• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.189-194
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• 1997

The life cycle of Theileria sergenti(T sergenti) in cattle, especially Korean native cattle, was not proved clearly. To find schizont stage in the life cycle of T sergenti in Korean cattle, T sergenti schizonts in the cells of parotid lymph nodes from 10 adult Korean cattle were examined. Lymphoid cells which were separated from these lymph nodes were cytocentrifuged to observe the parasites in the cells. T sergenti schizonts were detected in the cells of lymph nodes of 6 cattle out of them by IFA(Indirect Fluorescent Antibody) test and Giemsa stain. By peroxidase stain, the cells which contain schizonts were proved lymphoid cells. T sergenti schizonts identified by IFA test were able to be restained by Giemsa stain. Also, merozoites were observed in peripheral blood of the same 6 cattle that had schizonts, by giemsa stain, but not observed in the 4 cattle that had not been detected schizonts. As a part of life cycle of T sergenti, schizonts were observed in the lymphoid cells of Korean cattle.

• Korean Journal of Veterinary Research
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• v.48 no.2
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• pp.197-201
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• 2008

Plasmodium spp. in domestic and wild birds are microscopic, intracellular parasitic protozoa within the blood cells and tissues cause avian malaria. A 17-month-old Magellan penguin (Spheniscus magellanicus) with a clinical signs of anorexia, depression, and respiratory distress for 3 days was submitted to the Pathology Department of Veterinary Medicine, Cheju National University in October 2005. It was born and reared in the Jeju Island. Grossly, the liver was enlarged, pale and friable. The spleen was also enlarged with dark red coloration and friable. Histopathologically, the lesions in the liver were characterized by multifocal infiltration of macrophages and lymphocytes especially in perivascular regions. The schizonts of Plasmodium spp. contained up to 30 merozoites were found in numerous infiltrated mononuclear cells. Similarly, histiocytic cells were proliferated in red pulp of spleen and the schizonts were found in these cells. Numerous dark brown pigments were widely distributed in the liver and spleen. The result of the nested polymerase chain reaction clarified the causative agent of this case was Plasmodium spp.. This is the first report for the outbreak of avian malaria caused by Plasmodium spp. in a penguin that was born and reared in Jeju Island in Korea.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.135-139
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• 1994

In the year 1992/93 leucocytozoonosis could be first diagnbosed in 87 chickens of 4 chicken farms in Honam districts. The diagnosis was confirmed by detection of the blood merozoites or gametocytes and histological finding of the schizonts from various organs with some clinical signs. Cases of leucocytozoonosis only occurred from the end of June to the middle of September. Artificial infection could be observed by means of inoculation of infected blood merozoites. The schizonts were found in the liver and cardiac muscle of the different chickens recovered from the natural infection, respectively, in September and next February. Thus the relapse or long-term infection in cold seasons might be possible. The unique gametocyte antigen polypeptide was 50.1 kD.

• Korean Journal of Veterinary Service
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• v.23 no.3
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• pp.223-226
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• 2000

Pathological findings of leucocytozoonosis naturally occurred in Korea are described. Most of the affected chickens showed paleness of comb and wattle, egg drop, approximately 20 to 30% mortality, green diarrhea, anorexia and weakness. On the blood smear merozoits and gametocytes were detected. At necropsy, petechial and ecchymotic hemorrhages in liver, kidney, heart, muscle, and splenomegaly were frequently observed. Microscopically schizonts with fine granular merozoits were often detected in kidney, intestine, brain, lung, myocardium, muscle, liver with cenrilobular fatty change, and spleen.

