Efficacy of azithromycin dihydrate in treatment of cryptosporidiosis in naturally infected dairy calves

The objective of this study was to evaluate the therapeutic efficacy of azithromycin treatment of cryptosporidiosis in naturally infected calves under field conditions. Fifty Holstein calves with cryptosporidiosis infection were divided into 5 groups: 1 group (10 calves) was unmedicated and served as the control group and was given distilled water only, whereas the other groups (10 animals per group) were medicated orally with azithromycin at the doses of 500 (group 1), 1,000 (group 2), 1,500 (group 3), and 2,000 mg (group 4) PO once daily for 7 days. The animals were examined clinically and fecal samples were collected on the 1st (inclusion day), 7th, 14th, and 21st days of the study. Drug efficacy was assessed by evaluating diarrhea, oocyst shedding, and weight gains from days 1 to 21 (4 assessments). Significant differences were observed in reductions of oocyst shedding (P < .05) and the fecal diarrhea incidence (P < .05) in groups 3 and 4 when compared with groups 1 and 2 and the control group. Weight gain of medicated calves was significantly higher than that of the unmedicated calves throughout the study (P < .05). The drug significantly suppressed oocyst shedding and resulted in significant improvements in clinical signs. Therefore, this suppression may have significant effect on the reduction of environmental contamination by cryptosporidial oocysts. From the economic point view, authors suggest that the most effective dose of azithromycin for the treatment of cryptosporidiosis in calves should be at 1,500 mg/d for 7 days.     

Coccidiostatic action of monensin fed to lambs: body weight gains and feed conversion efficacy.

Thirty crossbred ewe lambs weighing an average of 37.3 kg were allotted to 6 groups of 5 lambs each so that group weights were nearly equal. Lambs were fed dehydrated alfalfa pellets, initially at 1.14 kg/day and subsequently increased after experimental day 15 and 42. Each lamb was artificially infected with 18,000 sporulated oocysts of Eimeria ninakohlyakimovae. Groups 1, 2, 3, and 4 were given monensin in the form of medicated alfalfa pellets at dose levels of 5, 10, 20, and 30 g/metric ton, respectively. Groups 5 and 6 were infected controls (infected, nonmedicated). Lambs in groups 5 and 6 developed severe clinical coccidiosis, having diarrhea and losing weight rapidly. Group 1 lambs did not have diarrhea, but the lambs did not gain well. All other medicated lambs gained weight during the experimental period of 84 days. Feed conversion was good in medicated groups 2, 3, and 4 and was poor in control groups 5 and 6. Statistically significant differences in feed conversion and body weight gains (5 and 1% level of confidence) were observed between control and medicated groups.     

Effect of monensin on experimental infections of Eimeria ninakohlyakimovae in lambs.

Two nearly identical experiments were conducted to determine the effects of the coccidiostatic compound monensin on Polled Dorset lambs experimentally infected with oocysts of Eimeria ninakohlyakimovae. Prophylactic medication at a dose level of 1 mg/kg of body weight was started 2 days before inoculation and prevented diarrhea and reduced oocyst production. Therapeutic medication at a dose level of 2 mg/kg, started with the appearance of signs of infection, reduced oocyst production below that of nonmedicated controls but did not eliminate diarrhea. Weight gains of medicated lambs were less than those of noninoculated, nonmedicated controls in both experiments. Apparently monensin, at the dose levels used, reduced oocyst production but also prevented weight gains as high as those in inoculated nonmedicated controls.     

Infectivity of Cryptosporidium parvum isolated from asymptomatic adult goats to mice and goat kids.

