Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Necatoriasis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1992

Cross-reactivity between Necator americanus and Schistosoma mansoni in mice.

Poly-parasitism is common in endemic communities and reactivity of sera from hookworm-infected patients against schistosomular antigens has been reported. Protective cross-immunity between N. americanus and S. mansoni was investigated in NIH and BALB/c mice. Protective resistance to homologous challenge with both parasites was confirmed in this model, however, functional immunity to heterologous challenge was not demonstrated. Sera from animals which had received homologous challenge with N. americanus and from hookworm-infected mice, which had previously been exposed to radiation-attenuated S. mansoni, exhibited an enhanced IgGAM response to infective stage N. americanus somatic antigens. The implications of these results with respect to serodiagnosis are discussed.

Animals↗
PubMed1993

Sensitivity to ivermectin and pyrantel of Ancylostoma ceylanicum and Necator americanus.

Experiments were carried out in the hamster to compare the relative susceptibility of Necator americanus and Ancylostoma ceylanicum to treatment with ivermectin. A. ceylanicum was found to be 300 times more sensitive to the anthelmintic with a 50% effective dose (ED50) of the order of 10-15 micrograms kg-1 body weight whilst that for N. americanus approximated to 3-5 mg kg-1. Furthermore, whereas complete clearance of A. ceylanicum was observed with a dose of 100 micrograms kg-1, N. americanus was not totally removed after treatment with 25 mg kg-1, the highest dose tested. Both parasites proved equally sensitive to pyrantel with an ED50 of 1-12 mg kg-1 for A. ceylanicum and 5-25 mg kg-1 for N. americanus. Treatment with pyrantel at 100 mg kg-1 completely eliminated worms of both species and doses of 25-50 mg kg-1 were > 90% effective. In addition to worm burdens, changes in host weight and PCV were also recorded and it was shown that both parameters could be used to evaluate the success/failure of treatment.

Ancylostoma↗
PubMed1994

Resistance of the hookworms Ancylostoma ceylanicum and Necator americanus to intestinal inflammatory responses induced by heterologous infection.

Experiments were carried out to ascertain whether the acute inflammatory phase of the intestinal response of hamsters to infection with Trichinella spiralis would adversely affect hookworms in concurrently infected animals. The survival and growth of hookworms were unaffected. However, the presence of hookworms reduced the establishment of T. spiralis, the initial growth of female worms and their fecundity. The expulsion of T. spiralis was also significantly slower in concurrently infected animals and there was significant depression of the serum IgG antibody response to muscle stage and adult worm antigens of T. spiralis in concurrently infected animals. These results are discussed in relation to the chronicity of human hookworm infections.

Acute Disease↗
PubMed1978

Antibody responses in self-infections with Necator americanus.

Antibody responses were measured in a volunteer infected four times with Necator americanus over a 27-month period. The main source of antigen was culture fluid in which living adult N. americanus had been maintained for several days. Antibodies to worm acetylcholinesterase and IgE antibodies were detected only with this material, but antibodies were identified by the enzyme-linked immunosorbent (ELISA) assay, with either adult worm secretions or extracts of third-stage infective larvae. The total serum IgE level fell after the first infection, but although it then increased during subsequent infections, it never rose above 600 U per ml. None of the antibody responses suppressed the rat of worm development to maturity, or reduced the fecundity of the parasites. However, it is suggested that the development of the immune response may be associated with the waning of the severe gastro-intestinal symptoms which were experienced in this infection, and which are frequently characteristic of hookworm infections.

Acetylcholinesterase↗
PubMed1983

Albendazole: placebo-controlled study in 870 patients with intestinal helminthiasis.

