Trichiura Infection Research Articles

Efficacy and Safety of Nitazoxanide, Albendazole, and Nitazoxanide-Albendazole against Trichuris trichiura Infection: A Randomized Controlled Trial

BackgroundThe 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.MethodologyThe 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 FindingsComplete 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/SignificanceNitazoxanide 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 RegistrationControlled-Trials.com ISRCTN08336605

Household social determinants of ascariasis and trichuriasis in North Central Venezuela

Ascariasis and trichuriasis are highly prevalent parasitoses in tropical countries caused by Ascaris lumbricoides and Trichuris trichiura, respectively. Their prevalence is associated with poor sanitation and hygiene, among other biological and social factors. In this study, the associations of household social determinants with these soil-transmitted helminthiases in North Central Venezuela was assessed in the context of a National Study on Human Growth and Development (SENACREDH). This was a probabilistic, stratified, cross-sectional survey with a sample of 3388 individuals that weighted represents 4 675 433 inhabitants from the region. The prevalence of ascariasis and trichuriasis was 3.73% and 1.13%, respectively. In the univariate and multivariate analyses, these prevalences were significantly higher in those living in vulnerable houses [adjusted OR (AOR) = 1.479, 95% CI 1.428-1.532; and AOR = 10.519, 95% CI 9.971-11.097, respectively], houses located in rural areas (AOR = 2.067, 95% CI 2.035-2.101; and AOR = 1.918, 95% CI 1.868-1.970, respectively) and houses with a soil floor (AOR = 5.027, 95% CI 4.895-5.162; and AOR = 5.190, 95% CI 4.944-5.448, respectively), among other factors. People living in rural households with inappropriate building materials, insufficient basic public services such as water and waste disposal, and surrounding disease-prone environments are at higher risk of acquiring A. lumbricoides and T. trichiura infections.

The global limits and population at risk of soil-transmitted helminth infections in 2010.

BackgroundUnderstanding the global limits of transmission of soil-transmitted helminth (STH) species is essential for quantifying the population at-risk and the burden of disease. This paper aims to define these limits on the basis of environmental and socioeconomic factors, and additionally seeks to investigate the effects of urbanisation and economic development on STH transmission, and estimate numbers at-risk of infection with Ascaris lumbricoides, Trichuris trichiura and hookworm in 2010.MethodsA total of 4,840 geo-referenced estimates of infection prevalence were abstracted from the Global Atlas of Helminth Infection and related to a range of environmental factors to delineate the biological limits of transmission. The relationship between STH transmission and urbanisation and economic development was investigated using high resolution population surfaces and country-level socioeconomic indicators, respectively. Based on the identified limits, the global population at risk of STH transmission in 2010 was estimated.ResultsHigh and low land surface temperature and extremely arid environments were found to limit STH transmission, with differential limits identified for each species. There was evidence that the prevalence of A. lumbricoides and of T. trichiura infection was statistically greater in peri-urban areas compared to urban and rural areas, whilst the prevalence of hookworm was highest in rural areas. At national levels, no clear socioeconomic correlates of transmission were identified, with the exception that little or no infection was observed for countries with a per capita gross domestic product greater than US$ 20,000. Globally in 2010, an estimated 5.3 billion people, including 1.0 billion school-aged children, lived in areas stable for transmission of at least one STH species, with 69% of these individuals living in Asia. A further 143 million (31.1 million school-aged children) lived in areas of unstable transmission for at least one STH species.ConclusionsThese limits provide the most contemporary, plausible representation of the extent of STH risk globally, and provide an essential basis for estimating the global disease burden due to STH infection.

Association between anaemia, iron deficiency anaemia, neglected parasitic infections and socioeconomic factors in rural children of West Malaysia.

