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We have investigated whether Trypanosoma brucei can undergo self-fertilisation. A group of 27 metacyclic clones derived from the tsetse transmission of a mixture of two genetically marked stocks was analysed and 22 clones were observed to be of non-hybrid phenotype. A group of 10 clones from this non-hybrid subset were then analysed for one isoenzyme, one restriction fragment length polymorphism and three karyotype markers potentially informative for the detection of self-fertilisation. Five of the 10 clones were found to be recombinant for at least one marker and we interpret these recombination events as indicating the clones to be products of self-fertilisation. We have also analysed a limited number of metacyclic clones from stocks of T. brucei each singly transmitted through tsetse flies but, so far, no evidence of recombination has been detected. We conclude that T. brucei is able to self-fertilise but there may be a requirement for the presence of dissimilar stocks to initiate such an event.

Extrasporogonic stages of Sphaerospora sp. from the kidneys of Atlantic salmon (Salmo salar L.) were successfully transmitted via intra-peritoneal injection to naive Atlantic salmon and brown trout (Salmo trutta L.). Rainbow trout (Oncorhynchus mykiss Walbaum) could not be infected in this way. Transmitted extrasporogonic stages continued their development to form sporogonic stages and mature spores in the kidney tubules. Extrasporogonic stages, sporogonic stages and mature spores of the parasite in both experimentally infected hosts were morphologically identical to the equivalent stage in naturally infected Atlantic salmon, although minor differences were seen in spore dimensions. A farm-based exposure experiment confirmed the susceptibility of brown trout to the salmon Sphaerospora. These results are consistent with the view that the salmon Sphaerospora is Sphaerospora truttae Fischer-Scherl, El-Matbouli et Hoffmann, 1986. The parasite is redescribed according to the guidelines of Lom and Arthur (1989) since details of extrasporogonic stages, the ultrastructure of extrasprogonic and sporogonic stage development, and of the parasite's epidemiology are known from Atlantic salmon but not from other reports.

Denman Island disease, characterized by clinical signs of focal green lesions on the body surface or within the mantle, palps, and adductor muscle of Pacific oysters (Crassostrea gigas), is caused by a protozoan parasite of unknown taxonomic affiliations, Mikrocytos mackini. Detection of M. mackini was more sensitive and rapid by use of tissue imprints than histological sections. Of several isolation procedures investigated, centrifugation of homogenized infected tissues through a 15% sucrose solution enabled the isolation of the highest number of M. mackini with the lowest amount of oyster debris. Experimental transmission showed that oysters exposed to M. mackini by inoculation with isolated parasites had shorter prepatent periods and higher prevalences and intensities of infection than those incubated in homogenates from infected oysters (bath exposure) or those naturally exposed in the field. Experimental transmission was also used to propagate M. mackini in vivo in the laboratory year round. For the development of the disease, exposed oysters required prolonged incubation at low temperatures (about 10 degrees C).

The ixodid ticks are the vectors of several hundreds of agents of transmission diseases of vertebrates and human. This agents are represented by viruses, rickettsiae, bacteria, protozoans and filariae. For the majority of these agents the ticks are not only vectors, but also are intermediate or final hosts. In the system agent-tick the antagonistic relationships dominate, and therefore the agent is actually a parasite of its vector. A wide spectrum of parasitic relationships form the high pathogenicity and lethality of an agent for its vector to the fast and complete elimination of a microorganism in a tick could be observed within the system in question. Somewhat balanced type of relationships occurs most often, thus pathogen agent causes a minimal damage to the tick-vectors and could stay in their organism and hold a capability of the transmission to the vertebrate hosts and within the population of ticks.

