[Effect of sulfamonomethoxine and ormetoprim on leucocytozoon infection in chickens]

The preventive effect of sulfamonomethoxine (Smm) and ormetoprim (Omp) medicated in combination against leucocytozoon infection in chickens was tested in field trials. In trial 1, medication was given continuously throughout the experimental period. In trial 2, medication was given for seven days and no medication was given for the next seven days; then this schedule for the medication was repeated throughout the experimental period. In trial 1, almost complete prevention was obtained when Smm and Omp were added to the feed at the level of 12 ppm and 14 ppm, respectively, or at the level of 15 ppm and 5 ppm, respectively. Only a partial effect was obtained, however, when these drugs were used at the level of 9 ppm and 3 ppm, respectively. In trial 2, a nearly complete effect was obtained when Smm and Omp were added to the feed at the level of 18 ppm and 6 ppm respectively, but we found no effect when these drugs were used at the level of 15 ppm and 5 ppm, respectively. There were no significant differences among the groups as to the weight gain.

[Zschokkella (Protozoa: Myxosporea) in the gallbladder of Cyprinus carpio (Osteichthyes) in East Germany]

The gallbladder of two-yearling carps caught in a lake in the region of Frankfurt-on-Oder was found invaded with Zschokkella sp., which is the first case recorded in the German Democratic Republic.

Parasite transmission in confined hogs

Examinations of fecal specimens from swine of all ages maintained in a totally enclosed confinement facility in south Georgia were conducted in a 5-year survey (1977-1981) to determine the prevalence, intensity, and transmission patterns of intestinal nematode and protozoan parasites. Weaned pigs in the nursery had no detectable parasitic infections except sporadic Isospora suis in newly weaned pigs. Growing-finishing hogs had a low prevalence of Ascaris suum, Oesophagostomum spp. and Balantidium suis. Mean A. suum prevalence and mean eggs per gram feces (EPG) increased until about 200 days of age and then declined. Oesophagostomum spp. and B. suis prevalence and intensity tended to increase throughout life. Gilts (mean age 273 days) in the gestation unit had a higher (P less than 0.01) prevalence of A. suum and lower (P less than 0.01) prevalences of Oesophagostomum spp. and B. suis than sows (mean age 706 days). Similarly, A. suum EPG was higher (P less than 0.01) and Oesophagostomum spp. EPG and B. suis cysts per gram feces (CPG) were lower (P less than 0.01) in gilts than in sows. No evidence for a peri-parturient increase in parasite eggs or cysts was found. Instead, there was a higher prevalence of B. suis (P less than 0.01) in gestating than in lactating animals and more lactating sows than gestating sows were negative for parasites (P less than 0.01). Apparent differences due to location (gestation unit or farrowing unit) were largely attributable to age differences. Trichuris suis infections were rare and not shown to be established in the herd. Strongyloides ransomi in suckling piglets was controlled by anthelmintic therapy. I. suis occurred in piglets throughout the study but was never found in sows in the farrowing unit, either before or after birth of a subsequently infected litter of piglets. No parasites requiring intermediate hosts occurred.

[Discovery of a protist parasite, apparently akin to Acrasiae, in the genital tract and various organs of primates]

Microcysts were first observed in histological sections of the placenta of a gibbon, the uterus of a Microcebus, showing a pyometra, the placenta, spleen and lung of a new born mangabey which died soon after birth from an interstitial pneumonia. Plasmodial forms were also discovered in the sections, either encysted or infiltrating the tissues. Cultures from all the above mentioned pathological material were attempted on a special medium, the composition of which will be given later. All cultures shew myxamoeba-like organisms aggregating and merging into pseudoplasmodial forms that produced microcysts. Attention is drawn to the pathogenic rôle of this new kind of parasites in order that they should be searched for, in every case of genital troubles not ascribable to other causes.