An experimental study was carried out in neonatal goat kids to examine the infectivity of Cryptosporidium oocysts, pattern of oocyst shedding and morphological changes in the intestine during the infection. Cryptosporidium oocysts isolated from adult asymptomatic goats, and identified as C. parvum by polymerase chain reaction (PCR) were used in this study. Of three 4-day-old goat kids, two were orally infected with C. parvum oocysts (10(5) oocysts in 10 ml PBS/kid). One goat kid given 10 ml PBS only by the oral route served as a control. Cryptosporidium oocysts were detected in the faeces of one infected kid on day 3 post-inoculation (pi) whereas in the other 6 days pi. The faecal oocyst counts gradually increased and the peak counts in the two kids were 2 x 10(6)g(-1) (on day 12 pi) and 3.2 x 10(6)g(-1) (on day 14 pi). The increase in faecal oocyst output coincided with diarrhoea in an infected kid from days 10-17 pi. Although the oocyst excretion declined gradually after the peak, both infected kids excreted oocysts until euthanized on days 20 and 22 pi. Light and scanning electron microscopic investigations of the ileum revealed the endogenous stages on the brush border of the enterocytes, infiltration of neutrophils and mononuclear cells into the lamina propria, atrophy, stunting and fusion of villi. For purposes of comparison, goat Cryptosporidium oocysts were inoculated orally (10(3) oocysts/mouse) to eight, 1-week-old mice. All experimental mice excreted oocysts from day 3 pi, and four infected mice continued to excrete oocysts up to day 42 pi. The experimental infection described in goat kids resembled the natural disease in terms of oocyst excretion, clinical signs and intestinal pathology. The ability of oocysts excreted by asymptomatic goats, to infect goat kids and mice is likely to have a major impact on the epidemiology of cryptosporidiosis in livestock and man.     

Prevalence and analysis of potential risk factors for Cryptosporidium parvum infection in lambs in Zaragoza (northeastern Spain)

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.     

柔嫩艾美耳球虫扬州分离株对8种抗球虫药的抗药性

将柔嫩艾美耳球虫(Eimeria tenella)扬州分离株感染14日龄苏禽黄羽肉鸡,设立8个用药组、1个感染不用药对照组和1个不感染不用药对照组,以相对卵囊产量、病变记分减少率、最适抗球虫百分数和抗球虫指数为指标对该虫株对盐霉素、马杜拉霉素、球痢灵、氯羟吡啶、氨丙啉、尼卡巴嗪、甲基三嗪酮、地克珠利等8种常用抗球虫药的抗药性进行了综合评定,分析了该地区球虫的抗药性及对策。结果表明,该虫株对甲基三嗪酮敏感,对氨丙啉具有中度抗药性,对盐霉素、马杜拉霉素、球痢灵、氯羟吡啶、尼卡巴嗪、地克珠利等其他6种药物具有完全抗药性。提示目前在扬州地区甲基三嗪酮抗球虫疗效最好,氨丙琳效果稍差,应合理使用,盐霉素等其他6种药物应慎用、减少或暂停使用。     

Comparative therapeutic effect of toltrazuril, sulphadimidine and amprolium on Eimeria bovis and Eimeria zuernii given at different times following infection in buffalo calves (Bubalus bubalis)

We compared the therapeutic effect of three anticoccidial drugs (toltrazuril, sulphadimidine and amprolium) in buffalo (Bubalus bubalis) calves experimentally infected with Eimeria bovis (E. bovis) and E. zuernii oocysts (3 x 104oocyst/calf). Buffalo calves (1.5-4 month old, 70-kg body weight) were randomly allocated into 3 groups (9 calves each). Group T was experimentally infected with oocysts and treated with toltrazuril (20 mg/kg BW twice orally at a 1-week interval). Group S was experimentally infected with oocysts and treated with sulphadimidine (125 mg/kg injected IM followed by half dose for 4 successive days). Group A was experimentally infected with oocysts and treated with amprolium (50 mg/kg orally for 7 successive days). Each group had three subgroups (three calves/subgroup) to represent timing of the drug administration: 1st day of coccidia infection (FD), onset of clinical signs of coccidiosis (CC), and onset of oocyst shedding into the faeces (OS). Clinical signs, body-weight gain (BWG) and number of oocysts per gram feces (OPG) were monitored daily for 35 days post-infection (DPI). The OPG were reduced (but the BWG was not different) in the T calves compared to S and A calves. Within the same group, treatment from the 1st day of infection reduced the OPG and increased the BWG compared to the later treatment timings.     

