Control of Isospora suis-induced coccidiosis on a swine farm

Results of a program designed to control neonatal porcine coccidiosis on a total confinement, farrow-to-finish swine farm are reported. The control program consisted of washing, phenol disinfection, and steam cleaning of farrowing houses and treatment of sows with amprolium HCl before and after farrowing. Before initiation of the control program, 88.9% of the sows examined in the farrowing house were negative for coccidian oocysts, 9.9% were positive for Eimeria spp, and 1.2% were positive for Isospora suis. Most pigs nursing on sows before initiation of the control program had diarrhea at 5 to 10 days of age, which led to dehydration and weight loss. Morbidity was high, and mortality was moderate. Composite fecal samples from these litters were all positive (100%) for I suis. After initiation of the control program, 99.6% of the sows examined in the farrowing house were negative for coccidian oocysts and 0.4% were positive for Eimeria spp. Clinical signs of coccidiosis were rarely present in nursing pigs examined after the control program was initiated; however, I suis was still present in 19.8% of the composite fecal samples from pigs examined. An association between oocyst production in sows and I suis infections in pigs was not found in the present study. Oocysts of Eimeria spp were not found in the feces from the pigs.     

Differential diagnosis of five avian Eimeria species by polymerase chain reaction using primers derived from the internal transcribed spacer 1 (ITS-1) sequence

Chicken coccidia are protozoan parasites of the genus Eimeria. They cause economical losses in the poultry industry globally. The various species can be distinguished on the basis of the morphology of the oocysts and parasitic site in intestine, but these criteria sometimes are unreliable. Therefore, a species-specific polymerase chain reaction (PCR) was developed. Based on variable sequence regions, specific primers were constructed for the differentiation of five Eimeria species (Eimeria acervulina, E. brunette, E. maxima, E. necatrix, and E. tenella). PCR products were amplified from coccidian vaccine (coccivac-D and coccivac-B) and E. tenella and were subsequently sequenced. Similarities of the five species sequences between the vaccines and Genbank were 94-100%. Analysis of the E. tenella internal transcribed spacer 1 (ITS-1) partial sequence from Taiwan and from Genbank indicated that the similarity was 99.6%. The PCR sensitivity test of E. tenella in Taiwan is 50 oocysts. The five sets of primers will not amplify any non-specific bands of the chicken genome or its intestinal contents. Therefore, the five sets of specifically designed primers are guaranteed to be useful for differential diagnosis of avian coccidiosis caused by Eimeria spp.     

Prevalence of Isospora suis and Eimeria spp. in suckling piglets and sows in Poland

The aim of this investigation was to determine the prevalence of coccidian infections in suckling piglets and sows in Poland. The research was carried out in 14 out of 16 Polish provinces in the years 2003-2005. The investigation was conducted on three types of farms: large farms (>100 sows), medium farms (25-100 sows) and small farms (<25 sows). Diarrhoea of unweaned piglets was observed on all the examined farms. Overall, 780 litters of suckling piglets from 104 farms and 267 mother sows were examined. The faeces were analyzed with the modified McMaster method. Isopsora suis was found in 217 (27.8%) litters from 70 (66.7%) farms. Eimeria spp. was detected only in 20 (2.6%) litters from 12 (11.5%) farms. On the large farms I. suis infection was detected in 31.7% of litters whereas Eimeria spp. in 1.4% of them. On the medium sized farms I. suis was found in 18.1% of litters and Eimeria spp. in 0.6%. On the small farms I. suis was detected in only 13.2% of litters, whereas Eimeria spp. in as many as 28.9%. I. suis and Eimeria spp. oocysts were found in 18 (6.7%) and 16 (6%) sows respectively. From 72 sows producing I. suis infected piglets only 12 (16.7%) shed I. suis oocysts and as little as 4 (5.6%) shed Eimeria oocysts. In the remaining 56 sows (77.8%) no cases of coccidian infections were detected. The results of this investigation demonstrate the high prevalence of I. suis in suckling piglets on the large swine farms in Poland.     