Thirty-five heifers were allotted to 3 groups. Group 1 (control) consisted of 10 heifers that were not vaccinated and were challenge exposed by breeding to infected bulls. Group 2 (natural challenge exposure) consisted of 10 heifers that were vaccinated and challenge exposed by breeding to infected bulls. Group 3 (experimental challenge exposure) consisted of 15 heifers that were vaccinated and challenge exposed by breeding to infected bulls and by intravaginal inoculation with 10(7) Tritrichomonas foetus. Total immunoglobulin concentrations and specific trichomonal antibodies were determined in serum and vaginal secretions of heifers, using radial immunodiffusion and ELISA procedures. Control heifers remained infected for a mean of 10.6 weeks (range, 0 to 18 weeks), and heifers of the natural and experimental challenge-exposure groups remained infected for 3.2 and 5.0 weeks, respectively (range, 0 to 12 weeks). Total serum and cervicovaginal mucus concentrations of IgM, IgA, IgG1, and IgG2 did not change significantly after vaccination or challenge exposure. However, ELISA titers of total trichomonal antibodies increased up to 1:10,000 (range, 1:400 to 1:10,000) in serum after vaccination, and increased approximately tenfold above background in cervicovaginal mucus. In serum, the predominant trichomonal antibody isotype was IgG1, although trichomonal IgA and IgM antibodies also increased. The predominant trichomonal antibody detected in cervicovaginal mucus was IgA. Antibody titers in serum and cervicovaginal mucus of vaccinated heifers were not increased by infection. However, in control heifers, the total local trichomonal antibody response increased three- to fivefold after infection.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of disease resistant breeds is recognised as an economically realistic alternative to acaricide application and drug administration in tick and tick-borne disease control schemes. Although resistance is mainly associated with zebu (Bos indicus) breeds, studies carried out in The Gambia show a higher resistance to ticks and tick-borne diseases in N'dama (Bos taurus) than in Gobra (B. indicus) cattle. Tick resistance in N'dama breed appears to be effective against those species with long hypostome, such as Amblyomma variegatum and Hyalomma spp. The possible mechanisms involved are discussed. Further investigations are identified to assess the economic value of tick and tick-borne disease resistance in the N'dama breed.

Over the last dozen years the relative frequencies of specific transfusion reactions have markedly altered, in general for the better. Although AIDS remains the Public's primary concern, the risk of AIDS from a transfusion is extremely low at this point. Hepatitis remains the most common infectious complication of blood transfusion, but only 1 in 6,000 units now carry a risk, whereas in the early 1980's the risk is believed to have been close to 10% per patient. Transmission of HTLV-I/II has also been markedly reduced by tests of donor sera. In contrast, cytomegalovirus has become of increased importance in view of the large number of patients immunosuppressed for transplantation and cancer therapy; bacterial growth in blood components appears to be increasingly common; and Chagas disease is likely to become a serious transfusion problem in this country. More widespread use of filters which remove three logs or more of white blood cells from components should play a major role in reducing transfusion reactions further.

Annually, over 75 million international passengers travel to tropical areas, more than 20 million of whom come from industrialized countries. They experience a high rate of traveler's diarrhea (TD), varying from 20 to 56%, which may result in serious limitations to their activities. The cause of TD is considered to be infectious in the overwhelming majority of cases and, apart from differences in relative importance, the list of responsible microbial agents is fairly constant regardless of geographic origin. The ingestion of contaminated food or water is considered to be the principal mode of transmission of the enteric pathogens of TD. Several factors have been proposed as playing a role in the etiogenesis of diarrhea in travelers, including personal (age, socioeconomic status, body weight, preexisting gastrointestinal illnesses), behavioral (mode of travel, standard of accommodation, eating in public places, dietary errors) and travel-related (destination, duration of stay, country of origin, season) factors, which are reviewed in detail.

Four primary and two secondary schools at Kafr Hakeem, El-Mansuria and Berkash villages in Imbaba district were surveyed. Urine and stool specimens of 791 students were examined. Results revealed amoebiasis (22.4%); hymenolepiasis nana (6.2%); ancylostomiasis doudenale (5.7%); ascariasis (1.5%) and enterobiasis (1.1%). Parasites transmitted by autoinfection represented 15.9% of the total infected subjects; those transmitted by the skin penetration 27.2% and by contaminated food 56.9%. There was no statistical difference between primary and secondary school students as regards the rate of infection.

Thin blood smears from 37 juvenile mallards (Anas platyrhynchos) collected in the Playa Lakes Region of Texas during summers 1990 and 1991 were examined for hemosporids. Only one bird was infected with a Plasmodium sp. Parasite intensity was seven per 10,000 erthrocytes. The low prevalence of Plasmodium sp. and the lack of other blood parasites in resident mallards suggests that hemosporid parasitism at the southern periphery of their breeding range is very different from that at the northern breeding grounds.