BackgroundGiven that micronutrient deficiency, neglected intestinal parasitic infections (IPIs) and poor socioeconomic status are closely linked, we conducted a cross-sectional study to assess the relationship between IPIs and nutritional status of children living in remote and rural areas in West Malaysia.Methods/FindingsA total of 550 children participated, comprising 520 (94.5%) school children aged 7 to 12 years old, 30 (5.5%) young children aged 1 to 6 years old, 254 (46.2%) boys and 296 (53.8%) girls. Of the 550 children, 26.2% were anaemic, 54.9% iron deficient and 16.9% had iron deficiency anaemia (IDA). The overall prevalence of helminths was 76.5% comprising Trichuris trichiura (71.5%), Ascaris lumbricoides (41.6%) and hookworm infection (13.5%). It was observed that iron deficiency was significantly higher in girls (p = 0.032) compared to boys. Univariate analysis demonstrated that low level of mother's education (OR = 2.52; 95% CI = 1.38–4.60; p = 0.002), non working parents (OR = 2.18; 95% CI = 2.06–2.31; p = 0.013), low household income (OR = 2.02; 95% CI = 1.14–3.59; p = 0.015), T. trichiura (OR = 2.15; 95% CI = 1.21–3.81; p = 0.008) and A. lumbricoides infections (OR = 1.63; 95% CI = 1.04–2.55; p = 0.032) were significantly associated with the high prevalence of IDA. Multivariate analysis confirmed that low level of mother's education (OR = 1.48; 95 CI% = 1.33–2.58; p<0.001) was a significant predictor for IDA in these children.ConclusionIt is crucial that a comprehensive primary health care programme for these communities that includes periodic de-worming, nutrition supplement, improved household economy, education, sanitation status and personal hygiene are taken into consideration to improve the nutritional status of these children.

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.

Soil-transmitted helminthiasis: a critical but neglected factor influencing school participation of Aboriginal children in rural Malaysia

Soil-transmitted helminthiasis (STH), among the most common neglected tropical diseases, is a major public health problem in Malaysia with a possible impact on the nutritional status and school participation of rural children. This study was carried out among Aboriginal schoolchildren, living in an endemic area for STH in Malaysia, to determine the possible relationship between intestinal helminthiasis and school absenteeism. We also evaluated whether successful treatment of the infection will affect school attendance among the subjects. Stool analysis revealed that more than 90% of the subjects were infected with at least 1 helminth species, with Ascaris lumbricoides and Trichuris trichiura infections being most prevalent. Infection of moderate-to-heavy worm burdens, low level of fathers' education and anaemia were identified as the significant predictors of high absenteeism among the subjects (P<0·05). Following treatment of the infected children, it was found that school absenteeism was reduced significantly (P<0·01). In conclusion, STH continues to have significant impacts on public health, particularly in rural communities with a negatively significant effect on the school participation of Aboriginal children. A school-based de-worming programme should be introduced and incorporated in the current educational assistance targeted towards the Aboriginal communities, under the auspices of the government.

Risk factors for helminth infections in a rural and a peri-urban setting of the Dongting Lake area, People’s Republic of China

Schistosomiasis japonica and soil-transmitted helminthiasis are endemic parasitic diseases in the People’s Republic of China (PR China). As very few studies have reported on the distribution and interaction of multiple species helminth infections, we carried out a comparative study of households in a rural village and a peri-urban setting in the Dongting Lake area of Hunan province in November and December 2006 to determine the extent of single and multiple species infections, the underlying risk factors for infection, and the relationships with clinical manifestations and self-reported morbidity. In each household, stool samples were collected and subjected to the Kato-Katz method for identifying Schistosoma japonicum, Ascaris lumbricoides, hookworm and Trichuris trichiura infections. Clinical examinations were performed and questionnaire surveys conducted at both household and individual subject levels. Complete parasitological, clinical and questionnaire data were obtained for 1,298 inhabitants of the two settings. The overall prevalences of single infections of S. japonicum, A. lumbricoides, hookworm and T. trichiura were 6.5%, 5.5%, 3.0% and 0.8%, respectively; the majority of the infections were of light intensity. We found significant negative associations between wealth and infections with S. japonicum and A. lumbricoides. Clinical manifestations of splenomegaly, hepatomegaly and anaemia were prevalent (9.0%, 3.7% and 10.9%, respectively), the latter two being significantly ( P < 0.05) associated with schistosomiasis. Self-reported symptoms were more common among females but there was considerable under-reporting in both sexes when relying only on spontaneous recall. Our findings may guide the design and targeting of a more equitable, comprehensive and integrated parasitic disease control programme in Hunan province and in other areas of PR China.

P2-522 Soil transmitted helminth infections in preschool and school aged children in Ekiti and Ile-Ife, southwest Nigeria

IntroductionSoil transmitted helminths are among the neglected tropical diseases prevalent in developing countries, and children are the most vulnerable. The objective of the cross—sectional study was to determine the prevalence...