Porcine coccidia in Papua New Guinea

Faecal samples from 232 domestic pigs raised on concrete, 98 free-ranging village pigs, and five wild boar showed 46.6 (108/232), 54 (53/98) and 80% (4/5) prevalence of coccidian oocysts, respectively. Eight species of Eimeria, and Isospora suis, were recovered. In their descending order of predominance in the pigs raised on concrete, the species of coccidia were E. debliecki (26.7%), E. scabra (22.4%), E. neodebliecki (19.8%), E. porci (15.5%), E. suis (11.6%), E. polita (8.6%), E. perminuta (7%), E. spinosa (5.6%) and I. suis (3.9%). The first five species listed above predominated in the village pigs as well. E. polita, E. spinosa and I. suis were not found in the wild boar. I. suis oocysts prevailed in 8.3% of the 36 sows on concrete, and in 11.1% (3/27) of those which were positive for coccidia. Isosporoid oocysts were absent in the village sows. Of the 125 less than 24-day-old piglets, 29.6% were diarrhoeic, and of these, 43.2% were positive for coccidia. Four of the 16 (25%) coccidia-positive, diarrhoeic piglets, and four of the 37 (10.8%) coccidia-positive non-diarrhoeic piglets shed I. suis oocysts, an observation which seems to weaken the present contention that I. suis is the primary causative agent of neonatal porcine coccidiosis. The highest mean number of oocysts per gram faeces (23,550) was recorded from the diarrhoeic farm piglets on concrete, and the lowest of 6,100 from the gestating farm sows. Mean opg data revealed very little significant quantitative variation between the corresponding age groups of the free-ranging village pigs and the commercially-farmed ones. One of the most interesting findings in the study was that the sows were more frequently infected than all other age groups.     

Prevalence and age-dependent occurrence of intestinal protozoan infections in suckling piglets

A cross-sectional survey was performed on 20 pig breeding farms in southern Hesse, central Germany, to evaluate the prevalence and age-dependent occurrence of intestinal protozoan parasites in unweaned piglets. Faecal samples of 514 clinically unaffected piglets of different age (< 1 to 5-7 weeks) were examined using the sodium acetate-acetic acid-formalin (SAF) concentration technique. Infections with the following protozoan species were detected: Balantidium coli (16 of 20 farms), Entamoeba sp. (15), Jodamoeba sp. (14), Isospora (I.) suis (9), Chilomastix sp. (6) and Eimeria spp. (6). The protozoan species differed in the start and course of (oo)cyst excretion. I. suis oocysts and Jodamoeba cysts were detected already in the first week of life whereas shedding of the other parasites started later on. The prevalence of Isospora oocyst excretion increased to a maximum (18%) in 2-3 weeks old animals followed by a sharp decline. The proportion of Balantidium, Entamoeba or Jodamoeba positive suckling piglets continously increased until the age of 5-7 weeks to 60%, 52% and 22%, respectively, whereas that of Chilomastix positive animals remained on a low level of 8-12% independent of the age. Eimeria oocysts were found transiently in the faeces of 1-4 weeks old piglets.     

Epidemiology of porcine neonatal steatorrhoea in Sweden. 1. Prevalence and clinical significance of coccidal and rotaviral infections

A study of neonatal steatorrhoea in unweaned piglets was carried out in randomly visited herds. Isospora suis and rotavirus were shown to be incriminated in this type of enteric disease and these agents may be considered important enteropathogens for 1-3-week-old piglets in Sweden. More extensive studies of I. suis were undertaken in one large herd. It was found that steatorrhoea may appear in 4-day-old piglets but oocysts were not detected until some days latter. Piglets that were shedding I. suis were not necessarily steatorrhoeic but oocysts were more frequently found in steatorrhoeic faeces than in faeces of normal consistency. The earliest oocyst output was detected at 5 days of age, the average litterage at first appearance being 12.8 +/- 4.0 days. The occurrence of I. suis oocysts in piglets did not correlate with the oocyst output in sows, which almost exclusively included genus Eimeria. Repeated parasitological and virological examination of steatorrhoeic faecal samples from 5-10 litters per herd at an age of 1-3 weeks would be helpful for making a herd diagnosis.     

Isospora orlovi infection in suckling dromedary camel calves (Camelus dromedarius) in Kenya