柔嫩艾美球虫常州株对5种抗球虫药的抗药性分析

将柔嫩艾美耳球虫(E.tenella)常州分离株感染14日龄苏禽黄羽肉鸡,设立5个用药组、1个感染不用药对照组和1个不感染不用药对照组,以相对卵囊产量、病变记分减少率、最适抗球虫百分数和抗球虫指数为指标对该虫株对球虫宁、地克珠利、马杜霉素、磺胺氯吡嗪、癸氧喹酯5种常用抗球虫药的抗药性进行了综合评定,分析了该地区球虫的抗药性及用药对策。结果表明,该虫株对癸氧喹酯敏感,对球虫宁、地克珠利、马杜霉素、磺胺氯吡嗪具有完全抗药性,提示目前常州地区球虫抗药性非常严重,癸氧喹酯抗球虫疗效最好,其他药物应合理使用、应慎用、减少或暂停使用。     

Influence of toltrazuril treatment on parasitological parameters and health performance of piglets in the field--an Austrian experience

Porcine coccidiosis caused by Isospora suis is one of the leading causes of neonatal diarrhea in suckling piglets. Currently the only registered drug for metaphylaxis is toltrazuril. To evaluate the effect of treatment on piglets from 7 Austrian farms without and 8 Austrian farms with toltrazuril application we examined oocyst excretion (including determination of oocysts per gram of feces; OPG), diarrhea (fecal score FS 1-4 with 3 and 4 being diarrhea), and general health (health score HS 1-4 with 3 and 4 describing poor health). Both groups included farms with different levels of hygiene. Samples from 265 litters without treatment, comprising 1588 individual samples, and 1548 samples from 258 treated litters were taken twice (around the 14th and the 21st day of life, respectively), examined by autofluorescence and, if positive, by McMaster counting. In both groups animals had less diarrhea and lower health scores during the second sampling but the treated piglets were always significantly healthier and had less diarrhea. The percentage of weaned piglets was higher in treated animals although this was not significant (p=0.052). In the first round of sampling 17.8% of the individual samples from untreated piglets were positive for oocysts (with a maximum prevalence on the 12-15th day of life) while in the treated piglets only 0.4% shed oocysts p<0.001). At the second sampling only 2.1% of the untreated animals and none of treated piglets excreted I. suis (p=0.083). Positive animals shed up to 8 × 10(3)OPG. There was an increased risk for infected piglets to develop diarrhea (odds ratio, OR 4.73) and poor health (OR 5.05) in untreated piglets, and poor hygiene without disinfection was identified as a risk factor for poor health (OR 1.90), diarrhea (OR 1.42) and oocyst excretion (OR 1.73). The risk of poor health (OR 2.89) and diarrhea (OR 1.44) was also increased for piglets under poor hygienic conditions receiving toltrazuril, so both metaphylaxis of coccidiosis and good hygiene are necessary to effectively control neonatal diarrhea. The costs of treatment are considerably lower than the estimated financial production losses. Therefore, treatment is recommended for farms where clinical coccidiosis is diagnosed.     

Excretion of Cryptosporidium oocysts by goats in relation to age and season in the dry zone of Sri Lanka.

Pattern of Cryptosporidium oocyst shedding in relation to age and season was investigated monthly from May 1999 to April 2000 in three groups (24 goats per group) of naturally infected goats (from 1 month of age). The three groups designated 1, 2 and 3 were studied for 12, 6 and 3 months, respectively. An association between Cryptosporidium oocyst counts and age was demonstrated. In Group 1, oocyst excretion in the first, second and fourth months of age were significantly higher than that in 6, 7, 8, 9 and 12 months of age (p<0.01), whereas in Group 2, oocyst excretion in the first month of age was significantly higher than that in 2, 4, 5 and 6 months of age (p<0.01). The 3-month observations made in Group 3 showed high oocyst excretion during 1 and 3 months of age. The mean maximum count for Group 1 was 592 oocyst per gram of feces when the animals were 2 months old, while in Groups 2 and 3, this was observed at 3 months of age and the oocyst counts were 787 and 520, respectively. A close association between the prevalence of the Cryptosporidium infection and age of the animal was also observed (p<0.01). At least one-third of the Group 1 animals were excreting Cryptosporidium oocysts during the first 5 months of age. Goats excreted Cryptosporidium oocysts irrespective of the dry or rainy season. The long periods of Cryptosporidium oocyst shedding by goats may have implications for the epidemiology of the disease in susceptible hosts.     

Coccidial infections in housed lambs: oocyst excretion, antibody levels and genetic influences on the infection

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.     

Relative value of oocyst counts in evaluating anticoccidial activity.

