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1.
Faecal samples from three groups of yearling Awassi sheep fed three different nutritional planes were taken at 2-week intervals over a period of 3 months. Eimerian oocysts were found in 252 (80%) of the 315 samples collected. The species of Eimeria were identified and 30.2% of the samples contained three or four species, 27.3% had two species and 22.2% had one species. The prevalences in decreasing order were: E. pallida (37.1%); E. parva (28.9%); E. crandallis (17.8%); E. marsica (15.6%); E. bakuensis (syn. E. ovina) (13.7%); E. ovinoidalis (11.4%); E. intricata (11.1%); E. ahsata (9.2%); E. faurei (7.0%); E. granulosa (4.4%). The prevalence of E. bakuensis was significantly (P less than 0.05) higher in sheep fed the high and moderate planes of nutrition, while the prevalence of E. faurei was significantly (P less than 0.05) lower in sheep fed on the moderate plane. The numbers of E. marsica were also significantly higher (P less than 0.05) than other Eimeria species in the moderate plane group. 相似文献
2.
Faecal Eimeria oocyst excretion, body weights, humoral antibodies against E. ovinoidalis sporozoite antigen and related heritabilities were determined in housed Merinoland sheep lambs throughout a period of 100 days after birth in Germany. Altogether 10-11 Eimeria spp. were found. Cumulative incidences of E. ovinoidalis and E. weybridgensis/crandallis increased rapidly resulting in almost 100% incidence in 8 weeks old lambs. In the other species, the cumulative incidence increased more continuously. Except for E. granulosa oocysts of all species had been excreted at last once until day 30. By far the highest oocyst counts (OpG) were observed with E. ovinoidalis, followed by E. weybridgensis/crandallis. High counts were limited to the period of 5-8 weeks after birth. In the other Eimeria species oocyst counts persisted at comparatively low levels until the end of the observation period although their proportion of the total counts increased with age of the lambs. Time courses of oocyst excretion suggest an early onset of effective immunity to the major Eimeria spp., which differed for the minor species. Mean and maximum oocyst counts and body weights of the lambs were inversely correlated suggesting negative effects of the infection on the lamb's performance. High mean antibody levels on day 7 after birth dropped until day 40 and increased subsequently again. There were no indications that maternal antibodies were protective. Antibody levels on day 40 after birth were positively correlated with oocyst counts in the faeces whereas those determined on day 80 were independent of infection parameters. Heritabilities of log(10)OpG were not significantly different from 0 up to an age of 60 days. Later estimated values were between 0.54 and 0.79 suggesting that immune protective effects rather than innate effects determining disease susceptibility are under genetic influence. 相似文献
3.
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. 相似文献
4.
The purpose of this experiment was to characterize the species of Eimeria affecting lambs and their infection pattern. Faecal samples were collected from each animal at 14-day intervals, beginning when lambs were 2 weeks old and ending when they were 32 weeks old. The oocysts were counted and identified as E. intricata, E. parva, E. pallida, E. crandallis, E. bakuensis, E. weybridgensis, E. ahsata and E. ovinoidalis. The highest oocyst counts were observed when the lambs were 4-8 weeks old. 相似文献
5.
The aim of this study was to investigate the spread of infection and population dynamics of ovine coccidosis under dairy sheep production systems in the Mediterranean area, taking into account differences between management systems, lambing season and climatic conditions. Data were collected from six (intensive and semi-intensive) dairy sheep flocks located either in the North or the South of Greece, with groups of lambs born during two consecutive lambing periods (autumn, spring) from each flock. Faecal consistency and oocyst excretion were recorded from faecal samples taken from 220 lambs in total, starting at days 7-9 after lambing and subsequently every 6 days for 5 times. Eleven Eimeria species including the highly abundant pathogenic E. ovinoidalis and E. crandallis were isolated. The onset of excretion was noted from 13 to 33 days after birth with a peak at 19-21 days. The cumulative incidence of infection per flock until the end of the study ranged from 64.29% to 100% during both lambing periods. A significant tendency for animals to get infected earlier during spring lambing was observed. This trend was even higher for lambs from farms located in the South and is possibly related to the higher contamination level of the farms after lambing during that time. Predominantly subclinical cases of coccidiosis were observed during the course of the study with a relatively low proportion of diarrhoeic faeces which did not significantly differ between the two rounds. Considering the significance of dairy sheep production in the area and the economic losses that can be caused by eimeriosis, monitoring of infection levels in the farms, taking into account the lambing period and environmental conditions, is highly recommended. 相似文献
6.
