The dynamics of the host-parasite relationship

Parasitology ◽  
1965 ◽  
Vol 55 (3) ◽  
pp. 515-525 ◽  
Author(s):  
J. K. Dineen ◽  
A. D. Donald ◽  
B. M. Wagland ◽  
Jan Offner
Keyword(s):  
Egg Production ◽  
Technical Assistance ◽  
Parasitic Infection ◽  
Immunological Response ◽  
Major Effect ◽  
Infective Larvae ◽  
Parasite Relationship ◽  
Group 3 ◽  
Host Parasite ◽  
Group 1

Two groups of sheep born and raised worm-free were dosed with 3000 infective Haemonchus contortus larvae. Group 1 were each given a single dose of infective larvae on day 0 while the group 3 animals were dosed with 100 infective larvae per day for 30 consecutive days. The results of faecal worm-egg counts performed on alternative days, and of differential worm counts carried out on animals slaughtered at crucial times during the course of infection, showed that retardation of development at the 4th larval stage occurred in the group 3 infections and was the major effect of control of the parasitic burden. There was no evidence that egg production per female was affected.Three animals of the nineteen infected in group 1 died during the course of the experiment owing to the pathogenic effects of the worm burden. Deaths did not occur among the animals of group 3. This finding was correlated with the observation that haematocrit levels were consistently lower among the animals of group 1 than among those of group 3.The results are interpreted in terms of the theory of threshold behaviour of the immunological response to parasitic infection.We are greatly indebted to Dr D. F. Stewart for his interest and constructive criticism during the course of these studies, and to Mr E. Teleki and Misses Helen Giller and Lindy Stothart for their valuable technical assistance.

The dynamics of the host-parasite relationship

Parasitology ◽  
1964 ◽  
Vol 54 (3) ◽  
pp. 527-544 ◽  
Author(s):  
A. D. Donald ◽  
J. K. Dineen ◽  
J. H. Turner ◽  
B. M. Wagland
Keyword(s):  
Single Dose ◽  
Egg Production ◽  
Technical Assistance ◽  
Parasitic Infection ◽  
Treatment Groups ◽  
Infective Larvae ◽  
Total Fecundity ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

The studies presented in this paper describe the effects of control exerted by the immunological response of the host (sheep) on the developmental stages and fecundity of the parasite Nematodirus spathiger. Thirty Merino lambs, maintained worm-free, were randomly divided among three treatment groups each containing ten animals. The group 1 lambs were each given a single dose of 50,000 infective larvae, the group 2 animals were given a single dose of 130,000 infective larvae, and the group 3 animals were given twenty-five consecutive daily doses of 2000 infective larvae. Group fecundity was estimated by performing worm egg counts on daily faecal samples and development of the parasite burden was followed by carrying out differential worm counts on animals slaughtered at crucial stages during the infections. Total fecundity was greatest in group 1 and least in group 3 with group 2 intermediate. An inverse relationship between total fecundity and percentage retardation of development (percentage of 4th-stage larvae in the total worm burden) was demonstrated between the three treatment groups.The results of the studies also show that control of the parasitic infection is mediated about threshold levels of immunological responsiveness and is expressed by (1) elimination at the infective (L3) stage, (2) retardation of development at the L4 stage, (3) reduction in egg production of the adult female, (4) elimination of adult worms, and (5) discrimination against the female in both the degree of retardation in the L4 stage and the extent of elimination in the adult stage.Great variation in response was observed between individuals within treatment groups. The source of variation is attributed to differences in degree of antigenic disparity of the parasite with individual members of the heterozygous host population in which antigenic characters are not uniformly segregated.The concept of ‘fitness’ of the parasitic species was introduced into the discussion to provide a rational interpretation of the results.We are indebted to Dr S. S. Y. Young, Division of Animal Genetics, C.S.I.R.O., for advice and assistance with the statistical analyses, which were performed by Mrs M. Tonkin, and to Dr D. F. Stewart for his constructive criticism of the manuscript. Careful technical assistance was given by Mr E. Teleki and Misses Helen Giller and Berenice Merchant.

