Combination of Kato–Katz faecal examinations and ELISA to improve accuracy of diagnosis of intestinal schistosomiasis in a low-endemic setting in Brazil

Considering the decrease of disease burden caused by intestinal schistosomiasis in many endemic settings, more sensitive diagnostic methods are needed to plan and monitor control measures. We conducted a cross-sectional survey in a rural community in northeast Brazil (317 inhabitants). A combined approach including repeated faecal examinations and ELISA testing was applied. In a first round, single stool samples were collected from 305 (96.2%) participants. Three Kato–Katz (KK) smears were prepared from each sample, and IgG ELISA was performed from serum samples. In the 85 cases of negative KK smears, but positive ELISA results, three additional faecal samples were collected in a second round, and another five KK smears prepared. In the first round of KK analysis, 11/287 (3.8%; 95% confidence interval; 1.92–6.75) were positive. After examining up to eight smears per individual (second round), prevalence of schistosomiasis increased to 8.7% (95% confidence interval: 5.9–12.5). In total, 96/287 (33.4%, 95% confidence interval: 28.0–39.2) samples were positive by ELISA testing. There were no false negative ELISA results. Specificity, positive and negative predictive values of ELISA as compared to up to eight KK smears from three stool samples (reference diagnosis) were 72.9%, 26.0% and 100%, respectively. A single KK smear detected only 12% of the 25 infections; this increased to 44% (three smears, one stool sample), 84% (five smears, three stool samples) and 96% (six smears, four stool samples). We conclude that in low-endemic areas in Brazil the use of KK continues being an important tool. The additional benefit of preparing more than six KK smears from repeated stool samples is negligible. ELISA may be useful for screening populations, with subsequent confirmation of diagnosis by KK or other more sensitive, but highly specific methods

Evaluation of Polymerase Chain Reaction(PCR) in stool samples for diagnosis of shistosomiasis in low endemicity region in state of CearÃ.

A esquistossomose ainda à um problema de saÃde pÃblica no Brasil, amplamente disseminada nas regiÃes sudeste e nordeste. O diagnÃstico laboratorial dessa doenÃa à realizado principalmente atravÃs de mÃtodos diretos que detectam os ovos nas fezes, atravÃs da microscopia e por mÃtodos indiretos, que se baseiam na determinaÃÃo e identificaÃÃo de antÃgenos, anticorpos e fragmentos especÃficos de DNA que estÃo associados à infecÃÃo por Schistosoma mansoni. Nesse estudo, objetivamos avaliar a reaÃÃo em cadeia da polimerase (PCR) para diagnÃstico da esquistossomose mansoni, em indivÃduos da localidade de Planalto do Cajueiro, uma Ãrea de baixa endemicidade, em Maranguape- CearÃ. Realizamos o mÃtodo de ELISA, para detecÃÃo de anticorpos IgG contra antÃgenos de verme adulto de S. mansoni, e a coproscopia, pelos mÃtodos de Kato-Katz e de Lutz, para detecÃÃo de ovos de S. mansoni e de outros parasitos. Diante dos resultados obtidos nesses mÃtodos, selecionamos 56 amostras de fezes, dentre as 125 analisadas, que compuseram os seguintes grupos: Grupo I - ELISA reativo/Outros parasitos (+) ; Grupo II- ELISA reativo/Outros parasitos (-); Grupo III- ELISA nÃo reativo/ Outros parasitos (+) ; Grupo IV-ELISA nÃo reativo/Outros parasitos (-); Grupo V- ELISA Reativo/Coproscopia para S. mansoni (+). Os parÃmetros da PCR seguiram o protocolo de Pontes et al., 2002. Do Grupo I, 02 das 10 amostras foram positivas na PCR; do Grupo II, 04 das 10 amostras foram positivas na PCR e no Grupo III, 01 das 07 amostras foi positiva no PCR. Dentre as 10 amostras do Grupo IV, 01 amostra foi positiva no PCR e no Grupo V, 13 das 19 amostras foram positivas no PCR. Dos 39 indivÃduos que apresentavam reatividade pelo ELISA, o exame parasitolÃgico, realizado pela tÃcnica de rotina, mÃtodo de Kato-Katz, foi positivo em 06 amostras e a PCR em 19 amostras. Ao comparar os resultados obtidos no Grupo V, com o mÃtodo de Kato-Katz, observa-se que este detectou 06 indivÃduos, enquanto PCR detectou 13. Ao compararmos PCR ao mÃtodo do Gradiente SalÃnico, observa-se que o Gradiente SalÃnico detectou 09 indivÃduos, enquanto PCR detectou 11. Ao compararmos PCR ao HelmintexÂ, verificamos que o Helmintex detectou 10, enquanto PCR detectou 08 amostras. Diante disso, concluÃmos que a PCR à mais uma ferramenta importante para melhorar a sensibilidade na detecÃÃo do parasito nas fezes, sendo indispensÃvel à associaÃÃo dos vÃrios mÃtodos disponÃveis, com intuito de alcanÃar o diagnÃstico real da doenÃa.Schistosomiasis is still a public health problem in Brazil. The infection is widespread in southeast and northeast. The laboratorial diagnosis of schistosome infection has been based on direct coproscopic examination and by indirect methods for detection of antigen, antibodies and specific DNA fragments that are associated with Schistosoma mansoni infection. The aim of the present study was to evaluate polymerase chain reaction (PCR) designed for detection of Schistosoma mansoni DNA in individuals from a low endemic area in Cearà state. The study was conducted in the Planalto do Cajueiro, Maranguape, CearÃ, Brazil. In the laboratory performed the ELISA for detection of IgG antibodies against adult worms antigen of S. mansoni, and stool examinations (Kato-Katz, Lutz, Saline gradient and Helmintex methods), considering the results obtained, for distribution of 56 stool samples selected among the 125 examined, in the following groups: Group I - ELISA reactive / Others parasites (+ ), Group II- ELISA reactive / Others parasites (-), Group III- ELISA non reactive / Others parasites (+), Group IV- ELISA non reactive / Others parasites (-), Group V- ELISA reactive / Coproscopic examination S. mansoni (+).The PCR was carried out according to a protocol described by Pontes et al.(2002) . Group I, 02 of 10 samples were positive in PCR; Group II, 04 of 10 samples were positive by PCR and in Group III, 01 of 07 samples were positive in PCR. Among the 10 samples of Group IV, 01 was positive in PCR and Group V, 13 of 19 samples were positive in PCR. Among the 39 individuals who showed reactivity by ELISA, 06 samples were positive in coproscopic examination and PCR was reactive in 19 samples. Comparing the results in Group V, with the Kato-Katz, this method detected 06 individuals, while PCR detected 13 individuals were positive. By comparing the PCR of Saline gradient, it is observed that the Saline gradient detected 09 individuals, while PCR detected 11. When comparing PCR to HelmintexÂ, we found that the Helmintex detected 10, while PCR detected 08 samples. We conclude that PCR is an important tool to improve the sensitivity in detecting S. mansoni infection in low endemic areas. We emphasize that is very important associate the exams in order to achieve the real diagnosis of the disease

