Transmission of intestinal helminths in Danish sow herds.

Faecal samples from sows and their litters, all untreated with anthelmintics, were examined in eight sow herds, ranging from very intensive to very traditional management. Four helminth genera were recorded, namely Oesophagostomum sp., Ascaris suum, Trichuris suis and Strongyloides ransomi. The herds with the most intensive management were only infected with A. suum, while the more traditionally managed herds were infected with three or four species. In one herd, the sows showed a small relative increase in the excretion of Oesophagostomum eggs during lactation, but in general there was no consistently observable peri-parturient increase in faecal egg output. Furthermore, faecal examination of 5-12-week-old pigs indicated that sow-to-piglet transmission was important in the traditionally managed herds, while it was negligible in the intensive herds. A seasonal variation in the excretion of Oesophagostomum sp. and A. suum eggs was observed in the youngest pigs in the traditional herds, with the highest faecal egg counts occurring in the summer and autumn. However, this pattern became indistinct during the fattening period and did not exist in the sows, except for A. suum infections in the heavily infected traditional herds. The helminths egg excretion in the intensive herds did not show any seasonal variation.     

Anthelmintic resistance in cattle nematode in the western Pampeana Region of Argentina

During the past three years there have been several reports of cattle anthelmintic resistance (AR) in Argentina. Twenty-five cattle herds in the west fattening area of the Pampeana Region were surveyed to assess the prevalence of AR and the species of nematode involved. The survey involved fattening and cow-calf systems with a mean of 6760 bovines. Resistance was determined in vivo by a faecal egg count reduction test (FECRT). Efficacies from the World Association for the Advancement of Veterinary Parasitology (WAAVP) formula were compared with those obtained from the Abbott formula. Sixty 6-12-month-old calves were selected from each property and divided into four groups, namely, IVM (ivermectin, 0.2mg/kg), BZD (fenbendazole, 5mg/kg or albendazole 7.5mg/kg), LVM (levamisole, 7.5mg/kg) and Control (untreated group). Nematode larvae were identified by four pooled faecal cultures for each group. Cooperia and Ostertagia were the predominant nematode larvae in pre-treatment cultures. The mean FECRT efficacies for IVM, BZD and LVM were 81.0+/-21%, 93.3+/-8% and 97.6+/-4%, respectively. AR was detected in 16 (64%) herds. IVM resistance was present in 15 herds and BZD resistance in eight herds (32%). Resistance to both ivermectin and fenbendazole was present in seven herds. LVM resistance was not detected. Cooperia was the predominant post-treatment nematode in all the herds with IVM resistance. In one herd with IVM resistance, Ostertagia counts were slightly increased over pretreatment counts. Ostertagia was the prevalent post-treatment genera in herds with BZD resistance. A high level of resistance to ivermectin was recorded in this fattening region of Argentina. Also several herds with resistance to benzimidazole were observed. These results show the importance of AR in Argentinian cattle production. High correlation between WAAVP and Abbott formulae was observed. However, under some uncertain diagnosis, both formulae could be applied as complementary to help result interpretations.     

Field evaluation of the efficacy of fenbendazole in captive wild ruminants

The efficacy of in-feed fenbendazole at a dose rate of 7.5 mg/kg bodyweight for three consecutive days was assessed in five Arabian oryx (Oryx leucoryx), six scimitar-horned oryx (Oryx dammah), 14 slender-horned gazelles (Gazella leptoceros), eight Soay sheep (Ovis aries aries soay), 13 alpine ibex (Capra ibex ibex), six red deer (Cervus elaphus hippelaphus) and 11 Nelson's elk (Cervus elaphus nelsoni) kept in five herds in a zoo. The efficacy was assessed by means of repeated faecal egg count reduction (fecr) tests and in vitro egg hatch assays. Fenbendazole was highly effective against nematodes in five of the seven species, consistently reducing egg shedding by more than 90 per cent. In the egg hatch assays of the five herds, 50 per cent inhibition of hatching (ld50) was observed at a concentration of thiabendazole below 0.1 microg/ml. In the Arabian oryx and alpine ibex the efficacy of fenbendazole was less than 90 per cent, and the ld50 in the egg hatch assays was between 0.1 and 0.2 microg/ml thiabendazole.     

