The sensitivity and specificity of two methods for detecting Fasciola infections in cattle.

Counts of Fasciola spp. eggs in faeces and measurements of antibody concentration to the excretory/secretory antigens of Fasciola spp. by ELISA were related to the numbers of flukes in the livers of 92 cattle killed in the abattoirs of Hanoi City, Vietnam. In this population, about 22% of the cattle had no flukes, another 22% had between 1 and 10 flukes, 44% between 11 and 100 flukes and 12% had more than 100 flukes in their livers. Of the 14 animals less than 2 years of age, only three were infected. At 2 years of age the mean number of flukes per liver was 10 whereas at 3 years and older, the mean varied between 60 and 80 flukes. Prevalence of infection was 78.3%. No eggs of Fasciola spp. were detected in the faeces of one third of infected cattle and 60% of the counts were less than 100 eggs per gram. The sensitivity of the egg counting method was 66.7% and specificity 100%, overall accuracy was 73.9%. Corresponding values for the ELISA method were 86.1, 70 and 82.6%, respectively. The positive and negative predictive values for the egg counting method were 100 and 45.5% and for the ELISA method were 91.2 and 58.3%, respectively.     

The prevalence and economic importance of bovine fasciolosis in Kenya--an analysis of abattoir data

A retrospective study covering a period of 10 years (1990-1999) was carried out using post mortem meat inspection records at the Veterinary Department Headquarters at Kabete to determine the prevalence and economic importance of bovine fasciolosis in Kenya. Meat inspection records from abattoirs in 38 districts distributed over seven out of the eight provinces of Kenya were examined. Prevalence of fasciolosis was calculated as the number of cattle found to be infected with Fasciola, expressed as a percentage of the total number of cattle slaughtered. Using the average weight and market price of a bovine liver, the monetary loss occasioned by condemnation of Fasciola infected livers was calculated. A survey was also carried out at Dagoretti slaughterhouse complex in Nairobi to determine the relative occurrence of F. gigantica and F. hepatica in slaughtered cattle. Cattle slaughtered at Dagoretti slaughterhouse originate from all parts of the country. A total of 5,421,188 cattle were slaughtered in the seven provinces of Kenya during the 10-year period and 427,931 (8%) of these cattle were infected with Fasciola. The region with the highest prevalence of fasciolosis was Western Province (16%) followed, in descending order, by Eastem Province (11%), Nyanza Province (9%), Rift Valley Province (8%), Central Province (6%), Nairobi Province (4%) and Coast Province (3.5%). The total economic loss incurred by the country during the 10-year period as a result of condemnation of the infected livers was approximately US$2.6 million. The total annual economic losses during this period ranged from approximately US$0.2-0.3 million. The highest total economic losses for the 10-year period were recorded in Western Province (US$0.8 million) and Central Province (US$0.7 million). A total of 1584 cattle originating from five provinces of Kenya were slaughtered at Dagoretti slaughterhouse over a period of two months of which 147 (9.3%) were infected with liver flukes. All the liver flukes obtained from the infected livers were identified as F. gigantica. It is concluded that fasciolosis is prevalent in cattle in all provinces of Kenya, that it causes great economic losses as a result of condemnation of infected livers, and that F. gigantica is the main species of liver flukes affecting cattle in Kenya. Local climatic factors, cattle trade, rustling and population numbers, and the presence of the snail intermediate hosts are probably the main factors influencing the incidence of the disease in the various regions of the country.     

Epizootiology of fascioliasis in Montana.

During 1989-1990, the United States Department of Agriculture (USDA) meat inspection records were used to determine the distribution and incidence of liver flukes (Fasciola hepatica and Fascioloides magna) in Montana cattle. Of the cows and bulls slaughtered in USDA-inspected packing plants during a 12 month time period, 17.24% had livers that were condemned because of liver flukes. This was a 12% increase over USDA liver condemnations reported for 1973. Infected animals have been reported from 26 counties in Montana, mostly located in the south-central and western half of the state. Forty-nine percent of the 2.4 million cattle in Montana are raised in these counties. Lymnaeid snail species that may serve as intermediate hosts for Fasciola hepatica were found in most of the counties where liver flukes were reported. The principal vectors believed to be responsible for the transmission of Fasciola hepatica in Montana are species of the genus Fossaria. Stagnicola montanensis and Lymnaea stagnalis, which may serve as intermediate hosts for this parasite have also been collected. A known intermediate host for Fascioloides magna, Stagnicola caperata, was also found in several locations.     