• Journal of the korean veterinary medical association
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• v.46 no.3
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• pp.245-263
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• 2010

말 원충성척수뇌염(equine protozoal myeloencenphalitis; EPM)은 말에게 심각한 신경성 질병을 일으키는 원충성 질병으로서 Sarcocystis neurona가 원인체이다. 근육포자낭(sarcocyst)을 숨기고 있는 자연중간숙주를 포함한 S. nuerona의 완전한 생활사는 알려져 있지 않으나 주머니쥐의 일종인 opossum(Didelphis virginiana, Didelphis albiventris)이 최종 숙주이며, 말은 정상적 숙주로 알려져 있다. 왜냐하면 말에서는 분열체(schizonts)와 분열소체(merozoites)가 발견되기 때문이다. EPM 유사 질병들이 고양이, 밍크, 너구리, 스컹크, 태평양 점박이 바다표범, 포니, 바다수달 등을 포함한 다양한 포유류에서 발생한다. 고양이는 포자낭(sporocytes) 섭식 후 근육포자낭 단계를 숨기는 실험적인 중간숙주로서 역할을 할 수 있다. 최근 국내에서 신경증상을 나타내는 말에 대한 의심스러운 임상증상이 임상수의사들에 의해 관찰되어졌는, 정확한 진단을 하기위하여 S. nuerona에 의해 발생된 EPM의 역사, 구조, 생활사, 생물학, 병리론, 동물에서 질병 유도, 임상 증상, 진단, 병인론, 생태학, 치료 등에 대하여 알아보고자 한다.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.241-246
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• 2022

Felids are the unique definitive host of Toxoplasma gondii. The intestine of felid is the only site for initiating Toxoplasma gondii sexual reproduction. T. gondii excretes millions of infectious oocysts from the intestine, which are the primary source of infection. There are many difficulties in developing vaccines and drugs to control oocyst excretion due to the lack of an appropriate experimental model. Here, we established an in vitro feline intestinal epithelial cell (IEC) infection system and an efficient animal model of T. gondii Chinese 1 genotype, Wh6 strain (TgCtwh6). The Kunming mice brain tissues containing TgCtwh6 cysts were harvested 42-day post-infection. The bradyzoites were co-cultured with cat IECs in vitro at a ratio of 1:10. Five 3-month-old domestic cats were orally inoculated with 600 cysts each. The oocysts were detected by daily observation of cat feces by microscopy and polymerase chain reaction. We found that the parasite adhered and invaded cat IECs in vitro, transformed into tachyzoites, and then divided to form rose-like structures. These parasites eventually destroyed host cells, escaped, and finished the asexual reproduction process. Schizonts associated with sexual reproduction have not been observed during development in vitro cultured cells. However, schizonts were detected in all infected cat intestinal epithelial cells, and oocysts were presented in all cat feces. Our study provides a feasible cell model and an efficient infection system for the following studies of T. gondii sexual reproduction, and also lays a foundation to develop drugs and vaccines for blocking excretion and transmission of oocysts.

• Parasites, Hosts and Diseases
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• v.46 no.4
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• pp.223-227
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• 2008

Changes in selected blood and serum components and electrocardiography (ECG) were investigated in 20 adults (13 females and 7 males) of water buffaloes suffering from severe theileriosis. The age of all animals used in this study ranged 1.5-5yr. Theileriosis was diagnosed by observation of parasites in the peripheral blood and the presence of schizonts in lymphocytes that were provided from swollen lymph nodes. Statistically significant decreases were observed in the means of RBC, WBC, and packed cell volume (PCV) in blood of infected animals. The means levels of sodium, calcium, phosphorus, and potassium of infected animals were lower than healthy animals, but only the decrease of potassium was significant. The mean serum activities of aspartate transferase and alanine aminotransfrase were significantly higher than in un infected animals. Three cases had atrial premature beat, 2 cases had sinus tachycardia, 2 had sinus arrhythmia, and 1 had first degree of atrioventricular block in ECG. The present study showed that T. annulata infection in cattle is associated with hematological and biochemical, and ECG changes.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.137-143
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• 1993

