The prepatent and patent periods of Eimeria alabamensis and further description of the exogenous stages

Eimeria alabamensis infections were established in calves 5 to 6 weeks of age by adminestering 10 million, 80 million, or 100 million sporulated oocysts. The prepatent period was 6 to 8 days (mean 6.6). Oocyst discharges usually lasted for 2 to 3 days although a few calves passed oocysts throughout the rest of the 3-week observation period. Calves with oocyst discharge exceeding 1 million oocysts per g of feces had a moderate diarrhea at the time of peak oocyst discharge. No other clinical signs were observed in any of the infected calves. Reinoculations with 100 million sporulated oocysts given 3 weeks after the initial inoculations of 10 million or 80 million oocysts resulted in infections characterized by greatly reduced oocyst discharges. Sporulated oocysts of E. alabamensis were 16 to 24 μ by 12 to 16 μ and were usually ovoid. The oocyst wals consisted of two layers. Sporocysts were elongate-ellipsoid, had a distinct Stieda body, and were 10 to 12 μ by 4 to 6 μ. Completely sporulated oocysts were first observed after 5 days at 25 °C, and most were sporulated after 8 days. Oocysts did not sporulate at 4 °C, 33 °C, and 37 °C.     

Eimeria tenella in chickens: Studies on resistance to the anticoccidial drugs monensin and lasalocid

The response of the Houghton strain of E. tenella to monensin and lasalocid is described. Neither drug was able to completely control this strain at 125 ppm. At this concentration oocyst production was not completely suppressed by monensin in birds given ten oocysts. At higher concentrations both drugs were able to control E. tenella (H) in birds given 1 × 10⁵ oocysts but monensin was toxic. 375 ppm monensin did not prevent oocyst production in birds given 4 × 10⁶ oocysts. Resistance could not be developd to either of these compounds after 12 serial passages in the presence of drug. Serial passage of E. tenella (H) in the presence of monensin however resulted in an increase in pathogenecity. This greater pathogenecity was not due to a better ability to multiply in the host.     

Concurrent response to challenge infection with Cryptosporidium parvum in immunosuppressed C57BL/6N mice

We investigated the response to challenge infection with Cryptosporidium parvum oocysts in immunosuppressed C57BL/6N mice. In the primary infection, fecal oocyst shedding and parasite colonization were greater in immunosuppressed mice than in nonimmunosuppressed mice. Compared with primary infection, challenge infection with C. parvum didn''t show any oocyst shedding and parasite colonization. Especially, oocyst shedding and parasite colonization from the mice infected with heat-killed oocysts were not detected. After challenge infection with C. parvum oocysts, however, these mice were shedding small numbers of oocysts and parasite colonization. Except normal control and uninfected groups, the antibody titers of other groups appear similar. Based on the fecal oocyst shedding, parasite colonization of ilea, and antibody titers in the mice, these results suggest that the resistance to challenge infection with C. parvum in immunosuppressed C57BL/6N mice has increased.     

Prophylactic use of decoquinate for infections with Cryptosporidium parvum in experimentally challenged neonatal calves

OBJECTIVE: To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts. DESIGN: Clinical trial. ANIMALS: 75 calves. PROCEDURE: Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week. RESULTS: Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced.     

Course of the endogenous developmental phase of selected Eimeria species in pheasants

The localization and duration of developmental stages of Eimeria colchici and Eimeria duodenalis were studied histologically. The prepatent period of the most pathogenic species from the caeca of pheasants – Eimeria colchici – was 6 days. The patent period began on the 7th day and finished on the 11th day post-infection with the maximum production of oocysts on days 8–9. In the case of Eimeria duodenalis the prepatent period was shorter – 4 days, and the duration of the patent period was 3–4 days without a significant increase in oocyst production.     

