Anthelmintic activity of papaya seeds on Hymenolepis diminuta infections in rats.

The purpose of this study is to see the anthelmintic activity potential of papaya seeds against Hymenolepis diminuta in rats. The objectives of this study were: (1) to determine the effectiveness of papaya seeds on helminths especially H. diminuta in rats and (2) to determine the effective dose level on helminths in rats. Thirty six male rats from strain Sprague-Dawley were chosen as samples in this experiment. Two types of dose level were used for papaya seeds treatments such as 0.6 g kg-1 and 1.2 g kg-1. The geometric mean (GEM) was used to calculate mean for eggs per gram (EPG) before and after the treatment to be included in the reduction percentage calculation. After 21 days post treatment, necropsies were done to get the worm count and the GEM was used to calculate the efficacy percentage for the treatment. Results from this study showed that the reduction percentages in EPG for papaya seeds treatment for both doses level were very high which is 96.8% for 0.6g kg-1 dose level and 96.2% for 1.2 g kg-1 dose level. Whereas the efficacy percentage based on the worm counts for both doses level were also very high that was 90.77% for 0.6 g kg-1 dose level and 93.85% for 1.2 g kg-1.

The effects of first-season strategic and tactical ivermectin treatments on trichostrongylosis in the first- and second-season grazing.

A 2 year study was conducted to evaluate the effects of first-season strategic or tactical treatments with ivermectin on trichostrongylosis in heifer calves in the first and second-season grazing. Three groups of each eight Holstein-Friesian calves were turned out in early May onto a permanent pasture naturally contaminated with trichostrongyle larvae. Two of these groups were given ivermectin either as strategic treatments (Weeks 3, 8 and 13 after turnout) or as tactical treatments (Weeks 14, 18 and 22 after turnout); the third group served as untreated controls. The strategic ivermectin treatments prevented build-up of high herbage infectivity from mid-summer onwards as shown by low trichostrongyle egg outputs, serum pepsinogen levels and serum antibody responses. In spite of exposure to continuous high larval challenge in late season, the pathogenic effects of worm loads in calves receiving the tactical ivermectin treatment were significantly suppressed. The performance of the strategically treated calves tended to be higher than that of the tactically treated calves in the first-season grazing; yet, there was no statistical difference. During the following summer, all three groups were grazed in a single herd together with a new group of eight first-season calves. No anthelmintic treatments were given to any animals during the season. From late August until the end of the season all animals were given weekly experimental challenge infections. Following the challenge infections, the first-season calves developed clinical parasitic gastroenteritis, whereas the second-season heifers showed no symptoms. At post-mortem it was found that worm burdens mainly consisted of early fourth-stage larvae (L4) of Ostertagia ostertagi (> 97%). Fewer adult worms were recovered from the untreated animals than from the treated ones. However, serum anti-parasite IgG1 responses and post-mortem worm counts suggested that the untreated heifers harboured markedly fewer adult O. ostertagi than the previously treated ones, indicating a higher level of immunity against adult worms. However, this difference did not have any clinical impact in this experiment.

Strategic effects of early season treatments with Moxidectin on trichostrongylosis in young calves.

This study was conducted to evaluate the effects of strategic early season treatments with Moxidectin on trichostrongyles in first-season grazing heifer calves on a permanent pasture. Three groups of Black-Pied Friesian heifer calves were turned out in early May on a permanent pasture naturally infected with trichostrongyle larvae. Two of these groups were treated with Moxidectin at turnout or at turnout and again 8 weeks later, while one group served as untreated controls. For the first three weeks of the experiment all animals grazed together in one flock on one pasture. Subsequently, the pasture was divided into three comparable plots, which from then and until housing in mid October were grazed by each calf group. The results showed that the treatments significantly suppressed faecal egg excretion in the early part of the season, leading to reduced herbage infectivity and parasitism over the rest of the season. Results from faecal egg counts determined at genus level revealed that the persistent activity of Moxidectin appeared to be longer against Ostertagia spp. than against Cooperia spp. Two Moxidectin treatments, given at turnout and on week 8, protected the calves to a higher degree than a single Moxidectin treatment given at turnout. However, there was also a significant effect of only one Moxidectin treatment which possibly could be explained by a low overwintered larval population and a drought period in the early summer.

The effects of early-season treatments with doramectin on set-stocked calves naturally exposed to trichostrongyles.

A study was carried out to evaluate the effects of strategic early-season treatments with doramectin on first-season grazing calves exposed to trichostrongylid infection on a naturally contaminated pasture. Two groups of cross-bred Limousine/Red Danish calves were turned out in early May on two plots that were similar with respect to size and herbage infectivity. They grazed separately until housing in early October. One of these groups was given doramectin at turnout and 10 weeks later, while the other group served as untreated controls. The results showed that the treatments significantly reduced trichostrongylid loads throughout the season, as evidenced by significant reductions in both their Ostertagia ostertagi burdens and serum pepsinogen levels compared with the controls. Furthermore, the results of herbage larval counts and post-mortem worm counts in tracer animals demonstrated that the treatment had successfully suppressed herbage infectivity on the 'treated' plot.

Anthelmintic activity of papaya latex against patent Heligmosomoides polygyrus infections in mice.