A total of 870 patients, both males and females, from 3 to 79 years old, received either albendazole or a placebo for the treatment of nematode and cestode infections. Each patient was interviewed and underwent a complete physical examination on the initial visit. In addition, complete blood count, clinical blood chemistry values and routine urinalysis were performed before and at least 24 hours after the last treatment. Stool examinations were performed before, 7 and 21 days after treatment. Direct examination, an egg count using the Kato technique and faecal concentration were carried out for each patient. In ancylostomiasis and strongyloidiasis, faeces were cultured by the Harada-Mori technique. Albendazole, as a single 400 mg oral dose, was highly effective against Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale and Trichuris trichiura; efficacy against Strongyloides stercoralis was observed after three consecutive days of treatment at the same daily dose level. Efficacy against Hymenolepis nana was fair. Based on both clinical signs and biological values, albendazole did not produce any significant side effects.

Adolescent↗
PubMed1985

Hookworm burdens and faecal egg counts: an analysis of the biological basis of variation.

The relationships between various measures of faecal egg output and hookworm burdens were investigated in 84 villagers from West Bengal with mixed Necator americanus and Ancylostoma duodenale infections. The pattern of day to day variability in egg counts from individuals can be characterized by the linear relationship between the logarithms of the variances and means. Egg output is shown to be non-periodic in long runs of day-to-day records. The distribution of worm numbers per host is well described by the negative binomial probability model, and the relationship between per capita egg output and worm burden is non-linear where egg output declines as parasite burden rises. Density-dependent effects on fecundity are shown to act at comparatively low worm burdens in relation to the range of observed parasite loads. Egg output measures are shown to be qualitative as opposed to quantitative measures of worm burdens as a consequence of inherent sampling heterogeneity and variability induced by biological processes, such as density-dependent depression of parasite fecundity. The analyses suggest that it is possible, on the basis of egg counts, to discriminate between individuals with low and high hookworm burdens. The intrinsic per capita fecundities of the two species of hookworms are shown to be similar, but density-dependent constraints on egg production by N. americanus appear to be more severe than those acting on A. duodenale. This observation may help explain why A. duodenale appears to produce larger numbers of eggs per unit of time than N. americanus. The regulatory role of density-dependent fecundity and aggregated distributions of worm numbers per person are discussed in relation to the over-all transmission dynamics of hookworm parasites.

Adolescent↗
PubMed1985

Hookworm infection in Kweneng District, Botswana, A prevalence survey and a controlled treatment trial.

Stool specimens from a sample of schoolchildren at six schools in Kweneng District were examined for hookworm infection, using the brine flotation method. Necator americanus was the only hookworm identified. The western part of the District forms part of the Kalahari Desert, and in four villages here 90%, 88%, 88% and 86% of the children were infected. In two villages in the eastern non-desert part, only 13% and 9% were infected. Most infections were light. There was no significant correlation between severity of infection and anaemia. In one school (228 pupils; 86% infected with hookworm), half the children were treated with tetrachloroethylene (0.1 ml/kg, maximum 5 ml) and the other half with placebo. Two weeks after treatment the prevalence of infection were 28% and 75% respectively (p less than 0.001), and five months after treatment 51% and 69% (p less than 0.05). Measured over the five-month period there were no significant changes in haemoglobin and nutritional status (weight/height). Based on the results of the survey, a hookworm mass treatment programme was not recommended.

Adolescent↗
PubMed1987

Necator americanus in neonatally infected hamsters. The time-course of infection and antibody response to the surface antigens of L4 and adult worms.

Neonatal hamsters were infected with a hamster-adapted strain of Necator americanus, and the time-course of infection was followed by worm and faecal egg counts. Parasite eggs were first recorded during the 6th week of infection, increasing rapidly thereafter to peak in weeks 7-10. Male hamsters excreted more eggs than females, but both sexes were equally susceptible to infection and harboured comparable worm burdens. Faecal egg counts declined from week 10 onwards and this was associated with a loss of worms from animals with heavy infections. Low level infections were stable over the first 114 d of infection but worm fecundity nevertheless still declined over this period. Both hamster sexes responded similarly to surface antigens on adult worms, the antibody levels rising from week 5 onwards to reach a plateau in weeks 6-7, which persisted until the experiments were terminated. The major antigens recognised on the surface of adult worms had molecular masses corresponding to 25 kDa, 32 kDa, a doublet with the heaviest polypeptide resolving at 46 kDa, and a triplet with the heaviest at 67 and 93kDa. In contrast L4 had only 2 major cuticular antigens resolving at 41 and 93kDa. The 93kDa molecule on L4 and adult worms may be antigenically related.