Shedding of Oocysts in Piglets Experimentally Infected with Isospora suis

Christensen, S. AA. Henriksen: Shedding of oocysts in piglets experimentally infected with Isospora suis. Acta vet scand., 1994, 35, 165-172.–Forty-seven piglets were inoculated with doses of 100 to 50,000 sporulated oocysts of Isospora suis. After 5-7 days oocysts were found in faeces. The patent period extended from 8 to 16 days. The shedding of oocysts showed a cyclic pattern with 2-3 peaks separated by intervals of approximately 5 days. Subpatent periods were often seen between the peaks.The level of oocyst shedding during the initial days of the patent period reflected, to some extent, the inoculation dose. However, a maximum of OPG at the 100,000 level was observed among one or more piglets from all groups, regardless of the inoculation dose. Among the majority of piglets inoculated with more than 100 oocysts, the highest OPG-figures were observed in the first peak of the cyclic pattern. Unlike this, the maximum of OPG was observed in the second peak of the cycle among 6 of the 7 piglets inoculated with 100 oocysts only. The triphasic pattern was most pronounced in the low dosed group.The marked upscaling of oocyst production, as particularly registered in the low dosed groups, seams to explain at least part of the problems met under practical conditions, when trying to eliminate the transmission of oocysts between successive litters in the farrowing boxes.The cyclic excretion pattern and an apparent absence of autoinfections may indicate that the development of I. suis in the host includes several oocyst producing generations descending from the same initial infection.The presence of subpatent periods can probably explain the marked variation in OPG, as they are often recorded when examining faecal samples from piglets, even when the samples are originating from the same litter.     

A simple and efficient method for isolation of a single Eimeria oocyst from poultry litter using a micromanipulator

The chicken, which is the host for seven species of Eimeria, typically is infected simultaneously by multiple Eimeria species and the oocysts of coccidia are excreted in the feces. A prerequisite for investigation of individual Eimeria species is to isolate a single oocyst from fecal samples. A novel method for isolating a single Eimeria oocyst from poultry litter using a micromanipulator was developed. This simple method is fast and reliable, and provides direct isolation of a single sporulated oocyst from fecal samples harboring multiple Eimeria species or samples contaminated by other species of parasite.     

11株巨型艾美耳球虫繁殖力的比较研究

用巨型艾美耳球虫扬州株、南通株、连云港株、苏州株、凤阳株、青岛株、福州株、龙岩株、广州株、上海株和美国株孢子化卵囊100个/只或10 000 个/只,经嗉囔接种7 日龄或21 日龄无球虫黄羽肉公雏,以麦克马斯特法对感染后第6 天至第14 天间每天24 h排出的卵囊计数并进行统计分析。结果表明,各虫株的排卵囊量有差异,100个/只卵囊感染7日龄雏鸡时,广州株和凤阳株排卵囊量最多,上海株和苏州株排卵囊量最少;100个/只卵囊感染21 日龄雏鸡时,扬州株排卵囊量最多,上海株排卵囊量最少;10 000 个/只卵囊感染21 日龄雏鸡时,苏州株排卵囊量最多,连云港株和扬州株的排卵囊量最少;排卵囊量随着感染剂量的增加或鸡日龄的增大而增多;在同一感染剂量时,福州株和连云港株增加最多,上海株和苏州株增加最少;在同一感染鸡日龄时,苏州株和上海株增加最多,南通株和扬州株增加最少;各虫株的排卵囊规律极相似,在感染后第7 天排卵囊量达峰值,第8 天、第9 天排出的卵囊量显著减少,第10天排出的卵囊量仅占总量的2%,第14天接近于0%;第6天至第8天排出的卵囊量占总量的87%~99%。     

Porcine neonatal coccidiosis: evaluation of monensin as preventive therapy

In this study, we evaluated the efficacy of monensin as a preventive therapy for porcine neonatal coccidiosis. Fifteen three-day-old piglets were given 50,000 sporulated oocysts of Isospora suis and eight of them received 15 mg/kg of monensin orally every other day. Seven piglets served as normal controls. Fecal samples were collected and checked for oocyst shedding. At 18 days of age, piglets were euthanized and necropsied.

The onset of clinical signs was delayed in the treated group, but all inoculated piglets displayed anorexia, soft stool, or diarrheic feces. Treated piglets shed large numbers of oocysts in their feces (up to 201,200 oocysts per gram of feces). All infected piglets had lesions of villous atrophy in the jejunum and most of them were in the late atrophic or villous regrowth stages.

The results of this study suggest that monensin does not prevent clinical signs, oocyst shedding, and intestinal lesions caused by I. suis in neonatal piglets.