Eimeria oocysts were found in 89% of fecal samples collected from the rectum of 75 sheep from 3 locations in Papua New Guinea. Eighty five percent of the hosts which were positive for coccidia had multiple infections with up to 6 different species of Eimeria. In order of decreasing predominance in the 67 Eimeria-positive samples the species were: E. ovina (72%); E. parva (58%); E. ovinoidalis (48%); E. ahsata (45%); E. crandallis (39%); E. faurei (28%); E. intricata (24%); E. granulosa (4%). Fecal oocyst counts showed the highest mean of 1252 oocysts per gram (o.p.g.) for E. parva and a maximum of 8000 for E. ovina. 相似文献
7.
Ng'ang'a CJ Maingi N Munyua WK Kanyari PW 《The Onderstepoort journal of veterinary research》2004,71(3):219-226
A survey on the prevalence and intensity of infection with gastrointestinal helminths of Dorper sheep in relation to age and weather factors was carried out on a ranch in Kajiado district, a semi-arid area of Kenya for a period of 13 months (May 1999 to May 2000). Faecal samples from lambs (3 months to 1 year), yearlings (1-2 years) and adult breeding ewes (2-4 years) were examined for helminth egg output and helminth genus composition at 3-week intervals. The results indicated that the prevalence of strongyle and tapeworms infections were highest for lambs, followed by the adult breeding ewes and then for the yearlings. In all age groups the proportions of infected animals were higher during the wet season than in the dry season for both nematodes and tapeworms. The mean strongyle egg counts were higher during the dry season for lambs, but were higher during the wet season for the other age groups. Mixed strongyle infections were detected, with Trichostrongylus (55 %), Haemonchus (28 %), Cooperia (10.5 %) and Oesophagostomum (6.5 %) being the most frequently encountered genera throughout the study period. The trends in strongyle faecal egg counts indicated the occurrence of hypobiosis, with resumption of development towards the end of the dry season and at the onset of the short rains in October and November. Self-cure was also observed in September and November in all age groups, although less frequently in lactating ewes. The prevalence and intensities of infection with gastrointestinal helminths in this area appeared to be influenced by the age of the host and weather factors. 相似文献
8.
Information on the occurrence and diversity of coccidia infecting cattle in different farming systems in South Africa is lacking. The objective of the study was to determine the levels of infection of coccidia in cattle at three localities and to determine the Eimeria species occurring at each locality. Faecal samples (n=1936) were collected over a 13-month period from a dairy farm (Mallesons), a Bonsmara breeding farm (Kaalplaas) and a Nguni stud farm (Pienaars River). Samples were collected from adults >24 months old and calves <12 months old. The modified McMaster technique was used to determine OPG (oocysts per gram) of faeces. Samples with OPGs > or =2000 were allowed to sporulate in potassium dichromate solution at room temperature. Species identification was done by measurement and morphological characteristic of each species. At Mallesons, 29% of samples were positive, at Kaalplaas 50% and at Pienaars River 52%. The most prevalent species were Eimeria zuernii and E. ellipsoidalis at Mallesons, E. zuernii and E. bovis at Kaalplaas and E. bovis and E. zuernii at Pienaars River, respectively. Adults had very low OPGs. There was a pattern at the three localities in that high OPGs were only recorded in calves, which were also shedding the most pathogenic species. 相似文献
9.
Genetic resistance to gastrointestinal nematode parasites in Rh?n sheep following natural infection.
Genetic parameters of resistance to gastrointestinal nematodes were estimated in Rh?n sheep, a local sheep breed in Germany. In the first year, a total of 131 lambs (born between January and February 1998) from five rams were evaluated. Faecal egg counts (FEC) (n=1528) were measured in all lambs every 2 weeks until 4 months of age and every 4 weeks until 12 months of age in female lambs. In the second year, a total of 129 lambs (born between January and February 1999) from the same rams were evaluated. FEC (n=645) were measured in the lambs every 4 weeks until 5 months of age. Blood was taken in both years at the time of faecal sampling from the jugular vein and haematocrit was measured. Heritabilities for log(10)(FEC+25) were between 0.11 and 0.44. Heritabilities for the corresponding haematocrits were between 0.19 and 0.26 depending on the number of samples taken in account. A significant negative correlation was estimated for the parameters of FEC and daily weight gain (r=-0.57). The results confirm the feasibility of genetic selection in Rh?n sheep for resistance to nematode parasites in an environment where Trichostrongylus spp./Teladorsagia spp., Haemonchus contortus and Cooperia spp. are the dominant species. Breeding decisions can be based on one or two samples depending on the mean values and ranges of FEC and haematocrit, respectively. 相似文献
10.
