Toxoplasma gondii seroprevalence in wild boars (Sus scrofa) in Sweden and evaluation of ELISA test performance.

Toxoplasma gondii is a zoonotic protozoan parasite, infecting a wide range of warm-blooded animals. The Swedish wild boar population is expanding and increased hunting provides its meat to a growing group of consumers. We performed a spatio-temporal investigation of T. gondii seroprevalence in Swedish wild boars. An ELISA was set up and evaluated against a commercial direct agglutination test, using Bayesian latent class analysis. The ELISA sensitivity and specificity were estimated to 79% and 85%, respectively. Of 1327 serum samples, 50% were positive. Thirty-four per cent of young wild boars and 55% of adults were positive (P < 0.001). The total seroprevalence ranged from 72% in 2005 to 38% in 2011 (P < 0.001), suggesting a declining trend. The highest seroprevalence, 65%, was recorded in South Sweden. In other regions it varied from 29% in Stockholm to 46% in East Middle Sweden.

Identity of Sarcocystis species of the water buffalo (Bubalus bubalis) and cattle (Bos taurus) and the suppression of Sarcocystis sinensis as a nomen nudum.

There are uncertainties concerning the identity and host species specificity of Sarcocystis species of the water buffalo (Bubalus bubalis) and cattle (Bos taurus). Currently, in cattle three species are recognized with known endogenous stages, viz.: S. cruzi (with canine definitive host), S. hirsuta (feline definitive host), and S. hominis (primate definitive host). Recently, a fourth Sarcocystis species with an unknown life cycle has been reported from cattle. In the water buffalo, four species of Sarcocystis have been described: S. fusiformis (feline definitive host), S. buffalonis (feline definitive host), S. levinei (canine definitive host), and S. dubeyi (definitive host unknown but not cat or dog). Besides, there are studies of Sarcocystis infections in buffalo and cattle from China with results that are difficult to interpret and validate. For example, some of the studies report transmission of Sarcocystis species between cattle and buffalo, but steps to preclude exogenous exposures were not reported. A species of the water buffalo, 'S. sinensis', was proposed at a Chinese national conference in 1990, and published as an abstract without figures and with no archived type specimens for verification. The International Code of Zoological Nomenclature Articles 9 and 10 state that "abstracts of articles, papers, posters, text of lectures, and similar material when issued primarily to participants at meetings, symposia, colloquia or congress does not constitute published work"; therefore, S. sinensis is a nomen nudum.

Performance of second-season grazing cattle following different levels of parasite control in their first grazing season.

A 3-year grazing trial was performed during 2003-2005 on a commercial steer-producing farm in Sweden to study performance of second-season grazing (SSG) cattle following different levels of parasite exposure during their first grazing season. Initially, groups of 10 first-season grazing (FSG) cattle were each year assigned to four parasite control strategies: (1) turn-out onto pasture that during the previous year was grazed by SSG cattle, followed by a mid-July move to aftermath, (2) supplementation with concentrate and roughage for 4 weeks after turn-out, (3) no treatment, or (4) anthelmintic treatment (injectable doramectin) every fourth week. All animals were set stocked, except for those in group one. Next spring and following housing the cattle were turned out for their second grazing season onto approximately 25 ha communal pasturelands as a common mob. Weighing, faecal sampling and blood collection were performed at turn-out and then every 4 weeks for the 20-week grazing season. Faecal samples were also collected on day 10 after turn-out for detection of coccidian oocysts. Antibodies to Dictyocaulus viviparus were analysed at the time of their second housing period, and when elevated levels were recorded, stored serum samples from seropositive animals were analysed retrospectively. Results showed early-season weight losses of up to 47 kg in the SSG cattle. However, faecal egg counts were generally low and there was no correlation between SSG performance and treatment history as FSG cattle. Still, cumulative egg counts were significantly higher in animals that had been treated with anthelmintic as FSG cattle but serum pepsinogen concentrations showed no significant differences and the output of Eimeria alabamensis oocysts seldom exceeded 10,000 oocysts per gram faeces. Antibodies to D. viviparus were observed from July 2004 and from June 2005 but not in 2003. In 2004 and 2005, 64% and 83% of the animals, respectively, were seropositive for D. viviparus. It is concluded that weight gain penalties resulting from different levels of parasite infections the first grazing season remained during the second grazing season in 2004 and 2005 but no differences in weight gain could be identified in SSG cattle that had experienced different parasite control measures during their first grazing season. This was under conditions where the level of pasture infectivity was low to moderate during the second grazing period. However, D. viviparus was demonstrated in SSG animals during the two last years of the study and was an important confounding factor.