     

Pathogenic Effiects of the Coccidium Eimeria ninakohlyakimovae in Goats

Twenty-four coccidia-free goats were reared artificially in indoor cages and allocated to 6 groups of 4 animals each. At 20 days of age, goats in groups 1–3 received 10⁴,10⁵ and 10⁶ sporulated oocysts of Eimeria ninakohlyakimovae per goat, respectively, each as a single dose. Goats in group 4 received daily doses increasing over a 3-week period, starting with 100/day for the first week, followed by 1000, and 10 000/day in weeks 2, 3, respectively. Goats in group 5 received 10⁴ oocysts following a challenge dose of 10⁶ oocysts on day 32. Goats in group 6 were kept as uninoculated controls. Infected animals showed diarrhoea and weight loss. Goats in group 4 showed longer periods of diarrhoea and patency than other infected goats. Goats in group 5 showed the same severe clinical signs as those in group 3 but produced very low oocyst output after a challenge dose. The diarrhoea was associated with a reduction in alkaline phosphatase activity and increases in packed cell volume and haemoglobin. No significant differences were found in serum aspartate aminotransferase, alanine aminotransferase, total protein, albumin, globulin, Na⁺, K⁺,Cl⁻ between groups during 48 days after inoculation. There were no serum enzyme indications of damage to the liver. Histological examination performed 100 days after inoculation revealed that inoculated goats had mild subacute to chronic proliferative enteritis in the lower small intestine and the large intestine, and the mesenteric lymph nodes, gallbladders and livers also showed slight histological lesions. The results showed that E. ninakohlyakimovae was highly pathogenic.     

鸡巨型艾美耳球虫单卵囊分离及雏鸡扩增试验

采用饱和食盐水漂浮法收集就诊病死球虫阳性鸡小肠中段内容物中的球虫卵囊,恒温培养至孢子化后,用2%琼脂薄板进行球虫单卵囊分离,分别感染7只5日龄雏鸡,对据形态学鉴定为巨型艾美耳球虫的分离株进行2代单卵囊分离和雏鸡感染,取其后代以每只1.0×10⁴个卵囊感染10只10日龄雏鸡进行卵囊扩增,获得大量纯种巨型艾美耳球虫卵囊。结果表明,刀片切割琼脂薄板单卵囊分离法操作简便,单卵囊感染成功率较高,准确率达100%,适用于纯种卵囊的分离与扩增。     

京海黄鸡柔嫩艾美尔球虫抗性指标的研究简

为进一步筛选有效的鸡球虫病抗性评价指标,并为后续鸡球虫抗性评价体系的建立及鸡球虫抗病育种提供依据,试验将京海黄鸡分为感染和非感染对照2个组,感染组每只雏鸡灌饲2.5×10⁴个柔嫩艾美尔球虫卵囊,用酶联免疫检测法测定10个球虫抗性血液指标。结果显示,①感染后第3天感染组和非感染对照组的临床表现和各项指标差异均不明显,表明感染后这一阶段无法用现有指标检测到显著变化;②感染后3～5 d感染组鸡体增重为负,且感染组和非感染对照组相比差异极显著（P＜0.01）,表明感染后3～5 d的变化最为剧烈;③感染后8 d IFN-γ浓度显著低于非感染对照组（P＜0.05）;丙二醛(MDA)、超氧化物歧化酶（SOD）、谷胱甘肽—过氧化物酶（GSH-Px）、过氧化氢酶（CAT）浓度均有不同程度提高,且感染组与非感染对照组SOD浓度差异显著（P＜0.05）,其余3个指标均差异极显著（P＜0.01）;④白细胞介素2(IL-2)、IL-16、IL-17、一氧化氮（NO）、β-胡萝卜素（β-C）浓度感染组和非感染对照组相比差异均不显著（P＞0.05）。结果表明,感染后3～5 d内的体增重,CAT、GSH-Px、MDA、SOD 4种抗氧化酶及IFN-γ细胞因子在血浆中的浓度可作为鸡球虫抗性评价指标。     

Molecular characterisation of Cryptosporidium isolates from rivers,water treatment plants and abattoirs in Ibadan,Nigeria

