Taenia solium transmission in a rural community in Honduras : an examination of risk factors and knowledge

Taenia soliurn taeniasis and cysticercosis are recognized as a major public health problem in Latin America. T. soliurn transmission not only affects the health of the individual, but also social and economic development, perpetuating the cycle of poverty. To determine prevalence rates, population knowledge and risk factors associated with transmission, an epidemiological study was undertaken in the rural community of Jalaca. Two standardized questionnaires were used to collect epidemiological and T. soli urn general knowledge data. Kato-Katz technique and an immunoblot assay (EITB) were used to determine taeniasis and seroprevalence, respectively. In total, 139 individuals belonging to 56 households participated in the study. Household characteristics were consistent with conditions of poverty of rural Honduras: 21.4% had no toilet or latrines, 19.6% had earthen floor, and 51.8% lacked indoor tap water. Pigs were raised in 46.4% of households, of which 70% allowed their pigs roaming freely. A human seroprevalence rate of 18.7% and a taeniasis prevalence rate of 2.4% were found. Only four persons answered correctly 2: 6 out of ten T. soliurn knowledge questions, for an average passing score of 2.9%. In general, a serious gap exists in knowledge regarding how humans acquire the infections, especially neurocysticercosis was identified. After regression analysis, the ability to recognize adult tapeworms and awareness of the clinical importance of taeniasis, were found to be significant risk factors for T. soliurn seropositivity. These results demonstrate a high level of transmission and a low level of kn~,wledge about Taenia soliurn in Jalaca. Consequently, intervention measures integrated with health education are necessary to decrease the burden caused by this parasite.

Risk Factors for Soil-transmitted Helminth Infections in Schoolchildren from Rural Communities in Honduras

Background: Honduras is endemic for soil-transmitted helminth (STH) infections. However, knowledge gaps remain in terms of risk factors involved in STH transmission and infection intensity. Objectives: To determine the prevalence and intensity of STH infections in schoolchildren living in rural Honduras. Additionally, to investigate risk factors associated with STH infections. Methods: A cross-sectional study was done among Honduran rural schoolchildren, in 2011. Demographic and epidemiological data were obtained and STH infections were determined using Kato-Katz method. Results: A total of 320 children completed the study. Overall and specific prevalences for Ascaris lumbricoides, Trichuris trichiura and hookworms were 72.5%, 30%, 67% and 16%, respectively. Several risk factors associated with STH transmission and infection intensity were identified at the individual and familial level as well as at the schools. Conclusions: Improving hygienic conditions and providing semi-annual deworming treatment are feasible interventions that could enhance undergoing STH control activities.

Soil-Transmitted Helminth Infections and Nutritional Status in School-age Children from Rural Communities in Honduras

Background: Soil-transmitted helminth (STH) infections are endemic in Honduras and efforts are underway to decrease their transmission. However, current evidence is lacking in regards to their prevalence, intensity and their impact on children’s health. Objectives: To evaluate the prevalence and intensity of STH infections and their association with nutritional status in a sample of Honduran children. Methodology: A cross-sectional study was done among school-age children residing in rural communities in Honduras, in 2011. Demographic data was obtained, hemoglobin and protein concentrations were determined in blood samples and STH infections investigated in single-stool samples by Kato-Katz. Anthropometric measurements were taken to calculate heightfor- age (HAZ), BMI-for-age (BAZ) and weight-for-age (WAZ) to determine stunting, thinness and underweight, respectively. Results: Among 320 children studied (48% girls, aged 7–14 years, mean 9.7661.4) an overall STH prevalence of 72.5% was found. Children .10 years of age were generally more infected than 7–10 year-olds (p = 0.015). Prevalence was 30%, 67% and 16% for Ascaris, Trichuris and hookworms, respectively. Moderate-to-heavy infections as well as polyparasitism were common among the infected children (36% and 44%, respectively). Polyparasitism was four times more likely to occur in children attending schools with absent or annual deworming schedules than in pupils attending schools deworming twice a year (p,0.001). Stunting was observed in 5.6% of children and it was associated with increasing age. Also, 2.2% of studied children were thin, 1.3% underweight and 2.2% had anemia. Moderate-to-heavy infections and polyparasitism were significantly associated with decreased values in WAZ and marginally associated with decreased values in HAZ. Conclusions: STH infections remain a public health concern in Honduras and despite current efforts were highly prevalent in the studied community. The role of multiparasite STH infections in undermining children’s nutritional status warrants more research.