Prevalence of Cryptosporidium in sheep and goats bred on five farms in west-central region of Poland 总被引:3,自引:0,他引:3
Faecal specimens were taken from 205 sheep and goats housed in five different localities in the west-central part of Poland. All faecal specimens were examined for Cryptosporidium by using microscopy screening of smears stained by modified Ziehl-Neelsen technique and commercial enzyme immunoassay. PCR technique using genus specific primers was additionally applied in the surveys of 10 faecal specimens collected from lambs. C. parvum infection was identified in 16 of 159 sheep (10.1%). Lambs were more often infected than adult sheep, and the intensity of infection was higher in lambs than in sheep, as a rule. Both lambs and sheep examined in the study were asymptomatically infected with Cryptosporidium. Both microscopy and enzyme immunoassay methods gave one false negative result. The examination of 10 faecal samples revealed 100% agreement among the results obtained by microscopic, immunologic and molecular methods. None of the goats raised on three farms were infected with Cryptosporidium. 相似文献
11.
Coccidia were detected in the faeces of 556 out of 592 sheep (93.9%) in sheep in Kars province. The prevalence of coccidiosis was significantly higher (p>0.01) in young (97.9%) and immature sheep (96.6%) than in adult sheep (90.2%). Mixed infections were widespread (71.5%). Ten species of Eimeria were recognized. These species (and their prevalences) were: Eimeria ovinoidalis (47.7%), E. bakuensis (E. ovina) (46.6%), E. parva (37.1%), E. granulosa (27.7%), E. ahsata (23.4%), E. pallida (23.2%), E. faurei (15.1%), E. intricata (13.9%), E. crandallis (13.7%) and E. punctata (2.3%). Eimeria punctata is reported in sheep from Turkey for the first time. The mean oocyst count from infected animals was 3451±409 opg (range 50–117 600). The mean was higher (9529±502) in young sheep. Differences in the counts from young, immature and adult sheep were statistically significant (p>0.01). However, no clinical cases of coccidiosis were encountered. 相似文献
12.
A total of 620 bovine faecal samples collected from unselected animals brought for post-mortem to the Department of Veterinary Pathology and Microbiology or from animals in the Kabete (Kenya) practice area of the Faculty of Veterinary Medicine were examined to determine the types and prevalence of Eimeria spp. present. Coccidian oocytes were detected in 67.4% of the samples and eight different species of Eimeria were recognized. The species detected (and their prevalence) were E. bovis (79.0%), E. zuernii (60.2%), E. ellipsoidalis (26.1), E. cylindrica (13.4%), E. auburnensis (28.4%), E. alabamensis (10.3%), E. subspherica (5.0%) and E. wyomingensis (6.1%). E. bovis and E. zuernii led to few cases of clinical coccidiosis and the greatest number of E. bovis in one of the samples from the clinical cases was 30,600 oocysts per gram of faeces (OPG). Age and seasonal variation appeared to have an influence on the intensity of infection. 相似文献
13.
A three-year survey (1997-99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei. T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs. 相似文献
14.
Bakunzi FR Thwane SN Motsei LE Dzoma BM 《Journal of the South African Veterinary Association》2010,81(3):148-150
Diversity and seasonal occurrence of coccidia in a communally reared mixed flock of sheep and goats at Mafikeng, North West Province, South Africa, was determined between March 2008 and February 2009. Faecal specimens were collected directly from the rectum of the animals and the number of oocysts per gram of faeces (opg) determined. The mean monthly opg for goats was significantly higher than that for sheep. Higher oocyst counts were observed during the hot, rainy season than during the cold, dry season. The highest mean values for both the sheep (862.5 opg) and goats (1200 opg) were recorded during March. Six species (Eimeria crandallis, E. bakuensis, E. weybridgensis, E. ahsata, E. intricata, and E. ovinoidalis) were recovered from sheep, with E. crandallis and E. bakuensis occurring most frequently. The last 2 species, together with E. ahsata, are considered among the most pathogenic species in sheep. In goats, 7 species (E. arloingi, E. jolchijevi, E. caprina, E. alijevi, E. caprovina, E. christenseni and E. hirci) were recovered, with E. arloingi and E. jolchijevi occurring most frequently. Up to 5 Eimeria species were recovered from individual specimens in goats while up to 4 were recovered in sheep. No cross-infections between goats and sheep were recorded and no clinical coccidiosis was noted during the study. It is increasingly becoming evident that the pathogenic E. arloingi is one of the most commonly occurring Eimeria species in goats in South Africa. 相似文献
15.
