Diagnostic accuracy of Kato-Katz and FLOTAC for assessing anthelmintic drug efficacy

BACKGROUND

Sensitive diagnostic tools are required for an accurate assessment of prevalence and intensity of helminth infections in areas undergoing regular deworming, and for monitoring anthelmintic drug efficacy. We compared the diagnostic accuracy of the Kato-Katz and FLOTAC techniques in the frame of a drug efficacy trial.

METHODOLOGY/PRINCIPAL FINDINGS

Stool samples from 343 Zanzibari children were subjected to duplicate Kato-Katz thick smears and the FLOTAC basic technique in a baseline screening in early 2009. The FLOTAC showed a higher sensitivity than the Kato-Katz method for the diagnosis of Trichuris trichiura (95% vs. 88%, p = 0.012) and Ascaris lumbricoides (88% vs. 68%, p = 0.098), but a lower sensitivity for hookworm diagnosis (54% vs. 81%, p = 0.006). Considering the combined results from both methods as 'gold' standard, the prevalences of T. trichiura, hookworm and A. lumbricoides were 71% (95% confidence interval (CI): 66-75%), 22% (95% CI: 17-26%) and 12% (95% CI: 8-15%), respectively. At follow-up, 3-5 weeks after 174 among the 269 re-examined children were administered anthelmintic drugs, we observed cure rates (CRs) against A. lumbricoides, hookworm and T. trichiura of 91% (95% CI: 80-100%), 61% (95% CI: 48-75%) and 41% (95% CI: 34-49%), respectively, when using the Kato-Katz method. FLOTAC revealed lower CRs against A. lumbricoides (83%, 95% CI: 67-98%) and T. trichiura (36%, 95% CI: 29-43%), but a higher CR against hookworm (69%, 95% CI: 57-82%). These differences, however, lacked statistical significance. Considerable differences were observed in the geometric mean fecal egg counts between the two methods with lower egg reduction rates (ERRs) determined by FLOTAC.

CONCLUSION/SIGNIFICANCE

Our results suggest that the FLOTAC technique, following further optimization, might become a viable alternative to the Kato-Katz method for anthelmintic drug efficacy studies and for monitoring and evaluation of deworming programs. The lower CRs and ERRs determined by FLOTAC warrant consideration and could strategically impact future helminth control programs.

[Heterogeneity of parasitic contamination of megalopolis soils]

A morphological group ofwhipworm (Trichuris trichiura) eggs, which is detectable in the soil samples from the city's different control lands, shows that their origin is heterogeneous and it is possible to differentiate them by morphometric signs. At the same time is necessary to consider the specific biological factors contributing to soil contamination. Priority in parasitic soil contamination should be given to animals, dogs in particular, which is supported by the fact that the dog walking grounds exhibit the highest contamination rates.

Assessing the impact of misclassification error on an epidemiological association between two helminthic infections

BACKGROUND

Polyparasitism can lead to severe disability in endemic populations. Yet, the association between soil-transmitted helminth (STH) and the cumulative incidence of Schistosoma japonicum infection has not been described. The aim of this work was to quantify the effect of misclassification error, which occurs when less than 100% accurate tests are used, in STH and S. japonicum infection status on the estimation of this association.

METHODOLOGY/PRINCIPAL FINDINGS

Longitudinal data from 2276 participants in 50 villages in Samar province, Philippines treated at baseline for S. japonicum infection and followed for one year, served as the basis for this analysis. Participants provided 1-3 stool samples at baseline and 12 months later (2004-2005) to detect infections with STH and S. japonicum using the Kato-Katz technique. Variation from day-to-day in the excretion of eggs in feces introduces individual variations in the sensitivity and specificity of the Kato-Katz to detect infection. Bayesian logit models were used to take this variation into account and to investigate the impact of misclassification error on the association between these infections. Uniform priors for sensitivity and specificity of the diagnostic test to detect the three STH and S. japonicum were used. All results were adjusted for age, sex, occupation, and village-level clustering. Without correction for misclassification error, the odds ratios (ORs) between hookworm, Ascaris lumbricoides, and Trichuris trichiura, and S. japonicum infections were 1.28 (95% Bayesian credible intervals: 0.93, 1.76), 0.91 (95% BCI: 0.66, 1.26), and 1.11 (95% BCI: 0.80, 1.55), respectively, and 2.13 (95% BCI: 1.16, 4.08), 0.74 (95% BCI: 0.43, 1.25), and 1.32 (95% BCI: 0.80, 2.27), respectively, after correction for misclassification error for both exposure and outcome.