Outbreaks of isosporosis in young suckling dromedary camel calves (Camelus dromedarius) in Dubai, UAE and in Kenya were recently described. In the former outbreak the pathogen was shown to be Isospora orlovi by morphological features and was later characterized molecularly. In the present study, we have made a longitudinal investigation of 159 suckling dromedary calves < or =12 weeks of age belonging to 8 ranched camel herds (M1) in Northern Kenya. The study was carried out during 18 months. In three of the herds frequent samples were taken irregularly every 1-6 weeks. All calves < or =12 weeks of age present in the respective herds were sampled during the visits. In addition, 91 calves of the same age group but belonging to 42 pastoral herds (M2) in Northern Kenya were point sampled at convenience. Faecal samples from each calf were taken and the faeces were investigated for coccidia. Samples found with coccidian oocysts were suspended in a 2% potassium dichromate solution. Isospora sp. was identified and samples with relatively high numbers of Isospora sp. were analysed molecularly. The SSU rRNA gene and internal transcribed spacer 1 (ITS1) were amplified with primers complementary to conserved regions of the SSU rRNA gene in eukaryotes as well as a conserved part of the 5.8S rRNA gene of Eimeria. A relatively high number of the calves exhibited diarrhoea, 30.2% and 41.8% in the M1 and M2 herds, respectively. Isospora sp. was only found in diarrhoeic calves or in calves convalescent from recent scouring periods. No calf >8 weeks of age was found to be excreting Isospora sp. The parasite was only found in calves < or =4 weeks of age in the M1 herds and in the M2 herds in calves <8 weeks of age. Of the M1 and M2 calves exhibiting diarrhoea, 20.8% and 26.3% excreted Isospora sp., respectively. Morphologically the Isospora sp. was similar to I. orlovi and sequence analysis of the SSU rRNA gene from four Kenyan isolates (unfortunately only from the pastoral herds, M2) and ITS 1 segments from three of the isolates from Kenya and one from Dubai, confirmed that the Isospora isolates belonged to the species I. orlovi, and that the sequences were similar to the Dubai isolates.     

特异PCR方法用于鸡的3种艾美耳球虫混合感染鉴别的研究

用单卵囊分离法获得的鸡的3种艾美耳球虫（每种各2株）卵囊：柔嫩艾美耳球虫（Eimeria tenella）、巨型艾美耳球虫（E．maxima）、堆型艾美耳球虫（E．acervulina）。经纯化、提取基因组DNA后，用报道的种特异引物做PCR扩增分析，以确定是否为纯种。结果发现这3种球虫均存在混合感染的情况。该结果为进一步研究这3种球虫奠定了基础，并说明特异PCR方法能够有效地、快速地鉴别球虫虫种。     

The sporulation time of Isospora suis oocysts from different sources

Feces containing Isospora suis oocysts were collected from naturally- and experimentally-infected pigs from four different areas of the United States. The unsporulated oocysts were cleaned, concentrated, mixed with 2.5% aqueous potassium dichromate solution, poured into petri dishes to a depth of 5 mm, and incubated at 25 degrees C. The oocysts were examined with a microscope at 12 h intervals and the stages of sporulation present were counted. Although a few oocysts were completely sporulated after 12 h of incubation, in most fecal samples the majority of the oocysts were not completely sporulated until 24 or 36 h. In the present study, the sporulation time of I. suis oocysts was considered to be less than or equal to 48 h. There were no major differences in the sporulation times of I. suis oocysts from the different sources.     

Coccidiosis in suckling calves raised on large farms

In a large herd of pigs whose piglets suffered from diarrheas coprological examination revealed the great incidence of Isospora suis coccidia in piglets. The first oocysts were found out in seven-day piglets; the highest incidence was observed in twelve-day piglets (65.9%); the time of oocyst elimination (patency) was five to six days. The oocysts appeared in the excrements of piglets two to three days after the diarrhea onset. Individual examinations of piglets demonstrated the correlation between the intensity of clinical signs and the numbers of eliminated oocysts. No oocysts of I. suis were found either in sow excrements or gilt excrements. The I. suis oocysts were diagnosed in the excrements of piglets from first-farrowing sows and in the excrements of piglets from the sows, in the litters of which I. suis had already been demonstrated. Evaluating the therapeutic and preventive effects of the anticoccidic drug amprolium no significant difference was recorded in the I. suis incidence between the medicated group and the control group.     

Development of molecular assays for the identification of the 11 Eimeria species of the domestic rabbit (Oryctolagus cuniculus)

Coccidiosis are the major parasitic diseases in poultry and other domestic animals including the domestic rabbit (Oryctolagus cuniculus). Eleven distinct Eimeria species have been identified in this host, but no PCR-based method has been developed so far for unequivocal species differentiation. In this work, we describe the development of molecular diagnostic assays that allow for the detection and discrimination of the 11 Eimeria species that infect rabbits. We determined the nucleotide sequences of the ITS1 ribosomal DNAs and designed species-specific primers for each species. We performed specificity tests of the assays using heterologous sets of primers and DNA samples, and no cross-specific bands were observed. We obtained a detection limit varying from 500fg to 1pg, which corresponds approximately to 0.8-1.7 sporulated oocysts, respectively. The test reported here showed good reproducibility and presented a consistent sensitivity with three different brands of amplification enzymes. These novel diagnostic assays will permit population surveys to be performed with high sensitivity and specificity, thus contributing to a better understanding of the epidemiology of this important group of coccidian parasites.     