A field study on the effect of some anthelmintics on cyathostomins of horses in sweden.

The objective of the study was to investigate different aspects on the efficacy of three anthelmintics on cyathostomin nematodes of Swedish horses. A faecal egg count reduction (FECR) test was performed on 26 farms. Horses were treated orally with recommended doses of ivermectin, pyrantel pamoate or fenbendazole. Faecal samples were collected on the day of deworming and 7, 14 and 21 days later. No resistance was shown against ivermectin; the FECR was constantly >99%. The effect of pyrantel was assessed as equivocal in 6 farms 14 days after treatment; the mean FECR was 99%. As many as 72% of the fenbendazole-treated groups met the criteria for resistance; the mean FECR was 86%, ranging from 56% to 100%. A re-investigation of two farms where pyrantel resistance had been suspected clearly revealed unsatisfactory efficacy of pyrantel on one of these farms; the FECR varied from 72% to 89%. Twenty-six of the horses previously dosed with pyrantel or fenbendazole, and which still excreted >/=150 eggs per gram of faeces 14 days after treatment, were dewormed with ivermectin and fenbendazole or pyrantel in order to eliminate the remaining cyathostomins. A total of 13 cyathostomin species were identified from horses that initially received fenbendazole and seven species were identified from pyrantel-treated individuals. The egg reappearance period (ERP) following treatment with ivermectin and pyrantel was investigated on two farms. The shortest ERP after ivermectin treatment was 8 weeks and after pyrantel was 5 weeks. We conclude that no substantial reversion to benzimidazole susceptibility had taken place, although these drugs have scarcely been used (<5%) in horses for the last 10 years. Pyrantel-resistant populations of cyathostomins are present on Swedish horse farms, but the overall efficacy of pyrantel is still acceptable.

Assessment of anthelmintic resistance in nematode parasites of sheep and goats owned by smallholder farmers in eastern Ethiopia.

The anthelmintic resistance status was investigated of nematode parasites of sheep and goats owned by smallholder farmers in communities that received breeding stock from a source where a high level of anthelmintic resistance has been reported. The investigation used the faecal egg count reduction technique, whereby suitable animals within each of eight separate communities were pooled to achieve the numbers required to conduct separate tests for both sheep and goats. Anthelmintics tested were albendazole (ABZ), tetramisole (TET), a combination (ABZ + TET) and ivermectin (IVM), at the manufacturers' recommended dose rates. Results showed that there was no evidence of anthelmintic resistance in nematode parasites of either sheep an goats in any community. This indicates that dilution of resistant parasites imported with introduced breeding stock, and the low selection pressure imposed by the smallholder farmers themselves, has prevented anthelmintic resistance from emerging in nematode parasites of small ruminants in these communities.

A 3-year field evaluation of pasture rotation and supplementary feeding to control parasite infection in first-season grazing cattle--effects on animal performance.