Background: Neospora is a newly recognized Toxoplasma-like protozoan that causes spontaneous abortion and/or neonatal disease in a wide range of animals. The purpose of this study was to determine the susceptibility of primates to Neospora infection., Experimental Design: In experiment 1, two rhesus macaque fetuses were inoculated in utero at gestational day 65 with 1 x 10(6) culture-derived Neospora tachyzoites. A control fetus was given uninfected vehicle. The fetuses were removed by hysterotomy between 13 and 22 days postinoculation. In experiment 2, two pregnant macaques were inoculated intramuscularly and intravenously on gestational day 43 with a total of 1.6 x 10(7) culture-derived tachyzoites. A pregnant control macaque was given uninfected vehicle. The fetuses were removed by hysterotomy between 67 to 70 days postinoculation. Fetal tissues were collected for in vitro parasite isolation, histopathology, and Neospora immunohistochemistry. Fetal blood was examined for Neospora-specific antibody titers using an indirect fluorescent antibody test., Results: Neospora infections were confirmed in all fetuses that received tachyzoites either directly or via transplacental infection. In experiment 1, infected fetuses had reduced amniotic fluid volumes, marked protozoal amnionitis and dermatitis, and a mild multifocal encephalitis. Infected fetuses from experiment 2 had a chronic multifocal necrotizing nonsuppurative meningoencephalitis with microcavitation, that was confined to the cerebrum, and a mild multifocal necrotizing amnionitis. In both experiments, Neospora tachyzoites were detected in association with lesions in fetal tissues by immunohistochemistry, and the parasites were reisolated in vitro. IgG Neospora antibody titers were detected in blood from all infected fetuses, whereas Neospora-specific IgM and IgA titers were found in one and three fetuses, respectively., Conclusions: Results indicate that nonhuman primates are susceptible to transplacental Neospora infection. The fetal lesions after transplacental infection are similar to those induced by transplacental Toxoplasma infections in primates.

Piscicolid leeches from the Bering Sea that had been removed from Lycodes raridens in 1977 were examined histologically. Developmental stages of a haemogregarine blood parasite of fish were found in the intestinal ceca and in salivary tissues. The developmental sequence, including gametogenesis and sporogony followed by intestinal merogonic development and anteriad migration, was the same as is known for Haemogregarina (sensu lato) myoxocephali of Atlantic sculpins. Merozoites with perinuclear crystalloid inclusions were found in the dorsal blood vessel, interstitially between the blood vessel and salivary cells and within both the somata and ductules of salivary cells. This confirms the importance of rhynchobdellid leech circulatory anatomy in facilitating the transmission of apicomplexan parasites. The lack of distinguishing characteristics precludes assigning a specific name to this parasite and may be indicative of frustrations that will be encountered in future revisions of the systematics of the genus Haemogregarina.

The life cycle of Hepatozoon sipedon sp. nov. was studied in two snake species, the Northern water snake and the Eastern garter snake, in its mosquito hosts Culex pipiens and C. territans, and in the Northern leopard frog. Gametogenesis, fertilization and sporogony occurred within fat body cells in the haemocoel of mosquitoes that had fed on infected water snakes. Mature oocysts averaging 263 microns in diameter and containing more than 500 sporocysts were observed in mosquitoes 28 days post-feeding. Each sporocyst enclosed eight sporozoites. Dizoic cysts were found in the liver of frogs that had been fed infected mosquitoes seven days previously. Two rounds of merogony in various internal organs and intraerythrocytic gamonts were observed in snakes that had been fed frogs which had been orally inoculated with infected mosquitoes. Developmental stages were not seen in snakes that were fed infected mosquitoes directly. A comparison of this life cycle with those described for other Hepatozoon species infecting snakes is presented with reference to the different modes of transmission featured by these parasites.

Control of the vector is usually a crucial factor in control programs for tropical diseases spread by insect vectors. Successful control programs aim at vulnerable points in the interactions between the vector, the reservoir host, the pathogen, the human host, and the environment. The objective is to prevent potential transmission, or interrupt actual transmission, by reducing the abundance, longevity, or host contact of the vector--whichever is most appropriate to the particular pathogen or disease and the local situation. The importance of individual assessment in the light of local conditions and a knowledge of the biology of the local vector is stressed. The vector-borne diseases discussed here are malaria, filariasis, arbovirus diseases, trypanosomiasis, leishmaniasis, plague and rickettsiosis.