Cellular and humoral responses in liver of cattle and buffaloes infected with a single dose of Fasciola gigantica

The cellular components of the hepatic inflammatory infiltrate in cattle and buffaloes infected with a single dose of 1000 Fasciola gigantica were analysed by immunohistochemistry and histology. T and B lymphocytes, plasma cells, eosinophils and mast cells were present in the hepatic lesions. It is proposed that both cellular and humoral immune responses were induced in the liver of cattle and buffaloes during infection with F. gigantica probably by antigens released by the developing flukes and by damage caused by the flukes during their migration in the liver. The local T cell response differed between these animals, with the response decreasing after 3 weeks post-infection in cattle in contrast to a gradually increasing response in buffaloes. Difference in the T cell response between cattle and buffaloes may be related to their differences in resistance and resilience to infection with F. gigantica.     

The use of age-clustered pooled faecal samples for monitoring worm control in horses

A study was performed on two horse farms to evaluate the use of age-clustered pooled faecal samples for monitoring worm control in horses. In total 109 horses, 57 on farm A and 52 on farm B, were monitored at weekly intervals between 6 and 14 weeks after ivermectin treatment. This was performed through pooled faecal samples of pools of up to 10 horses of the groups 'yearlings' (both farms), '2-year-old' (two pools in farm A), '3-year-old' (farm A) and adult horses (four pools on farm A and five pools on farm B), which were compared with the mean individual faecal egg counts of the same pools. A very high correlation between the faecal egg counts in pooled samples and the mean faecal egg counts was seen and also between the faecal egg counts in pooled samples and larval counts from pooled faecal larval cultures. Faecal egg counts increased more rapidly in yearlings and 2-year-old horses than in older horses. This implied that in these groups of young animals faecal egg counts of more than 200 EPG were reached at or just after the egg reappearance period (ERP) of 8 weeks that is usually indicated for ivermectin. This probably means that, certainly under intensive conditions, repeated treatment at this ERP is warranted in these young animals, with or without monitoring through faecal examination. A different situation is seen in adult animals. Based on the mean faecal egg counts on both farms and on the results of pooled samples in farm A, using 100 EPG as threshold, no justification for treatment was seen throughout the experimental period. However, on farm B values of 100 EPG were seen at 9 and 11, 13 and 14 and 14 weeks after ivermectin treatment in pools 10, 12 and 13, respectively. This coincided with the presence of one or two horses with egg counts above 200 EPG. The conclusion is that random pooled faecal samples of 10 adult horses from a larger herd, starting at the ERP and repeating it at, for instance, 4-week intervals, could be used for decisions on worm control. However, there would be a certain risk for underestimating pasture contamination through missing high-egg excreters. An alternative use of pooled samples would be as a cheap first screening to detect which adult horses really contribute to pasture contamination with worm eggs on a farm. All horses should be sampled and subsequently animals from 'positive' pools can be reexamined individually.     

Comparative evaluation of the enzyme-linked immunosorbent assay (ELISA) in the diagnosis of natural Fasciola gigantica infection in cattle

The enzyme-linked immunosorbent assay (ELISA) was evaluated for the diagnosis of naturally acquired Fasciola gigantica infection in cattle in comparison with conventional parasitological techniques. Using unfractionated whole worm extract of F. gigantica as the antigen, it was observed that there was a good correlation between ELISA positivity and positive diagnosis of fascioliasis by post mortem liver examination, bile egg sedimentation and faecal egg sedimentation. There was, however, a disparity between ELISA results and faecal egg flotation results.     