CONCLUSIONS/SIGNIFICANCE

The misclassification bias increased with decreasing test accuracy. Hookworm infection was found to be associated with increased 12-month cumulative incidence of S. japonicum infection after correction for misclassification error. Such important associations might be missed in analyses which do not adjust for misclassification errors.

Assessment of the anthelmintic efficacy of albendazole in school children in seven countries where soil-transmitted helminths are endemic

Background

The three major soil-transmitted helminths (STH) Ascaris lumbricoides, Trichuris trichiura and Necator americanus/Ancylostoma duodenale are among the most widespread parasites worldwide. Despite the global expansion of preventive anthelmintic treatment, standard operating procedures to monitor anthelmintic drug efficacy are lacking. The objective of this study, therefore, was to define the efficacy of a single 400 milligram dose of albendazole (ALB) against these three STH using a standardized protocol.

Methodology/Principal Findings

Seven trials were undertaken among school children in Brazil, Cameroon, Cambodia, Ethiopia, India, Tanzania and Vietnam. Efficacy was assessed by the Cure Rate (CR) and the Fecal Egg Count Reduction (FECR) using the McMaster egg counting technique to determine fecal egg counts (FEC). Overall, the highest CRs were observed for A. lumbricoides (98.2%) followed by hookworms (87.8%) and T. trichiura (46.6%). There was considerable variation in the CR for the three parasites across trials (country), by age or the pre-intervention FEC (pre-treatment). The latter is probably the most important as it had a considerable effect on the CR of all three STH. Therapeutic efficacies, as reflected by the FECRs, were very high for A. lumbricoides (99.5%) and hookworms (94.8%) but significantly lower for T. trichiura (50.8%), and were affected to different extents among the 3 species by the pre-intervention FEC counts and trial (country), but not by sex or age.

Conclusions/Significance

Our findings suggest that a FECR (based on arithmetic means) of >95% for A. lumbricoides and >90% for hookworms should be the expected minimum in all future surveys, and that therapeutic efficacy below this level following a single dose of ALB should be viewed with concern in light of potential drug resistance. A standard threshold for efficacy against T. trichiura has yet to be established, as a single-dose of ALB is unlikely to be satisfactory for this parasite.

Trial Registration

ClinicalTrials.gov NCT01087099

Soil-transmitted helminths (roundworms, whipworms and hookworms) infect millions of children in (sub)tropical countries, resulting in malnutrition, growth stunting, intellectual retardation and cognitive deficits. Currently, there is a need to closely monitor anthelmintic drug efficacy and to develop standard operating procedures, as highlighted in a World Health Organization–World Bank meeting on “Monitoring of Drug Efficacy in Large Scale Treatment Programs for Human Helminthiasis” in Washington DC at the end of 2007. Therefore, we have evaluated the efficacy of a commonly used treatment against these parasitic infections in school children in Africa, Asia and South-America using a standardized protocol. In addition, different statistical approaches to analyzing the data were evaluated in order to develop standardized procedures for data analysis. The results demonstrate that the applied treatment was highly efficacious against round- and hookworms, but not against whipworms. However, there was large variation in efficacy across the different trials which warrants further attention. This study also provides new insights into the statistical analysis of efficacy data, which should be considered in future monitoring and evaluation studies of large scale anthelmintic treatment programs. Finally, our findings emphasize the need to update the World Health Organization recommended efficacy threshold for the treatment of STH.

Spatial modelling of soil-transmitted helminth infections in Kenya: a disease control planning tool

BACKGROUND

Implementation of control of parasitic diseases requires accurate, contemporary maps that provide intervention recommendations at policy-relevant spatial scales. To guide control of soil transmitted helminths (STHs), maps are required of the combined prevalence of infection, indicating where this prevalence exceeds an intervention threshold of 20%. Here we present a new approach for mapping the observed prevalence of STHs, using the example of Kenya in 2009.