Survival of Isospora suis oocysts under controlled environmental conditions

Isospora suis is a coccidian parasite infecting piglets soon after birth. While the gross epidemiology of I. suis is well known, little knowledge exists on the ecology of the oocysts. To study the development and survival of oocysts of I. suis under controlled laboratory conditions, known numbers of oocysts ( approximately 200 in each of 4 replicates) were exposed to all combinations of 4 relative humidities (53-100% RH) and 3 temperatures (20 degrees , 25 degrees , 30 degrees C). Determination of viability was based on morphological and fluorescent properties of the oocyst as well as on the permeability of the oocyst wall characterized by inclusion/exclusion of the fluorescent dye propidium iodide. The viability of the oocysts was studied over time by fluorescence and light microscopy until <5% of the oocysts were considered to be viable. The sporulation rate increased with temperature, however, the infective sporocyst stage was reached within 24h at all temperatures, while RH did not seem to affect sporulation. Results show a rapid reduction in viable oocysts exposed to high temperatures (25 degrees C and 30 degrees C) in combination with low relative humidities (53% RH and 62% RH), at which conditions oocysts died within 24h. Viability was higher when oocysts were exposed to higher relative humidities (75% RH and 100% RH) as well as a lower temperature (20 degrees C). However, even at 75% RH the oocysts died within 24-60 h at 30 degrees C to 20 degrees C, respectively, while the most favourable condition appeared to be 100% RH and 25 degrees C at which condition the percentage of viable oocysts decreased from 100% to 17% in 96 h. The results indicate that it may be possible to reduce the infection pressure of I. suis in modern sow herds by changing the environmental conditions and/or the management within the farrowing pens, and thereby increase animal welfare without relying on the use of routine medication.     

Quantitative determination of coccidian oocysts in beef calves from the coastal plain area of Georgia (U.S.A.)

For two consecutive years, determinations were made of the prevalence and abundance of coccidian oocysts from crossbred beef calves raised on Bahia grass pastures in the coastal plain area of Georgia. Of the 534 fecal samples collected during the survey, 461 (86.3%) contained one or more species of coccidian oocysts. The total mean oocysts per gram of feces (OPG) was significantly different (P less than 0.10) between the two years. Thirteen species of Eimeria were found during both years of the survey. Eimeria bovis was the most prevalent species found in the survey; E. ellipsoidalis, however, had the greatest number of OPG. Eimeria bukidnonensis, E. pellita, and E. brasiliensis were the least prevalent species and also had the lowest numbers of OPG. Only one clinical case of coccidiosis was seen. A nine-month-old calf had E. zuernii coccidiosis; it excreted E. zuernii oocysts in several fecal samples before the clinical disease appeared.     

Prevalence of coccidia in pigs in Zimbabwe.

Faecal specimens from 162 piglets, aged 1-5 months, from four farms around Harare were examined for coccidia during 1989-1990. Oocyst count per gram (OPG) of faeces was determined by the McMaster technique. Identification of Eimeria species was done after sporulation of oocysts in 2.5% potassium dichromate solution. Measurements of sporulated oocysts were taken from 20 positive cases by using calibrated eye micrometer. Overall incidence was 25.3% (41/162) varying between 15 and 39.5% at different farms. The OPG ranged between 150 and 11,300. Eight species of Eimeria were identified, namely, Eimeria debliecki, Eimeria perminuta, Eimeria suis, Eimeria polita, Eimeria neodebliecki, Eimeria porci, Eimeria scabra and Eimeria spinosa, shown in the order of their prevalence. Eimeria debliecki was the most predominant, showing highest oocyst counts in 45% of 20 pigs, followed by E. suis (25%) and E. polita (20%). On two occasions only one Eimeria sp. was found while in the other 18 (90%) cases, mixed infections of two to six species were recorded.     