Soil-Transmitted Helminths, Poverty, and Malnutrition in Honduran Children Living in Remote Rural Communities

Soil-transmitted helminth (STH) infections are endemic in Honduras, but their prevalence according to the levels of poverty in the population has not been examined. The present cross-sectional study is aimed to determine the role of different levels of poverty in STH prevalence and infection intensity as well as the potential associations of STH infections with malnutrition and anemia. Research participants were children attending a medical brigade serving remote communities in Northern Honduras in June 2014. Demographic data were obtained, and poverty levels were determined using the unsatisfied basic needs method. STH infections were investigated by the Kato-Katz method; hemoglobin concentrations were determined with the HemoCue system; and stunting, thinness, and underweight were determined by anthropometry. Data were analyzed using descriptive statistics and univariate and multivariable logistic regression models. Among 130 children who participated in this study, a high prevalence (69.2%) of parasitism was found and the poorest children were significantly more infected than those living in less poor communities (79.6% vs. 61.8%; P = 0.030). Prevalence rates of Trichuris trichiura, Ascaris lumbricoides, and hookworms were 69.2%, 12.3%, and 3.85%, respectively. In total, 69% of children had anemia and 30% were stunted. Households’ earthen floor and lack of latrines were associated with infection. Greater efforts should be made to reduce STH prevalence and improve overall childhood health, in particular, among the poorest children lacking the basic necessities of life.

Estudo de prevalência da esquistossomose mansônica no bairro do Maracajá, distrito de Mosqueiro, Belém, Pará

A esquistossomose mansônica é uma das doenças parasitárias mais difundidas no mundo e tem prevalência maior nos países em desenvolvimento, constituindo atualmente um sério problema de saúde pública no Brasil. Em Belém-PA, no Distrito Administrativo de Mosqueiro (DAMOS), há possibilidades de ocorrência de casos autoctones de esquistosomose mansônica, devido a proximidade geográfica com outras áreas onde há registros deste agravo, bem como, pela presença de outros fatores ambientais de risco, como a presença do Biomphalaria straminea. Com a proposta de determinar a prevalência de esquistosomose mansônica no bairro do Maracajá-DAMOS, foi realizado um estudo transversal prospectivo no período entre março de 2011 a janeiro de 2012, através de inquérito coproscópico pelo método quantitativo de Kato-Katz, associado a inquérito sócio-demográfico e ambiental da localidade. Participaram do universo amostral 407 indivíduos incluídos na atenção da Estratégia Saúde da Família, que aceitaram espontaneamente participar da pesquisa, segundo os preceitos éticos vigentes. O perfil sócio-demográfico populacional mostrou predomínio da faixa etária entre 11 e 40 anos, sem diferenças quanto ao gênero, cuja ocupação de dona de casa e estudante, com ensino fundamental incompleto foram as mais citadas. A maioria dos moradores nasceu e procede do DAMOS, residentes no bairro do Maracajá há mais de 20 anos, sem relatos importantes de deslocamentos para outras localidades. A maioria das residências apresentaram serviço de água encanada, com banheiro interno, presença de sanitário com destino das fezes em fossa séptica. As coleções hídricas peridomiciliares se caracterizaram por valas de baixo fluxo e com pequena vazão de água, alta concentração de produtos orgânicos, presença de vegetação macrófitica e do vetor Biomphalaria straminea. Esta população referiu não ter contato com as coleções hídricas e desconhecer o planorbideo vetor, assim como a própria esquistossomose. O inquérito coproscópico resultou em 100% de lâminas negativas quanto a identificação de ovos do S. mansoni, levando a conclusão que embora o bairro do Maracajá ainda seja indene, possui vários fatores para a instalação de um foco de transmissão ativa de esquistossomose, mas ainda existe um frágil equilíbrio ecológico, sustentado pela reduzida exposição dos indivíduos às coleções hídricas, pouco deslocamento da população para áreas com focos estabelecidos da endemia e razoável cobertura de esgotamento sanitário. Este conjunto de variáveis tem funcionado como fatores limitantes ao processo de endemização da esquistossomose no bairro do Maracajá, entretanto deve ser mantido sob vigilância pelas peculiaridades propicias ao fechamento do ciclo do S. mansoni.

