H. Prosl

Fasciola hepatica – Monitoring the milky way? The use of tank milk for liver fluke monitoring in dairy herds as base for treatment strategies

In this study 595 lactating cows originating from 31 carinthian farms were investigated in accordance of liver fluke infection using individual and tank milk as well as individual blood and faecal samples. Two commercial ELISAs were used to test the milk and blood serum, and the results were compared with coproscopy and a commercial copro-antigen ELISA. Receiver operating characteristics (ROC) and two-graph operating characteristics (TG ROC) of tank milk results were conducted based on the individual milk to determine the minimum reliable in-herd antibody prevalence for the predominant condition in the investigation area. In 17.8% of the examined individuals located in 64.5% of the farms eggs were detected by coproscopy. The copro-antigen ELISA delivered 13.4% positive individuals from 54.8% of the farms. The milk ELISAs showed 42.7% (Euroclone) and 44.2% (Pourquier) positive cows on 90.3% of the farms. The blood samples were positive in 43% (Euroclone) and 45.2% (Pourquier) of the individuals from 90.3% to 96.8% of the herds, respectively. Based on the milk and the blood an average in-herd prevalence of 30-45% can be assumed. The serum and milk samples delivered correlating results with kappa values between 0.94 and 0.97, whereas the coproscopy and copro-antigen ELISA did not correlate well with the ELISA results. The two different ELISA tests highly correlated on individual and on herd level. Both showed a reliable minimum in-herd prevalence of ∼20%, meaning that one fifth of the individuals in a herd have to be positive to obtain a positive bulk tank milk result. In the investigated area a higher in-herd prevalence is expected, therefore the tank milk is useful as a monitoring tool and can be used as a basis for intervention strategies.

Scraping or shaking—a comparison of methods for the quantitative determination of Echinococcus multilocularis in fox intestines

A modified sedimentation technique (the “shaking in a vessel” technique; SVT) to examine intestines for smaller helminths such as Echinococcus multilocularis is described and compared with the intestinal scraping technique (IST). Out of 356 foxes, 26 were E. multilocularis positive, 19 using IST (sensitivity 73.1%) and 25 with SVT (sensitivity 96.2%) after IST. Especially low infection intensities went undetected with IST. The result is comparable to the established sedimentation and counting technique (SCT). SVT is recommended for the routine examination of fox intestines as an alternative to SCT.

Canine isosporosis - epidemiology of field and experimental infections.

Summary Isospora spp. are the causative agents of canine isosporosis. Of the 3590 diagnostic samples from Austrian dogs (≤2 years old), 8.7% contained Isospora oocysts, 78% of which from dogs up to 4 months of age. Non‐haemorrhagic and haemorrhagic diarrhoea were significantly more prevalent in Isospora‐infected animals than in coccidia‐negative ones. Twelve of 15 litters from a large commercial dog breeding unit (examined from the third to the 10th week of life) also excreted Isospora (average prevalence: 36.4%) in intensities from 333 to 35 000 oocysts per gram of faeces (opg). In experimental trials 26 3‐week‐old Beagle puppies were infected with low (600–6000), medium (10 000) or high (20 000) dose of Isospora ohioensis‐group or Isospora canis field isolates. Additionally 21 puppies were infected as above and treated with a symmetrical triazintrione. Parasitological and clinical parameters were examined. The two Isospora species differed significantly concerning intensity and duration of excretion. The pre‐patent period was 6–7 days for I. ohioensis and 10–12 days for I. canis. The latter species showed significantly longer excretion and higher opg. This was not influenced by simultaneous infections with both species. Individual patterns of faecal consistency were very variable, irrespective of the infection dose. Treatment significantly reduced both the intensity and the duration of oocysts excretion as well as diarrhoea in comparison with the infected, untreated group and thus proved to be effective against coccidiosis in experimental infections.

Morantel sustained release bolus: A new approach for the control of trichostrongylosis in Austrian cattle

The efficacy of a morantel sustained release bolus to control gastrointestinal parasitism during two consecutive grazing seasons was assessed in replacement dairy heifers raised under field conditions in Austria. Thirty calves were randomly allotted into two equal groups and maintained throughout the 1979 summer pasturing season on adjacent pastures of equal size with identical grazing history. Twenty-four of the thirty calves used in 1979 were monitored throughout 1980, each animal remained in the same treatment group as the previous year and grazed the same pastures as the previous year. In both 1979 and 1980 the bolus was administered to each animal in the treated group one week before turnout onto spring pastures, while the control animals received no anthelmintic treatment during either year. The efficacy of the bolus was assessed by comparison of faecal worm egg counts, herbage larval counts, worm counts from tracer and principal trial animals, weight gains and by the incidence of clinical disease found in both tracer and trial animals throughout the grazing season. Milk production was also monitored for all animals in both treatment groups during the first lactation. The system of treatment used in the present study with the morantel sustained release bolus was highly effective in preventing a significant buildup of infective larvae on pasture to the end of the grazing season in both years. In 1979 worm counts of tracer calves grazed on the treated pastures in mid-August were similar to those recorded at the beginning of the season, while worm counts in the control tracers were five times the total found at the beginning of the season. In 1979 the bolus-treated calves outperformed the control group by 34.8 kg (P less than 0.001) over the 168-day grazing period. These results demonstrated that administration of the bolus to calves at the time of turnout onto spring pastures was most effective both in controlling parasites within the cattle themselves and in reducing the level of parasite contamination. During the second grazing season (1980) no beneficial effect in weight gain was observed due to the second bolus treatment. Weight gains realized during the first year, however, largely remained through the second year and the bolus-treated heifers reached breeding weight on average 19 days earlier. No difference in milk yield was observed between the treated and control animals during thier first year of lactation.

Effects of excretory/secretory products of Haemonchus contortus on cell vacuolation

Excretory/secretory (ES) products of the gastric nematode, Haemonchus contortus, have been implicated in the inhibition of gastric acid secretion which follows infection. Parietal cell vacuolation has been observed in abomasal sections from parasitised sheep, and ES prepared in vitro has been reported to cause vacuolation and to increase neutral red (NR) uptake in epithelial cell cultures. We have used the latter approach to examine, at the cellular level, the effects of ES prepared from L3 and adult nematodes. Both NR uptake and cellular vacuolation were increased following exposure to larval or adult ES products. ES preparations from adult worms induced more extensive vacuolation then those from L3 worms and, as with VacA treatment, adherent cells remained viable despite high levels of vacuolation. Whereas VacA-induced vacuolation resulted in NR uptake predominantly localised in vacuoles, this appeared not to be the case with ES-induced vacuolation, suggesting that different mechanisms might be involved. Both ES and VacA exposure was associated with an increased rate of cell detachment.