Comparison of the Kato-Katz and FLOTAC techniques for the diagnosis of soil-transmitted helminth infections

Decisions on individual or community treatment and evaluation of chemotherapy based control programs depend on parasitological diagnostic techniques. The aim of this study was to compare the accuracy of a single Kato-Katz thick smear and a single FLOTAC for the determination of the prevalence and intensity of soil-transmitted helminth infections. A total of 271 faecal specimens were collected from schoolchildren in Ethiopia, and microscopically examined using the Kato-Katz method (41.7 mg stool per slide) and the FLOTAC technique. The combined results from the Kato-Katz and FLOTAC methods were used as diagnostic ‘gold’ standard for reference in the analysis. Agreement between the two methods showed kappa values of 0.74, 0.73 and 0.28 for Ascaris lumbricoides, Trichuris trichiura and hookworm, respectively. A single FLOTAC revealed significantly more infections than a single Kato-Katz for each of the three soil-transmitted helminths (p < 0.01). The sensitivities of a single Kato-Katz for diagnosis of T. trichiura, A. lumbricoides and hookworm infections were 76.6%, 67.8% and 19.6%, respectively, while the sensitivity of FLOTAC was 100% for all the three soil-transmitted helminth species. A single Kato-Katz yielded considerably higher mean faecal egg counts (FECs) (729.1, 145.2 and 60.7 eggs per gram of stool (EPG) for A. lumbricoides, T. trichiura and hookworm, respectively) compared with a single FLOTAC (142.5, 54.5 and 14.6 EPG, respectively) (p < 0.05). Our study confirms that a single FLOTAC is more sensitive than a single Kato-Katz for the diagnosis of soil-transmitted helminth infections, but results in lower FECs. Further standardization and validation are still required in different epidemiological settings with varying levels of intensity of infections before recommending FLOTAC for large-scale community diagnosis.

Trichuris and hookworm infections associated with anaemia during pregnancy

To assess the following associations between the second and third trimesters of pregnancy: (i) the intensity of soil-transmitted helminth (STH) infection and haemoglobin/anaemia, (ii) the effect of mebendazole treatment on the occurrence of STH infection, and (iii) the effect of mebendazole treatment on haemoglobin/anaemia. Data originated from a trial of 1042 pregnant women recruited in their second trimester and followed to delivery. Baseline assessments included socio-demographic/health information from questionnaires, haemoglobin/anaemia from HemoCue ascertainment of fingerprick blood, and the presence and intensity of STH (Ascaris lumbricoides, hookworms and Trichuris trichiura) infections from Kato-Katz examination. All women were given iron supplements; half were randomly allocated to receive single dose 500 mg mebendazole, and half, placebo. Haemoglobin/anaemia and STH infection status were determined again in the third trimester of pregnancy. Complete information was available from 935 (89.7%) women. Mebendazole significantly reduced the prevalence and intensity of all three STH infections. Higher intensities of hookworm and Trichuris infections in the second trimester were associated with a higher risk of anaemia in the third trimester. Overall, women with moderate/heavy Trichuris infection were found to be at a higher risk of anaemia; the highest risk was observed among those with moderate/heavy hookworm co-infection (adjusted OR = 2.77; 95% CI: 1.26, 6.11). Mebendazole treatment did not reduce the risk of anaemia. Higher intensities of both Trichuris and hookworm infections are associated with anaemia in pregnancy. The importance of Trichuris infections during pregnancy requires renewed attention.

Geohelminth Infection in Rural Cameroonian Villages

A survey of human geohelminth infections was conducted in Bawa and Nloh, two rural agrarian villages in the West Province of Cameroon. The purpose of the study was to provide baseline data to assess the efficacy of a universal geohelminth control program that the Bawa Health Initiative, a nongovernmental humanitarian organization, has implemented in the 2 villages. In Nloh, A. lumbricoides, T. trichiura, and hookworm exhibited prevalences of 33.0%, 54.3%, and 26.6%, respectively, and mean intensities given as eggs per gram of feces (epg) of 2,490, 246, and 293, respectively. In Bawa, A. lumbricoides, T. trichiura, and hookworm exhibited prevalences of 15.3%, 41.5%, and 18.7%, respectively, and mean intensities of 18,904, 346, and 57 epg, respectively. All geohelminths investigated exhibited extreme overdispersion. Although the 2 villages are demographically nearly identical, prevalences of A. lumbricoides and T. trichiura infection in Nloh were significantly higher than those in Bawa. The only differences between the villages that might account for the differences in prevalence of geohelminth infection is that clean drinking water and basic sanitation, and hygiene education programs, have been implemented in Bawa. High prevalences of infection in senior adults indicate that they may represent a neglected group in regard to geohelminth infection. In Bawa, a clustering of moderate- to high-intensity infections was noted among family compounds for A. lumbricoides and T. trichiura. Comparison of these data to those gathered in the West Province of Cameroon during a Cameroonian National Survey of helminth infections, conducted between 1985-1987, suggests that the prevalences of infection with A. lumbricoides and T. trichiura have decreased while the incidence of hookworm infection may have increased. However, such comparisons between surveys must be interpreted very conservatively, given the multitude of factors leading to dramatic differences in prevalence of geohelminth infections, even

