Efficacy of toltrazuril against intestinal and hepatic coccidiosis in rabbits

The anticoccidial effect of toltrazuril (Bay Vi 9142) against Eimeria flavescens, E. intestinalis, E. magna, E. perforans and E. stiedai was tested in experimentally-infected rabbits. Continuous administration of 10-15 p.p.m. of the drug in the drinking water was highly effective in reducing oocyst output of all five species and in preventing clinical signs and macroscopic lesions. Sporulation of excreted oocysts was not affected. After 5 weeks of medication, no negative influence was noted on zootechnic performance of growing healthy rabbits. Medication of rabbits with 25 p.p.m. only during schizogony or gamogony (2 days of treatment, repeated after 5 days) quickly reduced clinical signs and oocyst output. When administered during late schizogony or gamogony, toltrazuril allowed development of immunity against reinfection with homologous species.     

Effect of subcutaneously administered diclazuril on the output of Eimeria species oocysts by experimentally infected rabbits

The effect of subcutaneously injected diclazuril on the output of Eimeria species oocysts was studied in experimentally infected rabbits. Diclazuril was administered either prophylactically at 0.5, 1 or 2 mg/kg bodyweight two days before each rabbit was inoculated with 20,000 oocysts of a mixed-species field isolate of Eimeria or therapeutically at 1, 2 or 4 mg/kg bodyweight five days after they were inoculated. The prophylactic treatments significantly reduced (P<0.05) the output of oocysts in faeces and the numbers in the rabbits' livers at all doses. The therapeutic treatment at 4 mg/kg also caused a significant reduction (P<0.05) in oocyst shedding, but the lower doses resulted in only a moderate reduction. The shedding of the pathogenic species Eimeria stiedae, Eimeria magna, Eimeria irresidua, Eimeria flavescens, Eimeria piriformis and Eimeria intestinalis was significantly reduced (P<0.05) in all the treated groups. The burden of oocysts in the livers of the therapeutic groups (4000 to 9000) were significantly lower (P<0.05) than in the inoculated but untreated control group (23,000), but higher than in the prophylactic groups (around 1000).     

Canine coccidiosis attributed to an Isospora ohioensis-like organism: a case report

Coccidiosis due to an Isospora ohioensis-like organism was diagnosed in a 10-week-old pup. The pup had diarrhea, dehydration, and weight loss before it died 7 days after onset of clinical signs. Lesions were limited to the intestinal tract. Beginning in the distal end of the small intestine and extending through cecum and colon were mild histiocytic proliferation in the lamina propria and multifocal cryptitis. Numerous meronts and gamonts of an unidentified coccidium were in or near the lesions. Parasites were in the villous epithelium, lamina propria, and intestinal glands of the distal one-half of the small intestine, cecum, and colon. It was concluded that infection was due to an unidentified coccidium with oocysts structurally similar to those of I ohioensis.     

Merogony and gametogony of Eimeria mccordocki (Protozoa-Eimeriidae) in the mule deer, Odocoileus h. hemionus

Eimeria mccordocki and E. madisonensis oocysts were isolated from feces of 21 of 40 captive mule deer in Fort Collins, Colorado. The two species were separated from each other by infecting one mule deer fawn, and the life cycle of E. mccordocki was studied for the first time. Four to six-weeks-old mule deer fawns were inoculated orally with E. mccordocki and killed 9, 13 and 15 days after infection. Asexual and sexual stages of life cycle developed in the ileum of mule deer, only in the surface epithelial cells of the villi. The asexual stages consisted of two generations of meronts.     