Identification of Toxoplasma gondii and Encephalitozoon cuniculi by immunoperoxidase techniques and electron microscopy, in stored, formalin-fixed, paraffin-embedded tissue

The peroxidase-anti-peroxidase (PAP), avidin-biotin-complex (ABC) techniques, and electron microscopy, were used to identify protozoan parasites in formalin-fixed material from routine necropsy cases. The material comprised paraffin blocks, that had been stored for up to 18 years, from 18 cases of suspected toxoplasmosis and encephalitozoonosis. With the ABC method a higher dilution of primary antibody could be used than with the PAP method. However, with both methods, a distinct reaction occurred with appropriate dilutions. The age of the material did not seem to effect the result. Frequently, phagocytized and necrotic parasites were also stained. Gystozoites (bradyzoites) of T. gondii were stained faintly compared to the endozoites (tachyzoites). A Toxoplasma-like parasite from a dog did not react with anti-Toxoplasma serum, and ultrastructurally it proved to be consistent with an unidentified cyst-forming sporozoan parasite previously reported in dogs. Electron microscopy based on paraffin-embedded tissue, seems to be a valuable method for identification of protozoan parasites, and thus provide a supplement or alternative to the immunoperoxidase methods.

The infectivity of Encephalitozoon cuniculi in vivo and in vitro

The infectivity of Encephalitozoon cuniculi grown in cell cultures was determined in cultured cells and in wild and domestic rabbits. The ratio of the total to tissue culture viable count was 1,300 (median of seven determinations). The mean ratio of intact spore count to total count, as determined by electron microscopy was 0.12. Although variation between infectivity experiments was large, the median animal infective dose contained 51 FFU (cell culture focus-forming units) for wild rabbits (Oryctolagus cuniculus) and 40 FFU for domestic rabbits. These two infectivities were not statistically different.

Use of hybridoma antibodies and recombinant DNA technology in protozoan vaccine development

The use of hybridoma antibodies developed against the sporozoite stage of avian coccidia, coupled with genetic-engineering techniques, has made it possible to begin bird-immunization studies utilizing an Escherichia coli-elicited coccidial protein. The coccidia are currently controlled in the poultry industry by use of anticoccidial compounds, but it now may be possible to use the bird's own immune system for defense against the parasitic infection. Since the sporozoite stage, which initiates the infection in poultry, is quite complex and is made up of hundreds of proteins or antigens, hybridoma antibodies were produced to identify specific antigens. These antigens, once identified, were found in such minute amounts that it became necessary to utilize genetic engineering in order to produce enough protein for immunization studies. One such protein, designated 5401, has been shown to stimulate an antibody response in immunized birds and to impart partial protection against a coccidial challenge infection. The results of these studies indicate that development of a vaccine against coccidial parasites may someday be possible.

[Encephalitozoonosis in farm-bred arctic blue foxes (Alopex lagopus)]

Occurrence of encephalitozoonosis in farm breeding of blue fox is described. Fifty youngs of eight breeding females were infected, mortality was 88%. The main clinical symptoms of the disease were somnolence, ataxia, vision disorders, clonic spasms, at a protracted course also retarded growth. Typical nonpurulent microgranulomata with occurrence of individual spores and cysts of Encephalitozoon cuniculi were demonstrated in liver and central nervous system. Further, diffusion interstitial nephritis and necrotizing angiitis were determined. In breeding females, chronical interstitial nephritis was determined, without detection of the causative agent. A probable source of infection was the feeding of dead rabbits with subsequent transmission to progeny.

Enigmatic cyst-forming sporozoon in the spinal cord of a dog

A female racing greyhound dog was presented to the clinic at the age of 3 months with a 2 months’ history of irregular hindleg movements and thin hindleg muscles. On examination 1 month later, a squatting standing posture, a week proprio-ceptive positioning reaction, and severe atrophy and pain of the lumbar and thigh muscles, were evident. The dog was sacrificed and necropsied. The adrenals, hindleg muscles, kidneys, myo-cardium, peripheral nerves, spinal cord, thyroid, and tonsils were fixed in 10 % neutral buffered formalin and processed for histo-pathology.

[Hexamitiasis in carrier pigeons in the Netherlands]

Hexamitiasis in carrier pigeons caused by Hexamita columbae was reported for the first time in the Netherlands. Infections tend to occur from April to July in 6-8 week old birds. The patients were affected with diarrhoea, became emaciated and died. Mortality may be considerable. Parasites may be identified in unstained wet specimens of very fresh droppings. Treatment consists in administration of ronidazole during a period from seven to ten days. Optimum hygiene should be observed.

Deaths in Australian freshwater fishes associated with Chilodonella hexasticha infection

The cause of the deaths of bony bream and other native fish in the Finke River near Alice Springs in winter 1984 was infection with the protozoan ciliate Chilodonella hexasticha. The parasites induced severe generalised epithelial hyperplasia in the gills, which would have compromised respiratory exchange and killed the fish through hypoxaemia. It is suggested that similar winter epizootics of ectoparasites have contributed to previous deaths of fish observed in the Finke River, in association with dry season conditions of low water temperatures and flow rates.

