Molecular and functional characterization of a recombinant protein of Trichuris trichiura.

The pore-forming protein of the human whipworm, Trichuris trichiura, has been postulated to facilitate invasion of the host gut and enable the parasite to maintain its syncytial environment. The data presented here describe the first, to our knowledge, molecular characterization of a pore-forming protein in any helminth and provide a unique demonstration of the functional interaction between a parasite antigen and host molecules. Immunological screening of a T. trichiura cDNA library with T. trichiura infection sera identified a clone of 1.4 kB, the cDNA consisting of 1495 base pairs encoding a protein of 50 kDa. The sequence has a highly repetitive nature containing nine four-disulphide-bonded core domains. Structural prediction analyses reveals an amphipathic nature. TT50 induced pore formation in bilayers in a manner identical to that of the native protein. IgG antibody isolated from T. trichiura infection serum was observed to abolish channel activity.     

Trichuris trichiura Infestations in the United Kingdom and Treatment with Difetarsone

Stool specimens were examined for the parasite Trichuris trichiura from 1,860 patients in 17 hospitals for the mentally subnormal in the U.K. It was found in 10 of these hospitals, and an overall incidence of 13·2% was recorded. Most cases occurred in the South, where the overall incidence was 36·3%.Difetarsone was used in the treatment of infestations in two hospitals, and proved to be very well tolerated, cure rates of 81 to 88% being obtained.     

Concurrent infection of a Patas monkey (Erythrocebus patas) by Citrobacter freundii and Trichuris trichiura

Concurrent infection of Citrobacter freundii and Trichuris trichiura in a Patas monkey (Erythrocebus patas) is reported. A synergistic effect of both organisms contributing to host mortality in this case is suggested.     

Modes of transmission for Ascaris lumbricoides and Trichuris trichiura among Chinese children in Macao City

To obtain more information on the transmission of Ascaris lumbricoides and Trichuris trichiura in Macao City, 308 Chinese children were surveyed. The infection rates of A. lumbricoides and T. trichiura were 14.9 and 6.8%, respectively. There was no association between the infections. A. lumbricoides infection was associated with age and T. trichiura with new immigrants from China. No association was found between the infections and family socio-economic factors. The results suggest that the modes of transmission for A. lumbricoides and T. trichiura may be different in highly urbanized areas.     

Random amplified polymorphic DNA analysis of DNA extracted from Trichuris trichiura (Linnaeus, 1771) eggs and its prospective application to paleoparasitological studies

Random amplified polymorphic DNA analysis was applied to DNAs extracted from Trichuris trichiura eggs recovered from human fecal samples. Four out of 6 primers tested displayed 18 distinct and well defined polymorphic patterns, ranging from 650 to 3200 base pairs. These results, upon retrieval and DNA sequencing of some of these bands from agarose gels, might help in establishing. T. trichiura specific genetic markers, not available yet, and an important step to design primers to be used in molecular diagnosis approaches.     

Isolation of a gene family that encodes the porin-like proteins from the human parasitic nematode Trichuris trichiura

The major E/S protein of Trichuris trichiura, the human whipworm, is a highly immunogenic 47-kDa protein that has a pore forming activity that is thought to be essential for the attachment of the worm to host mucosal epithelium. By gene analysis, we have demonstrated that this protein belongs to a multigene family, and we have obtained genomic and cDNA information for two of these genes. The encoded proteins are composed of tandem arrays of alternating 50- and 51-amino-acid domains within which the positioning of the cysteine residues is highly conserved. This structure resembles that of four disulphide core domain proteins, such as secretory leucocyte proteinase-1 (SLP-1), but the Trichuris protein family differs in being composed of multiple domains of this type (nine in TT50, 17 in TT95). An analysis of the relationship between the domains, and a comparison of the fine arrangement of the genes, suggests that TT95 has arisen relatively recently following duplication of the TT50 gene, which itself arose by duplication of a SLP-1-like ancestor.     