Birds medicated with roxarsone and in another experiment with zoalene in the feed produced higher oocysts counts than unmedicated control birds receiving the same oocyst dose of Eimeria tenella or a mixture of six species (E. tenella, E. necatrix, E. brunetti, E. maxima, E. acervulina, and E. mitvati). These experiments confirm the conclusion that oocyst counts constitute an unsatisfactory and unreliable parameter for judging effectiveness of an anticoccidial even though such increases are a relatively rare occurrence in anticoccidial evaluation experiments.     

Analysis of the kinetics, isotype and specificity of serum and coproantibody in lambs infected with Cryptosporidium parvum

Enteric cryptosporidiosis was studied in colostrum-deprived lambs each infected at five days old with 10(6) oocysts. The prepatent period was three to five days and faecal oocyst concentration fell below detectable levels by day 16 after infection. Specific IgA, the only isotype detected by immunofluorescent assay in faecal extracts from infected lambs, was first evident on day 10 and titres continued to rise until day 16 of infection in association with declining oocyst output. Specific IgM and IgG antibodies were first detected in serum seven days after infection. No specific antibody was detected in uninfected control lambs. Immunoblotting methods showed that serum antibody and faecal IgA had similar profiles of antigen recognition. Antigens with approximate molecular weights of 180,000, 23,000 and 15,000 were consistent features on immunoblots performed with convalescent sera and faecal extracts. The results suggest that specific IgA in intestinal secretions has an important role in immunity to cryptosporidiosis.     

Single and Low-level Oocyst Infections of Drug-resistant Field Strains of Eimeria tenella in Medicated Birds

Five out of ten birds infected with a single oocyst of strain Gt2 of Eimeria tenella and medicated with the recommended level of robenidine were found positive in the first experiment and four in the second in comparison with seven and six respectively in nonmedicated birds. Six birds out of ten were found positive in the two groups of similarly medicated birds infected with two or four oocysts each. Although single oocyst infections of strain Lilly 155 were unsuccessful, six out of ten birds were found positive in birds infected with ten oocysts each.All single and low-level oocyst infections were accomplished with oocysts previously treated with beta-glucuronidase and broken into sporocysts prior to infections.The overall results suggested that when a coccidium became resistant to an anticoccidial drug, only one or a few occysts were needed to start an infection if the drug was continued. The results also showed that, perhaps, successful single or low-level oocyst infections can also be used as a criterion for demonstrating drug resistance in coccidia.     

Studies on the stage of action of lasalocid against Eimeria tenella and Eimeria acervulina in the chicken

Broiler chickens in battery pens were either fed a diet containing 100 ppm lasalocid or no drug for 24 h prior to inoculation with sporulated oocysts of Eimeria tenella or Eimeria acervulina. Different groups of birds remained on medicated feed for 24, 48, 72, 96, 120 or 144 h after inoculation. Conversely, other groups started on an unmedicated diet, were given medicated feed at different times after oocyst inoculation. Starting lasalocid medication 24 h (E. tenella) or 48 h (E. acervulina) after inoculation reduced the lesions and improved the weight gain. There was no significant difference in performance of birds after withdrawal of the drug at 48 h (E. tenella) or 72 h (E. acervulina) and thereafter. Starting lasalocid medication at 96 or 120 h did not suppress but rather reduced oocyst production.     

Chemoprophylaxis of coccidiosis in lambs with a single oral dose of toltrazuril

The prophylactic efficacy of a single oral dose of toltrazuril against coccidiosis (mixed Eimeria infections) in naturally infected lambs was evaluated in two experiments. Toltrazuril at 20 mg kg-1, given on Day 7 or Day 10 after turnout on pasture, proved to be highly efficacious in preventing clinical coccidiosis under Norwegian conditions. Toltrazuril reduced the oocyst output to very low levels, prevented the development of diarrhoea and improved weight gain during the first 4-5 weeks after treatment. Treatment on Day 7 was superior to treatment on Day 10 with respect to improving weight gain and preventing the development of soft faeces. Lambs treated with toltrazuril on Day 7 seemed to be as immune as untreated lambs to natural reinfections with coccidia later in the grazing season. In one of the experiments, natural infections with the nematode Nematodirus battus produced a coccidiosis-like disease in some lambs simultaneously with the outbreak of coccidiosis.     

Toltrazuril and sulphonamide treatment against naturally Isospora suis infected suckling piglets: Is there an actual profit?