[Effect of sulfaquinoxaline and diaveridine on leucocytozoon infection in chickens]

The preventive effect of sulfaquinoxaline and diaveridine in combination against leucocytozoon infection in White Leghorn female chickens was tested in a field trial. The experiment was initiated when the animals were 120 days old, and it lasted for 10 weeks. The medication was given for the first seven days, and no medication was given for the next seven days; then this schedule for the medication was repeated throughout the experimental period. The almost complete preventive effect was obtained when sulfaquinoxaline and diaveridine were added to the feed at the level of 16 ppm and 4 ppm, respectively, or at the level of 8 ppm and 2 ppm, respectively. On the other hand, only a partial effect was obtained when these drugs were used at the level of 4 ppm and 1 ppm, respectively. These medications had no adverse effect on the weight gain in the experimental birds.

Chemotherapy of experimental Besnoitia besnoiti infection in rabbits

Rabbits were infected with a bovine strain of Besnoitia besnoiti parasites derived from VERO cell cultures. Oxytetracycline, given at 30 mg/kg i.m. simultaneously with infection, prevented the development of orchitis. The controls received no treatment. All infected animals showed a transient febrile reaction. It is concluded that oxytetracycline has some therapeutic potential against Besnoitia besnoiti and that rabbits are suitable models for therapeutic trials.

[Effect of HPS on leucocytozoon and coccidial infection in chickens]

The effect of HPS (halofuginonepolystyrene sulfonate), a derivative of halofuginone with lower toxicity, on natural leucocytozoon and coccidial infection in broiler chickens was evaluated in a floor pen trial. The experiment was conducted from one day to 10 weeks of age. On leucocytozoon infection, HPS added to the diet was completely effective at 60 ppm, fairly effective at 40 ppm and ineffective at 20 ppm. On the other hand, HPS concentrations of 20 ppm, 40 ppm and 60 ppm were completely effective on coccidial infection. HPS at 40 ppm which corresponds to the recommended level of halofuginone (3 ppm) and at 60 ppm had no adverse effect on the weight gain in experimental birds.

Head tilt in rabbits caused by pasteurellosis and encephalitozoonosis

Rabbits (Oryctolagus cuniculus) of non-dwarf (Group A) and dwarf (Group B) strains showing a common clinical sign of head tilt (torticollis) were examined. With 1 exception, all rabbits of group A had otitis and empyema of either one or both middle ears. Pasteurella multocida was isolated from pus and from the nose of all but 1 of these rabbits, and on occasion was also isolated from the brain. By contrast in all dwarf rabbits the presence of the protozoan Encephalitozoon cuniculi was confirmed both histologically and serologically. This parasite did not affect the ears of the animals but rather the central nervous system. We assume that the different exposure to both agents, rather than the degree of susceptibility, was responsible for the differences found between the 2 types of rabbits.

Haematology and pathology of captive southern grasshopper mice (Onychomys torridus)

A colony of Onychomys torridus was evaluated for the prevalence of infectious, parasitic and congenital diseases. Multiple limb defects including brachydactyly, syndactyly, and hemimelia were observed in offspring from the colony. The colony was parasitized by Ornithonyssus bacoti (tropical rat mites) on 2 occasions. No infectious diseases were detected. Normal haematologic values were determined in healthy adult animals.

Specific antibodies to Besnoitia besnoiti precipitated from serum of cattle by live parasites and by soluble antigen

Specific precipitable antibodies of both IgG and IgM classes were detected in sera of cattle naturally infected with B. besnoiti. The amount of specific antibodies of the IgG class precipitated by soluble antigen was in the range of 17-50 micrograms/ml serum while that of the IgM class ranged between 5 and 24 micrograms/ml serum. Specific antibodies precipitated by live B. besnoiti parasites were in amounts of 10 to 22 micrograms/ml serum for IgG and 4 to 26 micrograms/ml serum for IgM. Different ratios of IgG/IgM were obtained by the two methods of precipitation. This might indicate that antibodies to B. besnoiti of the IgM class can be precipitated and detected in sera of naturally infected cattle in similar amounts either by live parasites or by solubilized antigen, whereas antibodies of the IgG class can be preferentially detected when solubilized antigen is used for precipitation.