Ascaris lumbricoides and Trichuris trichiura infections associated with wastewater and human excreta use in agriculture in Vietnam

BackgroundWe assessed the risk of helminth infections in association with the use of wastewater and excreta in agriculture in Hanam province, northern Vietnam. In two cross-sectional surveys, we obtained samples from 1,425 individuals from 453 randomly selected households. Kato-Katz thick smear and formalin-ether concentration techniques were used for helminth diagnosis in two stool samples per person. Socio-demographic and water, sanitation and hygiene related characteristics, including exposure to human and animal excreta and household wastewater management, were assessed with a questionnaire.ResultsOverall 47% of study participants were infected with any helminth (Ascaris lumbricoides 24%, Trichuris trichiura 40% and hookworm 2%). Infections with intestinal protozoa were rare (i.e. Entamoeba histolytica 6%, Entamoeba coli 2%, Giardia lamblia 2%, Cryptosporidium parvum 5% and Cyclospora cayetanensis 1%). People having close contact with polluted Nhue River water had a higher risk of helminth infections (odds ratio [OR] = 1.5, 95% confidence interval [CI] 1.1–2.2) and A. lumbricoides (OR = 2.1, 95% CI 1.4–3.2), compared with those without contact. The use of human excreta for application in the field had an increased risk for a T. trichiura infection (OR = 1.5, 95% CI 1.0–2.3). In contrast, tap water use in households was a protective factor against any helminth infection (i.e. T. trichiura OR = 0.6, 95% CI 0.4–0.9). Prevalences increased with age and males had generally lower prevalences (OR = 0.8, 95% CI 0.6–1.0), participants performing agricultural (OR = 1.5, 95% CI 1.1–2.1) and having a low educational level (OR = 1.7, 95% CI 1.2–2.4) were significantly associated with helminth infections. None of the factors related to household's sanitary condition, type of latrine, household's SES, use of animal excreta, and personal hygiene practices were statistically significant associated with helminth infection.ConclusionsOur study suggests that in agricultural settings, direct contact with water from Nhue River and the use of human excreta as fertiliser in the fields are important risk factors for helminth infection. Daily use of clean water is likely to reduce the risk of worm infection. Deworming policies and national programs should give more attention to these agricultural at risk populations.     

Strategy of Ascaris lumbricoides and Trichuris trichiura for the environmental contamination, in an endemic area

The distribution of frequencies of the number per grame of Ascaris lumbricoides and Trichuris trichiura in the faeces of naturally infected human in endemic areas, were found following a negative binomial distribution and an overdispersal pattern, independently of the ages of hosts. These results show, that only few hosts, independently of their ages, are involved in the higher environment contamination.     

Trichuris eggs in animal coprolites dated from 30,000 years ago

Trichuris eggs were found in Kerodon rupestris (Rodentia, Caviidae) coprolites collected in archaeological layers dated from 30,000 yr BP (before present) to 8,450 yr BP. Adult worms and eggs of this genus were not found in a search of living mammals of the region. Results indicate that K. rupestris was a host for an unknown Trichuris species not found in this rodent presently. Climate changes that occurred by 10,000 yr ago in the region could be the cause of its disappearance. The finding of parasites in archaeological material can show the antiquity of host-parasite relationships and parasite losses through time.     

An epidemiological survey of oral mucosal lesions among elderly Malaysians

A house to house random survey on elderly subjects was undertaken in the District of Klang in Malaysia. The objective of this study was to investigate the prevalence of oral mucosal lesions (OML) among the elderly in this area. The primary units in the sampling frame were the Enumeration Blocks (EBs) as defined under the population census. All households of the selected EBs were considered as sampling units and members aged 60 and above were considered as respondents. There was a slight preponderance of females, with the Malays comprising the majority of the subjects. Of the 486 respondents, mean aged 69.1 ± 7.3 yr, 111 had at least one oral mucosal lesion, a prevalence of 22.8%. A total of 145 lesions were detected. The prevalence of OML was highest among Indians and least among the Chinese. The most common finding was tongue lesions, recording a prevalence of 10.7%, followed by oral pigmentation (4.9%) and white lesions (4.3%). Denture related lesions were comparatively low at 2.5%. Two cases of oral cancer if representative would give a relatively high prevalence of 0.4%.     

Sequence variation in the Trichuris trichiura beta-tubulin locus: implications for the development of benzimidazole resistance

Benzimidazole resistance has evolved in a variety of organisms and typically results from mutations in the beta-tubulin locus at specific amino acid sites. Despite widespread treatment of human intestinal nematodes with benzimidazole drugs, there have been no unambiguous reports of resistance. However, since beta-tubulin mutations conferring resistance are generally recessive, frequencies of resistance alleles less than 30% would be difficult to detect on the basis of drug treatment failures. Here we investigate sequence variation in a 1079 bp segment of the beta-tubulin locus in the human whipworm Trichuris trichiura from 72 individual nematodes from seven countries. We did not observe any alleles with amino acid mutations indicative of resistance, and of 40 point mutations there were only four non-synonymous mutations all of which were singletons. Estimated effective population sizes are an order of magnitude lower than those from another nematode species in which benzimidazole resistance has developed (Haemonchus contortus). Both the lower diversity and reduced population sizes suggest that benzimidazole resistance is likely to evolve less rapidly in Trichuris than in trichostrongyle parasites of livestock. We observed moderate levels of population subdivision (Phi(ST)=0.26) comparable with that previously observed in Ascaris lumbricoides, and identical alleles were frequently found in parasites from different continents, suggestive of recent admixture. A particularly interesting feature of the data is the high nucleotide diversities observed in nematodes from the Caribbean. This genetic complexity may be a direct result of extensive admixture and complex history of human populations in this region of the world. These data should encourage (but not make complacent) those involved in large-scale benzimidazole treatment of human intestinal nematodes.     

