, the Russians have systematically done what the rest of the world did haphazardly years ago in studying the parasites of wildlife. The Russians started behind everyone else. They had everyone else’s work as a background, so they have greatly improved on the work done elsewhere—and done a much better job looking at many larger numbers of individuals and doing a more thorough job of collecting and identifying. I spend more time comparing with Russian papers than with any other group. I've had to utilize papers from South America, Spanish and Portuguese and a few other things. There are a lot of languages that are complete blanks to me. There's a lot of work coming from Central Europe or Eastern Europe and Czechoslovakian, Hungarian, Yugoslavian, and et cetera. Unless these are translated into one of the more common European languages, I can't tell what is in them. Fortunately, they usually give a summary at least in one or more languages. Czechoslovakia, for example, very regularly gives the summary of the paper in English, German and Russian, sometimes all three of them. A lot of work is being done in Poland, but the major journals in Poland are written in English. The papers 16 are in English with a Polish summary instead of, as you would assume, in Polish with an English summary. Most of the Polish work is available even though it's done by native Polish people. Right after I studied Russian the first paper I wanted to translate, I thought I could get along. Finally, I was ready to utilize my Russian seeing if I could get some information on the description of a couple of gizzard worms. I sent for a copy of the paper obtained from Washington through the Department of Interior Library. The reference I had said that this paper was in Russian. When I got the paper it was in Azerbaidzhan, one of the Russian republics. It had a summary in Russian but the paper was in Azerbaidzhan. In Azerbaidzhan they have their own alphabet with about six additional letters other than the Russian. I have, as yet, been unable to get an Azebaidzhan dictionary and get this paper translated. I still don't have the description of those two gizzard worms except their brief description in the summary, as few of the characters are mentioned. I was a little perturbed wondering how many more papers I was going to run across that were supposedly in Russian and actually were in some other language. There are quite a few but almost all of them give a summary in Russian which gives the major points. Papers are coming out in Latvian, Estonian, Ukrainian, and Azerbaidzhan. Any of the Russian Republics publish papers in their own language, although most of them, fortunately, use Russian instead of their own native language. In regard to parasites of waterfowl which might affect humans, I meant to mention one in particular which does affect humans but not infect them. This is Swimmers Itch. Swimmers Itch is a fluke of which there are a number of different 17 species. There is one common one in muskrats, for example. There are a large number present in waterfowl. There are some in grebes, in blackbirds, in herons, and almost any aquatic bird or any animal coming in contact with the water may get infected. These parasites are the schistosones, a group which are of great public health importance in Africa, Asia, South and Central America because they do include species which infect humans. This group infects their final host by burrowing through the skin. The larvae are produced in snails, emerge from the snails, swim around in water, come in contact with a warm-blooded host, burrow through the skin, and go into the blood vessels, finally reaching the liver or the blood vessels along the lining of the intestine. There, they mature and produce their eggs. Their eggs break through the lining of the intestine into the lumen of the intestine and pass out with the waste food materials. Then they hatch in water, larva swim around until it enters a snail and starts over again. There are only two hosts, the snail and the final host. As I said, the group is found in a wide variety of aquatic animals, birds and mammals including three species which are found normally in man. This larva burrowing into the final host are attracted by temperature and come in contact or recognize somehow a warm blooded host, bird or mammal and they burrow through the skin. In the case of the bird and mammal parasites, which are not normally found in man, burrow through the skin of man, then find they are in the wrong host and they can't survive, can't develop. They can't back out of the skin, however, they burrowed inland and they are stuck there so they die, killed by the body chemistry, the serology of the human. The microscopic body includes protein and other materials. It is broken down and 18 carried off, eliminated by the normal body processes fighting off foreign proteins. This amounts to a little allergic reaction in the body and in fact sets up an itch. In fact this itch is an allergic response and doesn't occur the first time you get infected. The itch is produced only by the adjustment of the body to these particular proteins so that after you are sensitized to it by one attack next time you come in contact with this particular parasite then the itch develops. This itch is known as Swimmers Itch and is found in Willard Bay among other places. Most commonly these parasites which cause Swimmers Itch occur in the adult form in waterfowl as the normal host, so the waterfowl maintain the parasite causing Swimmers Itch and bring it into an area. Of course, the snails are also necessary. Controls usually involve trying to eliminate snails from a particular area. In Michigan, they have many resort areas which carry on regular programs of snail elimination trying to prevent Swimmers Itch among the resort people. You can imagine the problem a resort area might have if bad cases of Swimmers Itch developed among the people using their beaches. This often happens. I, myself, am susceptible to Swimmers Itch. I got sensitized years ago working in northwestern Iowa. I spent a series of summers at the biological station there. The first summer I was there I had no trouble. I didn't know what they were talking about in regard to Swimmers Itch. The second summer I found out. I had been sensitized the first summer and, after that, succeeding summers were always a bother. I remember one time a group of us were collecting tadpoles, wading around in a shallow marsh reaching down, grabbing the tadpoles with our hands and 19 putting them into buckets. This was the first week in July, the regular time for appearance of Swimmers Itch in the particular area. After we had been working a while we became aware of a tingling, me and one or two others became aware of a tingling in the skin, which indicated that the parasites were burrowing into the skin. It was too late to do anything then. We tried to wipe the water off our arms, but we continued to collect tadpoles until we had enough. The damage had already been done. The next day the red spots began appearing. For a week, my legs and one arm—the one which I was catching the tadpoles with—were covered with these little red pustules. They are sort of like a mosquito bite except they are much more intense and the itching lasts longer. I had something like four hundred such pustules on the one arm between my wrist and elbow. It was just lumpy with the swellings and the itching was very intense. Each leg had several hundred of these also. Swimmers Itch is a waterfowl parasite which was definitely does affect man and is very important in resort areas. It is found all the way across the country from New York to Oregon. Mostly in the more northern areas, the more northern states. In the summer resort states it's a big problem, in Michigan, Wisconsin, and so forth. It occurs in Colorado, Utah, Nevada, California, Oregon, Washington and so forth, almost any of the states. There are some that are marine—found in marine birds and marine snails—so that there is a bather’s itch of marine beaches sometimes called Clam Digger Itch due to the same thing. 20