Life cycle of Isospora suis in gnotobiotic and conventionalized piglets

Isospora suis had 3 asexual and 1 sexual intra-intestinal conventional life cycle. The first asexual generation was most prominent at 2 days p.i. (post inoculation) and produced 2–7 merozoites. The second-generation meronts were prevalent at 3–4 days p.i. and produced 2–12 large merozoites. At 4–5 days p.i. the third generation meronts were prominent and produced 4–24 small crescent shaped merozoites. Mature sexual stages were most prominent at 5–6 days p.i. The stages were most numeroous in the distal half of the small intestine. At 8–9 days p.i. stages morphologically similar to the second generation of meronts reappeared, followed by the further development into third generation merozoites and sexual stages. This was reflected in a prepatent period of 5 days and a biphasic patent period of 5–8 or 9, and 11–14 days p.i.Intraperitoneal injection of liver/spleen and intestinal lymph node homogenates, respectively, from piglets infected 24 and 48 h, previously with high doses of oocysts, resulted in a patent infection 10–12 days post inoculation of the donor piglets. No differences in the life cycle of I. suis were observed between conventionalized and germ-free piglets. An extra-intestinal life cycle of I. suis related to the second patent period was postulated.     

Clinical sarcocystosis in calves fed Sarcocystis hirsuta sporocysts from cats

Lesions of sarcocystosis were studied in 14 calves necropsied between seven and 110 days after inoculation with 5000 to 25 million sporocysts of Sarcocystis hirsuta from cats. Calves developed fever, anemia, and diarrhea between 11 and 30 days after inoculation. The development of first generation meronts in arteries of small intestine, mesentery, and mesenteric lymph nodes seven to 25 days after inoculation was associated with vascular occlusion and necrosis of associated tissues. The development of second generation meronts in capillaries of striated muscles 15 to 23 days after inoculation was associated with necrosis, edema, and nonsuppurative myositis in heart and other muscles. Sixty-two days after inoculation lesions were reduced to focal areas of granulomatous inflammation around degenerating sarcocysts in striated muscles, but not in the heart.     

Immunohistologic examination of monoclonal antibodies generated against Eimeria bovis sporozoites for reactivity to meronts and sexual stages of E bovis and other eimerian parasites

Seven monoclonal antibodies (MAB) generated against sporozoites of Eimeria bovis were tested for reactivity against immature and mature first-generation meronts, sexual stages, and oocysts in tissues from experimentally infected calves by use of an avidin-biotin peroxidase complex (ABPC) immunohistologic test. Three of the 7 MAB reacted in the ABPC test. One of these, MAB-4FB4, reacted only with mature E bovis meronts. The other 2 MAB, MAB-2AE7 and MAB-4AD7, reacted with all the developmental stages of E bovis tested. Asexual stages and sexual stages of E tenella from chickens and E papillata from mice also were examined in the ABPC test. Monoclonal antibodies MAB-2AE7 and MAB-4AD7 reacted with all stages of these eimerian protozoa. None of the other 5 MAB reacted with these parasites. Results of this study suggested that antigens are shared among the asexual and sexual stages of several diverse Eimeria species.     

Biological properties of RB51; a stable rough strain of Brucella abortus

A rifampin-resistant mutant of Brucella abortus, designated RB51, was derived by repeated passage of strain 2308 on Trypticase soy supplemented with 1.5% agar and varying concentrations rifampin or penicillin. The RB51 colonies absorbed crystal violet and RB51 cell suspensions autoagglutinated, indicating a rough type colonial morphology for this strain. No O-chain component was detected in lipopolysaccharide (LPS) extracted from RB51 on SDS-PAGE gels stained with silver. Western blot analysis with the monoclonal antibody BRU 38, which is specific for the perosamine homopolymer O-chain of smooth Brucella LPS, indicated that the LPS of RB51 is highly deficient in O-chain when compared with the parenteral smooth strain 2308 or rough strain 45/20. Biochemically, RB51 resembles parental strain 2308 in its ability to utilize erythritol. Intraperitoneal inoculation of RB51 into mice results in a splenic colonization which is cleared within four weeks post infection. RB51 does not revert to smooth colony morphology upon passage in vivo (mice) or in vitro. Mice infected with RB51 produce antibodies against B. abortus antigens including class 2 and 3 outer membrane proteins but not against the O-chain. Furthermore, rabbits, goats and cattle hyperimmunized with sonicates of RB51 develop antibodies to B. abortus cellular antigens but do not develop antibodies specific for the O-chain. Immunization of mice with 1 x 10(8) viable RB51 organisms confers significant protection against challenge with virulent B. abortus strain 2308.     