METHODS AND FINDINGS

Observed prevalence data for hookworm, Ascaris lumbricoides and Trichuris trichiura were assembled for 106,370 individuals from 945 cross-sectional surveys undertaken between 1974 and 2009. Ecological and climatic covariates were extracted from high-resolution satellite data and matched to survey locations. Bayesian space-time geostatistical models were developed for each species, and were used to interpolate the probability that infection prevalence exceeded the 20% threshold across the country for both 1989 and 2009. Maps for each species were integrated to estimate combined STH prevalence using the law of total probability and incorporating a correction factor to adjust for associations between species. Population census data were combined with risk models and projected to estimate the population at risk and requiring treatment in 2009. In most areas for 2009, there was high certainty that endemicity was below the 20% threshold, with areas of endemicity ≥ 20% located around the shores of Lake Victoria and on the coast. Comparison of the predicted distributions for 1989 and 2009 show how observed STH prevalence has gradually decreased over time. The model estimated that a total of 2.8 million school-age children live in districts which warrant mass treatment.

CONCLUSIONS

Bayesian space-time geostatistical models can be used to reliably estimate the combined observed prevalence of STH and suggest that a quarter of Kenya's school-aged children live in areas of high prevalence and warrant mass treatment. As control is successful in reducing infection levels, updated models can be used to refine decision making in helminth control.

Impact of a citywide sanitation program in Northeast Brazil on intestinal parasites infection in young children

BACKGROUND

Sanitation affects health, especially that of young children. Residents of Salvador, in Northeast Brazil, have had a high prevalence of intestinal parasites. A citywide sanitation intervention started in 1996 aimed to raise the level of sewer coverage from 26% to 80% of households.

OBJECTIVES

We evaluated the impact of this intervention on the prevalence of Ascaris lumbricoides, Trichuris trichuria, and Giardia duodenalis infections in preschool children.

METHODS

The evaluation was composed of two cross-sectional studies (1998 and 2003-2004), each of a sample of 681 and 976 children 1-4 years of age, respectively. Children were sampled from 24 sentinel areas chosen to represent the range of environmental conditions in the study site. Data were collected using an individual/household questionnaire, and an environmental survey was conducted in each area before and after the intervention to assess basic household and neighborhood sanitation conditions. Stool samples were examined for the presence of intestinal parasites. The effect of the intervention was estimated by hierarchical modeling, fitting a sequence of multivariate regression models.

FINDINGS

The prevalence ofA. lumbricoides infection was reduced from 24.4% to 12.0%, T. trichuria from 18.0% to 5.0%, and G. duodenalis from 14.1% to 5.3%. Most of this reduction appeared to be explained by the increased coverage in each neighborhood by the sewage system constructed during the intervention. The key explanatory variable was thus an ecological measure of exposure and not household-based, suggesting that the parasite transmission prevented by the program was mainly in the public (vs. the domestic) domain.

CONCLUSION

This study, using advanced statistical modeling to control for individual and ecological potential confounders, demonstrates the impact on intestinal parasites of sanitation improvements implemented at the scale of a large population.

Serological studies of neurologic helminthic infections in rural areas of southwest cameroon: toxocariasis, cysticercosis and paragonimiasis

BACKGROUND

Both epilepsy and paragonimiasis had been known to be endemic in Southwest Cameroon. A total of 188 people (168 and 20 with and without symptoms confirmed by clinicians, respectively, 84.6% under 20 years old) were selected on a voluntary basis. Among 14 people (8.3%) with history of epilepsy, only one suffered from paragonimiasis. Therefore, we challenged to check antibody responses to highly specific diagnostic recombinant antigens for two other helminthic diseases, cysticercosis and toxocariasis, expected to be involved in neurological diseases. Soil-transmitted helminthic infections were also examined.