Prevalence of fasciolosis in Zambian cattle observed at selected abattoirs with emphasis on age, sex and origin

The aim of this study was to determine the prevalence and some factors influencing occurrence of fasciolosis in cattle, carried out at selected major abattoirs in Zambia. Of 841 cattle livers inspected and 677 faecal samples analysed, prevalence rates of 53.9% and 48.9%, respectively, were found. Cumulative prevalence of 60.9% (n = 677) was recorded. According to age, no significant difference of infection was found. Female cattle on liver inspection (59.3%) and coprological examination (65.2%) had significantly higher (P < 0.001) rates than males (44.5% and 36.3% respectively). Origin of cattle had a significant influence (P < 0.001) on the prevalence rate. According to fluke egg count classification, 68.5% of cattle had light infection, 20.9% moderate, 4.4% heavy and 6.2% severe. These results indicate that Fasciola gigantica infection is an important condition that leads to high liver condemnations and/or trimmings in cattle tendered for slaughter.     

The Prevalence and Intensity of Helminth and Coccidial Infections in Dairy Cattle in Central Kenya

A survey of gastrointestinal parasite infections of young (<6 months old), immature (6–12 months old) and adult (>12 months old) dairy cattle on 16 farms in Kiambu District, Kenya was conducted during a dry season (September 1991 to January 1992) and during a wet season (March to July 1992). The survey was based on monthly coproparasitological examination of cohorts and worm counts in tracer calves. The effects of age, sex, farm and season on the prevalence and intensity of helminth and coccidial infections were determined. Faecal egg and oocyst counts revealed that the overall prevalences were: strongyles (including trichostrongyles) (85.5%), liver flukes (Fasciola gigantica) (34.0%), coccidia (30.9%) and tapeworms (9.6%). Eight species of the protozoan Eimeria were identified, the most prevalent species being E. bovis and E. zuernii. The most prevalent nematode genera were Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus. Season, farm and age of the animals had a significant (p<0.05) influence on the intensity of infection with strongyles, liver flukes and coccidia, whereas the sex of the animals had no significant (p>0.05) effect on the prevalence or intensity of infections. A higher intensity of infection with strongyles and coccidia was found in the wet season than in the dry season (p<0.05). The age-specific intensity was in the following order: for strongyles, immature animals of 6–12 months of age had the highest egg counts, followed by young calves and adults. Calves had significantly (p<0.05) higher oocyst counts than immatures or adults. Liver fluke egg counts did not differ significant (p>0.05) between immatures and adult cattle.     

Prevalence of gastrointestinal helminths,lungworms and liver fluke in sheep and goats in Norway

The present study describes the occurrence of various gastrointestinal helminths, lungworms and liver flukes in Norwegian sheep and goats as assessed from faecal samples and post mortem examinations performed between 2007 and 2010. Faecal samples for gastrointestinal nematode egg counts were collected from 77 sheep flocks and 30 dairy goat flocks from three geographical regions in Norway. Additionally, thirty-two lambs and 16 adult goats were euthanized for necropsy examination and for identification of adult gastrointestinal nematodes and tapeworms, lungworms and liver flukes. The survey showed that there was a higher mean excretion of trichostrongyle eggs in sheep than in goats at the individual level (392 EPG vs. 154 EPG, p < 0.001). For both host species, the mean prevalence and intensity of excreted trichostrongyle eggs were significantly higher in the southern coastal region compared with the inland and northern regions (p < 0.001). Third stage larvae of Trichostrongylus/Teladorsagia, Haemonchus and Nematodirus type were the most prevalent ones in the coprocultures from sheep, whereas larvae of Trichostrongylus/Teladorsagia and Nematodirus type dominated in goats. The most prevalent gastrointestinal nematode species found at necropsy was Teladorsagia circumcincta (75.0 and 81.2% respectively in sheep and goats), while the largest mean worm burdens were recorded for Haemonchus contortus in sheep (724 ± 623) and T. circumcincta in goats (377 ± 529). Other gastrointestinal nematode species were present at low prevalence or in low numbers.     