Causative agents of intestinal infections in humans are about 10 pathogenic or facultative pathogenic species of protozoa of which Giardia lamblia, Entamoeba histolytica, Cryptosporidium parvum and Enterozytozoon bieneusi are discussed. G. lamblia from humans is morphologically indistinguishable from Giardia isolates originating from several species of domestic and wild mammals. Swiss Giardia isolates of human, sheep, cattle and dog origin could be transmitted to Giardia-free rodents and were rather homogenous in biochemical parameters. These data support the hypothesis that zoonotic transmission of Giardia may occur. Routine faecal examinations in Zürich in 1991 revealed 3.61% of Giardia excretors among 5017 examined patients. Of the same group of persons 3.95% excreted E. histolytica. At present it is anticipated that the species E. histolytica consists of invasive and non-invasive strains which can be differentiated by isoenzyme electrophoresis. The confirmation of this assumption could deeply influence the opinion about medical and epidemiological significance of Entamoeba infections. Cryptosporidium parvum is an important cause of diarrhea in HIV-infected patients. Person-to-person, zonnotic and waterborne transmission may play a role. A short review of new data on Enterozytozoon bieneusi and other microsporidia is presented. E. bieneusi appears to be an important causative agent of diarrhea in HIV-infected persons.

Viral and other exotic diseases may be transmitted by blood transfusion. These infections include human immunodeficiency virus (HIV), hepatitis viruses (A, B, C, D and E), syphilis, malaria, retrovirus HTLV-1, and cytomegalovirus. Other more exotic diseases which may be transmitted by transfusion of blood or blood components include Chagas' disease (Trypanosomiasis cruzi), Lyme disease (Borrelia burgdorferi), and Jakob-Creutzfeldt disease. Screening procedures currently used in Australian blood banks minimise transfusion-transmitted infection. The risk of acquiring any infection in this manner may be less than 0.1%.

Caryosporan oocysts were found in the feces of a diamond rattlesnake, Crotalus atrox, kept in ZOO Ustí nad Labem, Czech Republic. Comparison of oocyst structure with hitherto described Caryospora species from snakes revealed that they were Caryospora bigenetica Wacha et Christiansen, 1982. The rattlesnake, Crotalus atrox, represents a new host for C. bigenetica. The common vole (Microtus arvalis) and gerbil (Meriones unguiculatus) were successfully infected with a mixture of C. bigenetica oocysts and sporocysts following oral inoculation. All experimentally infected animals displayed clinical signs of dermal coccidiosis, including swellings of the face, ears, footpads, and scrota or vagina. Gerbils developed more severe clinical signs of infection and had a higher mortality than voles. Developmental stages of C. bigenetica were found in connective tissue of the nose, cheeks, ears, scrotum or vagina. Transmission of C. bigenetica caryocysts between common voles and mice, between mice and common voles, common voles and gerbils, and common voles and pigs was demonstrated. This study demonstrates that C. bigenetica can be transmitted by predation or cannibalism between different species of rodents and pigs.

Five hundred fresh stool specimens of patients with clinical symptoms of protozoan infections were examined for parasites. During June 1988-May 1991, the total number of positive cases was 261 (52.2 per cent). When the infectivity frequencies were segregated among the samples of different localities, it was observed that 6 (1.2 per cent) persons from the University of Nigeria community, 89 (17.8 per cent) urban dwellers and 166 (33.2 per cent) rural populace were infected. The highest incidence of Giardia lamblia (83, 47.8 per cent), Entamoeba histolytica (49, 28.3 per cent) and Chilomastix mesnili (34, 19.7 per cent) was found among the rural community. The infection started in April of each year (onset of rainy season), peaked between July and August, and was the lowest between November and March (dry season). Statistical interpretation of the results indicated that the parasitic infections depended on times of the year x2 0.01 > 4 calculated x2 0.01, 0.05 > 4 tabulated. The vehicle of transmission of the infection was green vegetable (Amaranthus viridans) which gets polluted by sewage oxidation pond at the locality.

