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At least 19 recordsLinked to original sources
PubMed1995

Regulation of egg production, worm burden, worm length and worm fecundity by host responses in sheep infected with Ostertagia circumcincta.

Following infection with Ostertagia circumcincta there was considerable variation in worm burdens, worm size and number of inhibited larvae even among sheep matched for age, sex, breed, farm of origin and history of parasite exposure. There was also substantial variation among sheep in the concentration of mast cells, globule leucocytes, eosinophils, IgA-positive plasma cells and parasite-specific IgA in the abomasal mucosa. With the exception of faecal egg counts over time, the parasitological and immunological traits were all continually distributed among animals and sheep did not fall into discrete high and low-responder categories. The responses were correlated. Sheep with more mast cells also had more globule leucocytes, more eosinophils, more IgA plasma cells and greater amounts of parasite-specific IgA in the abomasal mucosa. Female worm length was strongly and positively correlated with the number of eggs in utero. Faecal egg counts were associated with variation in worm number and with variation in the number of eggs in utero. The worm burden was negatively correlated with the number of globule leucocytes in the abomasal mucosa, suggesting that worm numbers are regulated by immediate hypersensitivity reactions. Decreased female worm length was associated with an increased local IgA response to fourth stage larvae. The number of inhibited larvae was positively associated with the size of the local IgA response and positively associated with the size of the worm burden. The results suggest that variation among mature sheep in faecal egg counts is due, at least in part, to variation in local IgA responses which regulate worm fecundity and to variation in local immediate hypersensitivity reactions which regulate worm burdens.

Animals↗
PubMed1994

Inhibitory effects of concurrently present 'normal' Nippostrongylus brasiliensis worms on expulsion of 'damaged' worms and associated goblet cell changes in rats.

Nippostrongylus brasiliensis worms obtained from the stable phase of a primary infection ('normal' worms) are able to establish and survive in naïve recipient rats into which they have been adoptively transferred, whereas those obtained at the time of expulsion ('damaged' worms) are rapidly expelled. Expulsion is associated with quantitative/qualitative goblet cell changes. Thus, N. brasiliensis adult worms seem to stimulate the expulsion process only after being 'damaged' by the host's immunity, whereas it is possible that 'normal' worms may inhibit the expulsion process. To see whether 'normal' worms have such inhibitory effects, the fate of concurrently implanted 'normal' and 'damaged' worms was examined with reference to goblet cell changes in the intestine. By using either male or female worms as 'normal' or 'damaged' populations, it was possible to determine the origin of worms remaining in the intestine. The results show that not only 'normal' worms but also 'damaged' worms, which would normally be expelled, remained in the intestines of the recipients on Day five. Goblet cell hyperplasia and alteration of terminal sugars of mucins, which was induced within five days after implantation of 'damaged' worms, were completely inhibited by the concurrent presence of 'normal' worms. The inhibitory effects of 'normal' worms were destroyed when they were killed by heating before implantation. Possible mechanisms leading to expulsion of N. brasiliensis are discussed.

Animals↗
PubMed1984

Reproductive development of female Schistosoma mansoni (Digenea: Schistosomatidae) following bisexual pairing of worms and worm segments.

Maturation and maintenance of normal reproductive function in female Schistosoma mansoni require a permanent association with the male, but the nature of this relationship is not well understood. The regional localization of a stimulatory factor in the male and its target in the female were investigated. Unisexual female and mature male worms were transected into segments of various lengths. Various combinations of transected male and female segments and intact worms were transferred to the mesenteric veins of recipient hamsters and were also maintained in vitro. In hamsters and in vitro, pairing took place between intact worms of each sex and segments of the other, and between segments of both sexes. The majority of female worms and segments so paired showed some reproductive development, as assessed by vitelline gland differentiation. In intact unisexual females paired with small male segments, vitelline gland development was limited to that portion of the worm that had been held by the male. Worm segments continued to display normal body contractions throughout 24 days of in vitro maintenance and morphological integrity was retained. It is concluded that 1) in the absence of a functioning gut, worm segments can survive for prolonged periods on nutrients absorbed through the tegument; 2) worm pairing, male stimulation, and the female developmental response are independent of central nervous control by the cerebral ganglia; 3) males have no centralized localization for the female-stimulating factor; 4) vitelline gland differentiation in the female requires local stimulation through male contact, and this is not propagated throughout the worm.

