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PubMedDate not supplied

[Value of the string test in the diagnosis of duodenal parasitosis].

Diagnosis of small intestine parasitosis can be realized by string-test. This examination, easily performed, does not produce side-effects in ninety percent of cases. The main problems are: good string unrollment and duodenal passing over. When Necator ova or gardia cysts are found in the stools by the Junod's technic, string-test is always positive. In one case, this latter even showed Schistosoma mansoni ova. Among 18 patients with unexplained hypereosinophilia, in spite of a parasitologic check up involving three stools examinations, the string-test showed Necator ova. With regard to strongyloidiasis, when properly performed, string-test is positive in seventy percent of cases. Therefore, this technic seems very useful on the field or in laboratories which do not usually realize the Junod's technic.

Adolescent↗

PubMed1982

Epidemiological study and comparison of pyrantel and levamisole in the treatment of roundworm and hookworm infestations.

Stool examined for presence of nematodes from 467 school students in Dacca city showed 48% ova positive cases with 22% among them cases of mixed nematode infection. Highest prevalence of 58% was observed with roundworm and 5% was hookworm infestations. Among hookworm cases, Necator americana (68%) appears to be the predominant species. Two anthelmintics-pyrantel and levamisole achieved similar high cure rate (around 97%) and Egg reduction rate of 99% in roundworm infection. However, pyrantel was observed to be more effective in hookworm infestation (87% against 60%) particularly in Necator americana cases.

Adolescent↗

PubMed1994

Prevalence of intestinal helminthic infections in Kao District, north Halmahera, Indonesia.

A parasitological survey was conducted on the inhabitants of six villages of Kao District, Halmahera Island, North Maluku, Indonesia, in July 1993. A total of 422 fecal samples were examined by using Kato-Katz thick smear, modified Harada-Mori culture and formalin ether concentration techniques. Seven nematode species, ie Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, Enterobius vermicularis and unidentified rhabditoids of free-living nature, were detected. Trematode and cestode infection was not proven. Necator americanus was the predominant species of hookworm. Soil-transmitted nematode infections were highly prevalent. Among the young inhabitants aged less than 15, positive rates of Ascaris, Trichuris and hookworm infections were 32.7, 52.7 and 68.6%, respectively. Among the people aged 15 or more, the positive rate for hookworm (85.9%) was much higher than that for Ascaris and Trichuris (13.5 and 40.5%, respectively). Egg count revealed that more than 90% of inhabitants with Trichuris or hookworm had light infections. The latrines in the surveyed area seemed to have only limited effects on the improvement of the parasitological status because the prevalence of Trichuris infections was much higher in a village where most houses were provided with latrines. These conflicting conditions were considered to have been caused by many factors including the inadequate structure of the latrines.

Adolescent↗

PubMed1996

[Recent features of parasites detected from clinical specimens].

It is generally considered that we have already been through with problems caused by various kinds of parasites which had once raged throughout the country. On the contrary to our common concept, we occasionally encounter some kinds of parasites in a laboratory as well as in clinical fields, which have become unfamiliar to us in these days. Parasitic diseases are in the first place, proper and limited to certain local regions, but the present situation has been greatly changed. Nowadays, specific parasites are no longer limited to polluted areas, but also they can be detected in any part of the world owing to facilitated transportations and a promoted international exchange of people. A recent gourmet boom is also one of the causes of infection as seen in anisakiasis. This study was conducted on the investigation of parasites detected from clinical specimens in our laboratory during the period from 1989 to 1993. 1) The following parasites were detected : (1) Strongyloides stercoralis, (2) Giardia lamblia, (3) Diphyllobothrium latum, (4) Schistosoma mansoni, (5) Entamoeba histolytica, (6) Necator americanus, (7) Isospora belli. 2) Strongyloides stercoralis was detected at the highest frequency. This result gives an account of high prevalence of the parasite among the inhabitants in Okinawa. In addition, the agar plate medium method which has been newly adopted has definitely led to far-advanced results for detection of this parasite. 3) Schistosoma mansoni and Necator americanus were found from foreigners one of whom was a Tanzanian and the other was a Dominican. 4) Isospora belli was found from those compromised cases such as ATL and AIDS.

Animals↗

PubMed1997

Soil contamination with geohelminth ova in a tea plantation.

