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No description available.

The four objectives of this study were to determine: 1) the incidence of Dirofilaria immitis and Dipetalonema reconditum in dogs of East Central Indiana, 2) the variables significantly affecting the incidence of each parasite, 3) the correlation of heartworm infections with clinical symptoms, and 4) to determine whether Dirofilaria immitis and Dipetalonema reconditum are endemic in Indiana.From December, 1973 to April, 1974, blood samples were taken from 335 dogs in East Central Indiana and were examined for microfilariae using the direct smear and the modified Knott concentration techniques. At the same time, complete information on each dog was collected on a "SURVEY INFORMATION” form. The data was statistically analyzed by crosstabulation of each variable with the results of the blood tests for each parasite. Levels of significance were computed using chi square values with appropriate degrees of freedom. Values of 0.05 were considered to be significant.In this study, the overall incidence of Dirofilaria immitis was found to be 3°% which included one dog infected with both parasites. Of the 131 hunting dogs, 6.1% were infected, while only 1% of the 204 non-hunting dogs were infected. Furthermore, all of the dogs infected with heart-worms were those which were principally outdoor dogs. These differences were significant and they reflect thehigher exposure risk of hunting dogs and dogs living out-doors to the mosquito vectors.The incidence of Dipetalonema reconditum was 6% overall with 11.5 % of the hunting dogs and 2.5% of the non-hunting dogs infected. It was most prevalent in dogs three to six years of age. After age seven the prevalence declined sharply. This decrease with age may be the result of an immune response to the infective larvae which prevents reinfection.Clinical symptoms could not be correlated with infections with Dirofilaria immitis since 90% of the dogs infected with heartworms had no symptoms of the disease. This indicates that most of the heartworm infections in dogs of this area are light, probably involving few adult worms. The results of this study indicate that Dirofilaria imnitis and Dipetalonema reconditum are endemic in Indiana, as 60% of the dogs with heart-worms and 35% of the dogs with Dipetalonema reconditum had never been out of the state.

This research study is divided into 4 major sections. Section A deals with the world-wide distribution of the haematoprotozoan parasites of marine fishes. These are tentatively divided into 3 major groups: the Haemogregarines, the Trypanosomes and the Trypanoplasms and one group of ill defined and controversal organisms including Haemohormidium sp. and Dactylosoma sp. The results of extensive surveys of the coastal waters of France, Scotland and Wales with added examples from the Mediterranean Sea substantiate the zoogeographical distribution of these parasites. Two species of haematoprotozoan parasites Haemogregarina simondi and Trypanosoma soleae are re-described, earlier accounts dating from the beginning of the century being considered incomplete. A new species of haemogregarine is described from the farmed turbot (Scophthalmus maximus) as Haemogregarina sachai n. sp. and an unidentified species of Haemohormidium found occasionally in turbot and Dover sole (Solea soles) is also described. In addition Haemogregarina sp. were encountered in certain wild marine fish from the Atlantic coast of France e. g. Zeus faber, Sebastes sp., Trisopterus luscus, Pagellus bogaraveo and Raja sp. and from the coastal waters of Malta e. g. Peristedion cataphractum and Oblade melanura. However, they were not found in sufficient numbers to allow a definite description. The value of surveys of wild fish populations is discussed in the light of zoogeographical distribution, the apparent periodicity of these parasites and a seasonal variation of parasitism. Section B attempts to summarize the knowledge of the mode of transmission of marine haematoprotozoan parasites by piscicolid leeches as intermediate hosts and vectors. The developmental stages of a trypanosome, probably Trypanosoma murmanensis from the Atlantic cod Gadus morhua are described in the marine leech Calliobdella nodulifera. Stages of a haemogregaririe were observed in the same leech. The development of the turbot haemogregarine Haemogregarina sachai n. sp. in artificially infected leeches is also described up to the 20th day post infection. Transmission of this haemogregarine to apparently uninfected turbot via this leech was not successful. Various stages of development of Haemogregarina simondi are described in its apparently natural vector, the marine leech Hemibdella soleae, and transmission with infected leeches to apparently healthy hatchery reared soles was achieved. Thus it was shown for the first time that marine leeches can serve also as vectors for haemogregarines. Stages of this haemogregarine are also described in the blood-sucking ectoparasitic copepod Lernaeocera sp. parasitizing the haemogregarine infected soles. These results are discussed in relation to the feeding behaviour and migration patterns of the fish hosts, the periodicity of the parasites and possible other vectors or other ways of acquiring an infection with these haematoprotozoan parasites. In Section C the pathogenicity of the haematoprotozoan parasites of marine fishes is summarized from previous accounts among wild fish populations and compared with the situation in aquaculture. The pathogenicity of the two haemogregarines, Haemogregarina simondi and Haemogregarina sachai n. sp., accidentally introduced into several fish farming establishments connected with the effluent cooling waters of a nuclear power station is described with special reference to the possible source of the infection. The results of therapy trials and control programs are discussed in the light of the periodic reappearance of the parasites, the possibility of carrier fish existing, the immune status of the host and the possible role of an intermediate host or vector in maintaining the infection. Possible means of controlling the pathogenicity of marine haemogregarines and perhaps other haematoprotozoan parasites when they occur in farmed marine fishes are also discussed. In Section D are described for the first time, the ultrastructural characteristics of various stages of the haematoprotozoan parasites of marine fishes in fish hosts and vectors. The electronmicroscopical studies are limited to Haemogregarina sachai n. sp. and Haemogregarina simondi, for which the ultrastructure of schizonts from the spleen and blood, intracellular merozoites and free gametocytes were contrasted. In addition stages of H. simondi were demonstrated in Hemibdella soleae and Lernaeocera sp. The fine structure of the various organelles encountered was compared with that of related organisms from other cold-and warm-blooded vertebrates. In conclusion attention is drawn to the need for more investigations in this field of host-parasite relationship of marine haematoprotozoan parasites and their vectors and their pathogenic-action as seen in a confined and artificial environment such as the marine aquaculture.