Animals↗
PubMed1988

Trichinella spiralis: quantitative relationships between intestinal worm burden, worm rejection, and the measurement of intestinal immunity in inbred mice.

The effect of widely different doses of Trichinella spiralis muscle larvae on time to rejection of intestinal adults and on host survival was assessed in mice of the three rejection phenotypes; strong, intermediate, and weak. Rejection is weak with doses of less than 50 larvae per mouse. At these doses all mice rejected worms at a similar rate and no phenotypic variation was evident among strains. In contrast, rejection time was shortest for all strains and phenotypic variation among strains was evident in the range 50-100 muscle larvae/mouse. Above this dose the time taken to rejection increases monotonically with dose for all mouse strains examined. Despite this, the relative strength of rejection (i.e., phenotype) of a given strain of mouse was not changed at higher doses. Based on an end point of 98% rejection of the infective dose, time to rejection was predictable to +/- 1 day for all mouse strains and doses tested over the range 100-1000 worms administered. The principal reason for the increased time to complete rejection with larger worm doses was a delay in the initiation of intestinal rejection. This delay was evident above a dose of 50-100 larvae per mouse and occurred in all strains. Once begun, rejection was faster and eliminated more worms in unit time at higher doses (400-800 more) than at lower doses of worms. This appeared to be due to a stronger immune response of the host at higher doses. However, the increase in the rate of rejection was still not as great as the increase in the dose. We postulate that the delay in rejection with increased dose is due to a requirement for a "critical mass" of effectors/worm required to cause rejection. As dose increases, more time is required to reach the level at which worm rejection commences. Deaths due to higher doses of worms also occurred in a strain-specific manner and were temporally biphasic. The intestinal phase of infection produced mortality from 1 to 5 days after infection and the strongest rejection phenotype (NFS) was also the most resistant to intestinal deaths. Deaths occurring after Day 5 were due to the parenterally migrating newborn larvae. The weakest rejection phenotype, that of the B10 congenics, was also the least resistant to intestinal deaths. An experimental formula describing 98% worm rejection time with different doses was derived from the data.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1980

Accelerated rejection of Nematospiroides dubius intestinal worms in mice sensitized with adult worms.

After oral administration of infective third stage larvae (L3) of Nematospiroides dubius to young mice, intestinal worms persist for many weeks. However, in mice injected parenterally with N. dubius adult worms, the intraluminal intestinal infection arising after L3 administration can be terminated within 3 to 4 weeks. This accelerated rejection is seen in sensitized BALB/c mice (and (CBA/H X BALB/c)F1 mice) and in particular females, but has not been demonstrated in sensitized CBA/H mice. In female BALB/c mice, small numbers of living worms are more effective at sensitization than dead worms, intraperitoneal and subcutaneous implantations are both effective, and products from adult worms incubated in vitro (i.e. "excretory/secretory" (ES) products) will sensitize but only with very high doses in adjuvant. Using appropriate isolated antigen preparations, comparative immunoparasitological analyses in different mice should provide clues on the nature of host-protective immunities against intestinal nematode infections which are potentially chronic. From the present studies, two groups which differ most dramatically in the consequences of adult worm sensitization are young male CBA/H versus older female BALB/c mice.

Animals↗
PubMed1976

Host-parasite relationships of Fasciola hepatica in the white mouse. VII. effects of anti-worm incubate sera on transferred worms and successful vaccination with a crude incubate antigen.