METHODOLOGY/PRINCIPAL FINDINGS

Fecal samples were collected exclusively from the 168 people. Eggs of Ascaris lumbricoides, Trichuris trichiura and hookworms were found from 56 (33.3%), 72 (42.8%), and 19 (11.3%) persons, respectively. Serology revealed that 61 (36.3%), 25 (14.9%) and 2 (1.2%) of 168 persons showed specific antibody responses to toxocariasis, paragonimiasis and cysticercosis, respectively. By contrast, 20 people without any symptoms as well as additional 20 people from Japan showed no antibody responses. Among the 14 persons with epilepsy, 5 persons were seropositive to the antigen specific to Toxocara, and one of them was simultaneously positive to the antigens of Paragonimus. The fact that 2 children with no history of epilepsy were serologically confirmed to have cysticercosis strongly suggests that serological survey for cysticercosis in children is expected to be useful for early detection of asymptomatic cysticercosis in endemic areas.

CONCLUSIONS/SIGNIFICANCE

Among persons surveyed, toxocariasis was more common than paragonimiasis, but cysticercosis was very rare. However, the fact that 2 children were serologically confirmed to have cysticercosis was very important, since it strongly suggests that serology for cysticercosis is useful and feasible for detection of asymptomatic cysticercotic children in endemic areas for the early treatment.

Molecular evolution of Trichuris muris isolated from different Muridae hosts in Europe

A phylogeographic study was carried out of Trichuris muris, nematode parasitizing Murinae rodents from the Muridae family, isolated from four different hosts and from different geographical regions of Europe by amplification and sequencing of the ITS1-5.8S-ITS2 fragment of the ribosomal DNA. T. muris was found in the Apodemus sylvaticus, Apodemus flavicollis, Mus domesticus, and Rattus rattus rodents. The molecular results confirm the presence of DNA polymorphisms among T. muris isolates from Europe. The present study shows two clear-cut geographical and genetic lineages: one of them is widespread from northern Spain (Catalonia) to Denmark (Western European region), while the second is widespread in the Eastern European region (Croatia, Rumania, and Turkey). These two genotypes can be easily distinguished by a PCR-RFLP analysis of this sequence with the ApalI restriction enzyme. Moreover, networks and phylogenetic reconstructions also reveal that T. muris from various Murinae rodents did not differentiate according to the host species that they parasitize. Furthermore, T. muris isolated from The Canary Islands revealed a typical haplotype (H6) only present in The Canary Islands and not in continental Europe. It is suggested that one haplotype from La Gomera Island is the ancestor of T. muris in the Canary Islands.

Patterns and risk factors of helminthiasis and anemia in a rural and a peri-urban community in Zanzibar, in the context of helminth control programs

BACKGROUND

The control of helminth infections and prevention of anemia in developing countries are of considerable public health importance. The purpose of this study was to determine patterns and risk factors of helminth infections and anemia in a rural and a peri-urban community of Zanzibar, Tanzania, in the context of national helminth control programs.

METHODOLOGY/PRINCIPAL FINDINGS

We carried out a community-based cross-sectional study in 454 individuals by examining at least two stool samples with different methods for soil-transmitted helminths (Ascaris lumbricoides, hookworm, Strongyloides stercoralis, and Trichuris trichiura) and one urine sample for Schistosoma haematobium. Finger-prick blood was taken to estimate anemia levels and to detect antibody reactions against ascariasis, strongyloidiasis and schistosomiasis, using an enzyme-linked immunosorbent assay (ELISA) approach. Parasitological methods determined a helminth prevalence of 73.7% in the rural, and 48.9% in the peri-urban setting. Most helminth infections were of light intensity with school-aged children showing the highest intensities. Multiple helminth species infections were pervasive in rural dwellers regardless of age. More than half of the participants were anemic, with a particularly high prevalence in the peri-urban setting (64.7%). Risk factors for helminth infections were age, sex, consumption of raw vegetables or salad, recent travel history, and socio-economic status.

CONCLUSION/SIGNIFICANCE

After several years of chemotherapy-based morbidity control efforts in Zanzibar, helminth prevalences are still high and anemia is common, but helminth infection intensities are low. Hence, chemotherapy should be continued, and complemented with improved access to clean water, adequate sanitation, and health education, along with poverty alleviation measures for a more enduring impact.

[Helminthiasis in children--possible variants of symbiosis]

ACTUALITY

protozoal diseases and helminthiases are an essential part of infectious diseases. The massive spread of parasitic diseases had been identified in all regions of the world, including in children., number of suffering from parasitic infections exceeds 20 million and has a tendency to increase in Russia. The magnitude of damage to people's health, intestinal helminthiases are among the four leading causes of all diseases.