Three Jersey cows were inoculated SC and IM with 26 million Neospora caninum tachyzoites at 129 (cow 1), 126 (cow 2), and 81 (cow 3) days after mating. Cows remained clinically normal for at least 1 month after inoculation of N caninum. Cow 1 was euthanatized 32 days after inoculation because of gangrenous mastitis. Cow 1 had a live fetus with no gross lesions; however, microscopic lesions were seen in the fetus and consisted of severe nonsuppurative necrotizing encephalitis of the cerebral white matter. Neospora caninum was identified in lesions by staining with anti-N caninum serum in an immunohistochemical test, by bioassays in mice, and by inoculation of bovine monocyte cultures with fetal tissue homogenate. Neither N caninum nor lesions were associated with infection with the protozoon identified in tissues of cow 1. Cows 2 and 3 aborted small autolysed fetuses 101 and 74 days, respectively, after inoculation with N caninum; the fetuses and attached placenta were unsuitable for laboratory investigations. Cows 2 and 3 remained clinically normal 4 months after abortion. Results of this study indicated that N caninum can be transmitted transplacentally in cattle.

Reactivation of latent infection is the principal mechanism relating Toxoplasma gondii and Pneumocystis carinii to HIV. Less common is reactivation in Leishmania donovani, Trypanosoma cruzi, and microsporidian infections. An impaired primary immune response occurs in all these infections, and also with Cryptosporidium and Isospora belli. Association of HIV infection with gut parasites including Giardia lamblia and Entamoeba histolytica, and also with Trichomonas vaginalis infection is likely to be related to sexual modes of contact that favour both HIV and the parasite. The severity of malaria is not definitely associated with HIV, but Plasmodium falciparum infection may favour more rapid evolution of the HIV infection. Both malaria and trichomoniasis favour HIV transmission; the former by necessitating blood transfusion, and the latter by enhancing viral transmission during sexual contact.

Tissue cysts of Neospora caninum were found in sections of brain from a stillborn pygmy goat. The tissue cysts had 1-2-microns-thick cyst walls and stained with anti-N. caninum serum in an immunohistochemical test. Glial nodules, mononuclear perivascular cuffing, and foci of inflammation were associated with N. caninum tissue cysts throughout the brain. This report indicates that N. caninum can be transmitted transplacentally in goats.

The emergence of the acquired immunodeficiency syndrome (AIDS) has fueled concerns of both physicians and their patients about safety of blood transfusions. Although AIDS has generated the most fear, the risk today is extremely remote (1/60.000 units of blood). The risk of transmitting infectious disease by homologous transfusion is decreasing, as more donor screening and testing measures are implemented. The blood supply is safer that at any time, but small transfusion risks exist. The most common problems associated with transfusions are temporary: one in 100-300 recipients will experience fever or rash. The biggest problem is a mismatch of the well-known ABO blood groups and once in every 100-400.000 transfusions the hemolytic reaction is fatal. Viral hepatitis is another serious and important risk. At present hepatitis seems to strike between 1 and 3 percent of transfusion recipients. Most, if not all, of transfusion-associated hepatitis cases are caused by hepatitis C virus. Cytomegalovirus can cause primary infection, reactivation or reinfection by transfusion. Immunosuppressed patients are more likely to develop more severe disease. Epstein-Barr virus does not seem to cause significant post-transfusion disease. Bacterial or protozoal infections are an infrequently encountered adverse effect of transfusion. However, some clinical cases document the potential hazard of blood components as a vector for bacteria or protozoa. Homologous blood transfusion down-regulates some immune functions. Host defences against malignancy and infection may in some instances be severely compromised by transfusions of homologous blood.(ABSTRACT TRUNCATED AT 250 WORDS)

A descriptive study on the prevalence and intensity of infection with intestinal parasites was performed in three selected areas of the Futa Djalon highlands during the rainy season of 1989. Randomly selected households were visited in Daka (an important urban sector of Labé), in the town of Timbi Madina and in a rural village, Sombili. Prevalence of intestinal protozoa was 58.5% in Daka, 63.3% in Timbi Madina and 76.5% in Sombili, while infection rates for helminths were 10.4%, 24.7% and 47.7% respectively. The data point to a higher level of oro-fecal transmission in the rural village compared to the urban environments. Most of the protozoan parasites detected were non-pathogenic, while hookworms were the most prevalent heliminths and in about one third of the cases multiple infections were found. Analysis of questionnaire data failed to show significant associations between selected socio-behavioural factors and parasitic infections.