To evaluate non-chemical strategies to control pasture-borne parasites in first-season grazing (FSG) cattle, a 3-year grazing trial was conducted during 2002-2004 on naturally infected pastures on a commercial beef cattle farm in Sweden. A uniform pasture was divided in 4 equal 2 ha paddocks onto each of which 10, 5-9 months old dairy breed steer calves were allocated at turn-out in May each year. Two strategies were evaluated: (1) turn-out onto pasture which had been grazed the previous year by second-season grazing (SSG) steers, followed by a move to aftermath in mid-July (RT) and (2) supplementation with concentrate and roughage for 4 weeks from turn-out (FD). Comparisons were made with an untreated (UT), and an anthelmintic treated control group (DO). Animal parasitology and performance were monitored monthly throughout the 20 weeks grazing period. Additional sampling occasions were performed on day 9 (for coccidia) and 10 weeks after turn-out (mid-July). Due to clinical parasitic gastro-enteritis (PGE), salvage treatments were performed on all animals in group FD approximately 7 weeks after turn-out in 2003 and of three animals in group UT 5 weeks after turn-out in 2004. In 2003, the geometric mean oocyst excretion 9 days after turn-out was approximately 150,000 opg of mainly Eimeria alabamensis in group FD, and in 2004 approximately 180,000 opg in group UT. Apart from the DO group, geometric mean faecal egg counts (FEC) were between 80 and 400 epg 4 weeks after turn-out. Mean serum pepsinogen concentrations (SPC) of approximately 3.6 U tyrosine were recorded in the FD and UT groups from late August 2002. In 2003 and 2004, mean concentrations in these groups were between 4.1 and 7.2 U tyrosine 8 weeks after turn-out. By the end of the three grazing seasons the average weight gain difference compared to the DO group was for FD -29, -38 and -5 kg and for RT -4, -21 and +14 kg, and compared to the UT group -18, +2 and +22 for FD and +7, +19 and +41 kg for group RT. In conclusion, the rotation control strategy showed promising results, whereas the strategic feeding was poor from a parasite control standpoint.

Effects of single or concurrent infections with Eimeria alabamensis and gastrointestinal nematodes on the performance of calves on pasture.

Twenty-four calves unexposed to pasture were allocated to four groups and inoculated with either two doses of 5 million Eimeria alabamensis oocysts at turn-out (E), 90,000 L3 of Ostertagia ostertagi and Cooperia oncophora divided on six occasions (N) or both oocysts and larvae as above (E + N). A control group was left uninoculated (C). For 10 weeks, the groups grazed in separate uniform paddocks not previously grazed by cattle. By day 5, most calves in groups E and E + N developed clinical coccidiosis that resulted in reduced weight gain compared to C and N. Mean trichostrongylid faecal egg counts in groups N and E + N never exceeded 300 eggs per gram of faeces, and average serum pepsinogen levels were less than 3.8 U tyrosine. This experiment demonstrates the potential impact of E. alabamensis on the performance of previously unexposed calves, whereas no aggravated effects were observed due to concurrent infections with gastrointestinal nematodes.

Reindeer as hosts for nematode parasites of sheep and cattle.

The reindeer husbandry range of Scandinavia overlaps with sheep, goat, and cattle pastures. The aim of this study was to determine whether reindeer are suitable hosts for ovine or bovine nematode parasites, and thus may spread these parasites into the reindeer husbandry regions. To render worm-free, twelve 4-month-old male reindeer calves, six lambs, and six bovine calves were given ivermectin at 200 microg/kg body weight. Five weeks post-treatment, six reindeer calves were each artificially dosed with 10,000 third-stage larvae (L3) of gastrointestinal nematodes derived from sheep, and an additional six reindeer with L3 derived from cattle. Lambs and bovine calves received the same dose of ovine and bovine larvae as reindeer, from the same larval source, respectively. Faecal samples collected on five occasions after the larval dosing revealed that by the fourth week, all reindeer calves, lambs, and bovine calves were infected. Animals were slaughtered on days 40 (reindeer) or 47 (lambs and bovine calves) after the larval dosing. Reindeer calves were most susceptible to L3 derived from sheep. The overall mean intensity of Haemochus contortus, Trichostrongylus axei, and Teladorsagia circumcincta, did not differ between reindeer and sheep; however, early fourth-stage larvae of H. contortus were more abundant in reindeer (p = 0.002). The establishment of bovine-derived Ostertagia ostertagi was similar in reindeer (62%) and bovine calves (57%), but larval inhibition was much higher in reindeer (91%, p < 0.001) than in cattle (31%). Very poor establishment of bovine derived Cooperia oncophora was recorded in reindeer calves (2%) compared with bovine calves (59%). These results show that young reindeer are susceptible hosts to the important gastrointestinal parasites of sheep (T. circumcincta, H. contortus) and cattle (O. ostertagi), as well as being a suitable host for T. axei.

Isolation of Neospora caninum from a calf in Malaysia.