Larval Anisakis simplex, Pseudoterranova decipiens, Contracaecum osculatum and larvae and adults of Hysterothylacium aduncum were recovered from specimens of cod, haddock, blue whiting and bull rout; however, only A.simplex were retrieved from long rough dab. The epidemiology of infection by these four nematode species was examined both in whole fish, and in individual host tissues and organs. Frequency distributions of nematodes were found to be generally overdispersed in fish. Preliminary investigations revealed no strong evidence to suggest that competi tive interactions occurred between ascaridoid nematodes wi thin fish. Stomach lesions in gadoids were associated with single (partially penetrated) and mul tiple (throughout stomach wall) worm infections of larval A.simplex; such lesions were discrete and raised in appearance. Lesions associated with 1-3 larval P.decipiens in an open cavity within the stomach of angler fish were diffuse and not significantly raised. Histological examination of each form of ulcer revealed general similarities in pathology, with infil tration of inflamatory cells being the initial response to the nematode\s. Changes in the cephalic morphology of A.simplex, P.decip1ens, C.osculatum and H.aduncu were examined at different life cycle stages under scanning electron microscopy. Due to their small size, newly hatched third stage larvae of P .decip1ens were cultured in a bacterial mat prior to fixation for S.E.M., and the external ultrastructure of these larvae is described. The most prominent external feature at this stage is the cephalic boring tooth. Aspects of the internal ultrastructure of A. simplex, P.decipiens, C.osculatum and H.aduncu were examined using transmission electron microscopy. Newly hatched third stage larvae of P.decipiens show little differentiation of internal organs. The ultrastructure of sensory amphids in H.aduncum and A. simplex is cons i stent wi th that of a chemoreceptor, that of the single papilla in P.decipiens a mechanoreceptor. The ultrastructure of the digestive tract, excretory gland and body wall of marine ascaridoids were also examined.