Effectiveness of hyperbaric oxygen for experimental treatment of schistosomiasis mansoni using praziquantel-free and encapsulated into liposomes: Assay in adult worms and oviposition

The treatment of schistosomiasis depends on a single drug: praziquantel (PZQ). However, this treatment presents limitations such as low and/or erratic bioavailability that can contribute to cases of tolerance. Improvements to the available drug are urgently needed and studies with a controlled system of drug release, like liposomes, have been gaining prominence. The present study evaluated the activity and synergy between liposomal-praziquantel (lip.PZQ) and hyperbaric oxygen therapy (HBO). Mice received doses of 60 or 100mg/kg PZQ or lip.PZQ, 50 days post-infection, and after the treatment, were exposed to HBO (3 atmosphere absolute - ATA) for 1h. The viability of adult worms and oviposition were analyzed, by necropsy and Kato-Katz examination performed after 15 days of treatment. A concentration of 100mg/kg of lip.PZQ+HBO was more effective (48.0% reduction of worms, 83.3% reduction of eggs/gram of feces) and 100% of the mice had altered of oograms (indicating interruption of oviposition) compared to other treatments and to the Control group (infected and untreated). It is known that PZQ requires participation of the host immune system to complete its antischistosomal activity and that HBO is able to stimulate the immune system. The drug became more available in the body when incorporated into liposomes and, used with HBO, the HBO worked as an adjuvant. This explains the decreases of oviposition and worms recovered form hepatic portal system.

TF-Test Modified: new diagnostic dool for human enteroparasitosis

Intestinal parasitosis is highly prevalent worldwide, being among the main causes of illness and death in humans. Currently, laboratory diagnosis of the intestinal parasites is accomplished through manual technical procedures, mostly developed decades ago, which justifies the development of more sensitive and practical techniques. Therefore, the main objective of this study was to develop, evaluate, and validate a new parasitological technique referred to as TF-Test Modified, in comparison to three conventional parasitological techniques: TF-Test Conventional; Rugai, Mattos & Brisola; and Helm Test/Kato-Katz. For this realization, we collected stool samples from 457 volunteers located in endemic areas of Campinas, São Paulo, Brazil, and statistically compared the techniques. Intestinal protozoa and helminths were detected qualitatively in 42.23% (193/457) of the volunteers by TF-Test Modified technique, against 36.76% (168/457) by TF-Test Conventional, 5.03% (23/457) by Helm Test/Kato-Katz, and 4.16% (19/457) by Rugai, Mattos & Brisola. Furthermore, the new technique presented almost perfect kappa agreement in all evaluated parameters with 95% (P < 0.05) of estimation. The current study showed that the TF-Test Modified technique can be comprehensively used in the diagnosis of intestinal protozoa and helminths, and its greater diagnostic sensitivity should help improving the quality of laboratory diagnosis, population surveys, and control of intestinal parasites.

TF-Test modified: new diagnostic tool for human enteroparasitosis

Intestinal parasitosis is highly prevalent worldwide, being among the main causes of illness and death in humans. Currently, laboratory diagnosis of the intestinal parasites is accomplished through manual technical procedures, mostly developed decades ago, which justifies the development of more sensitive and practical techniques. Therefore, the main objective of this study was to develop, evaluate, and validate a new parasitological technique referred to as TF-Test Modified, in comparison to three conventional parasitological techniques: TF-Test Conventional; Rugai, Mattos & Brisola; and Helm Test/Kato-Katz. For this realization, we collected stool samples from 457 volunteers located in endemic areas of Campinas, São Paulo, Brazil, and statistically compared the techniques. Intestinal protozoa and helminths were detected qualitatively in 42.23% (193/457) of the volunteers by TF-Test Modified technique, against 36.76% (168/457) by TF-Test Conventional, 5.03% (23/457) by Helm Test/Kato-Katz, and 4.16% (19/457) by Rugai, Mattos & Brisola. Furthermore, the new technique presented “almost perfect kappa” agreement in all evaluated parameters with 95% (P < 0.05) of estimation. The current study showed that the TF-Test Modified technique can be comprehensively used in the diagnosis of intestinal protozoa and helminths, and its greater diagnostic sensitivity should help improving the quality of laboratory diagnosis, population surveys, and control of intestinal parasites.