Nematode infections in Slovak children hospitalised during 2008–2009

Abstract A study involved 1800 hospitalised children (age: 9 months to 16 years) examined by ovoscopic analyses and confirmed the occurrence of Ascaris lumbricoides and Trichuris trichiura in 46 patients (2.55 %). Of these, 30 patients had Ascaris infection, 13 were positive for both nematodes and 3 patients had Trichuris infection. The mean count of A. lumbricoides eggs in positive cases was 1050 eggs per gramme (EPG) in range 150–4450 EPG. The mean count of T. trichiura eggs was 150 EPG (50–250 EPG). The highest intensities of A. lumbricoides and T. trichiura infections occurred in children 3–5 years of age living in poor hygienic conditions. Most common clinical conditions in all the patients included anaemia combined with complicated bronchopneumonia, colitis and gastritis. The strongest correlation between the parasite burden and selected laboratory test data (eosinophil count, haemoglobin, total serum iron) was found in children of 2 years of age (P &lt; 0.05) and decreased with age.

Albendazole and Mebendazole Administered Alone or in Combination with Ivermectin againstTrichuris trichiura: A Randomized Controlled Trial

Single-dose albendazole and mebendazole show limited efficacy in the treatment of trichuriasis. The combination of albendazole with ivermectin improves efficacy, but a mebendazole-ivermectin combination has not been previously investigated. We performed a randomized controlled trial in 2 schools in Zanzibar, Tanzania, to assess the efficacy and safety of albendazole (400 mg) plus placebo, albendazole plus ivermectin (200 μg/kg), mebendazole (500 mg) plus placebo, and mebendazole plus ivermectin in children with a parasitologically confirmed Trichuris trichiura infection. Cure rate (CR) and egg reduction rate were assessed by intent-to-treat analysis. Adverse events were monitored within 48 h after treatment. Complete data records were available for 548 children. The highest CR against T. trichiura was achieved with a mebendazole-ivermectin combination (55%). Low CRs were observed with albendazole-ivermectin (38%), mebendazole (19%), and albendazole (10%). Compared with placebo, the use of ivermectin statistically significantly increased the CRs from 14% to 47% (odds ratio, 0.19; 95% confidence interval [CI], 0.12-0.28). The highest egg reduction rate (97%; 95% CI, 95%-98%) was observed using the mebendazole-ivermectin combination, followed by albendazole-ivermectin (91%; 95% CI, 87%-94%), mebendazole (67%; 95% CI, 52%-77%), and albendazole (40%; 95% CI, 22%-56%). The adverse events, reported by 136 children, were generally mild, with no significant difference between the treatment arms. Addition of ivermectin improves the therapeutic outcomes of both albendazole and mebendazole against T. trichiura and may be considered for use in soil-transmitted helminth control programs and individual patient management. isrctn.org Identifier: ISRCTN08336605.

Chronic Trichuris trichiura Infection Presenting as Ileocecal Valve Swelling Mimicking Malignancy

A 46-year-old man presented with a history of passing bright red blood per rectum over the last one month. He also had on and off diarrhea with visible mucus in the stool for two months' duration. Further history was unremarkable, and physical examination revealed hemorrhoids which were subsequently banded. A colonoscopy was arranged in view of the prolonged diarrhea whereby an edematous and swollen ileocecal valve was seen. This was shown to be due to Trichuris trichiura infection, confirmed on histopathological examination of biopsies taken from the site. The patient was started on oral albendazole treatment and has been asymptomatic on latest followup. This case illustrates an accidental finding of T. trichuria infection on colonoscopic examination, which was done to investigate the patient's prolonged diarrhea.

Risk factors for atopic and non-atopic asthma in a rural area of Ecuador

BackgroundAsthma has emerged as an important public health problem of urban populations in Latin America. Epidemiological data suggest that a minority of asthma cases in Latin America may be associated...