A 12-month survey of the gastro-intestinal helminths of antelopes, gazelles and giraffids kept at two zoos in Belgium

Faecal egg count patterns and clinical signs associated with gastro-intestinal (GI) nematodes of 107 zoo ruminants were monitored at fortnightly intervals for 1 year. The ruminants in this study were kept under different husbandry conditions at two sites of the Royal Zoological Society of Antwerp, the Antwerp Zoo and the Animal Park Planckendael. Artiodactylids involved were Arabian oryx (Oryx leucoryx), scimitar-horned oryx (Oryx dammah), bongos (Tragelaphus euryceros isaaci), sitatungas (Tragelaphus spekii gratus), common eland (Taurotragus oryx), impala (Aepyceros melampus), slender-horned gazelles, (Gazella leptoceros), blue wildebeest (Connochaetes taurinus taurinus), Kordofan giraffes (Giraffe camelopardalis antiquorum) and okapi (Okapia johnstoni). Nematode eggs were recovered from 586 of 1606 (36.5%) individual faecal samples, using flotation techniques. Infection levels were distinctly low at Antwerp Zoo, probably due to zero grazing and daily dung removal. At Planckendael, the herds of Arabian oryx, scimitar-horned oryx and slender-horned gazelles showed markedly higher egg counts than the other herds, with more than 10% of the faecal egg counts having more than 100 eggs per gram (epg) and maximum faecal egg counts of 600, 750 and 1350 epg, respectively. Faecal egg counts increased during the mid-grazing season (July) and peaked at the end of the grazing season (October). No clinical signs, such as loss of faecal consistency, could be correlated with faecal egg counts (P > 0.05). With the exception of significantly more Nematodirus spp. eggs that were present in juvenile eland, no differences in faecal egg counts could be found between the sexes and different age groups. Abomasa and intestines of 17 animals that died during the survey were available for total worm counts. In one Arabian oryx, four slender-horned gazelles and one sitatunga low burdens ranging from 200 to 14,300 were found. Nematode species recovered were Camelostrongylus mentulatus from the abomasa and Trichostrongylus retortaeformis, Nematodirus fillicollis, Capillaria spp. and Trichuris spp. from the intestines. Our findings suggest different nematode infection levels between herds, which are mainly due to husbandry conditions but to a lesser extent to species- or individual susceptibility. Identification of ungulates that are highly infected and knowledge of the seasonal variation of their helminths can contribute greatly to a well-adjusted species-specific management and helminth control program.     

Prevalence of cattle herds with ivermectin resistant nematodes in the hot sub-humid tropics of Mexico

The objective was to determine the prevalence of semi-intensive Bos indicus and Bos indicus × Bos taurus cattle herds with ivermectin (IVM) resistant nematodes in a sub-humid tropical zone of Mexico using the faecal egg count reduction test (FECRT). Thirty-three herds (28 beef and 5 dual purpose herds) were monitored in a period of 6 months (September 2008 to February, 2009). Only 14 of the 33 herds were included in the trial. The other herds had not enough animals with sufficient nematode eggs per gram of faeces (EPG) to be included in a FECRT. Some farms were visited twice trying to find more animals with egg counts higher than 150 EPG. In the 14 surveyed herds the calves were randomly distributed into two groups: (a) treatment group received 0.2mg of IVM/kg BW sc on day 0, and (b) control group without treatment. Faecal samples were obtained from each animal on days 0 and 14 post-treatment. Reduction percentages (% R) and 95% CI were calculated. The prevalence of cattle herds with IVM resistant nematodes was 78.6%. Those suspected of IVM resistance were 21.4%. All surveyed herds used IVM from two to three times a year (mainly beginning and end of the wet season) during 1-11 consecutive years. The farm with stronger resistance used IVM for 11 consecutive years (% R=0%; 95% CI=0-47%). Genera of nematodes resistant to IVM were: Ostertagia, Haemonchus, Cooperia and Trichostrongylus. A considerable effort is needed to perform FECRT in cattle herds under hot sub-humid tropical conditions.     