This paper provides parasitological data necessary to the epidemiology of the major parasitic zoonoses transmitted by companion animals. Possible modes of contamination of humans are reviewed, along with various factors linked to parasites, host animals and human beings in the spread of zoonoses.

Intestinal tissue samples of 9 cyprinid and gobiid fish species from several hatcheries and ponds in South Bohemia were found to harbour Goussia carpelli-like coccidian oocysts. Furthermore, laboratory transmission of Goussia carpelli, obtained from common carp, was attempted to 9 cyprinid fish species, both laboratory reared and obtained from pond environments. Infection experiments, carried out by fecal contamination (direct transmission) and by using tubificid oligochaetes as paratenic hosts resulted in weak infections in 4 out of 15 Carassius auratus used, but it was not possible to infect any of the other fishes used.

Studies were conducted primarily to ascertain the mode of transmission of Cryptobia dahli parasitizing the digestive tract of lumpfish (Cyclopterus lumpus). Another flagellate, morphologically similar to C. dahli, was also observed in the gut of a deepsea fish (Macrourus berglax). Several invertebrates, which are food for lumpfish, were examined for flagellates, but were neither infected nor showed evidence of cystic stages. Parasites were more abundant in the stomach, especially at about pH 5, than in other areas of the digestive tract. Transmission was achieved by pipetting the parasites into the stomach of uninfected fish, by feeding food contaminated with flagellates, and also by holding infected and uninfected fish in the same aquarium. In nature, lumpfish probably acquire parasites during winter when they aggregate and regurgitate into seawater because parasites can survive for short periods outside their host.

A laboratory cat died 12 days after intraperitoneal inoculation of a 1 ml suspension containing 1.5 x 10(6) blood mononuclear cells from a Florida panther (Felis concolor coryi). Gross, histologic and ultrastructural investigations revealed the cause of death to be infection by Cytauxzoon felis, a protozoal parasite known to cause a rapidly fatal disease (cytauxzoonosis) in domestic cats. The bobcat (Felis rufus) has been identified as a natural host for C. felis. This report implicates the Florida panther as another possible host for C. felis.

Although zoonotic spread of infectious disease continues to occur in laboratory animals used in biomedical research, reported outbreaks have been minimized with the advent of rigorous veterinary and husbandry procedures, the use of commercially reared animals, and the institution of appropriate personnel health programs. Maintaining animals in modern facilities with appropriate safeguards against introduction of vermin and biologic vectors is also important in preventing zoonotic disease in personnel. Nevertheless, established zoonotic agents, newly discovered microorganisms, or new animal species not previously recognized as carriers of zoonotic microorganisms are encountered, and the potential for spread of infectious disease from animals to humans still exists. Active dialogue between veterinarians and physicians regarding the potential of zoonotic disease, the species of animals that are involved, and the methods of diagnosis, is an indispensable component of a successful preventive health program involving personnel who deal with laboratory animals.

Blood donations by emigrants or other travelers from distant lands require special attention for the prevention of transfusion-transmitted infections. The human immunodeficiency virus, type 1 (HIV-1) is only one of several bloodborne viruses that may be introduced into non-epidemic areas by transfusion and spread further by sexual intercourse, needles shared by drug users or mother-child transmission. Although transfusion-transmitted parasites, such as Trypanosoma cruzi, do not spread further in non-endemic areas in the absence of specific vectors, such unlikely infections may cause serious disease before a diagnosis is made. The challenges posed by transfusion-transmitted infections in a shrinking world require specific preventive strategies and enhanced clinical awareness for timely diagnosis and treatment.

Myxobolus pavlovskii from the gills of silver carp (Hypophthalmichthys molitrix) were used in attempts to transmit the infection under laboratory conditions. Spores of M. pavlovskii were placed in aquaria that contained sterilized sand and had been filled with tap water at 15-16 degrees C. Furthermore, oligochaetes (90% Tubifex tubifex) were added and examined by wet mounts and histology. Hexactinomyxon spores developed after about 3 months only in T. tubifex that had been exposed to M. pavlovskii. Myxosporea-free silver carp developed cysts in their gills that contained M. pavlovskii at 120 days after contact with Hexactinomyxon spores, proving that M. pavlovskii also needs an oligochaete intermediate host for its development.