Mouse antisera against the 16-day-old worm incubate and sera from 25-day infections in mice debilitated migrating flukes in recipient animals as measured by worm recovery and host mortality. Mouse antisomatic and 100-day infection sera produced no such effects. Host mortality was significantly lower after challenge in mice given one ip immunizing injection of the worm incubate; however, worm recovery was not significantly reduced. Injections at 2, 7, 12, and 24 hr with the worm incubate elaborated over a 24-hr period protected 75% of the mice from infection after challenge, and reduced the worm burden by 83.3%.

Animals↗
PubMed1975

Nippostrongylus brasiliensis: further properties of antibody-damaged worms and induction of comparable damage by maintaining worms in vitro.

When adult Nippostrongylus brasiliensis were maintained in vitro they became damaged. Using the criteria of ultrastructural morphology, acetylcholinesterase isoenzyme pattern and the behaviour of the worms after transfer to a normal rat, this damage appeared to be similar to that produced by the in vivo action of antibodies. Antibodies were shown to be responsible for the anterior migration of adult worms which occurs during primary infections in mature rats and in the prolonged infections seen in lactating and immature rats. Antibody damaged worms and worms unaffected by antibodies were equally able to stimulate the immune response required for worm expulsion. Apparently antibody damage is not required for the initiation of the second immune component necessary for expulsion of this parasite.

Acetylcholinesterase↗
PubMed1997

Prevalence of infection, mean worm burden and degree of worm aggregation as determinants of prevalence of disease due to intestinal helminths.

Theoretical predictions of disease prevalence due to helminth infections based upon a simple probabilistic model which considers the infection prevalence, the mean worm burden and the degree of worm aggregation are presented. A numerical reappraisal of the likely estimates of the degree of aggregation based upon maximum likelihood estimates of the negative binomial distribution is presented. The prevalence of disease shows a positive relationship with the mean worm burden. This association is hyperbolic when helminth parasites are severely aggregated but is s-shaped when helminth parasites tend to be overdispersed. The prevalence of disease decreases with the degree of worm aggregation when the values of the mean intensity are low; as the mean intensity increases this association becomes positive. The relationship between prevalence of disease and prevalence of infection is hyperbolic for severe degrees of parasite aggregation and is s-shaped for intermediate degrees of aggregation. However, if the mean intensity is low and the degree of aggregation is high there could be a negative relationship between the prevalence of disease and the prevalence of infection. The presence of disease due to helminth parasites is feasible for determined ranges of values of the infection prevalence, mean intensity and the degree of worm clumping.

Animals↗
PubMed1997

"Stupidity or worms": do intestinal worms impair mental performance?

The title of a 1930s article asked the question, "Stupidity or Hookworm?" In this article, the authors discuss research that attempts to answer the question of whether intestinal worms--namely, hookworm, whipworm, and roundworm--harm the mental performance of their hosts. After introducing the biology and epidemiology of intestinal worms, the authors present the historical background to the problem. They review research from the 1910s through the 1990s; there is evidence that high intensities of worms can affect mental performance, but not all dewormed children show improved performance. They discuss the mechanisms of how worms might affect the mind.

Ancylostomatoidea↗
PubMed2006

Surgery still opens an unexpected bag of worms! An intraperitoneal live female Dirofilaria worm: case report and review of the literature.

BACKGROUND: Intra-abdominal filarial infection is extremely rare. METHODS: Case report and review of the literature. RESULTS: A 63-year-old man presented with a painful swelling in the peri-umbilical area. An urgent laparotomy was performed for suspected strangulated peri-umbilical hernia. A live intraperitoneal worm was retrieved during the repair of the hernial sac that proved to be a female Dirofilaria immitis. CONCLUSIONS: Only one previous case of intraperitoneal involvement by dirofilariasis is described in the medical literature. Ours is the first case report of a live dirofilarial worm in the abdominal cavity of a human being.

Abdominal Cavity↗
PubMed1998

Age-related worm load and worm fecundity patterns in human populations, as indicated by schistosome circulating antigens.