In order to attempt isolate the protozoan parasite Neospora caninum, an N. caninum seropositive pregnant Sahiwal Friesian cross heifer from a large-scale dairy farm in Malaysia was kept for observation until parturition at the Veterinary Research Institute, Ipoh. The heifer gave birth to a female calf that was weak, underweight and unable to rise. Precolostral serum from the calf had an N. caninum indirect fluorescent antibody test titre of 1:3200. It died 12 h after birth and necropsy was performed. Brain homogenate from the calf was inoculated into 10 BALB/c mice that were kept for 3 months after which brain tissue from the mice was inoculated onto 24 h fresh monolayer Vero cell lines. The cell cultures were examined daily until growth of intracellular protozoa was observed. DNA of the organisms from the cell cultures was analyzed by PCR and DNA sequencing. DNA fragments of the expected size were amplified from the isolate using N. caninum-specific primers, and sequence analysis of ITS1 clearly identified the isolate as N. caninum. This is the first successful isolation of N. caninum from a bovine in Malaysia, and the isolate is designated Nc-MalB1.

Toxoplasma gondii and Neospora caninum serological status of different canine populations from Uberlândia, Minas Gerais

Este trabalho teve como objetivo analisar a ocorrência de anticorpos contra Toxoplasma gondii e Neospora caninum em cães da cidade de Uberlândia, MG. As taxas de reatividade sorológica dos animais frente a esses parasitos foram comparadas em relação à sua origem e condições de vida. Um total de 369 amostras de soro canino foi obtido de três grupos de cães: (A) 213 pacientes do Hospital Veterinário da Universidade Federal de Uberlândia, (B) 62 pacientes de clínicas veterinárias particulares da cidade e (C) 94 cães errantes da cidade. As amostras foram analisadas para a presença de anticorpos contra os parasitos por meio de ELISA. Os resultados mostraram soropositividades de 30,3 por cento para T. gondii, 9,2 por cento para N. caninum e 5,7 por cento para ambos os parasitos. O grupo de cães errantes apresentou maior taxa de prevalência de anticorpos para os dois parasitos estudados. Pode-se concluir que as taxas de soropositividades para T. gondii e N. caninum nas populações caninas estudadas parecem ser fortemente influenciadas por suas origens e condições de vida.

Expulsion of small strongyle nematodes (cyathostomin spp) following deworming of horses on a stud farm in Sweden.

This study was conducted on a stud farm in Sweden to investigate the species composition of cyathostomins expelled in the faeces of horses after deworming using three different anthelmintic preparations. Twenty-seven horses excreting > or = 200 strongyle eggs per gram faeces (EPG) were divided into three comparable groups and dewormed on day 0 with either of following compounds: 0.2 mg ivermectin per kg body weight (bw), 19 mg pyrantel pamoate per kg bw or 7.5 mg fenbendazole per kg bw. For each of the 3 days following anthelmintic treatment faeces was collected from individual horses and subsamples were fixed in formalin. Four days after the anthelmintic treatment all horses were re-treated with ivermectin and faeces was collected on day 5. Individual subsamples from each of the four sampling occasions were examined for cyathostomin nematodes. Sixty-three to 270 worms per horse were identified to the species level. The majority of the worms recovered were expelled during the first day from horses treated with ivermectin or pyrantel pamoate, and during the second day from horses treated with fenbendazole. Fifteen cyathostomin species were identified and the six most prevalent were Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, Cylicocyclus leptostomus, Cylicostephanus minutus and Cylicostephanus calicatus. These species composed 91% of the total burden of cyathostomins. The number of species found per horse ranged from 6 to 13, with an average of 9. No significant differences in species composition or distribution were found between the treatment groups. On day 5, i.e. 1 day after the last ivermectin treatment, 93% of the adult worms were recovered from horses in the fenbendazole group. This study showed that it was possible to identify cyathostomins expelled in faeces of dewormed horses, and that the most prevalent species corresponded to those found in autopsy surveys performed in other countries.

Redescription of Neospora caninum and its differentiation from related coccidia.

Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.

Seroprevalences of Toxoplasma gondii and Neospora caninum in Swedish red foxes (Vulpes vulpes).