In three different areas in northern Germany, hippoboscids were collected from red deer (Cervus elaphus). Typanosomatids were demonstrated in the midgut and hindgut of 9/37 Lipoptena cervi. The trypanosomatids were morphologically similar to vector forms of the subgenus Megatrypanum that had been found in tabanids at the same location 5 years previously. Hippoboscids are therefore potential vectors of Trypanosoma (Megatrypanum) spp. that infect red deer.

Four litters of German Shorthaired Pointers from one owner developed a toxoplasmosis-like illness. According to the records, 29 of 39 dogs had hind limb paralysis. Six dogs from 2 litters were necropsied and had generalized encephalomyelitis. Tachyzoites and tissue cysts of Neospora caninum were found in the brain and spinal cord of each dog. Lesions were found in the eyes, extraocular muscles, or both in all of the dogs, and N caninum was detected microscopically in the eyes (retina and choroid in 1 dog), extraocular muscles, or both in 5 of the 6 dogs. Ocular lesions consisted of focal retinitis, choroiditis, mild nonspecific iridocyclitis, and myositis of extraocular muscles. Organisms stained with anti-N caninum serum, but not with anti-Toxoplasma gondii serum in an immunohistochemical test, except in 1 dog. In one dog, aged thick-walled N caninum tissue cysts reacted mildly with anti-T gondii serum.

The occurrence and seasonal patterns of transmission of the blood protozoa of wild turkeys (Meleagris gallopavo silvestris) were studied at Tallahala Wildlife Management Area (TWMA) (Jasper County, Mississippi, USA). Blood smears obtained from wild turkeys in winter, spring and summer, and from sentinel domestic turkeys throughout the year were examined for Haemoproteus meleagridis and Leucocytozoon smithi. Whole blood from wild turkeys captured in summer was subinoculated into malaria-free domestic turkey poults and recipient birds were examined for Plasmodium spp. The prevalence of H. meleagridis and L. smithi were not different (P greater than 0.05) between adults and juveniles or between male and female turkeys in any season. Leucocytozoon smithi was not detected in poults in summer or in juveniles examined in winter. Sentinel studies and information from wild birds revealed that transmission of H. meleagridis and L. smithi did not overlap. Haemoproteus meleagridis was transmitted from May through November, while L. smithi was transmitted only from January through April. The onset of transmission of H. meleagridis coincided with peak hatching (mid-May) and brood-rearing (May-November) of turkey poults. Plasmodium spp. were not found in turkeys from TWMA (n = 27) nor in birds from three widely separated counties (n = 28) in Mississippi.

In April and December 1989, 35 fish from Lake Huillinco (42 degrees 48'S, 74 degrees 02'W) and 36 fish from Lake Natri (42 degrees 48'S, 73 degrees 50'W), in the Great Island of Chiloé (Chile) were examined. Coprological samples from 159 persons, 17 dogs, 19 pigs and 4 cats from around both lakes were examined for Diphyllobothrium spp. infection. In the Lake Huillinco the following helminths of fishes were determined: Contracaecum sp. and Hysterothylacium sp. in Salmo trutta, Cauque mauleanum and Eleginops maclovinus; Dichelyne (Cucullanellus) dichelyneformis in S. trutta and E. maclovinus and Scolex pleuronectis in S. trutta. One specimen of Mugil cephalus did not show helminth parasites. Prevalence of infection were greater for Contracaecum sp. in S. trutta (75.0%) and C. mauleanum (76.0%); and Hysterothylacium sp. in E. maclovinus (75.0%). Mean intensity was higher for D. (C.) dichelyneformis in E. maclovinus. Contracaecum sp. in S. trutta, Oncorhynchus mykiss, Oncorhynchus kisutch and Galaxias maculatus; Acanthocephalus sp. in S. trutta and G. maculatus, S. pleuronectis in O. mykiss and Cystidicoloides sp. in G. maculatus were determined at Lake Natri. Prevalence and intensity of infection were higher for Contracaecum sp. in S. trutta and O. kisutch. Infection by Diphyllobothrium sp. was determined in one domestic cat. Prevalence of infection by intestinal protozoan and helminths in human population only showed significative differences for Ascaris lumbricoides and Trichuris trichiura that were higher in the Lake Huillinco. Importance of natural infection by helminth parasites for fish in cultured condition and possible mechanisms of infections in relation to the diet of fishes are discussed.