The extraintestinal stages of Eimeria tenella and E. maxima in the chicken

Donor chickens given feed medicated with one or two levels of decoquinate or given non-medicated feed were infected with oocysts of Eimeria tenella or E. maxima per os. Twelve hours after inoculation with oocysts liver, mid-intestine or ceca homogenates were fed to previously uninfected recipient chickens. The results showed that continuous medication with decoquinate was effective in preventing the transfer of sporozoites from the intestine to the liver. Oocysts were detected in the feces of all recipients of tissue from non-medicated donors, showing that some sporozoites of E. maxima and E. tenella are normally transferred to liver. Young broiler chickens were immunized by oral inoculation of E. maxima oocysts. The immune status of similar chickens inoculated with sporozoites of the same species directly into the liver or spleen were assessed. During the experimental period half of the chicks were provided with non-medicated food and the remainder were given feed supplemented with decoquinate; decoquinate was effective in arresting the development of the sporozoites. Two weeks after initial infection the birds were challenged with oocysts of E. maxima per os. Injection of sporozoites into the spleen did not protect against challenge. Birds inoculated with sporozoites into the liver were unable to develop a significant level of immunity. When the drug pressure was removed from these birds, parasitism of the intestine occurred and immunity developed.     

流产布鲁氏菌疫苗候选株RB6生物学特性研究

为了开发布鲁氏菌病新型标记疫苗,本研究对流产布鲁氏菌基因缺失株RB6的培养特性、染色特性、凝集特性、稳定性及小鼠体内毒力和免疫保护力进行了系统鉴定,旨在阐明该菌株具备的生物学特性。通过对亲本菌株和RB6的比较,发现固体培养基上RB6菌株单菌落可被结晶紫染成紫色,RB6菌株液体培养物可与0.1%吖啶黄染料以及抗布鲁氏菌粗糙型抗体发生凝集反应,证明该菌株为粗糙型。将RB6菌株在体外连续传代培养20次和牛体内连续5次继代,检测结果证明其表型未发生变化,说明该菌株遗传稳定性良好。通过小鼠体内试验发现该菌株毒力显著降低,并对流产布鲁氏菌强毒菌株2308攻毒的免疫保护力与现有疫苗A19接近。本研究结果表明,流产布鲁氏菌基因缺失株RB6为粗糙型菌株,毒力较低、安全性高、遗传性状稳定,并具有良好的免疫保护效力,有望开发成为动物布鲁氏菌病粗糙型标记疫苗。     

Evolution of coccidial infection in commercial and domestic rabbits between 1982 and 1986

Caecal samples were collected from 751 domestic rabbits of various origin and from 1229 diarrhoeic rabbits issued from 61 commercial rabbitries. They were screened for coccidiosis. In 1982, the year of introduction of the anticoccidial robenidine in commercial rabbit feeds, a dramatic decrease of coccidial infection ratio was detected in commercial rabbitries: only 6% of samples contained greater than 100 oocysts per gram against 85% in 1979, when sulphaquinoxaline/pyrimethamine was used. Only Eimeria magna, E. media and E. perforans were detected, whereas the highly pathogenic species E. flavescens and E. intestinalis had disappeared from commercial units. After 4 years of continuous use of robenidine, infection ratio rose progressively, although still far below the 1979 levels. Most of the other species reappeared, but only in very low proportions (1-4% of samples). The percentage occurrence of E. magna, E. media and E. perforans on the contrary rose progressively to 25, 26 and 34%, respectively, suggesting drug resistance. In domestic rabbitries, the incidence of coccidial infection was markedly higher and all nine species of Eimeria were detected. Eimeria magna, E. media and E. perforans were very common, E. flavescens, E. intestinalis, E. piriformis and E. stiedai were less common, whereas E. irresidua and E. coecicola were relatively rare. Notwithstanding the lower activity of robenidine against E. stiedai, no rise of hepatic coccidiosis became evident.     

Development of Isospora suis from pigs in primary porcine and bovine cell cultures

Sporozoites of Isospora suis penetrated and developed by endodyogeny in primary porcine kidney (PPK) and primary fetal bovine kidney (PFBK) cell cultures. Motile merozoites and binucleate Type I meronts were observed in both types of cultured cells. Multinucleate Type II meronts developed in PPK cell cultures only. These multinucleate meronts were always found singly, were nonmotile and did not form merozoites.     