Two Cases of Trichuris Trichiura Infection Diagnosed by Colonoscopy

Trichuris trichiura (T. trichiura) is soil-transmitted parasite and widely spreads all over the world. High infection rates occur especially in the poor hygiene area. T. trichiura is transmitted by the water and food contaminated with T. trichiura eggs. Most of mildly infected individuals could be asymptomatic, whereas heavily infected patients manifest with anemia, diarrhea, nausea, vomiting, abdominal pain, and weight loss. Serious manifestations such as intestinal obstruction and perforation were reported to be caused by Trichuriasis. Diagnostic methods are stool examination of T. trichiura eggs and eosinophil count in blood. Sometimes, colonoscopy can be useful diagnostic tool and treatment. We observed that the North Korean refugee with chronic abdominal pain and the patient with abdominal pain and loose stool have been diagnosed as T. trichiura infection confirmed by colonoscopy. After treatment, the patient's symptom has improved. Therefore we report two cases of trichuriasis with literature review.

Intestinal Helminthic Infections Diagnosed by Colonoscopy in a Regional Hospital during 2001-2008

The present study investigated characteristics of 24 parasite infection cases detected during colonoscopy in a regional hospital from January 2001 to December 2008. Sixteen patients were confirmed with Trichuris trichiura infection, 6 patients were with Ascaris lumbricoides infection, 1 patient with Enterobius vermicularis infection, and 1 patient with Anisakis infection. Among them, 7 patients (43.8%) were asymptomatic. Colonoscopy findings were normal in 18 patients (75.0%). Among the patients with T. trichiura infection, colonoscopy showed several erosions in 2 patients (8.3%) and non-specific inflammation of the affected segment of the colon in 3 patients (12.5%). In 1 patient with anisakiasis, colonoscopy revealed a markedly swollen colonic wall. Stool examinations were performed before treatment in 7 patients (29.2%) and were all negative for parasite eggs or worms. These results suggest that colonoscopy is a useful diagnostic approach for parasitic infections even for asymptomatic patients and for patients with negative stool examinations.

Geographical location and age affects the incidence of parasitic infestations in school children

Environmental factors affect the dissemination and distribution of intestinal parasites in human communities. To comprehend the prevalence of parasitic infestation and to examine whether geographical location and age also influence the prevalence of infection, fecal samples from 195 school children (rural = 95; male = 39; female = 56) (urban = 100; male = 60; female = 40) of five age groups ranging from 5 to 11 years in two different socio-economic zones (rural and urban) were screened for specific intestinal parasites using standard histological techniques. Percentage incidences of parasitic species found in fecal wet mounts and concentrates in rural children were Entamoeba coli (25.3%), Giardia lamblia (17.9%), Blastocystis hominis (14.7%), Entamoeba histolytica (4.2%), Iodamoeba butschlii (1.1%), Hymenolepis nana (1.1%) and Ascaris lumbricoides (1.1%). Whereas the percentage incidences among urban children were E. coli (26%), A. lumbricoides (21%), B. hominis (18%), G. lamblia (14%), T. trichiura (8%), I. butschlii (4%) and A. duodenale (1%). Such findings may be related to dietary differences, living conditions and the greater use of natural anti-helminthic medicinal plants in rural communities. These results are important for both epidemiological data collection and for correlating dietary differences to intestinal parasitic diseases. We chose to investigate whether geographical location and age affect the prevalence and distribution of intestinal parasites among school children from two separate regions (rural and urban) in areas surrounding, Chennai, Tamil Nadu, India. A study of the prevalence of parasitic infestations was undertaken among primary school children, in rural and urban communities around Chennai, Tamil Nadu, India. Faecal sample collection, direct microscopic techniques, macroscopic examination and concentration techniques for identifying the parasites. Percentage incidences of parasitic species found in faecal wet mounts and concentrates were done instead of statistical analyses. Both macroscopic and microscopic examinations of faecal samples revealed that the overall percentage prevalence of parasite species encountered in rural children were Entamoeba coli (25.3%), G. lamblia (17.9%), B. hominis (14.7%), Entamoeba histolytica (4.2%), I. butschlii (1.1%), H. nana (1.1%), Ascaris lumbricoides (1.1%). The prevalence among urban children were E. coli (26%), A. lumbricoides (21%), B. hominis (18%), G. lamblia (14%), T. trichiura (8%), I. butschlii (4%) and A. duodenale (1%). Overall, comparative significant differences were noted between rural and urban children for E. histolytica (4.2 vs. 14%), G. lamblia (17.9 vs. 14%), A. lumbricoides (1.1 vs. 21%) and T. trichiura (0 vs. 8%), with the major difference being the much higher occurrence of A. lumbricoides and T. trichiura infections in urban children. One of the greatest challenges for healthcare professionals is the prevention and treatment of protozoal and helminthic parasitic infections. From our study we conclude that the prevalence of different pathogenic species of amoeba such as Entamoeba histolytica (4.2 vs. 0%) and G. lamblia (17.9 vs. 14%), (P value was equal to 1) was significantly higher among rural children compared to children from urban areas. In contrast, the prevalence of nematodes such as A. lumbricoides (21% vs. 1.1%), T. trichiura (8% vs. 0%) and A. duodenale (1%) was also significantly higher among rural children.