Animals↗
PubMed1987

Hookworm infection in a rural community in south India and its association with haemoglobin levels.

Faecal samples were obtained from 1113 persons living in a rural area in South India, and the hookworm ova load (Necator americanus) was determined using Kato's thick smear method. Evidence of hookworm infection was present in 92%, 77% having a count of under 100 epg, 11% a count of 1000 to 1999 epg, and 4% having counts between 2000 and 12,000 epg. Females had significantly higher ova counts than males on the average, but age did not appear to have any effect. Haemoglobin was also estimated: 80% of adult males, 87% of adult females and 90% of children were anaemic. There was a significant negative association between ova load and haemoglobin level, and the decrease in haemoglobin for a doubling of the ova load was estimated by regression analysis to be 0.18, 0.29 and 0.16 g/dl in adult males, adult females and children, respectively. There was nearly perfect agreement in the ranking of 10 clusters by mean ova count and mean haemoglobin level or percentage with anaemia.

Adolescent↗
PubMed1987

Population biology of hookworms in west Bengal: analysis of numbers of infective larvae recovered from damp pads applied to the soil surface at defaecation sites.

The aims of this study were to analyze the seasonal distribution of infective larvae on the soil surface, to determine whether numbers of infective larvae near faeces were related to the faecal egg count of individuals, and to relate the distribution of larvae to environmental characteristics. Larvae were recovered from damp pads, applied to the soil surface in an annulus around fresh, identified stools of individuals who were participating in a larger epidemiological study. This provided an estimate of exposure to infection at the time of defaecation. Transmission was restricted to the rainy season and large aggregations of larvae were encountered earlier rather than later in the rainy season. Frequency distributions for the number of larvae extracted from each pad showed a high degree of aggregation, with most monthly counts showing good fits to the negative binomial probability distribution. Despite variations in monthly sampling means, the degree of aggregation in the population of larvae was remarkably stable over the 18 month sampling period (k of negative binomial = 0.01 to 0.08). Estimates of the degree of aggregation of the parasites in the human population were also available, and comparisons suggest that the infective larvae were much more aggregated than the parasitic stages. There was no relationship between the mean daily egg output of individuals and the number of larvae which developed and were recovered from the soil surface near the faeces. Thus, people who contribute large numbers of eggs to the environment are not necessarily those who are the greatest source of infection for others.(ABSTRACT TRUNCATED AT 250 WORDS)

Ancylostoma↗
PubMedDate not supplied

A field study of the effect of ivermectin on intestinal helminths in man.

A single stool specimen from each of 904 villagers participating in a placebo-controlled trial of ivermectin for onchocerciasis was examined for intestinal helminths by the formol-ether technique. Ivermectin had a significant effect on Ascaris infection, reducing prevalence and intensity for at least 3 months, but rapid reinfection occurred. There was no significant effect on Trichuris, Necator or Schistosoma mansoni infections. Incidental Strongyloides infections were not seen commonly in this population, but were significantly reduced in the ivermectin-treated group. Regular administration of ivermectin on a mass basis would reduce the prevalence of Ascaris infection and any attendant morbidity. This is a useful additional effect of the drug.

Animals↗
PubMedDate not supplied

Hookworm (Necator americanus) infection and storage iron depletion.

The relationship between iron status and the intensity of infection with hookworm was investigated in a rural population on Karkar Island, Mandang Province, Papua New Guinea. There was a significant negative correlation between plasma ferritin level and hookworm burden, which was strongest in males. In contrast, there was no correlation between plasma ferritin and hookworm egg count, and no consistent correlation between haemoglobin level or haematocrit and either measure of hookworm intensity. The results suggest that the role of hookworm in the aetiology of anaemia may be difficult to assess without the accurate measurement of hookworm burden.

Age Factors↗