Serum antibody isotype responses of Fasciola-infected sheep and cattle to excretory and secretory products of Fasciola species

This study investigated the immunoglobulin isotype responses of sheep and cattle chronically infected with Fasciola hepatica and Fasciola gigantica to adult F. hepatica excretory/secretory products (Fh-ES) or F. gigantica excretory/secretory products (Fg-ES), respectively. An antibody enzyme-linked immunosorbent assay (Ab-ELISA) was used to determine serum antibody (total Ig, IgG(1), IgM, IgG(2) and IgA) responses. At necropsy, the mean number of flukes recovered was lower in cattle than in sheep. All F. hepatica and F. gigantica infected sheep and cattle showed an increased total Ig levels from 3 to 4 weeks post-infection (wpi). Among isotypes IgG(1) was most dominant while IgM was the earliest (2 wpi) to be detected in both sheep and cattle infected with both F. hepatica and F. gigantica animals. IgG(2) response was early (2 wpi) in sheep infected by F. hepatica but there was no response in sheep infected with F. gigantica. There was a late and strong IgG(2) response in cattle infected with both flukes. The IgA isotype showed an early and a clear biphasic response in sheep with F. hepatica but was less pronounced in F. gigantica infected sheep. While IgA response to Fh-ES was noticed 5 wpi in F. hepatica infected cattle, it appeared much later (21 wpi) in those infected with F. gigantica. The dominance of IgG(1) isotype in infected sheep and cattle suggest an associated Th2 response. This early response to adult Fasciola spp. ES antigen suggests an early exposure to the antigen presumably through the cross-reacting ES products of juvenile flukes. There is clearly difference in IgG(2) isotype response in cattle (resistant) compared to sheep (susceptible). The late IgG(2) response in cattle may suggest late Th1 involvement in bovine cellular responses to adult Fh-ES/Fg-ES.     

Comparison of production losses caused by chronic Fasciola gigantica infection in yearling Friesian and Boran cattle

Yearling Friesian and Boran cattle were given a standard dose of Fasciola gigantica metacercariae designed to produce chronic infection. Their liveweights were then monitored for 23 weeks post-infection. Following standard meat inspection procedures, all the livers from the infected cattle were condemned. At 22 kg per animal, the mean reduction in liveweight gain in infected Borans was significantly greater than in infected Friesians. Compared to the control cattle and based on current sale prices in Kenya, the production losses from the combination of liver condemnations and reduction in liveweight gain constituted a loss in value of US$12.11 (4.92%) and US$23.41 (10.34%) for Friesians and Borans respectively. These data indicate that productivity losses and the economic consequencies of fasciolosis in yearling Boran cattle are much more severe than in Friesians. These findings have implications for assessing the likely benefits of control measures against this parasite.     

Precision, repeatability and representative ability of faecal egg counts in Heterakis gallinarum infected chickens

This study investigated whether a precise and repeatable quantification of Heterakis gallinarum egg excretion, which considerably reflects the actual worm burdens, can be achieved based on collection of the daily total amount of faeces from chickens. Three-week-old birds (N=64) were infected with 200 embryonated eggs of H. gallinarum, and placed into individual cages 3 wk after infection for 5 wk to collect daily faeces (N=2240). The total daily faeces was mixed and a randomly taken sample per bird was analyzed to estimate the numbers of eggs per gram of faeces (EPG) and total number of eggs excreted within 24h (EPD). A total of 235 daily faecal collections were randomly selected and further examined to determine between and within sample variations of EPG counts as a measure of precision. For this, two random faecal samples were taken from the daily produced faeces by a bird, and the EPG was determined for each of the samples (EPG1 and EPG2). The second faecal sample was analyzed once more to determine a parallel EPG2 count (EPG2a) of the suspended sample. Precision of an EPG count was defined as its relative closeness to the average of two EPG counts using a relative asymmetry index (Index(EPG)). At an age of 11 wk, i.e. 8 wk p.i. the birds were slaughtered and their worm burdens were determined. There were no significant differences between EPG1 and EPG2 (P=0.764) nor between EPG2 and EPG2a (P=0.700), suggesting that the differences between or within the samples were not different from zero. Correlations between EPG counts, as between and within sample coherences, were r=0.85 and r=0.86, respectively. Precision of EPG counts, as measured by Index(EPG), was not influenced by consistency (P=0.870) and total amount of faeces (P=0.088). However, concentration of eggs in faeces (mean EPG) had a significant effect on the precision of the EPG counts (P<0.001). Similar results were also observed for the within sample precision (Index(EPG2)). A segmented regression analysis indicated an abrupt change in the precision of EPG counts as the response to changing egg concentration in the examined faecal samples. The precision of analyses remarkably heightened up to a breakpoint with an EPG count of ≤ 617. A similar breakpoint was also determined for within sample precision (EPG2 ≤ 621). Moderate repeatabilities (R=0.49) for EPG and EPD were estimated in the first week of egg excretion, whereas the estimates were higher (R=0.67-0.84) in the following weeks. Correlations between number of female worms with daily measured EPG and EPD increased to an almost constant level (r ≥ 0.70; P<0.05) in a few days after the nematode excreted eggs and predominantly remained so for the rest of the sampling period. It is concluded that mixing daily total faeces provides samples with random homogenous distribution of H. gallinarum eggs. Precision of the EPG counts increases as the egg concentration in faecal sample increases. Egg excretion of H. gallinarum, quantified either as EPG or EPD, is highly repeatable and closely correlated with the actual worm burden of birds starting as early as in 5 th wk of infection.     