MATERIAL AND METHODS

under the supervision was a child with mixed-infestation of 7 helminths and parasites: enterobiosis + giardiasis, enterobiosis + ascariasis, ascariasis + trihotsefalez; enterobiosis giardiasis + toxocariasis.

RESULTS

the case is of interest to clinicians and pediatricians in terms of diagnosis, because the helminthiasis was proceeded under the guise of somatic diseases associated with severe visceral injuries. Highlight helminthiasis on the stage of mixed-infestation among several helminths and parasites indicates a lack of pediatricians' alertness on parasitosis.

Field validity and feasibility of four techniques for the detection of Trichuris in simians: a model for monitoring drug efficacy in public health?

Background

Soil-transmitted helminths, such as Trichuris trichiura, are of major concern in public health. Current efforts to control these helminth infections involve periodic mass treatment in endemic areas. Since these large-scale interventions are likely to intensify, monitoring the drug efficacy will become indispensible. However, studies comparing detection techniques based on sensitivity, fecal egg counts (FEC), feasibility for mass diagnosis and drug efficacy estimates are scarce.

Methodology/Principal Findings

In the present study, the ether-based concentration, the Parasep Solvent Free (SF), the McMaster and the FLOTAC techniques were compared based on both validity and feasibility for the detection of Trichuris eggs in 100 fecal samples of nonhuman primates. In addition, the drug efficacy estimates of quantitative techniques was examined using a statistical simulation. Trichuris eggs were found in 47% of the samples. FLOTAC was the most sensitive technique (100%), followed by the Parasep SF (83.0% [95% confidence interval (CI): 82.4–83.6%]) and the ether-based concentration technique (76.6% [95% CI: 75.8–77.3%]). McMaster was the least sensitive (61.7% [95% CI: 60.7–62.6%]) and failed to detect low FEC. The quantitative comparison revealed a positive correlation between the four techniques (Rs = 0.85–0.93; p<0.0001). However, the ether-based concentration technique and the Parasep SF detected significantly fewer eggs than both the McMaster and the FLOTAC (p<0.0083). Overall, the McMaster was the most feasible technique (3.9 min/sample for preparing, reading and cleaning of the apparatus), followed by the ether-based concentration technique (7.7 min/sample) and the FLOTAC (9.8 min/sample). Parasep SF was the least feasible (17.7 min/sample). The simulation revealed that the sensitivity is less important for monitoring drug efficacy and that both FLOTAC and McMaster were reliable estimators.

Conclusions/Significance

The results of this study demonstrated that McMaster is a promising technique when making use of FEC to monitor drug efficacy in Trichuris.

Worldwide, millions of people are infected with soil-transmitted helminths, particularly in developing countries. Efforts to control these infections involve periodic mass drug treatment in endemic areas. Since these large-scale interventions are likely to intensify, monitoring of drug efficacy has become a key issue in order to detect the emergence of resistance. At present, the drop in infection intensity is under examination for monitoring the drug efficacy. However, studies comparing detection techniques based on infection intensities are scarce. Moreover, little attention has been addressed to their feasibility and their ability to estimate drug efficacies. We have compared different techniques for the detection of whipworm (Trichuris) in simian stool samples based on prevalence, infection intensities, feasibility and ability to estimate the ‘true’ drug efficacy. We have found that techniques often fail to detect low infection intensities and that not all techniques are appropriate for estimating infection intensities. The time needed to obtain a test result varied from 3.9 to 17.7 min/sample. Finally, accurate estimates of drug efficacy were only obtained in high pre-drug administration infection intensities. To conclude, along with accurate estimates of infection intensities, feasibility is a considerable criterion for the detection techniques used in drug efficacy monitoring programs.