Effect of decoquinate on the control of coccidiosis in young ruminating calves

Twenty-five 6-week-old Holstein male calves were each inoculated with 500,000 sporulated oocysts of Eimeria bovis. Two nontreated (control) and 3 treated calves (1.5 mg of decoquinate/kg of body weight in feed) were necropsied 7 days after inoculation. Similar groups of calves were necropsied at 12, 18, 22, and 28 days after inoculation. Treated calves were started on medicated feed 2 days before inoculation or at 7, 12, or 15 days after inoculation or were on continuous medication from the day of inoculation. Control calves were not given medication. Early schizonts were in the small intestines of control calves at 7 days after inoculation, but none was in the treated calves that were started on medicated feed 2 days before inoculation. Schizonts were present in the small intestine of both treated and control calves at 12 days after inoculation. At 18 days after inoculation, control calves had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestines, but treated calves only had schizonts in the small intestine. At 22 days, control calves had schizonts in the small intestine and gamonts and oocysts in the large intestine; treated calves had schizonts in the small intestine. At 28 days, controls still had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestine; the treated calves that had been on continuous medication did not have schizonts, gamonts, or oocysts in the tissues. Decoquinate apparently kills sporozoites or arrests development and release of merozoites from the schizonts when fed at 1.5 mg/kg of body weight in the feed.     

Cryptosporidium infection in juvenile pet rabbits

Cryptosporidium infection was confirmed by fecal examination for the first time in pet rabbits in a wholesale store located in Kanagawa Prefecture, Japan. Fecal samples were obtained postmortem from juvenile rabbits (n=66), which had died after developing diarrhea. Feces from healthy rabbits (n=30) were also collected and examined as controls. Two types of Cryptosporidium oocysts distinctive in size and shape were found (Type A and B). Types A and B oocysts were detected from 16.7% and 13.6% of the diarrheic, and 3.3% and 0% of the normal feces, respectively. Since Cryptosporidium oocysts were detected at a higher rate in the diarrheic rabbits than in the healthy rabbits, special caution should be taken when handling a pet rabbit presenting with diarrhea.     

Attenuation of Eimeria species: further characterisation of two lines of Eimeria mitis

The immunogenicity of a 'precocious' and attenuated line (HP10) of Eimeria mitis was studied and the stability of attenuation of two precocious lines was compared with that of an embryo-adapted line. Chicks housed in wire-floored cages and given 1 X 10(5) oocysts of the HP10 line were protected against challenge with the parent Houghton strain and two field strains, but remained partially susceptible to the Durham and one other field strain. However, when chicks were kept in litter pens so that reinfection could occur freely, inoculation with as few as 1 X 10(3) oocysts of the precocious line resulted in complete immunity to both the Houghton and Durham strains for at least five weeks afterwards. The stability of attenuation of the precocious and embyro-adapted lines was examined by relaxing the selection pressures used to produce attenuation and then testing the virulence of the resulting lines. The precocious lines remained attenuated after several consecutive relaxed passages, in contrast to the embyro-adapted line which showed a marked reversion to virulence after six passages in chickens.     

Results of cytologic and microbiologic analysis of bronchoalveolar lavage fluid in New Zealand White rabbits