Helminths in horses: use of selective treatment for the control of strongyles

The current level of anthelmintic resistance in the horse-breeding industry is extremely high and therefore more emphasis is being placed on studies that focus on the judicious use of anthelmintic products. The aims of the study were to: 1) establish if there is variation in the egg excretion pattern of strongyles between the different age classes of Thoroughbred horses in the Western Cape Province (WCP), 2) test if a selective treatment approach successfully reduces the number of anthelmintic treatments and maintains acceptably low helminth burdens in adult Thoroughbred horses, and 3) evaluate the efficacy of subsampling large horse herds for faecal egg counts (FECs) to monitor the strongyle burden. In 2001 the FECs of 4 adult mare, 5 yearling and 3 weanling herds from 8 different farms were compared in the WCP Within the mare herds there were generally fewer egg-excreting individuals with lower mean FECs compared with the younger age classes. Individual faecal samples were collected every 3-4 weeks from 52 adult Thoroughbred mares from 1 farm in the WCP during a 12-month period (2002/2003). Animals with strongyle FECs > or =100 eggs per gram (epg ) were treated with an ivermectin-praziquantel combination drug (Equimax oral paste, Virbac). The mean monthly strongyle FEC for the entire group was <300 epg throughout the study and the number of treatments was reduced by 50 %. Resampling methods showed that an asymptote to mean FEC was reached at 55 animals for each of the pooled weanling, yearling and mare egg counts. Resampling within 4 different mare herds recorded asymptotes of between 24 and 28 animals. Subsampling entire herds for FECs therefore provided an effective approach to treatment management. This study demonstrates that selective treatment is both a practical and an effective approach to the management of anthelmintic resistance.     

Efficacy of 3 anthelmintics in communally grazed sheep as reflected by faecal egg count reduction tests in a semi-arid area of South Africa

A survey was conducted on the occurrence of anthelmintic resistance of nematodes in communally grazed sheep in a semi-arid area near Mafikeng, South Africa, from January to March 2006. In the herds belonging to twelve smallholder sheep farmers, the efficacies of albendazole, levamisole and closantel were tested by faecal egg count reduction tests where 80 % efficacy was considered the cut off for anthelmintic resistance. The results of the faecal egg count reduction tests showed more than 80% efficacy with all the drugs used in most cases, but there were notable exceptions. In 1 case, closantel had an efficacy of 72%, albendazole had an efficacy of 68% and levamisole showed efficacies of 58%, 60% and 75% respectively on 4 farms. The occurrence of anthelmintic resistance in this farming sector is of concern and steps should be taken to prevent its further spread and development to avoid a situation developing as on numerous commercial sheep farms in South Africa where resistance is common.     

Resistance to thiabendazole, fenbendazole and levamisole in Haemonchus and Trichostrongylus species in sheep on a Kenyan farm

Resistance to thiabendazole (TBZ), fenbendazole (FBZ) and levamisole (LVM) in naturally acquired gastrointestinal nematode parasites in sheep was investigated on a farm where anthelmintic resistance was suspected. This was measured by both the in vitro egg hatch assay, and reductions in faecal egg and worm counts in treated animals. In the egg hatch assay, nematode eggs were incubated in various concentrations of either TBZ or LVM. The level of resistance was expressed as the drug concentration inhibiting 50% of the eggs from hatching (LC50). The nematode population had LC50 values of 0.26 microgram ml-1 TBZ and 3.12 micrograms ml-1 LVM. In the faecal egg and worm count reduction test, naturally infected sheep were treated with either TBZ (88 mg kg-1), FBZ (10 mg kg-1) or LVM (15 mg kg-1). Faecal egg and total worm counts from these sheep were then compared with counts from untreated sheep. TBZ, FBZ and LVM failed to reduce the faecal egg counts and total worm counts by more than 90%. Based on the identification of larvae from faecal cultures, the most predominant nematode species in the resistant population were Haemonchus (62%) and Trichostrongylus (28%). TBZ reduced faecal egg counts for both species by less than 90%. FBZ and LVM also reduced Haemonchus spp. eggs by less than 90%. Other nematode species numbers did not satisfy criteria for the determination of efficacy.     