[Contamination of soil with geohelminth eggs on vegetable organic farms in the Lublin voivodeship, Poland]

Organic farming, despite being more difficult and labour consuming than traditional farming, gains increasingly more followers among farmers. Currently in Poland there are approximately 10 000 organic farms. Pure, uncontaminated soil in the Lublin voivodeship makes this area an ideal location for organic agriculture production. In 2006-2007, 102 soil samples were examined from 40 organic farms specializing in vegetables and berries. Farms for the study were selected by ecology- and food-production specialists from the Lublin Agriculture Advisory Centre in Końskowola. The following plants were cultivated on the farms examined: berry-bearing plants, carrots, parsley, zucchini, cabbage, lettuce, cucumbers, cauliflowers, leeks, onions, kidney beans, beetroots, potatoes, pumpkins, broad beans, rhubarb and herbs. The presently reported parasitological survey was performed on 102 soil samples. Each sample consisted of 100 g of soil and the methodology followed that of the Polish Standard PN-Z-19000-4 (flotation method by Quinn et al.). The survey yielded eggs of parasites representing genera: Ascaris, Trichuris and Toxocara. Contamination with eggs of intestinal parasites was noted in 43 (42.16%) soil samples. Toxocara spp. eggs were found in 24 samples (55.81%). Eggs of Ascaris spp. were detected in 18 samples (41.86%) while eggs of Trichuris spp were present in one sample (2.32%). In total, 29 eggs of Toxocara spp., 19 eggs of Ascaris spp., and 1 egg of Trichuris spp. were found. The largest amount of soil for examination was taken across the plantations of berry-bearing plants - 57 samples. In the group examined, plantations of raspberries and strawberries dominated. The soil was contaminated with the eggs of Toxocara spp. and Ascaris spp. No eggs of Trichuris spp. were detected. The presence of eggs of intestinal parasites in soil poses a threat of geohelminthoses to people who eat contaminated fresh fruits and vegetables.

[The sanitary and parasitological characteristics of environmental objects in the south of Russia. Wastewaters and their precipitations]

The relative uniformity of helminthic eggs has been noted in the wastewaters of the Rostov Region, Krasnodar Territory, and the Republic ofAdygea. An ovogram is mainly presented by the eggs of Ascaris, Toxocaras, and whipworms. By taking into account incomplete dehelmintization during waste treatment, 5,000 to 1,080,000 helminth eggs may annually come into the water reservoirs where purified wastewaters are discharged, 33% remaining viable. Irrespective of the efficiency of dehelmintization, wastewaters and their precipitations continue to remain epidemiologically dangerous substrates and to create prerequisites for the spread of an invasive source in the environment, by risking the infection of the population with parasitic diseases.

A 6 year Geohelminth infection profile of children at high altitude in Western Nepal

BACKGROUND

Geohelminth infections are a major problem of children from the developing countries. Children with these infections suffer from developmental impairments and other serious illnesses. This study aimed to measure the prevalence of geohelminth infection, infection intensity as well as the change in the intensity in children from Western Nepal over years.

METHODS

This 6-year hospital based prospective study at the Manipal Teaching Hospital, Pokhara included children (< 15 years) visiting the hospital from Kaski and 7 surrounding districts. Samples were also collected from children in the community from different medical camps. Three stool samples from every child were processed using direct and concentration methods. The Kato-Katz technique was used for measuring the intensity of infection.

RESULTS

The overall prevalence in hospital - attending children was 9.2% with 7.6% in preschool (0 - 5 y) and 11.0% in school-age (6 - 15 y) children, and in community 17.7% with 14.8% in pre-school and 20.5% in school-age children. Ascaris lumbricoides, Trichuris trichiura, Ancylostoma deodenale and Strongyloides stercoralis were the common geohelminths with a gradual decrease in worm load over the years. School-age children were found to be significantly more prone to geohelminth infection as compared to preschool children, but no statistical difference was detected by gender, district as well as season.

CONCLUSION

This heavy infection of geohelminths in children should be corrected by appropriate medication and maintaining strict personal hygiene. Health education, clean water, good sewage management and a congenial environment should be ensured to minimise infection.

Diagnosis of soil-transmitted helminths in the era of preventive chemotherapy: effect of multiple stool sampling and use of different diagnostic techniques

BACKGROUND

Soil-transmitted helminth infections are common throughout the tropics and subtropics and they disproportionately affect the poorest of the poor. In view of a growing global commitment to control soil-transmitted helminthiasis, there is a need to elucidate the effect of repeated stool sampling and the use of different diagnostic methods in areas targeted for preventive chemotherapy that are characterized by low-infection intensities. In this study, we focused on schoolchildren on Unguja Island, Zanzibar, an area where anthelminthic drugs have been repeatedly administered over the past decade.

