Protective efficacy of Barbervax® in Merino weaner sheep trickle infected with five doses of Haemonchus contortus infective larvae

2021 ◽  
pp. 109386
Author(s):  
M.M. Kebeta ◽  
B.C. Hine ◽  
S.W. Walkden-Brown ◽  
L.P. Kahn ◽  
E.K. Doyle
Keyword(s):  
Haemonchus Contortus ◽  
Protective Efficacy ◽  
Infective Larvae

Improved Methods of Obtaining Clean Larvae of Haemonchus contortus

1963 ◽  
Vol 37 (4) ◽  
pp. 251-254 ◽  
Author(s):  
M. G. Christie ◽  
J. E. Patterson
Keyword(s):  
Free Surface ◽  
Surface Area ◽  
Haemonchus Contortus ◽  
Water Repellent ◽  
Optimum Conditions ◽  
Infective Larvae ◽  
Mucous Coat ◽  
Third Stage ◽  
Free Surface Area ◽  
Improved Methods

A pellet of sheep faeces containing eggs of Haemonchus contortus forms an adequate environment for the development of those eggs to third stage infective larvae, provided that it is kept moist. Observation shows a concentration of developing larvae on the external mucous coat of the pellet. These data suggest that optimum conditions for development would occur when pellets are separated one from another and standing on a water repellent surface, thus presenting the maximum free surface area and minimum opportunity for aggregation and hence of over crowding. The best method of recovering the infective larvae would be one that obtained larvae free from contamination without requiring them to expend energy in separating themselves from the contamination.

Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp. and on the immunological reactions of sheep exposed to infestation. I. The preparation of antigens for the complement fixation test and the reactivity of the biochemical fractions of H. contortus

1950 ◽  
Vol 1 (3) ◽  
pp. 285 ◽  
Author(s):  
DF Stewart
Keyword(s):  
Haemonchus Contortus ◽  
Complement Fixation Test ◽  
Complement Fixation ◽  
Fixation Test ◽  
Mature Adult ◽  
Infective Larvae ◽  
Lipid Fractions ◽  
Significant Difference ◽  
Third Stage ◽  
Free Material

All antigen was developed to detect circulating antibodies by means of the complement fixation test in sheep infested with Haemonchus contortus and Trichostrongylus spp. Extraction of worm material at 100°C. for 10 minutes was found to be the most satisfactory method for the preparation of antigens. Potent antigens were prepared from young adult H. contortus, from third-stage infective larvae, and from the eggs. Old mature adult H. contortus yielded antigens of low potency. No significant difference was found between the potency of antigens prepared from male and female adult H. contortus collected from the same sheep. Both adult Trichostrongylus spp. and third-stage infective larvae consistently yielded antigens of high potency. No significant difference was found in the results obtained with larval or adult H. contortus antigens, adjusted to the same potency and tested with natural H. contortus antisera. H. contortus and Trichostrongylus spp. absorbed the antiserum to each other. It was shown that a lipid was an essential constituent of the boiled antigen in the complement fixation reaction with natural antisera. Lipid-free antigens from H. contortus failed to react with natural antisera. The lipid was not antigenic when injected into rabbits. The carbohydrate fraction of H. contortus did not fix complement in the presence of natural antisera and was not antigenic when injected into rabbits. The lipid fraction of a variety of nematode parasites reacted with natural antisera to H. contortus infestation. Similar lipid fractions of two species of trematodes did not react with natural antisera to H. contortus infestation. Normal saline suspensions of the lipid-free material from a variety of helminths showed a greater degree of specificity when tested with artificially prepared antisera than did the lipid fractions.

Kinetics of exsheathment of infective ovine and bovine strongylid larvae in vivo and in vitro

Parasitology ◽  
2002 ◽  
Vol 125 (1) ◽  
pp. 65-70 ◽  
Author(s):  
H. HERTZBERG ◽  
U. HUWYLER ◽  
L. KOHLER ◽  
St REHBEIN ◽  
M. WANNER
Keyword(s):  
Haemonchus Contortus ◽  
Buffer System ◽  
Bicarbonate Concentration ◽  
Infective Larvae ◽  
Nylon Mesh ◽  
Mesh Bags ◽  
Sheep Rumen ◽  
Kinetics Of

The aim of the study was to investigate the longitudinal changes of exsheathment of ovine and bovine 3rd-stage strongylid larvae in an artificial rumen (RUSITEC) and to compare the results with in vivo data obtained from rumen-fistulated sheep. Infective larvae were incubated in nylon mesh bags in the sheep rumen or the RUSITEC apparatus for periods of 1, 6 and 12 h, respectively. The 12 h exsheathment rates in the rumen and the RUSITEC apparatus (in parentheses) were as follows: Haemonchus contortus: 100% (100%), Ostertagia circumcincta: 100% (76%), O. leptospicularis: 100% (100%), O. ostertagi: 53% (59%), Trichostrongylus axei: 100% (100%), T. colubriformis: 37% (36%), Cooperia curticei: 94% (76%), C. oncophora: 95% (89%), Nematodirus filicollis: 0% (N.D.), N. spathiger: 11% (15%), N. battus: 7% (5%), Oesophagostomum venulosum: 17% (9%), Chabertia ovina: 7% (2%), Dictyocaulus filaria: 1% (N.D.). Larvae of Nematodirus spp. and T. colubriformis showed a quick rise of the exsheathment rate 2 h after transfer into the abomasum. These results confirm that exsheathment generally occurs in the part of the gastrointestinal tract immediately anterior to the habitat of the adult parasite. The overall similar course of exsheathment in both systems indicates that the essential stimuli for exsheathment were generated and maintained under in vitro conditions of the artificial rumen. In both systems, the bicarbonate concentration and the pH reflected a similar status of the H2CO3/HCO buffer system, which is known to provide the essential stimuli for larval exsheathment of the abomasal species. These results give evidence that the RUSITEC system represents a valid system for studying the kinetics of exsheathment of strongylid nematodes under in vitro conditions. For 7 of the species investigated the obtained results represent the first data on larval exsheathment in vivo and in vitro.

Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp. and on the immunological reactions of sheep exposed to infestation. III. The antibody response to infestation with Trichostrongylus spp.

1950 ◽  
Vol 1 (4) ◽  
pp. 413 ◽  
Author(s):  
DF Stewart
Keyword(s):  
Antibody Response ◽  
Haemonchus Contortus ◽  
Complement Fixation Test ◽  
Complement Fixation ◽  
Immunological Response ◽  
Serological Response ◽  
Apparent Effect ◽  
Relative Resistance ◽  
Infective Larvae ◽  
Immunological Reactions

In infestation of sheep with Trichostrongylus spp., both the intake of larvae and infestation with adult worms stimulated the production of antibodies. The character of the antibody response in infestation with Trichostrongylus spp. thus differed from that caused by Haemonchus contortus. Sera of sheep dying from infestation with Trichostrongylus spp. were negative to the complement fixation test. It was found that older sheep responded serologically earlier and more vigorously to infestation with Trichostrongylus spp. than did young sheep. Subsequent doses of larvae of Trichostrongylus spp. elicited a more rapid and grester serological response, even in young sheep, than an initial dose of larvae. Previous infestation with H. contortus did not result in resistance to Trichostrongylus spp., whereas previous infestation with Trichostrongylus spp. heightened the resistance of sheep to subsequent infestation with the same species. It is concluded that the relative resistance of older sheep to Trichostrongylus spp. is due, a t least in part, to an earlier immunological response which is strengthened by subsequent doses of larvae. When infective larvae of Trichostrongylus spp. were superimposed upon an existing infestation of the same species, the egg count declined ;apidly and the development of the superimposed larvae resisted Doses of infective larvae of Trichostrongylus spp. had no apparent effect on the egg counts of sheep infested with H. contortus.

In vitro trapping capability of Arthrobotrys spp. on infective larvae of Haemonchus contortus and Nacobbus aberrans

1994 ◽  
Vol 68 (3) ◽  
pp. 223-229 ◽  
Author(s):  
P. Mendoza-de Gives ◽  
E. Zavaleta-Mejia ◽  
D. Herrera-Rodriguez ◽  
H. Quiróz-Romero
Keyword(s):  
Microscopic Examination ◽  
Haemonchus Contortus ◽  
Three Dimensional ◽  
Arthrobotrys Oligospora ◽  
Second Stage ◽  
Infective Larvae ◽  
Third Stage ◽  
Nacobbus Aberrans

AbstractThe trapping capability of Arthrobotrys oligospora and A. conoides (Hyphomycetales) against third stage larvae (L3) of Haemonchus contortus (Trichostrongylidae) was evaluated in an in vitro trial. Arthrobotrys oligospora showed a 35.87% and 25.71% trapping effectiveness against H. contortus infective larvae at 18 and 25°C, respectively; whereas the trapping capability of A. conoides was 92.17% and 90.40% at the same temperatures, respectively. Microscopic examination demonstrated that A. conoides spontaneously developed a large quantity of three-dimensional loops before the nematodes were added. Neither of the two species studied developed three-dimensional adhesive loops at 30°C, consequently no trapped nematode was observed. In a second trial, the trapping capability of A. conoides against H. contortus (L3) and second stage larvae (J2) of Nacobbus aberrans (Pratylenchidae), was evaluated at 25°C. The trapping capability shown by A. conoides was higher than 90% for both kinds of nematode. The possible use of A. conoides to control ovine haemonchosis is discussed.

Assessment of acquired resistance in previously infected lambs with gastrointestinal nematodes in a tropical climate

2018 ◽  
Author(s):  
R. González Garduño ◽  
M.E. López-Arellano ◽  
G. Torres-Hernández ◽  
J. Oliva-Hernández ◽  
J.A. Hinojosa-Cuéllar
Keyword(s):  
Body Weight ◽  
Post Infection ◽  
Haemonchus Contortus ◽  
Acquired Resistance ◽  
Parasitic Infection ◽  
Tropical Climate ◽  
Gastrointestinal Nematodes ◽  
Infective Larvae ◽  
Oral Doses ◽  
Different Doses

The aim of this study was to determine the parasitological traits and productive response in Pelibuey lambs re-infected with gastrointestinal nematodes (GIN) previously infected with different doses of infective larvae (L3). One infection with 60% Haemonchus contortus and 40% Cooperia curticei larvae was induced in three groups of six lambs using oral doses of 100, 200 and 300 L3 per kg of body weight (BW), respectively. Nine weeks post-infection all lambs were treated with albendazole (ABZ). A second parasitic infection was induced using 300 L3 per BW followed for six weeks of parasitological sampled and four lambs of each treatment were slaughtered after this period to count adult nematodes. Results showed reduction of eggs per gram of faeces (EPG) between first (2463±4400 EPG) to second infection (327±66 EPG) for pre-infected lambs with 300 L3. Through first infection, the packed cell volume (PCV) decreased until 35 days post-infection (32.0% to 26.0%) for all groups. In conclusion Pelibuey lambs infected with 300 L3 showed low re-infection to contribute in the reduction of parasitic traits under tropical climate.

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