Comparative sensitivity of various faecal culture methods and ELISA in dairy cattle herds with endemic Johne's disease

In three New South Wales dairy cattle herds with endemic Johne's disease, prevalence rates by faecal culture were determined to be 12, 18 and 22%, respectively. Whole herd faecal culture was shown to detect markedly more infected cattle than whole herd testing by the EMAI absorbed ELISA, particularly in the two herds with greatest prevalence. In the three study herds, five methods for whole herd faecal culture were compared in each. These included two methods based on primary culture on Herrold's egg yolk medium with mycobactin J (HEYM): (1) conventional decontamination with sedimentation and primary culture on HEYM; (2) Whitlock decontamination and culture on HEYM. The remaining three methods were based on radiometric (BACTEC) culture: (3) decontamination and filtration to BACTEC medium; (4) modified Whitlock decontamination to BACTEC medium and (5) Whitlock decontamination to BACTEC medium. For BACTEC cultures, two methods were compared as confirmatory tests for Mycobacterium paratuberculosis: mycobactin dependence on conventional subculture to HEYM and IS900 PCR analysis of radiometric media.Among 179 cattle tested simultaneously by all five culture methods, 38 cattle were confirmed to be shedding M. paratuberculosis. In identifying shedder cattle, method 5 was the most sensitive, followed by methods 2, 4, 1, and 3 was the least sensitive. The number of BACTEC cultures confirmed by mycobactin dependence or PCR was similar.     

Repeated treatment faecal egg counts to identify gastrointestinal nematode resistance in a context of low-level infection of sheep on farms in eastern Algeria

The efficacy of benzimidazoles and ivermectin was tested in 14 pilot farms in eastern Algeria. Resistance was detected in strongyle nematodes against benzimidazoles (five farms) and ivermectin (one farm). The main genera in the region were resistant: Teladorsagia, Trichostrongylus, Marshallagia and Nematodirus. The evaluations based on FECRT (faecal egg count reduction tests) were not always consistent due to the low-level of infection, and we developed a simplified, repeated treatment strategy to investigate resistance. The results obtained with repeated treatment faecal egg counts match globally those obtained with conventional faecal egg count reduction tests. This simplified, repeated treatment method should be investigated further since it is quicker, and this could make it possible to test larger farm samplings.     

Detectability and prevalence of Brachyspira species in herds rearing health class feeder pigs in Finland

Faeces samples were taken three times at two-week intervals, from the farrowing units of four herds of known Brachyspira (formerly Serpulina) status and one of unknown Brachyspira status. Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira intermedia and Brachyspira group III were isolated from the faecal samples from the weaners in the herds using either a maximum of 50 ppm of olaquindox or no feed additives. The detection rates were relatively consistent. However, B hyodysenteriae was not detected at one sampling in a known positive herd. The prevalence of Brachyspira species was also studied in feeder pigs originating from LSO 2000 health class farrowing units, comparable with specific pathogen-free herds. These farms were free from swine dysentery, sarcoptic mange, swine enzootic pneumonia and progressive atrophic rhinitis. Fifty of 428 herds were sampled once. B hyodysenteriae was not isolated from any of them, but B intermedia, B pilosicoli and Brachyspira group III were isolated from five, 14 and 37 of the herds, respectively. The detection of Brachyspira species did not relate to the prevalence of diarrhoea in the herds, as judged by the farmers. The herds using carbadox (40 to 50 ppm) had a lower prevalence of Brachyspira species than those using olaquindox (40 to 50 ppm).     