METHODOLOGY/PRINCIPAL FINDINGS

Three serial stool samples from each of 342 schoolchildren were examined using the Kato-Katz (K-K), Koga agar plate (KAP), and Baermann (BM) techniques. These methods were used individually or in combination for the diagnosis of Ascaris lumbricoides (K-K), Trichuris trichiura (K-K), hookworm (K-K and KAP), and Strongyloides stercoralis (KAP and BM). The examination of multiple stool samples instead of a single one resulted in an increase of the observed prevalence; e.g., an increase of 161% for hookworm using the K-K method. The diagnostic sensitivity of single stool sampling ranged between 20.7% for BM to detect S. stercoralis and 84.2% for K-K to diagnose A. lumbricoides. Highest sensitivities were observed when different diagnostic approaches were combined. The observed prevalences for T. trichiura, hookworm, A. lumbricoides, and S. stercoralis were 47.9%, 22.5%, 16.5%, and 10.8% after examining 3 stool samples. These values are close to the 'true' prevalences predicted by a mathematical model.

CONCLUSION/SIGNIFICANCE

Rigorous epidemiologic surveillance of soil-transmitted helminthiasis in the era of preventive chemotherapy is facilitated by multiple stool sampling bolstered by different diagnostic techniques.

Some aspects of nematode infection in pigs from small herds

Two traditionally maintained, small herds from southern Poland, with 8 and 12 sows, respectively, were surveyed coprologically during 2006-2007. In one of the herds, while deworming a group of sows with levamisole, faecal samples were collected on Day -7, Day 0 (the day of treatment) and Day 10, in order to assess the therapeutic effect of the drug. Coprological investigation was performed also in 26 fatteners originating from other small farms and slaughtered in a local abattoir, with their intestines washed through for the presence of roundworms. In both herds examined, Ascaris suum and Oesophagostomum spp. were prevalent, whilst Trichuris suis appeared only very rarely. Mainly fatteners, replacement gilts and young sows were highly infected with A. suum. The roundworm occurrence in 2- 3-week-old piglets, with the intensity of 300 eggs per gram of faeces (EPG), indicated the possibility of parasite transmission to offspring very early in age. The highest level of Oesophagostomum spp. infection was observed in sows, but weaners were also much affected. For the group of dewormed sows, the mean faecal egg count reduction (FECR) was estimated to be 77.1- 80.4%, suggesting the presence of resistant nodular worms. A very high false-positive A. suum egg counts found in slaughtered animals (240 to 320 EPG) testified to a high contamination level of the environment of small piggeries, as well. Since the reciprocal transmission of parasites between pigs and poultry might occur, it implies that the flocks should be raised separately.

Seasonal fluctuations in prevalence of dog intestinal parasites in public squares of Mar del Plata city, Argentina and its risk for humans

The aim of this work is to analyze whether there is a seasonal prevalence of parasites in dog feces from public squares in Mar del Plata city, Argentina, and to evaluate the climatic conditions that promote the development of parasites and allow the transmission to people. The study was performed in 21 squares from June 2001 to May 2002. Samples were processed by the Willis technique. Differences in prevalence of parasites were examined for significance by the Chi-square test. Climatic data were obtained from the Library of the National Meteorological Service of Argentina. Total parasitic prevalence was higher in winter than in summer. The prevalence of Ancylostoma spp. was higher in the summer-autumn period. For Toxocara canis, the prevalence was higher in winter whereas for Trichuris vulpis, it was higher in winter, spring and summer. This work shows high prevalence of total parasites throughout the year. For Ancylostoma spp., summer and autumn might be the seasons with higher sanitary risk. On the other hand, T. canis could present the higher risk to people in winter and, T. vulpis, would be transmitted throughout the whole year. The seasonal variation in prevalence of dog parasites results in continuous exposure to people visiting the squares, not only Mar del Plata residents but also tourists from other regions of Argentina and the world, with at least one species of parasite with sanitary risk.