This study was carried out to completelycure the experimental bovine theileriasis with small unilamella vesicle liposome incorporated buparvaquone which was effective both to schizonts in lymphocyte of lymph nodes and piroplasmic stage in erythrocytes. Small unilamella vesicle liposome incorporated buparvaquone was prepared by French pressure cell method using egg phosphatidylcholine. The diameter of the vesicles was ranged from 5 to 220 nm, but the most vesicles were ranged from 10 to 50 nm in diameter. The incorporation rate for buparvaquone was 100%. Parasitaemia of the 10 calves inoculated with $5{\times}10^8$ erythrocytes infected with Theileria sergenti were first detected from on day 16 to day 23 after inoculation. In calves treated with a dose rate 2.5 mg/kg BW of free buparvaquone, a gradual decrease in piroplasmic parasitaemia was observed following treatment to day 5. However parasitaemia levels returned to near pretreatment values after approximately 60 days. In calves treated with a dose rate 5.0mg/kg BW of free buparvaquone, parasitaemia were disappeared on day 3 after treatment, but there was a mild recrudescence of infection on day 28 after treatment. In calves treated intraavenously with a dose rate 2.5 mg/kg BW of buparvaquone incorporated in liposome, the calves were all cured on day 2 or day 3 after treatment. In calves treated subcutaneously and intraperiotoneally with a dose rate 2.5 mg/kg BW of buparvaquone incorporated in liposome, parasitaemia were disappeared on day 3 or day 4 after treatment, but there was a mild recrudescence of infection on day 40 or day 45 after treatment.

• Parasites, Hosts and Diseases
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• v.51 no.2
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• pp.207-212
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• 2013

Chronic diarrhea with a 35 kg weight loss (75 kg to 40 kg) occurred during 2 years in an alcoholic patient was diagnosed with Isospora belli infection in the Republic of Korea. The patient, a 70-year old Korean male, had been a heavy drinker for more than 30 years. He was admitted to the Seoul National University Hospital because of long-standing diarrhea and severe weight loss. He had an increased white blood cell (WBC) count with high peripheral blood eosinophilia (36.8-39.9%) and lowered protein and albumin levels but without any evidence of immunosuppression. A parasitic infection was suspected and fecal examination was repeated 3 times with negative results. Peroral endoscopy with mural biopsy was performed in the upper jejunum. The biopsy specimens revealed villous atrophy with loss of villi together with various life cycle stages of I. belli, including trophozoites, schizonts, merozoites, macrogamonts, and microgamonts. The patient was treated successfully with oral doses of trimethoprim 160-320 mg and sulfamethoxazole 800-1,600 mg daily for 4 weeks. A follow-up evaluation at 2.5 years later revealed marked improvement of body weight (68 kg), increased protein and albumin levels, and normal WBC count with low eosinophils (3.1%). This is the first clinical case of isoporiasis with demonstration of various parasitic stages in the Republic of Korea.

• Korean Journal of Veterinary Service
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• v.28 no.4
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• pp.367-373
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• 2005

Coccidiosis of domestic fowl is a parasitic disease that infects poultry drastically and can cost the pastured poultry producer much in the course of a year. Two hundred forty, day-old-broiler chicks were purchased and were randomly divided in eight groups, containing thirty birds in each group. Decoquinate $6\%$, maduramicin ammonium $2\%$, monensin sodium $13.2\%$, salinomycin sodium $12\%$, a live attenuated vaccine, and trivalent live attenuated vaccine, was provided to the day chicks of six groups, respectively. The chicks of last two groups served as infected non-medicated and uninfected non-medicated, respectively. Feed consumption, weight gain, feed conversion ratio, mortality and oocyst count per gram feces were recorded during the conduction of the experiment. Among treated groups, performance of salinomycin group was significantly better (p<0.05) in all aspects. Salinomycin acts against the sporozoites, trophozoites and first generation schizonts and is highly effective against the economically important species of Eimeria. The present study confirms that use of salinomycin, as an anticoccidial, is a drug of choice.