重庆市猪球虫病流行病学调查与虫种鉴定

目的为了解重庆市猪场球虫感染情况。方法选取重庆市9个县14个猎场作为采样点,对被检猪采用直肠取粪法或采集猪刚排出的新鲜粪便,饱和食盐水漂浮法收集卵囊,镜检观察。对收集到的卵囊进行培养,待其孢子化后进行种类鉴定。结果14个猪场均感染了球虫,球虫的平均感染率为33.83%,阳性率最高的场为76.09%;仔猪感染率为41.87%,后备猪感染率为26.33%,种猪感染率为67.80%。发现8种艾美耳属球虫和1种等孢属球虫,分别是猪艾美耳球虫(检出率13.56%),豚艾美耳球虫(检出率41.59%),有刺艾美耳球虫(检出率12.84%),平滑艾美耳球虫(检出率4.70%),新蒂氏艾美耳球虫(检出率10.49%),蒂氏艾美耳球虫(检出率11.03%),粗糙艾美耳球虫(检出率2.35%),极细艾美耳球虫(检出率3.07%),及猪等孢球虫(检出率0.36%)。结论重庆市猪球虫感染率较高,应加强猪球虫病的防制。     

An observational study on the prevalence and impact of Isospora suis in suckling piglets in southwestern Ontario, and risk factors for shedding oocysts

An observational study was conducted to determine the prevalence of Isospora suis oocysts in fecal samples from suckling piglets in Ontario, and to evaluate the relationship between the presence of I. suis oocysts and diarrhea. Fifty farms and 709 litters of piglets were included in the study. Oocysts were detected on 70% of farms, with 187 litters infected. A litter of pigs that was positive for oocysts was significantly more likely to exhibit diarrhea than a litter that was negative [odds ratio (OR) = 4.0; 95% confidence interval (CI) = 2.8 to 5.8; P < 0.001]. Management and housing factors were examined with respect to risk factors for the presence of I. suis. Farms that did not use a detergent when cleaning farrowing crates were 10-times more likely to be positive for I. suis than those that used a detergent (P = 0.007). It was concluded that coccidiosis is a common problem on Ontario swine farms.     

Prevalence of Eimeria in faeces of cattle in Saudi Arabia

The faeces of 205 domestic cattle (Bos taurus) from 5 regions of Saudi Arabia were examined for the presence of coccidian parasites. The following species of Eimeria were recovered: Eimeria auburnensis, E. bovis, E. cylindrica, E. ellipsoidalis, E. subspherica, E. wyomingensis and E. zuerni. A total of 34.1% of the individual faecal samples were positive for the presence of coccidial oocysts. Mixed infections of 2-4 species were found in 15.7% of the specimens. E. zuerni and E. bovis occurred most frequently and were generally the most predominant species. The incidence of coccidia-infected cattle was higher in the eastern region.     

Coccidia in cows and calves on pasture in north Georgia (U.S.A.)

The prevalence and abundance of coccidian oocysts were determined in a herd of beef cows and calves on fescue pastures in the Piedmont area of Georgia during 4-consecutive grazing seasons. Twelve species of Eimeria were found in the feces of the calves and 10 species were found in the feces of the cows. Eimeria bovis was the most prevalent species found in both the calves and cows. It occurred in 72.5% of 1090 samples from the calves and 10.2% of 719 samples from cows. Eimeria bovis also comprised the majority of oocysts present in the fecal samples from the calves and cows. The greatest number of E. bovis in a sample was 45 800 oocysts per gram of feces (OPG) from a calf and 1900 OPG from a cow. No cases of clinical coccidiosis were seen in any of the animals sampled during the survey.     

Isospora suis species in a Danish SPF-herd

In two studies carried out in 1974-75 on 10 eight and 25 two week old piglets obtained from a SPF-herd the endoparasitic status was determined. Samples of faeces were examined by microscopy which revealed the presence of Isospora suis, a finding that was quite unexpected in a SPF-herd. During days 17-23 pp. the 25 piglets were not found to excrete oocysts, the earliest findings of oocysts being made 24-35 days p.p. The 10 piglets being kept isolated in individual pens excreted oocysts up until 88 days p.p. The epidemiology of Isospora suis is discussed.     

Dung beetles, Onthophagus spp., as potential transport hosts of feline coccidia

Cockroaches and filth-flies have been known to be transport hosts of Toxoplasma gondii but the role of dung beetles as the carrier of coccidian oocysts is not known. We attempted to clarify the role of dung beetles (Onthophagus spp.) as the transport host of feline coccidia including Toxoplasma. Toxoplasma oocysts were found in the feces of the beetles until day 3 after the insects were exposed to cat feces mixed with the oocysts. Furthermore, oocysts on the body surface of beetles were not easily detached but remained infective for a prolonged period of time. Infective dung beetles may contaminate the water with infective oocysts passed in their feces when they dropped into the water. In the field survey feline coccidia, Isospora felis and I. rivolta, were detected in dung beetles collected from dog feces; they play an important role in the transmission of feline coccidian oocysts in the field.