Efficacy and safety of nitazoxanide, albendazole, and nitazoxanide-albendazole against Trichuris trichiura infection: a randomized controlled trial

Background

The currently used anthelmintic drugs, in single oral application, have low efficacy against Trichuris trichiura infection, and hence novel anthelmintic drugs are needed. Nitazoxanide has been suggested as potential drug candidate.

Methodology

The efficacy and safety of a single oral dose of nitazoxanide (1,000 mg), or albendazole (400 mg), and a nitazoxanide-albendazole combination (1,000 mg–400 mg), with each drug administered separately on two consecutive days, were assessed in a double-blind, randomized, placebo-controlled trial in two schools on Pemba, Tanzania. Cure and egg reduction rates were calculated by per-protocol analysis and by available case analysis. Adverse events were assessed and graded before treatment and four times after treatment.

Principal Findings

Complete data for the per-protocol analysis were available from 533 T. trichiura-positive children. Cure rates against T. trichiura were low regardless of the treatment (nitazoxanide-albendazole, 16.0%; albendazole, 14.5%; and nitazoxanide, 6.6%). Egg reduction rates were 54.9% for the nitazoxanide-albendazole combination, 45.6% for single albendazole, and 13.4% for single nitazoxanide. Similar cure and egg reduction rates were calculated using the available case analysis. Children receiving nitazoxanide had significantly more adverse events compared to placebo recipients. Most of the adverse events were mild and had resolved within 24 hours posttreatment.

Conclusions/Significance

Nitazoxanide shows no effect on T. trichiura infection. The low efficacy of albendazole against T. trichiura in the current setting characterized by high anthelmintic drug pressure is confirmed. There is a pressing need to develop new anthelmintics against trichuriasis.

Trial Registration

Controlled-Trials.com ISRCTN08336605     

Trichuris vulpis (Froelich, 1789) infection in a child: a case report

We present a human infection with the canine whipworm, Trichuris vulpis, in a child suffering from rhinitis with a diagnosis of rhinitis. T. vulpis eggs resemble those of T. trichiura but they can be differentiated based on their morphological features and egg size, using micrometry with an ocular micrometer. T. vulpis eggs measured an average of 90 μm by 44 μm (range 86-99 μm by 38-47 μm). Prevalence of hookworms (28.1%), Toxocara canis (11.8%), and Trichuris vulpis (3.5%) was found in 292 fecal samples of dogs collected at the peri-domicile, which showed that the risk of infection was not only fortuitous. The treatment of canine whipworm infections is similar to that of T. trichiura infection. We recommend differentiation of the 2 species for their epidemiological and prevention implications.     

Prevalence of oral mucosal lesions in institutionalized elderly people in Mashhad, Northeast Iran

doi: 10.1111/j.1741‐2358.2011.00588.x
Prevalence of oral mucosal lesions in institutionalized elderly people in Mashhad, Northeast Iran Objective: The aim of this study was to determine the prevalence of oral mucosal lesions in institutionalized elderly people in Mashhad, northeast of Iran. Background: This study was conducted to assess the prevalence of oral lesions in the institutionalized elderly. Methods: In this survey, we studied all of the nursing homes in Mashhad; a total of five encompassing 237 residents. The subjects were examined and lesions recorded in a designed checklist. T‐test, chi‐square and Fisher’s exact tests were used for the analysis. Results: The mean age of the patients was 79.59 ± 8.88. Ninety‐eight per cent of cases had at least one oral mucosal lesion. The most common lesions were fissured tongue (66.5%), atrophic glossitis (48.8%), sublingual varicosity (42%) and xerostomia (38%). There was no significant difference in the prevalence of denture‐related lesions (DRLs) between men and women (p > 0.05). Xerostomia was more prevalent in 70–79‐year‐old than in 60–69‐year‐old subjects. No case of oral malignant lesion was detected. Discussion: These findings revealed a higher prevalence of oral mucosal lesions in Mashhad city compared with other studies conducted in other major cities in Iran and abroad. The results emphasise the necessity of national programmes towards oral health promotion.