A retrospective study of the prevalence and seasonal variation of Fasciola gigantica in cattle slaughtered in the major abattoirs of Zimbabwe between 1990 and 1999

A retrospective study covering a period of 10 years (1990--1999) was conducted using post mortem meat inspection records of the Veterinary Department Information Management Unit at Harare to determine the prevalence and seasonal variation of bovine fasciolosis in Zimbabwe. Records of monthly and annual returns from five major abattoirs were examined in regard to total cattle slaughtered and the corresponding number of livers condemned due to Fasciola gigantica infection. Prevalence of fasciolosis was calculated as the number of cattle found to be infected with F gigantica, expressed as a percentage of the number of cattle slaughtered. Seasonal variations in the prevalence were examined by pooling respective monthly condemnation data over a 10-year (1990--1999) period. A total of 2,474,232 cattle were slaughtered during this period and 917,565 (37.1%) of these cattle were infected with F. gigantica. The pattern of distribution of F. gigantica was significantly higher in cattle originating from catchment areas of high rainfall than in those of relatively low rainfall, and in those slaughtered during the wet season than those slaughtered during the dry season (P< 0.05). Based on the study findings a control programme for the disease in Zimbabwe is suggested.     

Experiments on anthelmintic control of Fasciola hepatica in Brazil.

Two separate field trials involving naturally infected cattle were carried out on two farms known to have a history of Fasciola hepatica infection. On the first farm, 15 animals per group were allocated as follows: G1, triclabendazole (TCBZ) four times a year; G2, TCBZ twice a year (May and September); G3, untreated control. All groups grazed together and after 3.5 years the animals were slaughtered and their livers examined by federal meat inspectors who condemned 100% of livers in G3 and 8.3% in G2 owing to the presence of lesions of fasciolosis. In G1 no livers were condemned. Significant differences in weight gains were not detected and fluke counts remained at low levels in the treated groups. Also, in the control group, egg counts started to decrease when animals were 2 years old. On the second farm, groups of 20 animals were treated as follows: G1, TCBZ three times a year (May, September and December); G2, TCBZ twice a year (May and September); G3, nitroxynil twice a year (May and September); G4, rafoxanide twice a year (May and September); G5, untreated controls. All animals were weighed and faecal samples examined at approximately 28-day intervals. During the period of the study, larger weight gains were detected in the TCBZ treated groups than in the others. TCBZ treatment kept F. hepatica egg counts at a lower level for longer periods than the other drugs and significant differences in weight gains were only obtained between the group receiving TCBZ three times a year and the control group.     