Two different types of sludges from two popular sewage treatment systems were used in this study; namely, anaerobic pond sludge from a wastewater stabilisation pond system and filter pressed primary sludge from a primary sewage treatment plant. Under Egyptian conditions, Ascaris eggs represent the main health concern for sludge application on land and, accordingly, the effect of sand drying beds and a passive composting system (using agricultural wastes as bulking agents and cement dust as an additive to the sludge) were studied in terms of the inactivation of Ascaris eggs. From the characterisation and assessment of the anaerobic pond sludge from the Mit Mazah wastewater stabilisation pond system, it has been concluded that the sludge was well digested and free of viable Ascaris eggs. Consequently, this sludge is considered to be safe for land application, after appropriate dewatering. For the purposes of the study, anaerobic pond sludge was seeded with Ascaris vitilorum eggs (cattle ascarid). Within 30 days of dewatering on sand drying beds during the winter season (October and November), the Ascaris eggs were found to be inactivated only in the top layers, where the average solids content was approximately 85%. By the end of the two month drying period, the middle and bottom layers of sludge on the drying beds contained an average solids content of 74% to 77% and 72 to 73%, respectively, yet viable Ascaris eggs were still detected. During a second sludge application during the winter season (December and January), unfavourable weather conditions prevailed and, by the end of the 60 days drying period, total solids content averaged 54% in the top layer of sludge. The middle and bottom layers had an average total solids content of 49% and 44%, respectively. Throughout the winter drying period, all samples collected were positive for viable Ascaris eggs throughout the full depth of sludge. However, during the summer season, samples collected from the drying beds after 17 days of drying did not contain viable Ascaris eggs in the top sludge layers, where the solids content ranged from 74% to 63%. After one month of summer drying, no viable Ascaris eggs were detected throughout the entire depth of sludge on the drying beds and the lowest solids content recorded was 80% for the bottom layers. From this study, it can be concluded that, during the wet season in Egypt, drying beds were not efficient in destroying Ascaris eggs throughout the entire sludge depth. During the summer season, Ascaris eggs can be inactivated much more rapidly, compared to the winter season. Desiccation does not seem to be the only factor influencing the destruction of Ascaris eggs, with sludge temperature, solar radiation intensity and exposure time being possible major factors. By comparing the composting of filter pressed primary sludge in passive and windrow piles (used as control piles), it has been proved that the passive composting system is much more efficient in maintaining regular high temperatures in the composting mixture for a much longer duration (additional 10 days), due to the favourable aerobic conditions. Moreover, passive composting preserves the nitrogen content through the naturally controlled internal temperature, less need for turning and lower loss of moisture. By the end of the composting process, the total nitrogen content for the passive and windrow piles was a gain of 17.5% and a loss of 0.7%, respectively, while the ammoniacal nitrogen content in the product was 1109 mg/l and 837 m/l, respectively. From the hygienic point of view, passive composting technology proved to be much more effective in inactivating Ascaris eggs present in the primary sludge, compared to the windrow pile system. Viable Ascaris eggs were not detected after 30 days of composting using the passive system, compared with 60 days of composting for the windrow pile. Industrial cement dust as an additive and agricultural wastes (from fennel and basil production) were incorporated with sludge to form a range of composing mixtures. From the sludge/cement dust composting piles with agricultural wastes as bulking agent, it can be concluded that more than 35% concentration of cement dust was unfavourable for the decomposition process, due to the high pH and high temperature levels attained as a result of the effect of cement dust and dehydration of the organic matter. Moreover, loss of nitrogen was very high, due to the release of ammonia, encouraged by the high pH and high temperature in the composting mixture. The passive composting system was very efficient in naturally controlling the internal temperature in all the sludge/cement dust piles with bulking agent. Excessive heat was released to the atmosphere through the chimney effect created by the circulation of air through the perforated pipes and upwards into the pile. Internal temperatures for even the piles with the highest proportion of cement dust did not exceed 73°C. Inactivation of Ascaris eggs was achieved after only 15 days of composting for all the different cement dust concentrations, mainly due to the influence of high pH and high temperature levels for long periods but may also be due to the high release of ammonia gas. The passive composting of sludge amended with 30% cement dust without bulking agent was inefficient for both the decomposition process and inactivation of Ascaris eggs. No biological activity was taking place during the two months fermentation stage, due to the prevailing anaerobic conditions (lack of air voids and high moisture content) By considering all the different parameters for evaluating a treated compost, including the stability, maturity, nutrient content, heavy metals content and viable Ascaris eggs content for the sludge/cement dust piles with bulking agent, it can be concluded that more than 30% cement dust concentration would be unfavourable, according to the relatively high loss of nitrogen. More than 35% cement dust concentration is certainly unfavourable, mainly as a result of the delay of the decomposition process, the elongation of the composting period and the high loss of nitrogen content. There is no need to separate out the agricultural waste bulking materials after composting because they are organic in nature. Likewise, there is no need to consider separating out the cement dust, as the physicochemical analysis of the final sludge/cement compost with bulking materials showed its suitability for adding to agricultural land as an amendment. In conclusion, sand bed drying is considered to be a suitable process for dewatering of anaerobic stabilisation pond sludge in Egypt and, for extended periods between pond desludging of the order of 6 years, the dewatered sludge will be suitable for direct application to agricultural land. Passive composting is an appropriate technique for preparation of Egyptian filter pressed primary sludge for safe application to agricultural land. Cement dust additions of less than 30% concentration, to the composting mixture in a passive composting system produces sanitised and mature compost. The potential for co-disposal of agricultural wastes and cement kiln dust as bulking agents and additive, respectively, with sewage sludge in the production of compost, is very promising to produce a safe and beneficial outcome to the community.