Trichuris dysentery syndrome: a common cause of chronic iron deficiency anemia in adults in an endemic area (with videos)

There are few published reports of Trichuris dysentery syndrome (TDS) in children. The disease has not been reported in adults. To report the clinical, colonoscopic, and histologic findings of TDS in adults in an endemic area. Case series. Tertiary gastroenterology center. Eighty-four consecutive adult patients with chronic iron deficiency anemia over a 3-year period were investigated. Ten patients had severe Trichuris trichiura infection and received a diagnosis of TDS. Colonoscopy and colonic biopsies. Patients received anthelmintic treatment, and their response was assessed. Ten patients with TDS were studied, including 8 female and 2 male patients with a mean (+/- standard deviation) age of 43 (+/- 15.5) years (range 15-65 years) and a hemoglobin level (+/- standard deviation) of 6.0 +/- 1.5 g/dL (range 4-8 g/dL); the duration (+/- standard deviation) of disease was 2.1 +/- 1.1 years (range 1.5-8.5 years). None of the patients had growth retardation, malnutrition, or immunodeficiency. Abdominal symptoms included abdominal pain, diarrhea, and hematochezia in 1 patient. Nine other patients had no abdominal symptoms. Colonoscopy revealed actively motile T. trichiura worms in large numbers in the right colon in 7 patients, in the ileum in 1, in the left colon in 1, and worms carpeting of the whole colonic mucosa in 1. Associated mucosal changes included petechial lesions, blotchy mucosal hemorrhages, and active mucosal oozing. Biopsy of the colon revealed worm segments with a thick outer cuticle. The posterior segment of the worm contained gravid uterus with numerous characteristic T. trichiura eggs. There was paucity of associated mucosal changes in most of the sections. Similar studies in other endemic areas are lacking. TDS should be considered in all patients in endemic areas with chronic iron deficiency anemia and/or occult blood loss.

Estimating the sensitivity and specificity of Kato-Katz stool examination technique for detection of hookworms, Ascaris lumbricoides and Trichuris trichiura infections in humans in the absence of a ‘gold standard’

The accuracy of the Kato-Katz technique in identifying individuals with soil-transmitted helminth (STH) infections is limited by day-to-day variation in helminth egg excretion, confusion with other parasites and the laboratory technicians’ experience. We aimed to estimate the sensitivity and specificity of the Kato-Katz technique to detect infection with Ascaris lumbricoides, hookworm and Trichuris trichiura using a Bayesian approach in the absence of a ‘gold standard’. Data were obtained from a longitudinal study conducted between January 2004 and December 2005 in Samar Province, the Philippines. Each participant provided between one and three stool samples over consecutive days. Stool samples were examined using the Kato-Katz technique and reported as positive or negative for STHs. In the presence of measurement error, the true status of each individual is considered as latent data. Using a Bayesian method, we calculated marginal posterior densities of sensitivity and specificity parameters from the product of the likelihood function of observed and latent data. A uniform prior distribution was used (beta distribution: α = 1, β = 1). A total of 5624 individuals provided at least one stool sample. One, two and three stool samples were provided by 1582, 1893 and 2149 individuals, respectively. All STHs showed variation in test results from day to day. Sensitivity estimates of the Kato-Katz technique for one stool sample were 96.9% (95% Bayesian Credible Interval [BCI]: 96.1%, 97.6%), 65.2% (60.0%, 69.8%) and 91.4% (90.5%, 92.3%), for A. lumbricoides, hookworm and T. trichiura, respectively. Specificity estimates for one stool sample were 96.1% (95.5%, 96.7%), 93.8% (92.4%, 95.4%) and 94.4% (93.2%, 95.5%), for A. lumbricoides, hookworm and T. trichiura, respectively. Our results show that the Kato-Katz technique can perform with reasonable accuracy with one day’s stool collection for A. lumbricoides and T. trichiura. Low sensitivity of the Kato-Katz for detection of hookworm infection may be related to rapid degeneration of delicate hookworm eggs with time.