To understand the molecular characteristics of Cryptosporidium species contaminating rivers, water treatment plants and abattoirs in Ibadan Nigeria, water samples were obtained from ten rivers used for household and agricultural purposes, three major functional water treatment plants and three major abattoirs located within Ibadan metropolis during dry and rainy seasons between November, 2016 to October, 2017. Obtained samples were examined for Cryptosporidium oocysts using microscopy after using modified formalin–ether concentration method and modified acid-fast staining. Cryptosporidium oocysts were detected in samples from five rivers with mean oocyst count/field ranging from 7.70 ± 0.57–1.34 ± 0.57, oocysts were also detected in samples from two abattoirs with mean oocyst count/field ranging from 4.60 ± 0.33–2.50 ± 0.33. Genomic DNA were extracted from microscopy positive river and abattoir samples using sucrose gradient purification method and genotypes and subtypes of parasites were detected by nested PCR amplification and nucleotide sequence analysis of both 18S rRNA and 60-kDa glycoprotein (gp60) genes. Cryptosporidium parvum, C. muris and C. fragile were the only genotypes detected in some river samples, while gp60 gene sequence analysis showed that the C. parvum strain detected was subtype IIa. This study provides evidence that rivers used for household and agricultural purposes in studied area may be potential reservoirs and infection sources for Cryptosporidium species and zoonotic subtypes of public health importance.     

Epidemiological Studies on Gastrointestinal Parasitic Infections of Lambs in the Coastal Savanna Regions of Ghana

The types of gastrointestinal parasites (Eimeria and helminths) encountered by 70 lambs and the seasonal pattern of both Eimeria and strongylate infections in these lambs in the derived Coastal Savanna were followed for three years. Eimeria oocysts and helminth eggs were detected in the faeces of lambs at the same time, indicating the concurrence of both Eimeria and helminth infections. Eimeria oocysts were first seen in the lambs 20 days after birth (DAB) and the level of oocyst output increased by the fourth week. Eimeria species identified in the lambs were E. parva, E. pallida, E. faurei, E. ahsata, E. bakuensis, E. intricata, E. granulosa, E. ovinoidalis and, occasionally, E. marsica. E. ovinoidalis, the most pathogenic species, dominated the oocyst output during the early part of the life of the lambs. Strongyloides papillosus eggs appeared at 46 DAB, preceding strongylate nematode eggs, which were seen at 57 DAB and those of Moniezia at 69 DAB. The pattern of Eimeria oocyst output paralleled that of the worm egg output, and high oocyst and strongylate worm egg counts corresponded with the period of high rainfall during the study period. Although oocyst and worm egg output fluctuated, high Eimeria oocyst counts were seen again in the lambs when they were 1 and 2 years old. Haemonchus species formed 71% of the infective larvae revealed by larval culture.     

Comparative effects of Herba Cox®, a commercial herbal extract,on rabbits (Oryctolagus cuniculus) experimentally infected with Eimeria stiedae

The objective of this study was to evaluate the efficacy of Herba Cox®, a commercial herbal compound containing extracts from Bombax malabaricum, Aegle marmelos, Anethum foeniculum, Resina salvia, Ferula asafoetida and Papaver somniferum, for the treatment of rabbit hepatic coccidiosis. Thirty rabbits were allocated into three groups (10 × 3), the G1 group served as a negative control group, G2 group (positive control group) was infected with 5 × 10⁴ sporulated E. stiedaeoocysts and served as infected-untreated group, and G3 group was infected with 5 × 10⁴ sporulated E. stiedaeoocysts and treated with Herba Cox®, 1 ml/liter of drinking water, starting 7 days before infection and continuing for 4 weeks post-infection. When compared to the infected group (G2), body weight and weight gain were significantly (P ≤ 0.05) increased, the feed conversion rate was improved and no mortality was detected in infected treated group (G3) and similar to negative control group (G1). In addition, faecal oocyst output and liver enzymes were significantly decreased. Malondialdehyde, nitric oxide, and glutathione concentrations observed in G3 were similar to those in G1. In infected-untreated rabbits (G2), the haemoglobin, lymphocytes, and CD4+/ CD8+ ratio were significantly decreased, while the total leukocyte count, percentage of heterophils, and heterophil/lymphocyte ratio were increased. Significantly more severe histopathological hepatic lesions were observed in G2 when compared to G1 and G3. In conclusion, the obtained results showed that Herba Cox® should be considered a safe and novel effective compound for the treatment of E. stiedae infection in rabbits.     