A prospective study was carried out in 229 chronic patients (of both sexes) from the Psychiatric Hospital of Putaendo, in order to find out the frequency of intestinal parasites and/or commensals in the period 1987-1989. One hundred and ninety four (84.7%) out of the 229 studied patients were infected by parasites and/or commensals. The high prevalence of commensals Entamoeba coli (55.0%) and Endolimax nana (50.5%) became more evident. Among the parasites, the most frequent was Trichuris trichiura (41.5%). The presence of Pediculus humanus capitis and lesions suggestive of those produced by Sarcoptes scabiei were detected in 7.2 and 0.6 of the examined patients. The results obtained show the high frequency of intestinal infections by parasites and commensals in the patients of the studied hospital.

The copepod Microcyclops varicans was infected with Parathelohania anophelis by unincleate meiospores from a field-collected fourth instar Anopheles quadrimaculatus larva. Large numbers of unincleate, pyriform spores developed in the copepod. These spores were fed to early instar A. quadrimaculatus larvae, infecting both males and females, resulting in the production of cylindrical, binucleate spores in the adult. These spores were responsible for vertical transmission, through the eggs, to the larvae. The original spore type collected from the field was found in the male progeny from the infected females. Another P. anophelis-infected mosquito colony was established by feeding spores from a single, field-collected, infected copepod to A. quadrimaculatus larvae. The microsporidium was continuously maintained by vertical transmission in newly established infected colonies.

During May to August 1988, the prevalence of Lankesterella minima in bullfrog tadpoles and adults in the vicinity of Lake Sasajewun, Algonquin Park, Ontario, was 54.8% and 29.4%, respectively. The parasite was transmitted to laboratory-reared tadpoles through the bite of experimentally infected, laboratory-reared leeches (Batracobdella picta). Intraerythrocytic sporozoites were observed in the experimentally infected tadpoles 36 days postexposure (PE) to leech bites. Sporogonic stages in these tadpoles were examined by light and electron microscopy. Oocysts developed in vascular endothelial cells of several organs. Multinucleate oocysts at 29 days PE lay in a parasitophorous vacuole and contained several large inclusions. Mature oocysts, observed 32 days PE, contained about 70 sporozoites that exhibited typical apicomplexan features. In the posterior region of the sporozoites, 12 helically arranged chains of electron-lucent intrapellicular extended anteriorly from a dense terminal ring.

Orthotopic liver transplantation is a therapeutic option for selected patients with end-stage liver disease. Among the complications of orthotopic liver transplantation infectious problems are a major cause of mortality. In this report the different types of infection following orthotopic liver transplantation are reviewed. In addition, currently available data regarding to transmission of infectious agents from organ donor to transplant recipient are reported.

The importance of treating public water supplies to destroy pathogenic micro-organisms has long been recognized. In the past, emphasis has been laid on bacteria, but the hazard posed by certain protozoan parasites is being increasingly recognized. Some of these present a particularly serious problem in that they can survive chlorination and most purification treatments regarded by international standards, as giving adequate protection to the consumer.

Spores of Myxobolus cotti El-Matbouli and Hoffmann 1987 and M. cerebralis Hofer 1903 (fresh or after 5 months in mud) are taken in by tubifex worms and develop in their gut epithelium cells into actinosporea of the genus Triactinomyxon. Triactinomyxon deriving from M. cotti differ distinctly from those derived from M. cerebralis in morphology and the number of sporozoites in the epispore. It could be shown that Triactinomyxon spores infect fish either via the water (bullhead, rainbow trout) or by feeding of infected tubifex (rainbow trout), developing into Myxobolus spores in central nervous tissue (bullhead) or cartilage (rainbow trout). Fresh or ripened spores of M. cotti and M. cerebralis were not infectious for bullheads or rainbow trout, respectively. The results of our experiments confirm the hypothesis that the life cycle of M. cotti and M. cerebralis includes an intermediate host and a metamorphosis into actinosporea of the genus Triactinomyxon.