OBJECTIVE: To determine cytologic and microbiologic findings in bronchoalveolar lavage (BAL) fluid and SpO(2) values obtained during BAL in healthy rabbits. ANIMALS: 9 rabbits. PROCEDURES: Bronchoscopic BAL of left and right caudal lobar bronchi (LB2 and RB4) was performed with 3 mL of sterile saline (0.9% NaCl) solution; SpO(2) was measured before, during, and after BAL. Percentage fluid recovered, total leukocyte counts, and differential cell counts were determined. Aerobic and anaerobic bacterial, mycoplasmal, and fungal cultures were performed from combined LB2 and RB4 samples. RESULTS: Mean +/- SD percentage fluid volumes recovered from LB2 and RB4 were 53 +/- 13% and 63 +/- 13%, respectively. Mean +/- SD total leukocyte counts from LB2 and RB4 were 422 +/- 199 cells/microL and 378 +/- 97 cells/microL, respectively. Macrophages were most frequently identified. There were no significant differences in volumes retrieved, total leukocyte counts, or differential cell percentages between LB2 and RB4. Microbial culture results were negative for 3 rabbits and positive for mixed aerobic and anaerobic bacterial growth in 6 and 2 rabbits, respectively. The SpO(2) was > or = 95% in 7 of 9 rabbits after anesthetic induction, < 95% in 5 of 6 rabbits 1 minute after BAL, and > or = 95% in 5 of 9 rabbits and > 90% in 4 of 9 rabbits 3 minutes after BAL. CONCLUSIONS AND CLINICAL RELEVANCE: Bronchoscopic BAL with 3 mL of saline solution provided adequate fluid recovery for microbiologic and cytologic examination from the caudal lung lobes. Transient low SpO(2) was detected immediately after BAL.     

Ultrastructural observations on different developmental stages of Goussia sinensis (Chen, 1955), a parasite of the silver carp (Hypophthalmichthys molitrix Valenciennes, 1844)

The development of Goussia sinensis, a coccidium parasitizing the intestine of the silver carp (Hypophthalmichthys molitrix) was studied by electron microscopy. All stages developed in the epithelial cells, less frequently in the goblet cells, and were located within a parasitophorous vacuole. In some cases one cell was invaded by several merozoites. Eight to sixteen merozoites were formed within the meront by ectomerogony. The ultrastructural processes characteristic of gamogony were the same as those found for Goussia spp. parasitizing other species of fish. A hitherto unknown mechanism of oocyst wall formation was observed. The oocyst membrane developing within the zygote surrounded only part of the zygote material. Thus, a small part of the zygote material left the oocyst proper. It is suggested that this zygote residue and the necrotic host cell constitute the so-called "yellow bodies" which include the excreted oocyst. The oocyst wall was 40 to 60 nm thick. Oocyst sporulation took place within the fish. The sporocysts consisted of two hemispheres connected by sutures and had a 100 to 120 nm thick double wall. They were surrounded by sporocyst veils fixed to the oocyst wall by membranes.     

Infectivity of Cryptosporidium sp isolated from wild mice for calves and mice

A study was conducted to determine the incidence of cryptosporidiosis in wild mice (Mus musculus) and the infectivity of oocysts from their feces for susceptible calves. The presence of oocysts and the duration of shedding of oocysts in the feces were evaluated in 115 wild mice. Approximately 30% of the mice shed Cryptosporidium sp oocysts, without evidence of clinical infection; recurrence of oocyst shedding was found in about 50% of the mice. Oocysts from the feces of naturally infected mice were infective for calves and mice. Calves began shedding oocysts at 7 days and shed oocysts for about 10 days. Nonfatal, clinical cryptosporidiosis developed in 7 infected calves. The mice began shedding oocysts at 6 days and shed oocysts for 12 days. Fatalities or clinical infection did not develop in 5 infected mice. The results indicated that Cryptosporidium-infected wild mice may be a source of cryptosporidiosis in susceptible calves.     

Anatomical and histological characterization of ileal and jejunal Peyer's patch in lesser mouse deer (Tragulus javanicus)

Tragulidae is a primitive ungulate family within the order Cetartiodactyla, suborder Ruminantia. Domestic ruminants such as cattle, sheep, and goat have two types of Peyer's patches (PP): jejunal and ileal PP, in which there are morphological and functional differences. In this study, lesser mouse deer (Tragulus javanicus) PP was studied by gross anatomical and histological procedures. At the fetal stage, both types of PP were formed in the small intestine. Ileal PP was observed as a single continuous aggregation of lymphatic follicles extending cranially from the ileo-caecal junction. However, jejunal PP was observed as multiple and discrete accumulations of lymphatic follicles. This study showed that the lesser mouse deer has two types of PP in the small intestine. In addition, the anatomical and histological characteristics of jejunal and ileal PP are quite similar to those of other ruminants' jejunal and ileal PP. Further studies are needed to analyze immune function of both PP in lesser mouse deer in order to determine the evolutionary process of Cetartiodactyla.