Studies on the prevalence and laboratory transmission of fascioliasis in animals in the Kashmir Valley

In Kashmir, 85.1% of cattle, 51.3% of sheep and 14.8% of goats were found infected with Fasciola spp. The prevalence rate varied from 66.6 to 100.0%, 25.0 to 100% and nil to 66.0% in cattle, sheep and goats respectively in different months of the year. Fasciola gigantica was the predominant species in all animal species but sheep harboured both F. gigantica and F. hepatica. The prevalence of F. hepatica infection in sheep happens to be the first report from India. Lymnaea auricularia sensu stricto supported the development of F. gigantica under laboratory conditions. The incubation temperature affected the shedding of the cercariae. Snails maintained at 25-27 degrees C started cercarial shedding as early as day 20 post-infection (PI), whereas those maintained at 10-12 degrees C commenced it from day 64 PI. One out of three experimentally infected guinea pigs aged 1 month revealed adult flukes in the liver at necropsy on day 52 PI.     

Host responses during experimental infection with Fasciola gigantica or Fasciola hepatica in Merino sheep I. Comparative immunological and plasma biochemical changes during early infection

This study reports the early biochemical changes in plasma, comparative host-immune responses and parasite recovery data in Merino sheep during the first 10 weeks of infection with Fasciola gigantica and Fasciola hepatica. One group of sheep were uninfected, four groups of sheep received incremental challenge doses of F. gigantica metacercariae (50, 125, 225 and 400, respectively) and the sixth group was challenged with 250 F. hepatica metacercariae. At 10 weeks post infection (wpi), sheep challenged with F. hepatica showed the greatest fluke recovery (mean 119, range 84-166); a significantly higher biomass of parasites recovered (2.5-fold greater than the highest dose of F. gigantica); and a greater mean % parasite recovery (39.3%, range 27-55%) than any group challenged with F. gigantica. Within the groups dosed with F. gigantica a strong dose-dependent response was observed in both fluke recovery and fluke biomass with increasing dose of metacercariae. The mean % parasite recovery of F. gigantica infected groups 1-5 were 26, 23, 26 and 25%, respectively, suggesting a uniform viability of parasite establishment independent of infection dose. At 6 wpi, elevated levels of plasma GLDH were observed in the F. gigantica infected groups compared to the uninfected sheep (p<0.005) whereas the F. hepatica challenged group had four-fold higher levels of GLDH compared to the F. gigantica infected group (p<0.001). Elevated levels of GGT as an indicator of epithelial damage in the bile duct was only seen in the group challenged with F. hepatica at 10 wpi when it rose from below 100 IU/l to approximately 250 IU/l (p<0.0001) whereas no detectable increase in GGT was observed in any of the groups challenged with F. gigantica. The white blood cell response to F. hepatica infection was biphasic with the initial peak at 4 wpi and a second peak at 9 wpi, corresponding to the period of migration of juvenile fluke in the liver and the time when adult flukes are migrating into the bile duct, respectively. This biphasic response was also evident in the changes in the eosinophil counts and serum haemoglobin levels. There was a trend toward higher parasite-specific IgG2 titres in sheep infected with lower worm burdens, suggesting that higher F. gigantica or F. hepatica burdens suppress IgG2 responses. The findings of this study suggest that, in early infection in a permissive host, F. hepatica appears to be more pathogenic than F. gigantica because of its rapid increase in size and the speed of its progression through the migratory phases of its life cycle.     

Field efficacy of a morantel sustained release bolus for control of gastrointestinal nematodes in yearling steers

The efficacy of a morantel sustained release bolus (MSRB) for control of gastrointestinal nematodes in yearling steers was evaluated over a 6-month grazing period commencing on 26 March 1982. Three groups of 15 steers were allotted to the following treatments: Group 1 -- one MSRB at start of trial; Group 2 -- one therapeutic dose of thiabendazole at start of trial; Group 3 -- untreated control. The treatment groups were grazed separately. Parasite egg counts (EPG), herbage larval counts, pepsinogen levels and weight gains were monitored. Every other month, sets of 2 parasite-free tracer calves were placed in the pasture grazed by each treatment group and allowed to graze for 3 weeks before being subsequently necropsied for worm counts. At the end of the trial, 6 animals from each group were also necropsied for worm counts. The MSRB treatment resulted in significantly lower egg counts, fewer infective larvae on pasture, lower pepsinogen levels and lower worm burdens in tracer calves than was the case for the untreated group, but generally the levels were not significantly different from those associated with the thiabendazole treatment. The mean weight gain for the MSRB treated steers showed a significant advantage (70.9 lb) over the untreated animals, but was not significantly different from those which received thiabendazole. Total worm counts at the end of the trial were not different from any treatment group.     