Oocyst Discharge, Rumen Metabolism and Performance of Early Weaned Lambs with Naturally Occurring Coccidiosis Fed Monensin

Ninety-six 9.5 kg early-weaned lambs with naturally occurring coccidiosis were fed monensin either at 0, 11, 22, or 33 mg/kg of feed for 105 days. Fecal oocyst discharge during the first three days was highest with monensin 22 mg, lowest with monensin 33 mg and averaged 149.6 × 10³ oocysts per gram feces for all lambs. Monensin at 22 mg/kg of feed reduced Eimeria ninakohlyakimovae and E. ahsata oocyst discharge.

Organic matter and crude protein digestibilities were highest (P ≤ 0.05) in lambs fed monensin 22 mg/kg of feed. Monensin increased (P ≤ 0.01) rumen ammonia and propionic acid and decreased (P ≤ 0.01) acetic acid. Feeding monensin 33 mg decreased (P ≤ 0.05) feed intake by 5% and had no effect on gain or feed efficiency. Optimal responses were observed with monensin at 11 mg, feed consumption was not affected, gains were 8% higher (P ≤ 0.05) and feed was utilized 9% more efficiently (P ≤ 0.05) than the controls. In conclusion, monensin was an effective therapeutic agent against naturally occurring coccidial infections in early weaned lambs. Performance responses were largest with monensin fed at the rate of 11 mg/kg of feed.

     

Resistance to Eimeria zuernii produced after chemotherapy of experimental infection in calves

Nineteen Holstein-Friesian bull calves were inoculated with 2.4 × 10⁶ sporocysts of Eimeria zuernii by stomach tube. The calves were divided into three groups 10 days after infection. The first group (seven calves) was treated with monensin (1 mg/kg body weight daily) from the 10th–20th day after infection; the second group (six calves) with amprolium (10 mg/kg body weight daily) for the same period of time and the third group (six calves) acted as infected controls. Both drugs were effective in preventing clinical signs, in reducing rates of weight gain and in suppressing oocyst production. The calves were reinfected with E. zuernii 35 days after the initial infection. The calves of all three groups were resistant to the second infection with E. zuernii as measured by rates of weight gain, fecal oocyst output and lack of clinical signs.     

Eimeria acervulina Infections from Each of the Four Sporocysts of a Single Oocyst

Oocysts were found in all four birds each infected with one of the four sporocysts of a single oocyst of Eimeria acervulina and in three of the four birds infected with single sporocysts from two other oocysts. Possible use of these infections for genetic studies was discussed. An efficient method for collecting fecal material containing sometimes rather low levels of oocysts was also described.     

Radiofrequency‐Induced Thermal Inactivation of Toxoplasma gondii Oocysts in Water

Toxoplasma gondii, a ubiquitous parasitic protozoan, is emerging as an aquatic biological pollutant. Infections can result from drinking water contaminated with environmentally resistant oocysts. However, recommendations regarding water treatment for oocyst inactivation have not been established. In this study, the physical method of radiofrequency (RF) power was evaluated for its ability to inactivate T. gondii oocysts in water. Oocysts were exposed to various RF energy levels to induce 50, 55, 60, 70 and 80°C temperatures maintained for 1 min. Post‐treatment oocyst viability was determined by mouse bioassay with serology, immunohistochemistry and in vitro parasite isolation to confirm T. gondii infections in mice. None of the mice inoculated with oocysts treated with RF‐induced temperatures of ≥60°C in an initial experiment became infected; however, there was incomplete oocyst activation in subsequent experiments conducted under similar conditions. These results indicate that T. gondii oocysts may not always be inactivated when exposed to a minimum of 60°C for 1 min. The impact of factors such as water heating time, cooling time and the volume of water treated must be considered when evaluating the efficacy of RF power for oocyst inactivation.