The dynamics of the host–parasite relationship IV. The response of sheep to graded and to repeated infection with Haemonchus contortus

Parasitology ◽  
1966 ◽  
Vol 56 (4) ◽  
pp. 639-650 ◽  
Author(s):  
J. K. Dineen ◽  
B. M. Wagland
Keyword(s):  
Haemonchus Contortus ◽  
Egg Production ◽  
Female Worm ◽  
Challenge Infection ◽  
Single Infection ◽  
Infective Larvae ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Consistent Increase ◽  
Host Parasite

In the present experiment the response of sheep to a single infection with Haemonchus contortus at graded doses, and their responses to two subsequent infections with 3000 infective larvae, were studied. The response of the sheep was investigated by estimation of faecal worm egg counts on alternate days throughout the course of the experiment and by following the development of the parasite by differential worm counts performed on animals slaughtered at crucial times.Initial infections were established with graded doses of 500–2700 infective larvae. The proportion of infective larvae which became established at each dose, development of the worm burden and fecundity per adult worm were similar for each dose.Following first challenge infection with 3000 infective larvae there were no effects which could be related to the previous level of infection. Whereas there was no difference in egg production per female worm, a small but consistent increase in the number of retarded larvae was observed in the previously infected animals (6% of the burden was in the 4th larval stage at day 56) compared with the previously uninfected control animals (2% in the 4th stage at day 56).Following a second challenge with 3000 infective larvae an increase in the number of retarded larvae was again observed, and, in addition, egg production per female worm was reduced compared with egg production in previously uninfected sheep given a similar challenge infection.The results of the initial infections suggest that control of the growth and development of H. contortus infection by factors independent of an active host response does not occur in worm burdens established from doses as high as 2700 infective larvae.

The dynamics of the host–parasite relationship

Parasitology ◽  
1966 ◽  
Vol 56 (4) ◽  
pp. 665-677 ◽  
Author(s):  
J. K. Dineen ◽  
B. M. Wagland
Keyword(s):  
Larval Stage ◽  
Challenge Infection ◽  
Immune Mechanism ◽  
Control Groups ◽  
Infective Larvae ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Group 3 ◽  
Group 5 ◽  
Host Parasite

The response of sheep given six sensitizing infections each of 3000 infective larvae of H. contortus at fortnightly intervals to a challenge infection of 3000 infective larvae has been studied. While a large proportion of the challenge infection (ca. 3000 parasites) persisted to termination of the experiment on day 141 in sheep (group 3) in which the challenge was superimposed upon the sensitizing infections, only a mean of 437 worms, including both 4th-stage larvae and adults, was recorded at this time in another group (group 5) in which the sensitizing infections were terminated by anthelmintic treatment on day 90, i.e. 8 days before challenge. The proportion of the total worm burdens of the challenge infections arrested at the 4th larval stage was increased for both groups (25% for group 3 and 18% for group 5) by comparison with unsensitized control groups (4% for group 6 and 2% for group 7).As the effect of immunological control was expressed more vigorously in the group (group 5) in which the sensitizing infections were terminated before challenge it seems likely that recovery of immunological competence occurred in these animals following removal of the sensitizing infections. This conclusion suggests that, owing to the persistence of the sensitizing infections and therefore exposure of the immune mechanism to continuous antigenic insult, the animals which received the superimposed challenge infection had entered a phase of immunological exhaustion during the challenge period.

