Effect of the nematophagous fungus Pochonia chlamydosporia on soil content of ascarid eggs and infection levels in exposed hens

BACKGROUND

The nematophagous fungus Pochonia chlamydosporia can degrade ascarid (e.g. Ascaridia galli) eggs in agar and soil in vitro. However, it has not been investigated how this translates to reduced infection levels in naturally exposed chickens. We thus tested the infectivity of soil artificially contaminated with A. galli (and a few Heterakis gallinarum) eggs and treated with P. chlamydosporia. Sterilised and non-sterilised soils were used to examine any influence of natural soil biota.

METHODS

Unembryonated eggs were mixed with sterilised (S)/non-sterilised (N) soil, either treated with the fungus (F) or left as untreated controls (C) and incubated (22 °C, 35 days) to allow eggs to embryonate and fungus to grow. Egg number in soil was estimated on days 0 and 35 post-incubation. Hens were exposed to the soil (SC/SF/NC/NF) four times over 12 days by mixing soil into the feed. On day 42 post-first-exposure (p.f.e.), the hens were euthanized and parasites were recovered. Serum A. galli IgY level and ascarid eggs per gram of faeces (EPG) were examined on days -1 and 36 (IgY) or 40 p.f.e. (EPG).

RESULTS

Egg recovery in SF soil was substantially lower than in SC soil, but recovery was not significantly different between NF and NC soils. SF hens had a mean worm count of 76 whereas the other groups had means of 355-453. Early mature/mature A. galli were recovered from SF hens whereas hens in the other groups harboured mainly immature A. galli. Heterakis gallinarum counts were low overall, especially in SF. The SF post-exposure IgY response was significantly lower while EPG was significantly higher compared to the other groups.

CONCLUSIONS

Pochonia chlamydosporia was very effective in reducing ascarid egg numbers in sterilised soil and thus worm burdens in the exposed hens. However, reduced exposure of hens shifted A. galli populations toward a higher proportion of mature worms and resulted in a higher faecal egg excretion within the study period. This highlights a fundamental problem in ascarid control: if not all eggs in the farm environment are inactivated, the resulting low level infections may result in higher contamination levels with associated negative long-term consequences.

Effect of different contents of proteins and vitamin B2 in the feed on the prevalence and infection intensity of Ascaridia galli in chickens

A group of 10-day-old chickens was experimentally infected with a dose of 500 infective eggs of Ascaridia galli (Schrank, 1788) (Nematoda). Forty-nine days post infection the chickens were necropsied and the infection intensity and prevalence were determined. The group maintained on the feed containing 11% of protein showed higher infection intensity and prevalence compared to the chickens fed a diet containing 19% of protein. The addition of vitamin B2 to the feed containing 11% protein resulted in lower intensity and prevalence of the infection. In both series of experiments no effect of Zn-bacitracin or vitamin B2 on infection intensity or prevalence was observed for chickens fed feed containing 19% of protein.

Ascaridia galli infections in free-range layers fed on diets with different protein contents

1. One hundred and twenty 17-week-old Lohman Brown hens were divided into 4 groups. Groups 1 and 3 were given a diet with 180 g protein/kg and groups 2 and 4 were given a diet with 140 g protein/kg. Groups 1 and 2 were orally infected with 500 (+/- 50) embryonated Ascaridia galli eggs. 2. Marked differences in mean weekly weight gain for the 4 groups were observed. 3. Hens given 140 g protein/kg had a significant lower mean worm burden of adult A. galli worms and a significant lower weight gain compared to the group given 18 g protein/kg. 4. There was no significant difference in faecal egg counts between the 2 parasitised groups. 5. The egg production did not differ significantly between any of the groups. 6. The results of this study indicate that the amount of dietary protein in the diet has an effect on the establishment of A. galli infections in the gut of layers kept under free range conditions.

[Impact of improved sanitary conditions and domestic hygiene on the incidence of ascaridiasis and ancylostomiasis in children two to four years old in the rural zones of Ivory Coast]

The purpose of this study is to assess the impact of improvement measures for hygiene and water supply, installation of latrines and health education on the incidence of ascaridiasis and ankylostomiasis with 2 to 4 years old children in some villages of southern Côte d'Ivoire. The method used is the comparison of children carrying parasites before and after intervention. Initially in 1988, the stools of all children aged from 2 to 4 were collected and examined in order to look for the presence of parasites in the stools. Two identical inquiries were made in 1990 and 1992. The results show a reduction of the rate of incidence for ascaridiasis by 75% and ankylostomiasis by 82%. They demonstrate the importance of an appropriate evacuation of excreta, of an education of mothers and of domestic hygiene in the process of prevention of children parasitosis.

Ascaridia dissimilis larval migration associated with enteritis and low market weights in meat turkeys

A meat turkey ranch had a history of producing flocks with low market weights. Live bird samples and environmental samples from the ranch were collected over a period of eight months and analyzed at the California Veterinary Diagnostic Laboratory System-Turlock Branch. The disease condition consistently present was enteritis associated with Ascaridia dissimilis infection in birds from growout houses. After aggressive control measures for A. dissimilis were implemented, subsequent flocks reached expected market weights.

Evaluation of three water-suspensible formulations of fenbendazole against Ascaridia galli infection in broiler chickens

Three formulations of water-suspensible fenbendazole, at target doses of 30.3 or 60.6 ppm in the drinking water, were administered to broilers infected with Ascaridia galli. The medication was administered in the water through automatic medicators for 6 hours on 3 consecutive days. Three days after treatment, chickens were killed and their worms were counted. Efficacy of fenbendazole was 99.2-100% and 69.0-89.6% at administration doses of 60.6 ppm and 30.3 ppm, respectively. Worm burden and percentage of broilers infected were lower in treated broilers than in controls (P < or = 0.05). Formulation A was dispensed most consistently and in the highest concentration through automatic medicators into the drinking water.

Immunization of chicks at various ages with irradiated infective eggs of Ascaridia galli

The possibility of safe immunization of chicks at an appropriate age with a double-dose irradiated Ascaridia galli vaccine given orally at two weeks interval was explored. Chicks immunized at 7 or 10 days of age were not affected adversely since they did not develop any clinical signs and there was no worm establishment after challenge infection. Immunization also elicited detectable circulating antibody titres, with IHA and the conglutinating complement absorption test having a tendency to be enhanced after the booster dose.

Effect of irradiated Ascaridia galli eggs on growth and cell-mediated immune responses in chickens

Growth and cell-mediated immune (CMI) responses were studied in 7-day-old chicks given orally 1000 irradiated (12.5 kR) or normal infective eggs of Ascaridia galli. Chicks immunised with irradiated eggs showed normal weight gains. CMI responses, as assessed by dinitrofluorobenzene (DNFB)-induced contact and delayed hypersensitivity reactions, were enhanced in the immunised group as compared with healthy controls, suggesting stimulation of CMI responses due to irradiation of A. galli eggs. CMI as well as growth responses were, however, found to be depressed in the birds administered normal infective eggs of A. galli. The present study highlights the role of the CMI response in protection against A. galli infection.