Recently, our group determined the relationship between serum CAA levels and fecal egg counts in two foci with very intense Schistosoma mansoni transmission: Maniema (Zaire), an area endemic for S. mansoni since several decades, and Ndombo (Senegal), where transmission has only been established since a few years. The objective was to study and compare age-related worm load and worm fecundity patterns in these two different endemic settings. Here, we will summarize the most important findings and conclusions of this study.

Africa↗
PubMedDate not supplied

[Characteristics of the fine structure of embryonic membranes in the spiny-headed worms of the class Eoacanthocephala, by an example of the spiny-headed worm species Neoechinorhynchus crassus].

Five embryonic membranes are found in the spiny-headed worm species Neoechinorhynchus crassus. Four embryonic membranes are analogous to the membranes in all other spiny-headed worms studied, and one membrane is additional. The last is situated between the external and second membranes and is characteristic only for some species of the class Eoacanthocephala. Terminology of the embryonic membranes in connection with their origin and possible functional significance is discussed.

Acanthocephala↗
PubMed1989

Epidemiological studies on guinea-worm in some newly discovered villages of Jhabua District (M.P.) and test of carica papaya leaves of guinea worm infection.

Epidemiological survey was carried out for prevalence of guinea worm infection in 12 villages having a total population of 10281 persons in Jhabua district of M.P. The prevalence of 2.85 percent. Infection was more common in males. A paste of leaves of carica papya with opium and common salt applied for 3 days was helpful in relief of symptoms and easy extraction of worm from the body.

Adolescent↗
PubMed1995

[Parasitologic significance of the alteration of the causative Anisakidae worm and of the Pseudoterranova decipiens female immature adult worm, casting off the cuticles, and excreted from human in Kanazawa City].

We have been studying Anisakidae larvae, their intermediate hosts and their final hosts in the northern Japan Sea area. These larvae cause anisakidosis. According to the investigation, the recent burst of pseudoterranovosis in this area can be attributed to the increased presence of sea lions, which proliferate in the Arctic region, then migrate to the northern Japan Sea and eat the intermediate host fish. In a stomach of a male sea lion that was captured in February 1995, we found more than 4,500 Pseudoterranova decipiens. Although there is no known circumstance in which a human would consume an adult worm of Anisakis nematode, an astonishing case of this was found in Kanazawa; a female young adult Pseudoterranova decipiens undergoing the final metamorphosis was emitted from a patient. This indicates that the Anisakis larva can mature into the adult worm in humans. It is postulated that the Pseudoterranova decipiens larva is in the process of adapting to use humans as the final host.

Adult↗
PubMed2004

Increases in human T helper 2 cytokine responses to Schistosoma mansoni worm and worm-tegument antigens are induced by treatment with praziquantel.

Levels of Schistosoma mansoni-induced interleukin (IL)-4 and IL-5 and posttreatment levels of immunoglobulin E recognizing the parasite's tegument (Teg) correlate with human resistance to subsequent reinfection after treatment. We measured changes in whole-blood cytokine production in response to soluble egg antigen (SEA), soluble worm antigen (SWA), or Teg after treatment with praziquantel (PZQ) in a cohort of 187 individuals living near Lake Albert, Uganda. Levels of SWA-induced IL-4, IL-5, IL-10, and IL-13 increased after treatment with PZQ, and the greatest relative increases were seen in the responses to Teg. Mean levels of Teg-specific IL-5 and IL-10 increased ~10-15-fold, and mean levels of IL-13 increased ~5-fold. Correlations between the changes in cytokines suggested that their production was positively coregulated by tegumentally derived antigens. Levels of SEA-, SWA-, and Teg-induced interferon- gamma were not significantly changed by treatment, and, with the exception of IL-10, which increased slightly, responses to SEA also remained largely unchanged. The changes in cytokines were not strongly influenced by age or intensity of infection and were not accompanied by corresponding increases in the numbers of circulating eosinophils or lymphocytes.

Adolescent↗