POPULATION ASSESSMENTS OF INFECTION WITH SCHISTOSOMA MANSONI: EFFECTS OF BIAS CAUSED BY THE RELATIVE SENSITIVITY OF DIAGNOSTIC TECHNIQUES (PUERTO RICO)

This study establishes the extent and relevance of bias of population estimates of prevalence, incidence, and intensity of infection with Schistosoma mansoni caused by the relative sensitivity of stool examination techniques. The population studied was Parcelas de Boqueron in Las Piedras, Puerto Rico, where the Centers for Disease Control, had undertaken a prospective community-based study of infection with S. mansoni in 1972. During each January of the succeeding years stool specimens from this population were processed according to the modified Ritchie concentration (MRC) technique. During January 1979 additional stool specimens were collected from 30 individuals selected on the basis of their mean S. mansoni egg output during previous years. Each specimen was divided into ten 1-gm aliquots and three 42-mg aliquots. The relationship of egg counts obtained with the Kato-Katz (KK) thick smear technique as a function of the mean of ten counts obtained with the MRC technique was established by means of regression analysis. Additionally, the effect of fecal sample size and egg excretion level on technique sensitivity was evaluated during a blind assessment of single stool specimen samples, using both examination methods, from 125 residents with documented S. mansoni infections. The regression equation was: Ln KK = 2.3324 + 0.6319 Ln MRC, and the coefficient of determination (r('2)) was 0.73. The regression equation was then utilized to correct the term "m" for sample size in the expression P ((GREATERTHEQ) 1 egg) = 1 - e('-ms), which estimates the probability P of finding at least one egg as a function of the mean S. mansoni egg output "m" of the population and the effective stool sample size "s" utilized by the coprological technique. This algorithm closely approximated the observed sensitivity of the KK and MRC tests when these were utilized to blindly screen a population of known parasitologic status for infection with S. mansoni. In addition, the algorithm was utilized to adjust the apparent prevalence of infection for the degree of functional sensitivity exhibited by the diagnostic test. This permitted the estimation of true prevalence of infection and, hence, a means for correcting estimates of incidence of infection. ^

Real-time PCR demonstrates high prevalence of Schistosoma japonicum in the Philippines:implications for surveillance and control

BACKGROUND: The Philippines has a population of approximately 103 million people, of which 6.7 million live in schistosomiasis-endemic areas with 1.8 million people being at risk of infection with Schistosoma japonicum. Although the country-wide prevalence of schistosomiasis japonica in the Philippines is relatively low, the prevalence of schistosomiasis can be high, approaching 65% in some endemic areas. Of the currently available microscopy-based diagnostic techniques for detecting schistosome infections in the Philippines and elsewhere, most exhibit varying diagnostic performances, with the Kato-Katz (KK) method having particularly poor sensitivity for detecting low intensity infections. This suggests that the actual prevalence of schistosomiasis japonica may be much higher than previous reports have indicated.

METHODOLOGY/PRINCIPAL FINDINGS: Six barangay (villages) were selected to determine the prevalence of S. japonicum in humans in the municipality of Palapag, Northern Samar. Fecal samples were collected from 560 humans and examined by the KK method and a validated real-time PCR (qPCR) assay. A high S. japonicum prevalence (90.2%) was revealed using qPCR whereas the KK method indicated a lower prevalence (22.9%). The geometric mean eggs per gram (GMEPG) determined by the qPCR was 36.5 and 11.5 by the KK. These results, particularly those obtained by the qPCR, indicate that the prevalence of schistosomiasis in this region of the Philippines is much higher than historically reported.

CONCLUSIONS/SIGNIFICANCE: Despite being more expensive, qPCR can complement the KK procedure, particularly for surveillance and monitoring of areas where extensive schistosomiasis control has led to low prevalence and intensity infections and where schistosomiasis elimination is on the horizon, as for example in southern China.

Hookworm-like eggs in children’s faecal samples from a rural area of Rwanda.

Background: Hookworm eggs identification and quantification is usually carried out by Kato-Katz method. However various structures present in the smear may be confused with eggs of such parasites. Objective: To document the presence of structures in Kato-Katz slides that could initially be misinterpreted as hookworm eggs. Method: 497 faecal samples were analysed by Kato-Katz technique, diphasic concentration technique, agar-plate coprocultive and larvae obtained were analysed by PCR and characterized by sequencing. Results: Hookworm-like eggs were found in 159 (32%) of the samples by Kato-Katz, finally identified as Caenorhabditis elegans by PCR technique. Conclusion: The diagnosis of human hookworm eggs, only by the use of Kato-Katz technique can lead to false positives because of similarities with eggs of other free-living worms, from wet soils like those of Rwanda that could contaminate stool samples.

