Theobold Smith (23) in 1895 described an amoeboid protozoan parasite of turkeys which he identified as the aetiological agent of the disease enterohepatitis (blackhead). Smith tentatively described it as a species of enteric amoeba. Tyzzer (26) later suggested a definite classification for this organism in a new genus. The species name he proposed was Histomonas (gen. nov.) meleagridis (Smith 1895) Tyzzer, 1919. Incidence of the fatal condition referred to as enterohepatitis results in heavy annual losses to commercial turkey and poultry producers.

The earliest mention of an amoeba, causing disease in reptiles, was by Ratcliffe and Geiman (1933), when they discovered that acute intestinal disease in certain lizards and snakes was associated with an amoeba, which they designated Endamoeba sp. Ratcliffe and Geiman isolated the organism in cultures and later they reported experimental infection of water snakes of the genus Natrix with cysts of the amoeba obtained from their cultures (Ratcliffe and Geiman 1934a).

Phenothiazine has been known to the dye industry since 1883, when Bernthsen (5, 6) first synthesized it and subsequently investigated its chemistry. The realization that the drug may have biological applications came with the publication by Campbell et al (8) in 1934 of its lethal action on culicine larvae. Knipling (59), in 1938, reported that by feeding it to cattle, the development of horn fly larvae in the faeces was completely inhibited for three days. [...]

Mange, scabies or acariasis is a dermatitis associated with various species of mites on domestic herbivores and other animals. One species on cattle is Chorioptes bovis (Héring, 1845) Gervais and Van Beneden, 1859. This mite has been incriminated as the cause of most clinical cases of mange reported in Canada during the past 20 years, although a few outbreaks of psoroptic, sarcoptic and demodectic acariasis were noted also. The last three kinds of mange are often severe and sometimes generalized, but chorioptic mange is generally mild and frequently restricted to small patches on the hind quarters.

The Sclerostomes, also known as Redworms and Palisade Worms, belong to the large group of parasitic bursate nematodes provided with a terminal buccal capsule and armed with one or more fringes of cuticle called “leaf -crowns”. They are found universally in horses and other equines, where they may cause serious diseases. The most important genera, from the standpoint of their prevalence in horses, are Strongylus, Triodontophorus, and Trichonema, the latter being generally known as the Cylicostomes. Other genera of the Family Strongylidae which comprise part of the Sclerostome grouping are Craterostomum, Oesophagodontus, and Gyalocephalus. There are approximately fifty different species of Sclerostomes known to be found in horses and other equines, but up to the present time it has been impossible to distinguish between them from the examination of the eggs alone, Theiler (1923), Taylor (1933), Cornils (1935), Kopirin (1941), and Hummelinck (1946a). Some degree of differentiation has been accomplished by means of the freeliving larvae, Albrecht (1933), Lucker (1936) and (1938), and Hummelinck (1947). The general description that Taylor (1933) gave for the life cycle of Strongylus edentatus may be applied to all of the Sclerostomes and their related groups. “The life cycle in general outline is the same for all species but is identical for none”, Cameron and Parnell (1939). The adult females, found in the colon of the host, lay eggs which reach the ground [...]

The story of blackhead, insofar as scientists have deciphered its perplexing problems, is that of a unique relationship existing between a number of avian hosts, a protozoan parasite and a parasitic nematode vector. Blackhead is acknowledged to be economically the most important disease of turkeys, having forced the abandonment of turkey rearing in many parts. Fortunately, in other susceptible species of birds, the disease seldom causes serious losses. In the caeca of the chicken, and perhaps,too, in the caeca of other susceptible birds, the blackhead organism, Histomonas meleagrldis, lives and multiplies without producing clinical disease except on rare occasions. Another inhabitant of the caeca is the worm, Heterakis gallinae, which picks up Histomonas, serving as vector host of blackhead by virtue of the fact that Histomonas becomes incorporated in its eggs. It is not known how Histomonas gets into the caecal worm egg or what form the egg-borne stage of the parasite takes. There is overwhelming evidence to show that it is there, however, because when the eggs of the worms from birds carrying blackhead are embryonated and fed to susceptible turkeys, the latter develop clinical blackhead. The work leading to the discovery of the above facts, and of others relating to the subject are considered in the historical review. H. gallinae does not always carry the organism that initiates blackhead.[...]

The genus Entamoeba, Casagrandi and Barbagallo 1895, includes a number of species parasitic on a wide range of animals from ciliates to man. Many of these are morphologically similar but differ in growth requirements and hosts. Entamoeba histobtica, Sohaudinn 1903, in man, and Entamoeba invadens, Rodhain 1934, in snakes, are the only two species known to invade host tissue. In 1930 Sanders and Cleveland described a new species, Entamoeba terrapinae, from the terrapin, Chrysemys elegans. Since then no further work has been pablished on this amoeba, and much information regarding it is still wanting. According to Sanders and Cleveland the life-cycle of E. terrapinae differs from any other life history of a parasitic amoeba heretofore described. As their observations have not been confirmed it was deemed advisable to reinvestigate the life-cycle of this parasite. A number of species of parasitic amoebae have been described in turtles by various workers. In many of these the specific identity, which was established on inadequate morphological study, is still in doubt. In some cases size alone was the characteristic used for differentiating a species. In the present investigation a detailed study of the morphology of Entamoeba terrapinae has been made. In an attempt to evaluate morphological characteristics and size as taxonomic characters a comparison of the morphology of Entamoeba terrapinae with that of two morphologically similar species [...]

The parasites of marine and anadromous fish occurring in Canada’s Pacific waters, their economic importance, pathological significance and host and geographical distribution have not been studied intensively. This becomes more apparent when one considers the number of species of fish inhabiting this area (245 listed in Clemens and Wilby’s “Fishes of the Pacifie Coast of Canada” 1949) and the relatively few species (thirty-one) and individuals of the species, and restricted areas which have been investigated for parasites. The only area in which fish have been subjected to parasitological studies is the Strait of Georgia. Again when the extensive investigations of parasites of fish found in European waters, in the North American Atlantic, in Japan and other localities are brought to one’s attention, it is evident that we must know little concerning the parasitic fauna of Canadian Pacific fish and the distribution of these parasites. Parasitological investigations of fish in the neighbouring United States and Alaskan Pacific no doubt contribute to our knowledge of what we might expect in the way of parasites in fish from the coastal waters of British Columbia, as most of the species of fish occurring in Canadian waters have a distribution range from Alaska to California. Studies of this nature have been more frequent in the United States than in Canada, but the parasitic fauna can still be considered as largely unknown. [...]

The species of the genus Entamoeba Casagrandi and Barbagallo, 1895, (Sarcodina, Protozoa), are all endoparasitic with one known exception. This latter is Entamoeba moshkovskii Chalaia, 1941, (Chalaia, 1941), which is encountered in sewage. Although attempts to infect various animals with this amoeba have failed, (Azzi Leal and Amaral; 1950: Neal, 1953), its life history is not yet fully known; it may be a parasite during a part of its life cycle when certain conditions prevail.

In a previous study of the two rabbit Trichostrongyles, Trichostrongylus retortaeformis (Zader, 1800) and Graphidium strigosum (Dujardin, 1845), the writer studied under laboratory conditions, the influence of the main environmental factors on the free-living stages of these nematodes. In the present work, a closer examination of the micro-environments of the infective and adult stages of these worms has been attempted. The term micro-environment is used in this study to denote the immediate surrounding of the worm.