Seasonal pattern of bovine fasciolosis in the Kafue and Zambezi catchment areas of Zambia

In order to establish seasonality of bovine fasciolosis in the Southern province of Zambia, 288 cattle were examined at slaughter at Turnpike slaughter slab for 1 year. The examination involved liver inspection and coprological examination. Liver condemnation rates were relatively high at the beginning of both the cold dry season and the rainy season (May/June and December, respectively). All cattle, regardless of age, had higher fluke abundances in the post-rainy season (39.1% young and 42.1% adult) while the lowest rates were in the hot dry season (13.3% young and 14.3% adult). On coprological examination, the highest abundance was in the post-rainy season (45.0%) and the lowest in the cold dry season (24.9%). From November (end of dry season) to February/March (end of rains), more fluke eggs were found than in any other period. The distribution of fluke eggs was significantly different (p<0.001) among the four seasons. Identified associations were: egg counts were highest in post-rainy (mean abundance=146) and lowest in cold dry season (mean abundance=118) at 95% confidence (CI 0.64-1.25). Differences in abundance observed according to origin, sex and age of cattle were not significant on both methods. Based on these results, it may be concluded that Fasciola gigantica was present throughout the year in cattle in Zambia but the abundance was highest in the post-rainy season and lowest in the cold dry season.     

The use of a morantel sustained release bolus in the seasonal control of parasitic gastroenteritis in second-season cattle

The efficacy of a morantel sustained release bolus was evaluated during the 1980 summer grazing season in 216 yearling, second-season cattle in nine trials in West Germany. In five trials individual farms were used, in which medicated and control groups could be grazed on adjacent pastures. In four additional trials medicated and control groups were maintained on separate farms where the sites and management practice were matched as far as possible. Faecal worm egg counts, herbage larval counts and weight gain were monitored at regular intervals throughout the season. The faecal output of gastrointestinal nematode eggs was reduced by 55.8 percent in the medicated animals during the period from May to early August, while worm egg counts were equal to that of the control animals during the later part of the season. Herbage larval counts were similar on pastures grazed by medicated and nonmedicated cattle. In the five trials where individual farms were used the average daily weight gains over the entire grazing period were 900 (+/- 222) g/animal/day in the medicated group compared with 826 (+/- 263) g/animal in the nonmedicated cattle, a non-significant advantage. No advantage for the treated over the control groups was detected in the additional 4 trials but this was attributed largely to the difficulty in obtaining comparable groups of animals in comparable grazing conditions in "matching" farms, leading to inter-farm variation.     

The use of the morantel sustained release bolus under special farm practices (deprime system) in France

The efficacy of the morantel sustained release bolus in controlling gastrointestinal and lungworm parasites when used in first-season grazing animals which followed older animals onto spring pasture (deprime system) was assessed in three trials conducted in Normandy, France. In each trial first-season grazing calves were equally allocated onto two separate but equivalent paddocks where they remained throughout the grazing season. A morantel sustained release bolus was administered to one group of animals at turnout, the other group remained as controls. The effect of the treatment on contamination of pasture (herbage larval counts and tracer worm counts), on faecal worm egg and lungworm larval counts, and on weight gain performance of the principal animals was assessed. In all three trials, worm egg output in the bolus-treated animals was substantially lower throughout the season compared with the control animals. Worm burdens of tracer calves grazing pastures of the treated cattle were also reduced compared with tracer calves grazing control pastures. Clinical parasitic gastroenteritis occurred in the control animals but not in the bolus-treated animals in one trial. Overall the bolus-treated animals outperformed the controls by a mean weight gain advantage of 10.5 kg (P less than 0.01).