OBJECTIVE: To determine the degree of soil pollution in an area of high prevalence and the risk of exposure to geohelminth infection. DESIGN: A cross-sectional study. SETTING: A division of a large tea plantation in Kandy. SUBJECTS: All persons resident in one division of the tea plantation, above the age of 1 year. MEASUREMENTS: Prevalence of geohelminth infection measured by microscopic examination of faeces of the study group. Soil samples from 38 specific locations, obtained on 3 different occasions, about 6 months apart, analysed for helminth ova. The average temperature, rainfall and the number of rainy days during the sampling period. RESULTS: Of the 99 subjects of the study group, 77.7% were positive for at least one geohelminth infection. The prevalence rates for ascariasis, trichuriasis and hookworm infection were 54%, 28%, and 22% respectively. At the first sampling, 10.5% of the soil samples were positive for helminth ova with 7.8% and 2.6% samples showing Ascaris and Necator ova respectively. At the second sampling of the same locations nearly 40% of the samples were positive for helminth ova with 21.6%, 7.8% and 10.5% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. At the third sampling, 26.2% of the samples were positive with 21%, 2.6% and 2.6% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. Necator ova were found only once in 2.6% of the samples of the first sampling. The larger number of samples positive for helminth ova were in the second and the third samplings which coincided with high rainfall in the pre-sampling period. CONCLUSIONS: The prevalence of geohelminthiases among the study group was high. Results of soil analysis confirmed continued contamination of soil in and around the home gardens and the work areas with human and dog faeces. With the knowledge of exact locations of soil pollution it was possible to advice the management on remedial measures.

Adolescent↗

PubMed2002

Innate and cognate mechanisms of pulmonary eosinophilia in helminth infection.

Passage of helminth larvae through the lungs can cause pulmonary eosinophilia that may have evolved as a means of parasite attrition. If allergic responses represent a misdirected activation of this arm of the immune system, then mechanisms governing eosinophil recruitment during infection would be expected to be closely related to those seen in allergy. We studied primary Necator americanus infection and compared this to multiply-infected or vaccinated mice. The arrival of larvae in the lungs triggered rapid eosinophil recruitment, which was greatly enhanced in previously sensitized mice. Interestingly, the presence of larvae in the lung was sufficient to trigger eosinophil chemoattractant production, including the chemokines eotaxin and MIP-1alpha, and was not enhanced by prior exposure to the parasites. Infection stimulated IL-5 production in all groups; however, this and IgE production were greatly enhanced in sensitized animals. Elevated IL-5 increased bone marrow production of eosinophils, and eosinophilia was abrogated by treatment with anti-IL-5 antibody. Therefore, trapping of larvae in the pulmonary vasculature is sufficient to trigger eosinophil recruitment, by induction of chemokines and IL-5. Primed cognate Th2 immunity does not increase local chemokine production, but does increase IL-5 production, which greatly enhances the availability of eosinophils for recruitment to the lung.

Animals↗

PubMed2006

Enhancement of protein secretion in Pichia pastoris by overexpression of protein disulfide isomerase.

A potential vaccine candidate, Necator americanus secretory protein (Na-ASP1), against hookworm infections, has been expressed in Pichia pastoris. Na-ASP1, a 45 kDa protein containing 20 cysteines, was directed outside the cell by fusing the protein to the preprosequence of the alpha-mating factor of Saccharomyces cerevisiae. Most of the protein produced by single copy clones was secreted outside the cell. However, increasing gene copy number of Na-ASP1 protein in P. pastoris saturated secretory capacity and therefore, decreased the amount of secreted protein in clones harboring multiple copies of Na-ASP1 gene. Overexpression of the endoplasmic reticulum (ER) resident, homologous chaperone protein, protein disulfide isomerase (PDI) was able to increase the secretion of (Na-ASP1) protein in high copy clones. The effect of PDI levels on secretion of Na-ASP1 protein was examined in clones with varying copy number of PDI gene. Increase in secreted Na-ASP1 secretion is correlated well with the PDI copy number. Increasing levels of PDI also increased overall Na-ASP1 protein production in all the clones. Nevertheless, there was still accumulation of intracellular Na-ASP1 protein in P. pastoris clones over-expressing Na-ASP1 and PDI proteins.

Animals↗

PubMed2002

Long PCR-based amplification of the entire mitochondrial genome from single parasitic nematodes.