Multiple infection diagnosis of intestinal helminthiasis in the assessment of health and environmental effect of development projects in Nigeria

Patterns of intestinal helminth infections among school-aged children have been assessed in Eko-ende and Ore, as part of an overall assessment of the public health impact of Erinle Dam Reservoir in Osun State, Nigeria. The investigation was carried out between January and May 2005 using the Kato Katz thick smear technique and simple questionnaire for information on the bio-data, knowledge, attitude and practice of individuals towards disease transmission and control.Ascaris lumbricoides,hookworm,Trichuris trichiura, Taeniaspp.,Strongyloides stercoralisandSchistosoma mansoniwere recovered at an overall prevalence of 78.3% among 309 children examined.Ascaris lumbricoides,hookworm,T. trichiuraandS. mansoniwere the most common infections whileS. stercoralisandTaeniaspp. were found only among a few children. Infection patterns of the common diseases were age-specific with peaks in the 11–15 age bracket. Children not attending school were significantly (P < 0.05) more at risk of infection than those attending school. Multiple infections were pronounced with over 54% double infections and 6% four parasites or more infections. The need for urgent intervention to arrest the obviously serious public health situation attributable to Erinle Dam is emphasized.

PALEOPARASITOLOGICAL REPORT ON THE STOOL FROM A MEDIEVAL CHILD MUMMY IN YANGJU, KOREA

Previous studies have successfully shown evidence for parasitic infections in human remains from various archaeological sites. However, in the case of Korea, since there have been very few paleoparasitological reports published, pre-20th century parasitic infection patterns remain obscure. Therefore, in order to partly fill this gap, we are reporting on a case of paleoparasitic infection from the feces of a 15th century child mummy from Yangju, Korea. In the course of the present study, we found the eggs of Clonorchis sinensis, Ascaris lumbricoides, and Trichuris trichiura in the feces of the mummy. Trichuris trichiura eggs were found in far greater numbers than other parasite eggs; in fact, intact bipolar plugs were clearly observed and even the larvae were still visible in some eggs. The eggs of C. sinensis and A. lumbricoides were also well preserved, though not in as great a number. Since we could find a number of well-preserved larvae-containing eggs, we are encouraged that successful extraction, amplification, and sequence determination of ancient DNA from the paleoparasite eggs might be possible in future studies. With additional paleoparasitological investigation using feces from Korean mummies, we hope that a history of parasite infection in Korea will be reconstructed.

A comparison of methods for detecting the eggs of Ascaris, Trichuris, and hookworm in infant stool, and the epidemiology of infection in Zanzibari infants

This study compared five methods for detecting the eggs of the human parasitic geohelminths Ascaris, Trichuris, and hookworm in infant stool, and describes the epidemiology of infection in infants from a parasite-endemic area. A total of 424 infants 5-11 months old were enrolled from three villages on Pemba Island, Zanzibar. Methods used included the Kato-Katz technique, formol ethyl acetate sedimentation, modified formol ethyl acetate sedimentation, modified Wisconsin floatation, and simple gravity sedimentation. Of methods used alone, Wisconsin floatation and simple gravity sedimentation each provided the highest sensitivity for detecting eggs of these three geohelminths (89.6%). Of methods used in combination, the Kato-Katz technique/simple gravity sedimentation and Wisconsin floatation/simple gravity sedimentation each provided the highest sensitivity (99.0%). Prevalence of geohelminth infection was 26.5%. Between five and nine months of age the mean prevalence was 9.4%, while at 10 and 11 months of age the mean prevalence was 43.4%. Village prevalence varied from 3.6% to 43.8%. Infant geohelminth infection can occur at a high prevalence, and what method is best depends on research specifics.

A new whipworm from arvicolid rodents, Trichuris arvicolae Feliu et al., 2000, in the helminth fauna of Poland

During the parasitological examination of wild rodents from the vicinity of Wrocław a single whipworm female was isolated from a field vole Microtus agrestis. The nematode was determined as Trichuris arvicolae. This is the first report of this parasite in Poland.

Caecal-caecal intussusception caused by Trichuris trichiura in a young healthy adult

Trichuris trichiura is a worldwide problem affecting millions of people. We report an unusual case of intussusception caused by T. trichiura that mimics acute appendicitis. The literature on T. trichiura associated intussusception is reviewed.