The purpose of this experiment was to study the possible anthelmintic activity of papaya latex (Carica papaya) against Heligmosomoides polygyrus in experimentally infected mice. Five groups of BALB/C mice were infected with 100 Heligmosomoides polygyrus infective larvae/mouse. After patency (day 22) four groups of mice (groups B, C, D and E) were given papaya latex suspended in water at dose levels of 2, 4, 6 and 8 g of papaya latex/kg body weight, respectively. One group of mice (group A) served as non-treated controls. All animals were necropsied on day 25, i.e. 3 days after treatment, for post-mortem worm counts. The papaya latex showed an antiparasitic efficacy of 55.5, 60.3, 67.9 and 84.5% in groups B, C, D and E, respectively. The results may suggest a potential role of papaya latex as an anthelmintic against patent intestinal nematodes of mammalian hosts.

Effect of papaya latex against Ascaris suum in naturally infected pigs.

An experiment was carried out to investigate the anthelmintic activity of papaya latex (Carica papaya) against natural infection of Ascaris suum in pigs. Sixteen naturally infected pigs were, on the basis of faecal egg counts and body weight, allocated into four groups, each of four pigs. Three groups (groups B, C, and D) were given papaya latex per os at dose levels of 2, 4, and 8 g of papaya latex per kg body weight, respectively. The fourth group (group A) served as a non-treated control. Results of post mortem counts on day 7 post treatment revealed worm count reductions of 39.5, 80.1 and 100% in groups B, C, and D, respectively. Some of the pigs receiving the highest dose of the latex showed mild diarrhoea on the day following treatment. Otherwise, no clinical or pathological changes were observed in the treated animals. The possible future use of this traditional herbal medicine for livestock and humans is discussed.

Experimental concurrent infections with Ostertagia ostertagi and Cooperia oncophora in the calf.

An experiment was conducted to investigate the effects of experimental concurrent infection with Ostertagia ostertagia and Cooperia oncophora compared with the effects of monospecific infections with O ostertagi under conditions designed to mimic natural conditions on pasture during a grazing season. The present experiment was not able to demonstrate any significant effect of C oncophora on the course of an O ostertagi infection. Neither did C oncophora influence the build up of immunity to O ostertagi as demonstrated by post mortem worm count results from challenge infections with hypobiosis-prone larvae.

Attempts to immunize cattle against Ostertagia ostertagi infections employing 'normal' and 'chilled' (hypobiosis-prone) third stage larvae.

Immunity to Ostertagia ostertagi infections in calves develops slowly and only becomes manifest towards the end of a grazing season in which they have been exposed to the parasite. In an attempt to hasten the onset of immune reactions, three immunization protocols were set up. Twenty four heifers were allocated into four groups. Beginning in January, animals in two of the groups were inoculated with four 1-monthly increasing dosages of either 'normal' or 'chilled' (hypobiosis-prone) larvae, those in the third group received a single large infection with 'chilled' larvae and those in the fourth group served as non-infected controls. All animals were turned out on a common pasture in late April. Development of immunity was evaluated through determinations of faecal egg counts, live weight gains, serum pepsinogen levels and specific serum antibody responses of three isotypes (IgG1, IgG2 and IgA). Significantly reduced egg excretions in the immunized groups were apparent early in the season, indicating that the immunizations had, in this respect, been efficacious. The 'chilled' and 'normal' larvae seemed equally efficient given as multiple and single infections. A single large dosage of 'chilled' larvae seemed to have adverse effects. Only moderate antibody responses were elicited probably because of low challenge infection level on pasture. Considerable variation in responses existed between and within the four groups, for which reason conclusions regarding correlations between antibody isotype responses and immune effects on parasites could not be made.

Experimental infections with Cooperia oncophora in calves. A study with two different larval dose levels and dosing regimens.

The effect of different larval dose level and dosing regimens on the course of Cooperia oncophora infection in calves was studied. Four groups each of 4 calves were experimentally infected either with 50,000 or 200,000 C. oncophora larvae (L3) given either as single infections or as daily trickle infections. An additional group of calves remained as uninfected controls. The animals were necropsied on week 4 after infection. Mild to moderate clinical signs of parasitic gastroenteritis developed among calves given high doses of larvae, but liveweight gains were not significantly different from those of the uninfected controls. Serum pepsinogen levels of dosed animals were within normal ranges but rose slightly, and on day 14 p.i. they differed significantly from those of the controls. On that occasion, the levels of serum pepsinogen in the trickle infected groups significantly exhibited the levels of the single infected groups. Hypoalbuminaemia was not a feature on any occasion. The various groups did not differ significantly with regard to total worm counts and adult worm counts, but the groups receiving high larval dose harboured significantly more fourth stage larvae than the group receiving low doses of larvae, both in terms of absolute counts and in terms of percentages of total worm burdens. Within the same dose level, there was a tendency of a more even distribution of worms along the small intestine when the infections was given as a single infection compared with a trickle infection. The results indicate that C. oncophora larval dose and dosing regimens may influence the pathogenic effects and to some extent the distribution of the parasite in the small intestine.

Ostertagia ostertagi in neonatal calves: establishment of infection in ruminating and non-ruminating calves.

An experiment was carried out to study the role of the ruminal function in the establishment of Ostertagia ostertagi in neonatal calves. Three groups of calves were fed either milk only (groups A and C), or hay and concentrate in addition to milk (group B) from birth. At the time of infection, ruminal function was negligible in groups A and C, whereas it was well developed in group B. Calves of groups A and B were each given 25,000 normal ensheathed infective larvae of O ostertagi and those of group C were given 25,000 infective larvae exsheathed in vitro. Daily faecal egg output and post mortem worm counts 28 days after infection were higher in calves with well developed ruminal function than those having only negligible ruminal function. In the latter group, exsheathed larvae established at a lower rate than did ensheathed larvae. The results suggest that the degree of development of the ruminal function influences the establishment of O ostertagi.