Anthelmintic resistance of nematodes in communally grazed goats in a semi-arid area of South Africa

A survey was conducted on the occurrence of anthelmintic resistance of nematodes in communally grazed goats in a semi-arid area in South Africa. In herds belonging to 10 small-holder goat farmers, the efficacies of fenbendazole, levamisole and rafoxanide were tested by faecal egg count reduction (FECR) tests. Efficacies of 80% were considered a threshold for anthelmintic resistance. The FECR tests showed that all drugs tested more than 80% effective in most instances, but there were notable exceptions. In 1 case, rafoxanide was only 31% effective and in another case fenbendazole was only 47% effective. The occurrence of anthelmintic resistance in this farming sector is of concern. Steps should be taken to prevent its further spread and to avoid the development of a situation as on numerous commercial sheep farms in South Africa where resistance is very common.     

Evaluation of test-strategies for estimating probability of low prevalence of paratuberculosis in Danish dairy herds

Paratuberculosis is a chronic infection affecting cattle and other ruminants. In the dairy industry, losses due to paratuberculosis can be substantial in infected herds and several countries have implemented national programmes based on herd-classification to manage the disease. The aim of this study was to develop a method to estimate the probability of low within-herd prevalence of paratuberculosis for Danish dairy herds. A stochastic simulation model was developed using the R^® programming environment. Features of this model included: use of age-specific estimates of test-sensitivity and specificity; use of a distribution of observed values (rather than a fixed, low value) for design prevalence; and estimates of the probability of low prevalence (Pr_Low) based on a specific number of test-positive animals, rather than for a result less than or equal to a specified cut-point number of reactors.

Using this model, five herd-testing strategies were evaluated: (1) milk-ELISA on all lactating cows; (2) milk-ELISA on lactating cows ≤4 years old; (3) milk-ELISA on lactating cows >4 years old; (4) faecal culture on all lactating cows; and (5) milk-ELISA plus faecal culture in series on all lactating cows.

The five testing strategies were evaluated using observed milk-ELISA results from 19 Danish dairy herds as well as for simulated results from the same herds assuming that they were uninfected.

Whole-herd milk-ELISA was the preferred strategy, and considered the most cost-effective strategy of the five alternatives. The five strategies were all efficient in detecting infection, i.e. estimating a low Pr_Low in infected herds, however, Pr_Low estimates for milk-ELISA on age-cohorts were too low in simulated uninfected herds and the strategies involving faecal culture were too expensive to be of practical interest. For simulated uninfected herds, whole-herd milk-ELISA resulted in median Pr_Low values >0.9 for most herds, depending on herd size and age-structure. None of the strategies provided enough power to establish a high Pr_Low in smaller herds, or herds with a younger age-structure. Despite this, it appears as if the method is a useful approach for herd-classification for most herds in the Danish dairy industry.     

Doramectin resistance in Haemonchus contortus on an alpaca farm in Belgium

Parasitism by gastrointestinal nematodes is a health concern in New World Camelids (NWC) worldwide, and anthelmintic treatment is often needed for parasite control. Although anthelmintic resistance has been reported in ruminants worldwide, data in NWC are only scarce. In the present study, a case of suspected doramectin resistance in alpacas was examined. A field efficacy study was conducted for the evaluation of two different dosages of doramectin using a faecal egg count reduction test. A group of 8 alpacas was treated with a subcutaneous injection of doramectin at 0.2mg/kg bodyweight. Individual faecal samples were collected before treatment and 7 days after treatment. The faecal egg counts indicated a treatment efficacy of only 68%. To determine whether the treatment failure was caused by true anthelmintic resistance or suboptimal dosage in this animal species, a group of 4 alpacas was subsequently treated at 0.3mg/kg bodyweight. Faecal egg counts 7 days post treatment were reduced by only 41%, indicating that the treatment failure was more likely to be caused by the presence of resistant parasites on this farm. Coprocultures of faecal samples collected after treatment indicated the presence of 98.5% Haemonchus contortus and a small percentage of Cooperia oncophora (<1.5%). A controlled efficacy trial in sheep, for which the optimal dosage of doramectin is known, was conducted to ensure that this truly was a case of resistant parasites. Infective larvae collected from the faeces of these alpacas were used to infect eight nematode-free lambs. These lambs were assigned to one of two groups based on faecal egg counts post infection. One group was treated with doramectin injectable at 0.2mg/kg bodyweight, the other group served as a non treated control group. Pharmacokinetics indicated that the doramectin treatment was adequate, yet an efficacy of only 16% was determined on day 7 after treatment. Identification of the larvae after treatment revealed 100% H. contortus. On day 7 after treatment, H. contortus worm counts were only reduced by 8% in the treated lambs. The results of the present study report for the first time a case of doramectin resistance in alpacas, mainly in H. contortus.     