The prevalences of antibodies to the protozoan parasites Toxoplasma gondii and Neospora caninum were investigated by the direct agglutination test (DAT) and ELISA, respectively, in 221 red foxes (Vulpes vulpes) from different parts of Sweden. A total of 84 (38%) of the analysed sera had antibodies to T. gondii, but none of the foxes had antibodies to N. caninum. The results indicate that T. gondii infection is fairly common in Swedish red foxes and that the infection is present in most parts of the country. They also show that N. caninum is not widespread as a latent infection among red foxes in Sweden.

Sporulation of Eimeria maxima oocysts in litter with different moisture contents.

The aim of this study was to determine if the sporulation of Eimeria maxima oocysts was affected by the moisture content of the litter. Fresh feces were collected from chickens experimentally infected with E. maxima. The feces were mixed with dried wood shavings and different amounts of water to obtain final moisture contents of 16, 42, and 62% and a final oocyst concentration of 5,000 per g of mixture. The samples were kept at 23 C and 75% relative humidity and were thoroughly aerated every 12 h. Oocysts kept under ordinary laboratory sporulation conditions in 2% wt/vol aqueous potassium dichromate at 27 C were used as a standard for optimal sporulation. The proportion of sporulated oocysts was determined microscopically every 12 h. Sporulation of E. maxima was most efficient under the driest conditions studied (16% moisture content), and poorest in the samples with the highest moisture content (62%). Even though the differences may not have resulted from a direct effect of humidity on the oocysts, but more likely resulted from limited oxygen in the moister substrates, it is clear that sporulation is not favored by moist litter.

Prevalence of Pneumonyssoides caninum infection in dogs in Sweden.

A prospective study of 474 dogs, 145 cats, and 66 wild red foxes submitted for necropsy to the Departments of Pathology at the National Veterinary Institute and the Swedish University of Agricultural Sciences, Uppsala, Sweden, was conducted to examine for the presence of Pneumonyssoides caninum, the canine nasal mite. Pneumonyssoides caninum (P. caninum) was found in 95 (20%) of the dogs but in none of the cats or foxes. The median number of P. caninum mites per infected dog was 13 (range, 1 to 250). Dogs older than 3 years of age were more often infected with P. caninum than younger dogs, and large-breed dogs were more often infected than small-breed dogs. No sex predisposition was found.

Eimeria infections in litter-based, high stocking density systems for loose-housed laying hens in Sweden.

1. Coccidiosis, caused by different Eimeria species, is believed to be a more prominent problem in loose-housed layers kept on litter than in battery cages. In this study, the impact and development of Eimeria infections were investigated in layers kept in litter-based, high stocking density systems for loose-housed hens. 2. Layers from 57 flocks on 26 farms were followed by necropsy of a representative sample of birds that died or had to be culled. Coccidiosis was diagnosed in 11 flocks (19.3%) from 9 (31%) of the farms. The outbreaks occurred when the birds were 19 to 32 weeks old. E. maxima was identified in 6 and E. tenella in 3 of the outbreaks. 3. Sixteen of the flocks were also monitored with faecal and litter samples collected at regular intervals. Oocysts were detected in samples from all these flocks. The pattern of oocyst excretion was similar in most of the flocks, with maximum counts at 4 to 8 weeks after introduction to the laying house. There was no significant correlation between the levels of oocysts in faeces and clinical coccidiosis. 4. Raising pullets without any coccidiostat, to increase their chance to develop immunity against coccidia, was not found to decrease the risk of coccidiosis during the production period when compared to the practice of giving amprolium and ethopabate during the rearing period.

Intestinal digesta viscosity decreases during coccidial infection in broilers.

1. The effect of intestinal digesta viscosity on bird performance in chickens with coccidiosis was compared to those without coccidiosis. 2. Six hundred chicks were divided into five groups: one control group was fed a basal maize/soyabean-based diet and the other groups were fed the basal diet supplemented with 2, 4, 6 or 8 g carboxymethyl cellulose (CMC) per kg of feed. At 14 d of age half the birds were individually inoculated with sporulated oocysts of Eimeria acervulina and Eimeria praecox. 3. Intestinal digesta viscosity increased with increasing inclusion of CMC. This effect was considerably less pronounced in inoculated than in non-inoculated birds. 4. There was a significant negative effect on live weight gain and feed conversion ratio (FCR) with increasing CMC inclusion in non-inoculated birds, but in inoculated birds there was no clear relation between CMC inclusion and performance. Neither intestinal lesion scores, nor numbers of Clostridium pefringens in the caeca, were significantly affected by CMC inclusion. 5. Across all diets inoculation impaired growth rate by 9% and FCR by 8%, but did not affect the amount of C. perfringens in the caeca.