Prevalência da esquistossomose em indivíduos do município de Itaobim no período de 2010 a 2013.

Realizou-se um estudo para determinar a prevalência da esquistossomose mansônica no município de Itaobim Minas Gerais, abrangendo a área urbana e rural do município, através de coletas de amostras de fezes e realização de exames coproscópicos pelo método Kato-Katz realizados pelo laboratório da vigilância epidemiológica de Itaobim, através do programa de controle da esquistossomose. Foram distribuídos 7.666 coletores de fezes que resultaram em 4.501 amostras a serem analisadas: 763 eram amostras de zonas rurais e 3.738 eram da zona urbana; 565 do total estavam contaminadas pela esquistossomose e outros parasitos encontrados nas amostras estão os Ancilostomídeos, Ascaris lumbricoides, Trichiurus trichiura, Strongyloides stercoralis, Enterobius vermicularis, Taenia sp, Hymenolepis nana. Das amostras analisadas na zona rural foram confirmados como positivo para esquistossomose 150 (19,6%) amostras e 241 (6,4%) da zona urbana respectivamente, observando-se uma média de 9% de infectividade. Os casos positivos para esquistossomose foram mais significativos nos residentes em comunidades rurais do que em zona urbana, com resultado de 19,6% e 6,4% respectivamente. Observou-se também uma menor proporção entre os residentes da área urbana. Algumas hipóteses para tentar explicar são discutidas tais como: processo intenso de urbanização e a melhoria das condições socioeconômicas do município.

Estudo comparativo dos métodos de Lutz, Kato e Simões Barbosa no diagnóstico cropológico da esquistossomose mansoni

Um estudo comparativo do método de sedimentação de Lutz (Hoffman-Pons e Janer) e dos métodos quantitativos de Simões Barbosa (FSB) e de Kato para o diagnóstico e contagem de ovos de S. mansoni, em uma amostra de fezes de 211 pessoas residentes em uma área endêmica para esquistossomose, revelou: 1) positividade de 50% com os métodos de Lutz e Simões Barbosa, e de 58,1 % com o método de Kato para o total de amostras; 2) maior concentração de ovos pelo método de Kato em relação ao de F.S.B.; 3) o método de Kato modificado por Katz & cols se impõe para o diagnóstico "quantitativo" da esquistossomose em inquérito de campo pela maior sensibilidade, facilidade de execução, baixo custo, possibilidade de conservação dos ovos de S. mansoni por longos períodos e por permitir ao investigador uma noção aproximada da intensidade da infecção no indivíduo e na população.

Sobre o método de Kato no diagnóstico da esquistossomose mansoni

Os autores fazem um estudo comparativo entre os métodos de sedimentação, MIF-C e Kato em relação à eficiência para diagnosticar ovos de helmintos, em especial os de Schistosoma mansoni. Discutem as possibilidades e limitações dos métodos assinalados e concluem pela maior eficiência do método de sedimentação.

Modelos de ajuste e métodos para a determinação da curva de retenção de água de um Latossolo-vermelho-amarelo

A caracterização da capacidade de retenção de água de um solo é fundamental para a descrição do fluxo de água através dele e para o adequado manejo da irrigação. São apresentadas comparações entre curvas de retenção de água do solo: ajustadas pelos modelos propostos por van Genuchten e por Hutson & Cass; obtidas pelo método do WP4 usando processo de umedecimento e de secagem; obtidas pelo método da centrífuga utilizando amostras deformadas e indeformadas; e obtidas pelo WP4 e centrífuga, usando um processo de secagem e amostra deformada. Amostras deformadas e indeformadas foram coletadas com trados específicos em um Latossolo Vermelho-Amarelo (LVA), textura argilosa. Foram determinadas as propriedades hídricas do solo necessárias à elaboração das curvas de retenção de água obtidas por análise de regressão. O modelo de van Genuchten possibilitou o melhor ajuste nas diversas situações estudadas. Considerando o processo de secagem, o teor de água útil obtido superou em 13 % o resultado do processo de umedecimento e evidenciou reduzido efeito de histerese. A amostra deformada apresentou-se com um teor de água útil superior 61,7 % ao valor obtido para a amostra indeformada. Entre os métodos estudados, verificou-se que aquele que usa o WP4 subestimou os dados obtidos pela centrífuga. Verificou-se que há diferenças entre amostra deformada e indeformada e os métodos utilizados na obtenção da curva de retenção.