Cases of reduced cyathostomin egg-reappearance period and failure of Parascaris equorum egg count reduction following ivermectin treatment as well as survey on pyrantel efficacy on German horse farms

In 2003 and 2004, on a total of 63 different German horse farms, a survey using the faecal egg count reduction (FECR) test was performed to investigate the efficacy of ivermectin (IVM, Ivomec) and pyrantel (PYR, Banminth) treatment against gastro-intestinal nematodes in a total of 767 horses. IVM treatment resulted in 100% reduction of the cyathostomin egg production 14 and 21 days post-treatment (d.p.t.) on 37 farms. On the remaining five farms, the mean faecal egg count reduction ranged between 97.7 and 99.9%. The mean cyathostomin FECR following PYR treatment ranged between 92.2 and 100% on the 25 farms tested. Therefore, based on the 90% FECR threshold suggested for detection of anthelmintic resistance in horses, neither IVM nor PYR anthelmintic resistance was detected. However, if the thresholds recommended for the detection of resistance in small ruminants were applied, on one and four farms signs of reduced IVM and PYR efficacy, respectively, were observed. In 2005, to further investigate these findings, the cyathostomin egg-reappearance period (ERP) following IVM treatment was examined on six selected farms, two of which were found to show less than 99.8% FECR in the previous survey. On these two latter farms, the ERP was less than 5 weeks, while on the other four it was at least 8 weeks. Earlier investigations described IVM cyathostomin ERP of at least 9 weeks. The efficacy of IVM to reduce Parascaris equorum egg excretion was also studied. On one farm in 2 consecutive years, IVM treatment did not lead to a significant reduction in P. equorum faecal egg counts in one and five young horses, respectively.     

Multiple anthelmintic resistance and the possible contributory factors in Beetal goats in an irrigated area (Pakistan)

This paper presents the first report of multiple anthelmintic resistance in the gastrointestinal nematodes of goats and its possible contributory factors in an irrigated area (Pakistan). A total of 18 privately owned Beetal goat flocks were selected in order to determine the anthelmintic resistance against commonly used anthelmintics. Forty to 48 animals from each flock were selected according to their weight and egg count. The three anthelmintics viz., oxfendazole, levamisole and ivermectin, were given to three groups at manufacturer’s recommended dose while one group was kept as untreated control. Anthelmintic resistance was determined through faecal egg count reduction and egg hatch tests while assessment of the contributory factors of anthelmintic resistance was measured through the rural participatory approach. Faecal egg count reduction test revealed high prevalence of anthelmintic resistance (83.3%) and it was either single (levamisole) or multiple (oxfendazole and levamisole). Egg hatch test confirmed the resistance against oxfendazole as detected with faecal egg count reduction test. None of the goat flocks was resistant to ivermectin. Copro-cultures revealed that Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta were the most common species exhibiting resistance to levamisole and oxfendazole. Step-wise logistic regression of the data on worm control practices revealed significant role of under-dosing, low-protein diets, healthcare supervision by the traditional healers and mass treatments.     