The dynamics of the host–parasite relationship

Parasitology ◽  
1967 ◽  
Vol 57 (1) ◽  
pp. 59-65 ◽  
Author(s):  
B. M. Wagland ◽  
J. K. Dineen
Keyword(s):  
Technical Assistance ◽  
Immunological Response ◽  
Developmental Rate ◽  
Threshold Behaviour ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Relationship Of ◽  
The Relationship ◽  
Immunological Attack

A group of thirty-nine Merino-Border Leicester cross-bred lambs were given six sensitizing doses each of 3000 infective Haemonchus contortus larvae. Previous studies showed that this treatment produced a state of immunological exhaustion (Dineen & Wagland, 1966a). In the present study the regeneration of the immunological response was followed by challenging the sensitized animals and previously uninfected control animals with 3000 infective larvae at 2, 4, 8 and 16 weeks after termination of the sensitizing infections with an anthelmintic. Faecal egg counts were carried out on infected animals twice weekly throughout the course of the experiment, and differential worm counts were performed on groups of animals slaughtered 48 days after challenge.The results show that maximum regeneration of the immune response occurred when periods of 4 and 8 weeks were permitted to elapse between removal of the sensitizing infections and challenge. At 16 weeks the response of the sensitized animals to challenge infection was not significantly different from that of the control animals.In contrast to results recorded in the previous communication, a high mortality (49%) occurred among the sheep during sensitization. In the earlier experiment the sensitizing infections were given at fortnightly intervals whereas they were given at weekly intervals in the present experiment.Interpretation of the study is based upon the threshold behaviour of immunological responsiveness in parasite immunity, the occurrence of an immunological latent period and the relationship of this period to the developmental rate of the parasite, the susceptibility of the 4th larval stage to immunological attack, and the immunological privilege of the adult worm. These phenomena have been described in previous communications in the present series.We are greatly indebted to Mr Emil Teleki and Misses Helen Giller and Lindy Stothart for their excellent technical assistance.

Virulence of the cestode Schistocephalus solidus and reproduction in infected threespine stickleback, Gasterosteus aculeatus

1999 ◽  
Vol 77 (12) ◽  
pp. 1967-1974 ◽  
Author(s):  
David C Heins ◽  
Scarlet S Singer ◽  
John A Baker
Keyword(s):  
Gasterosteus Aculeatus ◽  
Parasitic Infection ◽  
Population Level ◽  
Reproductive Period ◽  
Threespine Stickleback ◽  
South Central ◽  
Schistocephalus Solidus ◽  
Chi Squared ◽  
Parasite Relationship ◽  
Host Parasite

We investigated the relationship between reproduction in the threespine stickleback (Gasterosteus aculeatus) and parasitism by plerocercoids of the cestode Schistocephalus solidus in Walby Lake, Alaska, by quantifying stickleback reproduction and parasite infection using 1655 fish from four samples collected in 1990-1996. Stickleback in Walby Lake largely spawned during May and June as 2-year-olds in the second spring-summer after hatching, as was the case with other stickleback populations we studied in south-central Alaska. Contrary to an earlier hypothesis that S. solidus has been selected to delay its deleterious effects on threespine stickleback, i.e., limit its infection levels, until after the stickleback have reproduced, substantial levels of parasitic infection co-occurred with the stickleback reproductive period. Chi-squared analyses of individual samples suggested that in May, infected females were as capable of producing clutches of eggs as uninfected females but in June, S. solidus inhibited clutch production. An overall analysis, however, failed to support the hypothesis that the effect of S. solidus on clutch production differed between early and late periods of the spawning season. We concluded that S. solidus inhibits the ability of female stickleback in Walby Lake to produce a clutch, and that there was no differential effect on clutch production with season. Nonetheless, 77% of all infected females produced clutches. These results contrast with those of one study in which it was found only 9% of infected females became gravid (ripe) and another report that 23% of infected females were able to mature. We offer hypotheses for the co-occurrence of stickleback reproduction and substantial parasitism at the population level and for the ability of a large proportion of infected females to produce clutches. Our results suggest that the host-parasite relationship is more complex than was previously realized.