Glutamate binding studies on membrane preparations from unselected and ivermectin-selected strains of the parasitic nematode of ruminants, Haemonchus contortus, indicated a single class of saturable, high affinity binding sites which are sensitive to ivermectin and exhibit different pharmacological characteristics from any known mammalian glutamate receptor. These studies showed that H. contortus larvae possess substantially more glutamate binding sites with lower affinity than adults. Moreover, selection with ivermectin was associated with an increase in the number of glutamate binding sites in adults and an increase in the affinity for glutamate binding in larvae. When investigating the effects of ivermectin on glutamate binding kinetics, it was discovered that ivermectin decreased Bmax values in unselected, but not in ivermectin-selected, parasites. Inulin intake studies were performed in unselected and ivermectin-selected H. contortus worms to relate the glutamate binding results to the biological activity, pharyngeal pumping. These studies showed that glutamate, ivermectin and the structurally similar anthelmintic, moxidectin, inhibit pharyngeal pumping, and that glutamate influences the effects of ivermectin and of moxidectin, on pharyngeal pumping. Lastly, selection with ivermectin was associated with an alteration of the effects of ivermectin, but not moxidectin, on pharyngeal pumping. The results of this work suggest that a novel ivermectin-sensitive, glutamate receptor, which influences pharyngeal function, is involved in the development of ivermectin resistance in H. contortus.

Aedes aegypti pupae were exposed to cercariae of the digenean Plagiorchis noblei in order to assess the effects of infection on the spontaneous flying activity and reproductive success of surviving adults. Infections established primarily in the thorax and abdomen of the insects (mixed infections) or in the abdomen alone. In mixed infections, as few as one or two metacercariae in the thorax reduced the spontaneous flying time of females by almost half. Such infections also reduced total egg production, the number of ovarian cycles, fecundity per cycle, as well as fertility and life span of female hosts. The fertility and life span of males was similarly affected. Purely abdominal infections reduced the life span of males and females as well as the fertility of males, but only at high intensities. Such effects on adult behaviour, reproductive success and life span may augment the known lethal effects of the parasite.

The brook trout population in a 4.7 hectare subarctic lake was sampled in 1986 and intensively fished in 1987, 1988 and 1989 in order to study the effect of stock depletion on fish parasite transmission. Population density was originally high, with slow individual growth rates, and small maximum size. Brook trout bore infections of Eubothrium salvelini, Phyllodistomum umblae, Crepidostomum farionis and Diplostomum sp. as well as some rare parasites. After intensive fishing the growth rates and size of the remaining fish increased. In 1987 all parasites increased in abundance. E. salvelini decreased in 1988 whereas the abundance of the other parasites remained high. In 1989 two new parasites, Echinorhynchus lateralis and Philonema sp. appeared. Parasite community changes and improves fish growth were related to trout diets and the pattern of intermediate host consumption. In 1987 zooplankton feeding increased. It then declined in 1988 and 1989 as populations of large benthic invertebrate prey increased. Feeding shifts may also have been mediated in part by intraspecific competition and aggression.

A study on the epidemiological dynamics of gastrointestinal nematodes of small ruminants was conducted in a semi-arid area of Kenya over a period of two years. Three major trichostrongylid species were identified; Haemonchus, Trichostrongylus and Oesophagostomum. Trichuris and Strongyloides species were occasionally encountered. Of the major trichostrongylids, Haemonchus spp. was the most prevalent (90%) and accounted for about 80% of the total worm burden. This species was found to undergo hypobiosis at levels that varied with seasons: nil levels of hypobiosis were recorded during the wet months and as much as 80% was recorded during the dry months. Hypobiosis was not investigated in the other nematode species. Evaluation of the relationship between the faecal egg count and the worm burden showed that the two parameters were more highly correlated during the wet months than during the dry months. This was a desirable situation because it is during the wet season that livestock owners in this area need to closely monitor the worm burdens in their animals. Treatment with ivermectin before the onset of the rains not only delayed the onset of egg shedding but also controlled clinical helminthiasis. In addition, a temporal change in the pattern of the appearance of infective larvae on pasture was observed; the appearance was delayed for about a month after the onset of the rains. The effect of treatment administered during the rains was a temporary and a short-lived relief of infection as evidenced by a brief decline in egg output: it had no detectable impact on pasture infectivity. These results suggested that removal of hypobiotic larvae before they resumed development had the combined benefit of reducing both the severity of clinical helminthiasis and the level of pasture contamination. This impact was expressed in improved flock performance and particularly in the improvement of birth weights that subsequently enhanced kid and lamb survival rates. Probably due to