Resistance of Oesophagostomum spp. in pigs to pyrantel citrate

This study was undertaken to determine whether anthelmintic-resistant Oesophagostomum spp. populations occur in Danish swine herds. A controlled field trial on selected sow herds suggested resistance to pyrantel citrate in a herd where faecal egg count depression in response to treatment was only 28.3%. This was confirmed by subsequent experimental infection of pigs where the suspected resistant Oesophagostomum isolate was compared with a susceptible worm isolate. After treatment with the recommended dose of the drug, worm burdens of the suspected isolate were only reduced by 42.6% (p greater than 0.05) in contrast to the susceptible isolate, which was reduced by 94.6% (p less than 0.01). Differential counts of the resistant isolate suggested that O. dentatum might be more resistant than O. quadrispinulatum. The resistant isolate originated from a herd, where the anthelmintic had been administered four times a year over a period of 7 years. The potential for development of anthelmintic resistance in Oesophagostomum spp. under management practices in our country is discussed in the light of the current views on predisposing factors.     

Seroprevalence and antibiotic sensitivity of serotypes of Salmonella enterica in Greek pig herds

Blood samples were taken from 50 pigs in each of 59 farrow-to-finish production herds and from 40 pigs in each of four of five registered multiplying herds. Samples of feed and faeces were also collected from 17 of the production herds and from the four multiplying herds. The sera were tested for antibodies to Salmonella enterica by the Danish mix-ELISA, and the organisms were isolated, serotyped and sensitivity tested by standard techniques. The average within-herd seroprevalence was 3.4 per cent and at least one pig tested seropositive in 21 of the 59 herds. In the multiplying herds, only a single seroreactor was detected. Salmonellae were isolated from only five of 95 feed samples, from two of the 17 herds sampled, Salmonella tennessee in four of five samples from one herd and an untypable strain in one of five samples from another. Four infected faecal samples were detected in four herds; they harboured Salmonella typhimurium, Salmonella bredeney or Salmonella london. No salmonellae were isolated from the samples of feed and faeces taken from the multiplying herds. The S london and S typhimurium had a low sensitivity to streptomycin, kanamycin and neomycin, and the S typhimurium also had low sensitivity to amoxycillin, ticarcillin, piperacillin, amoxycillin + clavulanic acid, cefalotin and cefoperazone. The other isolates were sensitive to all the antimicrobial agents tested.     

Some aspects of nematode infection in pigs from small herds

Two traditionally maintained, small herds from southern Poland, with 8 and 12 sows, respectively, were surveyed coprologically during 2006-2007. In one of the herds, while deworming a group of sows with levamisole, faecal samples were collected on Day -7, Day 0 (the day of treatment) and Day 10, in order to assess the therapeutic effect of the drug. Coprological investigation was performed also in 26 fatteners originating from other small farms and slaughtered in a local abattoir, with their intestines washed through for the presence of roundworms. In both herds examined, Ascaris suum and Oesophagostomum spp. were prevalent, whilst Trichuris suis appeared only very rarely. Mainly fatteners, replacement gilts and young sows were highly infected with A. suum. The roundworm occurrence in 2- 3-week-old piglets, with the intensity of 300 eggs per gram of faeces (EPG), indicated the possibility of parasite transmission to offspring very early in age. The highest level of Oesophagostomum spp. infection was observed in sows, but weaners were also much affected. For the group of dewormed sows, the mean faecal egg count reduction (FECR) was estimated to be 77.1- 80.4%, suggesting the presence of resistant nodular worms. A very high false-positive A. suum egg counts found in slaughtered animals (240 to 320 EPG) testified to a high contamination level of the environment of small piggeries, as well. Since the reciprocal transmission of parasites between pigs and poultry might occur, it implies that the flocks should be raised separately.     

MILK PRODUCTION OF GRAZING DAIRY CATTLE AFTER A SINGLE ANTHELMINTIC TREATMENT

The prevalence of nematode infections in lactating dairy cattle was determined by faecal egg counts and cultures from over 350 cows selected at random from twelve herds. The mean egg count was 3 eggs per gram (epg) and 43% of the cows sampled were passing detectable concentrations of eggs (greater than 6 eggs) in their faeces. In June 1976 171 cows in 10 herds were treated with 7.5 mg/kg fenbendazole and their milk production compared over the following 2 months with that of 164 untreated cows in the same herds. Anthelmintic treatment had no significant influence on milk production in any of the herds. The contrasting results of this study and recent studies in the United States of America are discussed.