Serological investigation of an outbreak of Neospora caninum-associated abortion in a dairy herd in southeastern United States.

An outbreak of Neospora caninum-associated abortion occurred in a South Carolina dairy wherein greater than 10% of the herd aborted over a 4-month period. Of the total number of cows at mid-late gestation, nearly 40% (28/71) aborted while the remaining 60% (43/71) gave birth to normal calves. Immunohistochemical examination of brain tissue from a subset of aborted fetuses confirmed N. caninum as the causative agent of abortion in these animals. A variety of serological assays, including indirect fluorescence antibody test (IFAT), recombinant enzyme-linked immunosorbent assay (rELISA), ISCOM-ELISA, avidity ELISA, and Neospora agglutination test (NAT), were used to evaluate sera collected during the outbreak from 240 cows for antibodies to N. caninum. IFAT and ISCOM-ELISA testing showed that nearly 80% of the dairy cows had antibodies to N. caninum. NAT and rELISA had similar levels of seropositivity relative to IFAT and ISCOM-ELISA, but the percentage of positive sera was dependent on the cut-off value chosen. As indicated by kappa coefficient statistical analysis, ISCOM-ELISA and IFAT exhibited the highest level of agreement in identifying N. caninum-positive and -negative cows. A decrease in the percentage of seropositive cows as determined by ISCOM-ELISA and IFAT with increasing cow age was noted. However, no significant difference was observed between cow age and abortion status. In addition to these tests, an avidity ELISA was performed on all sera with high (> or =0.4) ISCOM-ELISA readings. Avidity index (AI) increased with time post-abortion suggesting that most abortions were due to recent N. caninum infection. Of the cows at risk for abortion, the mean serological AI of aborting cows was significantly lower (P<0.05) than mean serological AI of non-aborting cows.

Redescription of Parafilaria bovicola Tubangui, 1934 (Nematoda: Filarioidea) from Swedish cattle.

Parafilaria bovicola was introduced into Sweden and identified for the first time in Swedish cattle in 1978. Since then the parasite has become well established and has been responsible for substantial economic losses in Swedish beef production. Although studies have been undertaken on serodiagnosis, life cycle, vector and geographical distribution within Sweden this is the first full description of P. bovicola from Swedish cattle and the first study to use scanning electron microscopy. P. bulgarica Daskalov, 1944 is regarded as a synonym of P. bovicola Tubangui, 1934. Tooth-like thickenings described on the anterior lobes of the oesophagus for the first time may assist the parasite in its migration through the host tissues.

Neospora caninum and bovine virus diarrhoea virus infections in Swedish dairy cows in relation to abortion.

The protozoan parasite Neospora caninum and bovine virus diarrhoea virus (BVDV) are recognized as important causes of bovine abortion and congenital disease worldwide. In this study, serological investigations were performed to estimate the prevalence of N. caninum infection in Swedish dairy cattle, to assess to what extent it may affect abortion rates, and to determine possible effects of coinfection with BVDV. The overall N. caninum seroprevalence in Swedish dairy cows was estimated at 2% (16/780), and the BVDV seroprevalence was 32% (249/780). Among aborting cows from herds with abortion problems, 7% (26/378) had antibodies to N. caninum and 42% (153/378) to BVDV. Seventeen of the N. caninum positive animals also had antibodies to BVDV. There was a statistically significant (P = 0.013) association between presence of antibodies to N. caninum and BVDV. In a case-control study comprising sera from cows in herds without recognized abortion problems, 6% (5/89) and 1% (1/89) of sera from aborting and non-aborting cows, respectively, had antibodies to N. caninum. Two of the N. caninum seropositive aborting cows also had antibodies to BVDV. These results confirm that N. caninum infection is associated with bovine abortion in Sweden and also indicate that there might be concurrent effects of N. caninum and BVDV. It is concluded that Swedish dairy cows have a low prevalence of N. caninum infection which is favourable in relation to possible future control programmes.