Antagonistic effect of predacious Arthrobotrys fungi on infective Haemonchus placei larvae

1993 ◽  
Vol 67 (2) ◽  
pp. 136-138 ◽  
Author(s):  
J. V. Araújo ◽  
M. A. Santos ◽  
S. Ferraz ◽  
A. S. Maia
Keyword(s):  
Laboratory Experiments ◽  
Antagonistic Effect ◽  
Fungus Species ◽  
Infective Larvae ◽  
Group 3 ◽  
Group 2 ◽  
Predatory Capacity ◽  
Arthrobotrys Conoides ◽  
Haemonchus Placei ◽  
Group 1

AbstractLaboratory experiments were performed to investigate the ability of isolates from the predacious fungus species Arthrobotrys conoides (one isolate) and A. robusta (four isolates) to trap and kill infective Haemonchus placei larvae. Three groups for each isolate were formed: group 1, fungi and infective larvae; group 2, fungi; group 3, infective larvae. There were statistically significant differences (P<0.05) between the antagonistic effects of three isolates of A. robusta, but there was no such difference between the isolate of A. conoides and isolates of A. robusta. This result indicates that there can be a variation in the predatory capacity of different isolates within a single fungus species. After 20 days of assay, there was greater recuperation of infective H. placei larvae in group 3 compared to group 1.

scholarly journals Parasitic infection: a missing piece of the ocean acidification puzzle

2016 ◽  
Vol 74 (4) ◽  
pp. 929-933 ◽  
Author(s):  
Colin D. MacLeod
Keyword(s):  
Ocean Acidification ◽  
Parasitic Infection ◽  
Simulation Models ◽  
Scientific Discipline ◽  
Multiple Stressor ◽  
Great Insight ◽  
Parasite Relationship ◽  
Mesocosm Experiments ◽  
Host Parasite ◽  
Near Future

Ocean acidification (OA) research has matured into a sophisticated experimental and theoretical scientific discipline, which now utilizes multiple stressor, mesocosm experiments, and mathematical simulation models to predict the near-future effects of continued acidification on marine ecosystems. These advanced methodological approaches to OA research also include the study of inter-specific interactions that could be disrupted if participant species exhibit differential tolerances to stressors associated with OA. The host-parasite relationship is one of the most fundamental ecological interactions, alongside competition and predation, which can regulate individuals, populations, and communities. The recent integration of competition and predation into OA research has provided great insight into the potential effects of differential tolerances to acidified seawater, and there is no reason to believe that expanding OA research to include parasitology will be less fruitful. This essay outlines our current, limited understanding of how OA will affect parasitism as an ecological process, describes potential pitfalls for researchers who ignore parasites and the effects of infection, and suggests ways of developing parasitology as a sub-field of OA research.

The effects of host sex and age on the host-parasite relationship of the third-stage larva of Amplicaecum robertsi Sprent & Mines, 1960, in the laboratory rat

Parasitology ◽  
1965 ◽  
Vol 55 (2) ◽  
pp. 303-311 ◽  
Author(s):  
Colin Dobson
Keyword(s):  
Technical Assistance ◽  
Female Rats ◽  
Male Rats ◽  
Suckling Rats ◽  
Research Fellowship ◽  
Host Sex ◽  
Parasite Relationship ◽  
Senior Research ◽  
Host Parasite ◽  
Relationship Of

Male rats were more susceptible than female rats to experimental infection with Amplicaecum robertsi. This sex difference first appeared at the time of puberty, i.e. about 50 days of age.Suckling rats were less susceptible to infection than weanlings. This was attributed to the cumulative effects of intestinal structure, the indirect effects of milk on the physio-chemical factors in the gut, and the direct effects of milk on the worms themselves.The rat showed an age resistance to A. robertsi: this was greatest in the female host.The larvae recovered from females were shorter than those recovered from male rats except in immature animals.The longest larvae were recovered from suckling rats: in old rats the length of the larvae recovered became progressively shorter as the animals aged.This investigation was carried out during the tenure of a Senior Research Fellowship from the Wool Research Council of Australia. I should like to thank Professor J. F. A. Sprent for his help and Mr C. Wilkinson for his technical assistance.

