Cerithidea california is examined to determine the fecundity of the parasitic trematode species in its gonad. Five species of trematodes are studied (Cloacitrema michiganensis, Euhaplorchis californiensis, Parorchis acanthus, Himasthia rhigedana, and Acanthoraryphium sp.). Their fecundity is determined by direct counts of rediae and estimation of the cercarial population. Correlations are shown for trematode numbers and snail size. Incidences of infection are given with regard to site, snail size, and trematode species. Comparison is made between infection ratios of C. californica and another marsh snail, Batillaria zonalis.

The Meat Inspection Division of the Bureau of Animal Industry in 195 0 reported that 322,647 livers or 2. 4% of 13,112,802 cattle slaughtered under United States Federal Inspection were condemned due to liver fluke infections (Price, 1953). This would amount to an annual loss of 3 million dollars in livers alone considering each liver weighed 10 pounds and retailed 65 cents per pound. This figure could conceiv-ably double or triple if additional losses due to animal death, decreased milk production, poor economic utilization of feed or lower livestock prices were considered.

Fish culture for both food and sport utilization has been greatly increasing throughout the world. The editor of Fish Farming Industries (1973) predicted an increase by 1977 in the United States of 83% for catfish producers, 49% for trout farmers, and 91% for bait dealers. Concomitant with the renewed interest in fish culture has been a corresponding need to further understand fish diseases.

Feeding ecology and trophic interactions of six species of wading birds were explored through a combined analysis of stable isotope profiles and endoparasite communities. Stable isotopes broadly characterize the feeding preferences and geographic information, while parasite communities reflect long-term trends in feeding ecology. Deceased birds were obtained from four South Florida wildlife rehabilitation organizations. Of the 81 birds dissected, 73 contained parasites. Parasites were predominately found within the gastrointestinal tract. Host and range extensions were noted for several parasite taxa. Bird host species had a significant effect on the parasite community (P=0.001) while wildlife center location and maturity status did not. Stable nitrogen (δ15N) values for pectoral muscle tissues, representing approximately 24 days, ranged from 6.44 to 13.48‰ while stable carbon (δ13C) values ranged from -33.39 to -11.66‰. δ13C varied significantly among location (P=0.0002) and δ15N varied significantly among species (P15N and δ13C was analyzed in combination; bird species (P=0.001) and location (P=0.001) were significantly different. By using this combined approach of stable isotope analysis and parasite identification, it was possible to elucidate more components of bird feeding ecology. Stable isotope analysis provided knowledge on trophic interactions based on δ15N values, while δ13C was used to determine the differences in geographic foraging location. As endoparasites are acquired trophically via food-web interactions, identifying the parasite community allowed for trophic links to be drawn between organisms present within the same environment. Combining these two techniques allows for an abundance of information on feeding ecology and trophic interactions to be obtained.

This study consisted of several experiments designed to compare the ability of two species of fungi, Saprolegnia ferax and S. parasitica to grow on two species of fish, smallmouth bass (Micropterus dolomieui) and goldfish (Carassius auratus), and to determine the criteria necessary for the development of these infections. The results indicate that water in the fish tanks must be slightly acid (pH 6), warm (22°C), nonmoving, and that the fish must be wounded in order for fungal infection to occur. Cool water (18°C) and moving water, caused by aeration and filtration, are detrimental to fungal colony formation so that no infection occurs. Both S. ferax and S. parasitica infected both species of fish, on an average of three days after innoculation. The S. ferax infected a higher percentage of both fishes than did the S. parasitica. The difference in susceptibility of the two fish species to the fungi was negligible.

Indiana University-Purdue University Indianapolis (IUPUI) / Toxoplasma gondii is a ubiquitous, protozoan parasite contributing significantly to global human and animal health. In the host, this obligate intracellular parasite converts into a latent tissue cyst form known as the bradyzoite, which is impervious to the immune response. The tissue cysts facilitate wide-spread transmission through the food chain and give rise to chronic toxoplasmosis in immune compromised patients. In addition, they may reactivate into replicating tachyzoites which cause tissue damage and disseminated disease. Current available drugs do not appear to have appreciable activity against latent bradyzoites. Therefore, a better understanding of the molecular mechanisms that drive interconversion between tachyzoite and bradyzoite forms is required to manage transmission and pathogenesis of Toxoplasma. Conversion to the bradyzoite is accompanied by an altered transcriptome, but the molecular players directing this process are largely uncharacterized. Studies of stage-specific promoters revealed that conventional cis-acting mechanisms operate to regulate developmental gene expression during tissue cyst formation. The major class of transcription factor likely to work through these cis-regulatory elements appears to be related to the Apetala-2 (AP2) family in plants. The Toxoplasma genome contains nearly 70 proteins harboring at least one predicted AP2 domain, but to date only three of these T. gondii AP2 proteins have been linked to bradyzoite development. We show that the putative T. gondii transcription factor, AP2IX-4, is localized to the parasite nucleus and exclusively expressed in tachyzoites and bradyzoites undergoing division. Knockout of AP2IX-4 had negligible effect on tachyzoite replication, but resulted in a reduced frequency of bradyzoite cysts in response to alkaline stress induction – a defect that is reversible by complementation. Microarray analyses revealed an enhanced activation of bradyzoite-associated genes in the AP2IX-4 knockout during alkaline conditions. In mice, the loss of AP2IX-4 resulted in a modest virulence defect and reduced brain cyst burden. Complementation of the AP2IX-4 knockout restored cyst counts to wild-type levels. These findings illustrate the complex role of AP2IX-4 in bradyzoite development and that certain transcriptional mechanisms responsible for tissue cyst development operate across parasite division.