Sweeny JP Ryan UM Robertson ID Yang R Bell K Jacobson C 《Preventive veterinary medicine》2011,101(3-4):192-203
In this study, 96 faecal samples were collected from pregnant Merino ewes, at two broad-acre, commercial sheep farms in southern Western Australia, on two separate occasions (16 and 2 weeks prior to lambing). Following lambing, 111 (Farm A) and 124 (Farm B) female crossbred lambs (2-6 weeks old), were individually identified using ear tags (a numbered tag and a radio-frequency tag). A total of 1155 faecal samples were collected only from these individually identified lambs on five separate sampling occasions. All samples were screened using PCR to detect Cryptosporidium (18S rRNA and actin loci) and Giardia duodenalis (glutamate dehydrogenase and triosephosphate isomerise loci). The overall prevalences (lambs positive for a parasite on at least one of the five samplings) at Farm A and B were 81.3% and 71.4%, respectively for Cryptosporidium and similarly 67.3% and 60.5% for Giardia, respectively. Cryptosporidium and Giardia prevalences at individual samplings ranged between 18.5 and 42.6% in lambs and were <10% in the ewes. Cryptosporidium xiaoi was the most prevalent species detected at all five samplings and was also isolated from lamb dam water on Farm B. Cryptosporidium ubiquitum was most commonly detected in younger lambs and Cryptosporidium parvum was detected in lambs at all five samplings, typically in older lambs and as part of a mixed species infection with C. xiaoi. A novel, possibly new genotype (sheep genotype I), was identified in six Cryptosporidium isolates from Farm B. Giardia duodenalis assemblage E was the most common genotype detected at all five samplings, with greater proportions of assemblage A and mixed assemblage A and E infections identified in older lambs. This longitudinal study identified high overall prevalences of Cryptosporidium and Giardia in lambs grazed extensively on pastures, while reinforcing that sampling a random selection of animals from a flock/herd on one occasion (point prevalence), underestimates the overall prevalence of these parasites in the flock/herd across an extended time period. Based on these findings, grazing lambs were identified as a low risk source of zoonotic Cryptosporidium and Giardia species/genotypes, with these protozoa detected at all five samplings in some lambs, indicating that these individuals were either unable to clear the naturally acquired protozoan infections or were repeatedly re-infected from their environment or other flock members. 相似文献
16.
Fiuza VR Cosendey RI Frazão-Teixeira E Santín M Fayer R de Oliveira FC 《Veterinary parasitology》2011,175(3-4):360-362
Feces were collected from 125 sheep between January and December 2007, on ten farms in the State of Rio de Janeiro, Brazil, and examined for the presence of Cryptosporidium. Ninety samples were collected from lambs 2 to 6 months of age, and 35 were from sheep over 12 months of age. All samples were subjected to molecular analysis by polymerase chain reaction (nested PCR) in two steps of the SSU rRNA. Two samples (1.6%) from the lambs were positive, and after sequencing were identified as Cryptosporidium ubiquitum. This species has been reported worldwide and it is considered a zoonotic pathogen since it has been found and in several animal species and humans. However, because of the low frequency of C. ubiquitum found, the risk for public health in this region may not be high. 相似文献
17.
Sweeny JP Robertson ID Ryan UM Jacobson C Woodgate RG 《Veterinary parasitology》2012,184(2-4):298-308
On two separate sampling occasions, faecal samples were collected from lambs (2-5 months of age) grazing pasture on two separate sheep farms in southern Western Australia. Live weight, body condition score (BCS), faecal consistency score (FCS) and faecal dry matter percentage (DM%) were measured. Faecal samples were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and β-giardin) and patent strongylid nematode infections (ITS-2 nuclear ribosomal DNA for Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp. Chabertia ovina and Oesophagostomum spp.). Faecal worm egg counts (WECs) were performed using a modified McMaster WEC technique. The WECs were adjusted for FCS and transformed using log(10)(adjusted WEC+25) prior to statistical analyses. Cryptosporidium, Giardia and Trichostrongylus spp. detected by PCR were associated with an increased risk of non-pelleted faeces (FCS ≥ 3.0) for both flocks. Cryptosporidium-positive lambs were 2.8-11.6 times more likely to have non-pelleted faeces and Giardia-positive lambs were 2.4-14.0 times more likely to have non-pelleted faeces compared to lambs negative for each respective parasite. Lambs positive for both Cryptosporidium and Giardia were 2.9-11.8 times more likely to have non-pelleted faeces than lambs positive for only one or neither of these parasites. Mixed internal parasite infections were found to have greater impacts on FCS and BCS than single infections. A higher number of internal parasites detected per lamb was associated with lower BCS and more loose faeces. The relationship between parasite detection and live weight or growth rate were inconsistent for both flocks. Adjusted WEC was correlated with FCS and faecal DM% for one flock only, although little or no correlation was found with live weight and growth rate for both flocks. Cryptosporidium ubiquitum and Cryptosporidium parvum were the most prevalent Cryptosporidium species isolated in the two flocks. Giardia assemblage E was the most commonly isolated genotype assemblage from both flocks, while assemblage A was isolated almost as frequently as assemblage E in the one flock. One flock was a potential source of zoonotic Cryptosporidium and the other flock was a potential source of zoonotic Giardia. 相似文献
18.