The dynamics of the host-parasite relationship

Parasitology ◽  
1965 ◽  
Vol 55 (1) ◽  
pp. 163-171 ◽  
Author(s):  
J. K. Dineen ◽  
A. D. Donald ◽  
B. M. Wagland ◽  
J. H. Turner
Keyword(s):  
Primary Infection ◽  
Technical Assistance ◽  
Secondary Infection ◽  
Challenge Infection ◽  
Egg Laying ◽  
Control Group ◽  
Initial Infection ◽  
Parasite Relationship ◽  
Highly Correlated ◽  
Host Parasite

The present studies were designed to characterize the response of sheep infected with N. spathiger to challenge infection with the same species.The results showed that: (1) the level of worm counts attained on secondary infection with the parasite was much reduced compared with the counts recorded following initial infection; (2) the relative fecundities of parasite populations which developed in individual hosts following challenge infection, ranked in magnitude in an order which was similar to that established following initial infection; (3) as fecundity was highly correlated with the number of egg-laying females and the number of males and females was nearly equal in individual specimens, it was concluded that worm burdens were also ranked for individual animals on primary infection and following challenge; and (4) the animals of the control group remained as susceptible as the animals of groups 1 and 3 at the time of their primary infection; consequently, in the absence of previous immunological experience due to infection, there was no apparent change in susceptibility of the animals due to an effect of age during the course of the 17 weeks of the experiment.We are greatly indebted to Dr Michael Tallis, Division of Mathematical Statistics, C.S.I.R.O., for advice and assistance with the statistical analyses, and to Dr D. F. Stewart for his interest and constructive criticism during the course of these studies. Our thanks are also due to Mr E. Teleki and Misses Helen Giller and Lindy Stothart for their valuable technical assistance.

Remote sensing of intraperitoneal parasitism by the host's brain: regional changes of c-fos gene expression in the brain of feminized cysticercotic male mice

Parasitology ◽  
2004 ◽  
Vol 128 (3) ◽  
pp. 343-351 ◽  
Author(s):  
J. MORALES-MONTOR ◽  
I. ARRIETA ◽  
L. I. DEL CASTILLO ◽  
M. RODRÍGUEZ-DORANTES ◽  
M. A. CERBÓN ◽  
...  
Keyword(s):  
Parasitic Infection ◽  
Stressful Events ◽  
Male Mice ◽  
Infected Male ◽  
Sexual Stimulation ◽  
Interactive Network ◽  
Parasite Relationship ◽  
Cns Activity ◽  
Host Parasite ◽  
The Brain

Experimental intraperitoneal Taenia crassiceps cysticercosis in mice exhibits distinct genetical, immunological and endocrinological features possibly resulting from the complex interactive network of their physiological systems. Very notable is the tendency of parasites to grow faster in hosts of the female sex. It is also remarkable in the feminization process that the infection induces in chronically infected male mice, characterized by their estrogenization, deandrogenization and loss of sexual and aggressive patterns of behaviour. The proto-oncogene c-fos is a sex steroid-regulated transcription factor gene, expressed basally and upon stimulation by many organisms. In the CNS of rodents, c-fos is found expressed in association to sexual stimulation and to various immunological and stressful events. Hence, we suspected that changes in c-fos expression in the brain could be involved in the feminization of the infected male mice. Indeed, it was found that c-fos expression increased at different times during infection in the hypothalamus, hippocampus, less so in the preoptic area and cortex, and not in several other organs. The significant and distinctive regional changes of c-fos in the CNS of infected mice indicate that the brain of the host senses intraperitoneal cysticercosis and may also announce its active participation in the regulation of the host–parasite relationship. Possibly, the host's CNS activity is involved in the network that regulates the estrogenization and deandrogenization observed in the chronically infected male mice, as well as in the behavioural and immunological peculiarities observed in this parasitic infection.

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