Mitochondrial genome sequences provide useful markers for investigating population genetic structures because of their maternal inheritance and high evolutionary rates. There is, however, a paucity of information on mitochondrial genomes for many parasitic organisms, including nematodes, which appears to relate mainly to technical limitations and (for modestly funded laboratories) the cost associated with full mitochondrial genome sequencing. In this article, we describe a simple, relatively inexpensive long-PCR approach for the amplification (using two sets of primers) of the entire mitochondrial genome from individual parasitic nematodes for subsequent sequencing, which overcomes these limitations. We employed two species of human hookworm (Ancylostoma duodenale and Necator americanus; order Strongylida) to establish the long-PCR conditions, and then extended its use to a number of other species of parasitic nematode of the class Secernentea (orders Strongylida, Ascaridida and Rhabditida). The long-PCR method for the amplification of the entire mitochondrial genome from single nematodes, coupled with direct sequencing of amplicons, provides a useful tool for the comparative analysis of genome organisation and evolution of a range of nematode groups. It also creates a platform for molecular ecological and population genetic studies.

Ancylostoma↗

PubMed2006

Development and characterization of microsatellite markers for the canine hookworm, Ancylostoma caninum.

Microsatellites are repetitive genomic elements that show high levels of variation and therefore provide excellent tools to study the genetics of eukaryotic organisms. Hookworms are extremely common and important nematode parasites of humans and animals, causing potentially serious disease morbidity. Control of hookworms in dogs is achieved by frequent treatment with anthelmintics, and in humans, anthelmintics are frequently administered in a mass-treatment community-wide approach. Understanding the population genetics of hookworms has important implications for studies on the development and spread of drug resistance. We investigated the genome of Ancylostoma caninum for microsatellites by developing and then screening an enriched genomic library as well as by data mining published sequences of a whole genome shotgun library. Investigations revealed a high abundance of trinucleotide repeats. Dinucleotide repeats were characterized by a high number of AT, GA, and GT repeats. After testing and optimization of 68 markers, a panel of 34 polymorphic microsatellite markers were selected. Microsatellite analysis of hookworm isolates revealed a high degree of polymorphism, which was not influenced by the length of the repeats. This panel of microsatellite markers makes it possible to pursue investigations on the population genetics of A. caninum. Furthermore, a number of the markers demonstrated suitability for analysis of the human hookworm species Necator americanus and A. duodenale.

Ancylostoma↗

PubMed1994

Apparent feeding behaviour of ensheathed third-stage infective larvae of human hookworms.

The third-stage ensheathed infective larvae (L3) of hookworms are reputed to be non-feeding stages, and the L2-derived sheath is considered to be a barrier to macromolecular uptake and secretion. During a study of the lectin-binding characteristics of en- and exsheathed L3 larvae of Ancylostoma duodenale, fluorescein isothiocyanate conjugated lectins (con A and Ulex europaeus agglutinin) were repeatedly seen in the oesophageal lumen, as well as on the surface of L3 larvae encased in the L2 sheaths. Repetition of these experiments using Necator americanus L3 larvae yielded similar results. These observations suggest that ensheathed hookworm larvae can obtain/utilise and secrete macromolecules, despite the presence of a sheath.

Ancylostoma↗

PubMed1976

Measurement of anti-enzyme antibodies using an active-site directed radiolabel.

A new technique is described for measuring antibodies to an enzyme which is not available in pure form. The secretions of the rat parasitic nematode, Nippostrongylus brasiliensis, were treated with tritiated diisopropylfluorophosphate. Only one component, an acetylcholinesterase, was radiolabelled. Antibodies to this enzyme in rat antisera were estimated by the Farr technique using the labelled enzyme as antigen. The acetylcholinesterase secreted by Necator americanus, the human hookworm, was similarly specifically labelled.

Acetylcholinesterase↗

PubMed1978

Variation in delayed hypersensitivity in onchocerciasis.

Soluble antigen preparations were made from Onchocerca volvulus adults recovered from subcutaneous nodules, and from Necator americanus third-stage larvae. Intradermal skin tests were carried out on a total of 100 individuals clinically classified as having either the generalized form of onchocerciasis (86 cases, or the localized sowda form (14 cases). 91 of the people studied produced immediate reactions to the onchocercal antigen, but only those with sowda showed delayed reactions, though one person with generalized disease showed a doubtful delayed reaction. Reactions to N. americanus antigen, both immediate and delayed, were seen in both forms of the disease. The lack of delayed skin reaction in the generalized form of onchocerciasis is discussed, and a comparison is made with other diseases. Preliminary evidence for the existence of a true spectrum of clinical and immunological forms of onchocerciasis is suggested by one case in this study.

Adolescent↗

PubMed1981

The infectivity of ingested adult hookworms.

Fourth-stage larvae and adults of Ancylostoma ceylanicum (dog strain) produced patent infections, with fertile ova, in hamsters to which they had been given in a drench. Similarly, 36-day-old (immature adult) Necator americanus given in a drench to hamsters also produced patent infections with fertile ova. The epidemiological significance of these experiments is discussed.