The study was designed to better define the variables affecting the success of the establishment of ovine herpesvirus 2 (OHV-2)-free sheep flocks. A total of 38 lambs born to OHV-2-positive ewes was selected and divided into four groups. Three groups of 10 lambs each were separated from the positive ewes at 2, 2.5 and 3 months of age, respectively, and maintained in isolation facilities. One group of eight remained in the positive flock as controls. Peripheral blood samples from each lamb were examined regularly by PCR for OHV-2 DNA. All lambs (100%) that were weaned and maintained in isolation from the ages of 2, 2.5 and 3 months remained negative until the termination of the experiment at 1 year of age. One lamb was discovered to be PCR-positive on the day of isolation at 2.5 months of age, and was promptly removed from the isolation group. In contrast, all lambs (100%) that remained with the flock became PCR-positive by 6 months of age. The data confirmed that, with rare exceptions, separation of lambs from OHV-2 infected animals at around 2 months of age reliably yields OHV-2-free sheep. Appropriate PCR monitoring will enable the rare exceptions to be removed from the group, and is recommended as a safety measure. 相似文献
19.
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. 相似文献
20.
Prevalence and analysis of potential risk factors for Cryptosporidium parvum infection in lambs in Zaragoza (northeastern Spain) 总被引:2,自引:0,他引:2
Causapé AC Quílez J Sánchez-Acedo C del Cacho E López-Bernad F 《Veterinary parasitology》2002,104(4):287-298
An epidemiologic study was carried out to investigate the prevalence of and to identify factors associated with the risk of Cryptosporidium infection in sheep in Zaragoza (northeastern Spain). Faecal samples from 583 lambs aged from 1 day to 3 months and 205 ewes older than 1 year were collected at 89 farms in the two regions of the province of Zaragoza with the highest sheep population (Zaragoza and Ejea de los Caballeros). In every sheep farm, data of the factors potentially associated with the likelihood of C. parvum infection were analysed: geographical location, season, size of herd, number of lambs in the herd at sampling time, lambing period, cleaning of lambing area and presence of diarrhoeic lambs in the farm. C. parvum oocysts were identified by using the Ziehl-Neelsen technique in 344 lambs (59%) from 75 farms (84.4%). Infected lambs ranged from less than 7 days to 90 days of age, although the percentage of animals shedding oocysts peaked at 8-14 days of age (76.2%). Statistical analysis showed that infection rates were significantly higher in lambs aged between 1 and 21 days (66.4%) than in those aged between 22 and 90 days (23%) (P<0.0001, chi(2)). Analysis of correlation between excretion of oocysts and diarrhoea revealed a relationship in all age groups and the probability of presenting diarrhoea was significantly higher for lambs shedding oocysts (86.3%) than for those which did not excrete the parasite (32.2%) (P<0.0001, chi(2)). Similarly, cryptosporidial infection rates were significantly higher in diarrhoeic (79.4%) than in non-diarrhoeic lambs (22.4%). Furthermore, infection intensity was correlated with the presence of clinical symptoms. Presence of diarrhoeic lambs in the farm was the only factor significantly associated with an increased risk of infection since the percentage of herds testing positive was significantly higher in farms with diarrhoeic lambs (91.3%) than in those without cases of neonatal diarrhoea (12.5%) (P<0.0001, chi(2)). Factors associated with a decreased risk of C. parvum infection in lambs included low numbers of lambs in the farm and cleaning of the lambing area. Additionally, lambs 8-14 days of age were less likely to be infected at the first lambing period and in spring/autumn. Cryptosporidial infection was also detected in 16 ewes (7.8%) which excreted few oocysts and without diarrhoea. 相似文献