A study was carried out to assess the efficacy and the economic profit of prophylactic treatment against Isopsora suis with toltrazuril or with a sulfamethazine/trimethoprim combination in piglets from an intensive pig farm. Thirty-one litters were included in study. Eight litters were treated once with toltrazuril (20 mg/kg b.w.) at 3 days of age (Toltra group); 8 litters were treated with the sulphonamide combination (sodium sulfamethazine 35 mg and trimethoprim 7 mg/kg b.w.) for 3 consecutive days starting at 3 days of age (Sulfa group), and 15 litters were untreated (control group). Counts of oocyst per gram on pooled feces sampled from each litter were carried out on Days 7, 14, 21 and 28 and diarrhea was registered daily from pooled samples. Piglets were weighed on Days 1, 7 and 28 and mean weight gain (WG) and daily weight gain (DWG) were evaluated. The economic profit of treatment was evaluated comparing the WG of piglets of each treatment group from the day of birth to Day 28. On Days 14, 21 and 28, toltrazuril showed a better efficacy in controlling fecal oocyst output, diarrhea and weight gain compared with sulphamidic treatment (P < 0.001). The budgeting analysis showed a return of economic benefit of € 0.915 per toltrazuril-treated piglets and an additional cost of € 1.155 per sulphonamide-treated piglets.     

Efficacy of ionophorous anticoccidial drugs against coccidia in farm-reared pheasants (Phasianus colchicus) from Illinois

Litter samples obtained from a ring-necked pheasant propagation farm in Illinois contained coccidia: 57.5% of the oocysts were Eimeria duodenalis, 24.9% were E. tetartooimia, 8.8% were E. phasiani, and 8.8% were E. pacifica. Ionophorous anticoccidial drugs were tested for efficacy against the pheasant coccidia. All three drugs reduced oocyst production and prevented mortality in young pheasants; unmedicated infected controls had a 40% mortality rate. Monensin at 120 ppm in the feed was coccidiocidal against E. duodenalis and E. tetartooimia, partly coccidiocidal against E. pacifica, and only partly coccidiostatic against E. phasiani. Salinomycin at 60 ppm in the feed was highly efficacious and coccidiocidal against all four species, but the salinomycin-medicated pheasants gained the least of all medicated birds. Lasalocid at 120 ppm in the feed was the most effective, with nearly complete coccidiocidal activity against all four coccidial species.     

Performance and oocyst shedding in broiler chickens orally infected with Cryptosporidium baileyi and Cryptosporidium meleagridis

To study effects of experimental cryptosporidiosis, broiler chickens were infected per os with 5 x 10(5) oocysts of Cryptosporidium baileyi and Cryptosporidium meleagridis. In the first experiment, chickens were infected with oocysts of C. baileyi at the age of 7, 14, and 21 days. In the second experiment, chickens were infected with oocysts of C. baileyi, C. meleagridis, or both cryptosporidial species at the age of 7 days. Although clinical signs of infection were apparent, neither final live weight nor mortality was significanty influenced in chickens infected with a single Cryptosporidium species. In chickens infected with C. meleagridis, the growth retardation was observed in the 2-wk period after infection. The compensatory growth, however, started when the oocyst shedding had ceased. The number of oocysts in excreta specimens of chickens infected with C. meleagridis was two to three times lower than in excreta of chickens infected with C. baileyi. Chickens infected with both C. baileyi and C. meleagridis (5 x 10(5) oocysts of each) had significantly lower final live weight and worse feed efficiency than chickens of other groups. Concurrent infection did not influence individual C. baileyi or C. meleagridis oocyst shedding.     

Prophylaxis using paromomycin of natural cryptosporidial infection in neonatal kids

The chemoprophylactic effects of paromomycin sulfate against natural cryptosporidiosis in young kids were investigated. Two studies were carried out using two groups of 18 and 12 animals in two pens. In each pen, kids were allocated to treated or control groups. The treatment consisted of oral paromomycin given at 100 mg kg⁻¹ body weight day⁻¹ for 11 consecutive days from 2 days of age. All kids were weighed at 2, 6 and 10 days of age. Infection was monitored by collecting fecal samples and staining fecal smears every 3–4 days from days 4 or 5 to days 15 or 19. The results clearly showed the efficacy of paromomycin in reducing cryptosporidial oocyst output. Moreover, paromomycin prevented clinical signs and mortality.