Ancylostoma↗

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↗

PubMed1989

Filarial parasites exhibit unusually high levels of choline acetyltransferase activity.

The presence of unusually high levels of choline acetyltransferase (ChAT, EC 2.3.1.6) in human and animal filarial parasites has been demonstrated. The levels of ChAT were highest in male worms of Brugia malayi and Brugia pahangi, with specific activities in crude extracts of about 2.27 and 1.26 mumol min-1 (mg protein)-1, respectively. The enzyme levels in these worms were over 10-20 times higher than in male worms of Litomosoides carinii. The ChAT levels were about 2-5 times higher in male than in female worms. The enzyme was also present in appreciably high levels in microfilariae of Brugia species, L. carinii and Wuchereria bancrofti. The levels of ChAT in male worms of Brugia species were several thousand-fold higher than in the intestinal nematodes Trichuris muris and Necator americanus, and were over three orders of magnitude higher than in mammalian brain. Unlike the mammalian ChAT, the parasite enzyme was extremely stable. The parasite enzyme was not inhibited by any of the antifilarial agents except suramin. The filarial ChAT was strongly inhibited by sulphydryl reagents and diethylpyrocarbonate. Ethacrynic acid (EA), a diuretic and a sulphydryl reagent, irreversibly inhibited the filarial ChAT activity at low concentrations. In contrast, EA inhibited the activity of mammalian brain ChAT at much higher concentrations. The motility of adult worms and microfilariae was irreversibly inhibited by low concentrations of EA. Furthermore, the inhibition of motility was paralleled by the inactivation of ChAT in these parasites. These studies indicate that ChAT activity appears to be vital for parasite's survival and that acetylcholine might play a key role in the control of worm motility.

Acetylcholinesterase↗

PubMed2006

Intestinal allergy expels hookworms: seeing is believing.

It is unclear how immunity limits hookworm infection. Australian researchers, using capsule and conventional gastrointestinal endoscopy in volunteers inoculated with Necator americanus, have reported that virtually all larvae reach the intestine within six weeks. Unlike the neutral response surrounding resident hookworms, newly arrived adults provoke an eosinophilic enteropathy. This allergic reaction curtails the attachment of hookworms and accompanies the passage of additional worms as they are expelled from the proximal small intestine.

Animals↗

PubMed2001

Effective control of hookworm infection in school children from Dhofar, Sultanate of Oman: a four-year experience with albendazole mass chemotherapy.

After 4 years of mass chemotherapy with a single annual dose of albendazole 400 mg, health education and promotion of environmental health, the prevalence of Necator americanus in Wilayat Tagah, Dhofar, Oman was reduced from 40 to 1.3% and from 6 to 0%, respectively, among rural and urban school children. Stool samples with egg load >1000 egg/gm were reduced from 28 to 0% after the first year of intervention and maintained as such in subsequent years.

Adolescent↗

PubMed1999

Epidemiology of human hookworm infections among adult villagers in Hejiang and Santai Counties, Sichuan Province, China.

Hookworm infection as well as other intestinal nematodiases are endemic to Sichuan Province in China. In order to research the prevalence and intensity of these infections we visited two villages in Hejiang County (southern Sichuan Province) and Santai County (northwestern Sichuan Province) between July and October of 1997. Fecal examinations were performed on adult villagers over the age of 15 years (currently children under this age are dewormed annually with anthelmintic drugs). Among 310 residents of Lugao Village (Hejiang County), 87, 63 and 60% were infected with hookworm, Ascaris or Trichuris, respectively. The prevalence of hookworm determined to rise linearly with age (r = 0.97). High intensity infections with hookworm still occur in this region as 22% of the residents have over 3000 eggs per gram (PEG) of feces as determined by quantitative egg counts. The majority of these individuals harbored mixed infection with Necator americanus and Ancylostoma duodenale, although the former predominated when adult hookworms were collected from 30 village residents treated with pyrantel pamoate. In contrast, among the 334 Xinjian villagers examined (Santai County) the majority harbored predominantly light hookworm infections--66.1% of the residents has less than 400 EPG by quantitative fecal examination and only 3.7% exhibited greater than 3000 EPG. Again, N. americanus was the predominant hookworm seen after worm expulsion. We have round that despite economic development which is occurring in some parts of China, significant hookworm infections and clinical hookworm anemia still exist in areas of Sichuan Province. In Hejiang County we found that the intensity of hookworm infection has actually risen within the last 10 years. Hookworm is a medical problem among the elderly in Sichuan.

Adolescent↗