The purpose of the work leading to the writing of the thesis was two fold: (1) to survey birds of Northern California for hemoprotozoa of the genera Haemoproteus, Leucocytozoon, and Trypanosoma, and (2) to construct an up-to-date check-list of the Haemoproteus, Leucocytozoon, and Trypanosoma parasites of birds of North America.

Whlle making studies of the parasites of fishes and amphibians at the Pacific Marine Station, Dillon Beach, California, during August, 1949, the writer encountered a hitherto unreported trypanasome from a female Triturus torosua. From the information obtained from the one smear, which was stained, the animal was presumed to be monomorphic, However, during February, 1950, a search was made expressly for the purpose of' obtaining specimens of this Pacific Coast newt, and of the eight animals examined six were parasitized. Contrary to the primary observations, evidence was accumulated which proved beyond any doubt that the flagellate is polymorphic and that, evidently, it has not been reported or described. The name Trypanasoma barbari is proposed for this species.

Little information is available concerning the nematode parasites of salamanders in California. Lehmann (1954) reported the finding of Oxyuris dubia Leidy 1856, in the rectum of 33 Ensatine e. Eschscholtzii from Sonoma County, California, and in 3 of 10 Batrachoseps a. Attenuatus, from San Francisco County, California. He also reported Oxyuris magnivulvaris Rankin 1937 in the rectum of 1 to 2 Aneides flavipunctatus, from Marin County, California and Rhabdias sp., from lungs of 2 of 12 aquatic Triturus torosus from Contra Costa County, California. Lehmann (1960) reported O. dubia from the cloaca of 1 Aneides flavipunctatus and 3 Aneides lugubris taken in Marin and Sonoma Counties, California. Several similar studies have been made in other states citing the occurrence of nematodes in various species of salamanders. There is an even greater paucity of information concerning parasitism in those salamander species inhabiting the western slope of the Sierra Nevada. This investigation is concerned with the four most common salamanders of the central California clopes, Aneides lugubris Hallowell, Batrachoseps attenuatus attenuatus Eschscholtz, Ensatina eschscholtzii platensis Espada, and Taricha torosa sierrae Twitty. Individuals of these species were collected and examined for parasites over the fall, winter and spring months, commencing in the fall of 1960 and extending through the spring of 1962. Data were collected to determine what nematode species inhabit these hosts and to ascertain the incidence and sites of infection. An attempt was also made to determine whether time of year, environmental conditions, and geographic distribution are of particular significance in the host-parasite relationships studied. A second group of salamanders which included Aneides lugubris Hallowell and Taricha torosa Rathke was examined. Both of these species were taken in a coastal region and were used as a comparison group Special attention has been directed to the study of Oxyuris dubia Leidy, 1856, with the intent of clarifying Leidy’s description of this species. This nematode is a frequent parasite of the salamanders studied, and special consideration has been given to the culturing of their eggs in an attempt to better understand the pattern of development.

To date there has been only on major study concerned with parasites of freshwater fishes of California. E. C. Haderlie (1953) summarized investigations up to that year and conducted a general survey of the monogenetic and digenetic trematodes, cestodes, nematodes, acanthocephalans, copepods, and hirudinians of fishes of Northern California. From 2010 fishes representing 36 species of 11 families examined over a three-year period, he obtained a total of 59 species of helminth parasites, copepods, and hirudinians, which include 20 species of digenea and 16 species of cestodes. In addition to the taxonomic study, Haderlie attempted to correlate the relative occurrence of the parasites with various ecological habitats. These data are incomplete, except for a general ecological discussion of the parasites taken from Clear Lake and its contributing streams. In the Sacramento-San Joaquin area the monogenetic trematodes are the only group that has been extensively studied. This work has been done by Dr. J. D. Mizelle of Sacramento State College. The primary purpose of the current investigation is to gain some knowledge of the species of endoparasites of fishes of the San Joaquin Delta. Two hundred and thirty sic fish were examined, including diadromous, potamodramous, anandromous, and territorial species of San Joaquin Delta. This has resulted in the recovery of two previously described and one new adult digenea, three metacercariae, two adult and three larval cestodes,and two cestodarians. Not included in this study are the Acanthocephala and Nematoda. A few cestodes are also not included because of their poor condition. The Host-Parasite List (p. 49) of this paper gives a summary of the fishes examined by Haderlie (H) and the present author (E) with the number of each species examined and the species of trematodes and cestodes recovered.