Association between allergic responses and Schistosoma mansoni infection in residents in a low-endemic setting in Brazil

Introduction Schistosomiasis is endemic in 76 countries and territories. Several studies have found an inverse correlation between parasitic disease and the development of allergies. The purpose of the present study was to determine whether infection with Schistosoma mansoni in subjects with a low parasite load is protective against allergy. The final sample consisted of 39 S. mansoni-positive and 52 S. mansoni-negative residents of a small community in northeastern Brazil. Methods All subjects were submitted to the Kato-Katz test, anti-S. mansoni IgG measurement, the prick test for aeroallergens, eosinophil counts and serum IgE measurement. Results Subjects who reacted to one or more antigens in the prick test were considered allergic. Only 7 S. mansoni-positive subjects (17.9%) reacted to one or more antigens, whereas 20 S. mansoni-negative subjects (38.5%) tested positive for allergy. Conclusions Our findings suggest that, in areas of low endemicity, infection with S. mansoni significantly reduces the risk of the development of allergy in subjects with a low parasite load

Natural products as new antimitotic compounds for anticancer drug development

Cell cycle control genes are frequently mutated in cancer cells, which usually display higher rates of proliferation than normal cells. Dysregulated mitosis leads to genomic instability, which contributes to tumor progression and aggressiveness. Many drugs that disrupt mitosis have been studied because they induce cell cycle arrest and tumor cell death. These antitumor compounds are referred to as antimitotics. Vinca alkaloids and taxanes are natural products that target microtubules and inhibit mitosis, and their derivatives are among the most commonly used drugs in cancer therapy worldwide. However, severe adverse effects such as neuropathies are frequently observed during treatment with microtubule-targeting agents. Many efforts have been directed at developing improved antimitotics with increased specificity and decreased likelihood of inducing side effects. These new drugs generally target specific components of mitotic regulation that are mainly or exclusively expressed during cell division, such as kinases, motor proteins and multiprotein complexes. Such small molecules are now in preclinical studies and clinical trials, and many are products or derivatives from natural sources. In this review, we focused on the most promising targets for the development of antimitotics and discussed the advantages and disadvantages of these targets. We also highlighted the novel natural antimitotic agents under investigation by our research group, including combretastatins, withanolides and pterocarpans, which show the potential to circumvent the main issues in antimitotic therapy

Increased detection of schistosomiasis with Kato-Katz and SWAP-IgG-ELISA in a Northeastern Brazil low-intensity transmission area

INTRODUCTION: The laboratory diagnosis of schistosomiasis is based mainly on the detection of parasite eggs in stool samples through the Kato-Katz (KK) technique, reading one slide by test. However, a widely known limitation of parasitological methods is reduced sensitivity, particularly in low endemic areas. METHODS: To increase sensitivity, we conducted further slide readings from the same stool sample using the parasitological method associated with a serological test. We used the KK method (three slides) and the IgG anti-Schistosoma mansoni-enzyme-linked immunosorbent assay (ELISA) technique to diagnose schistosomiasis in low endemic areas in the Brazilian State of Ceará. Fecal samples and sera from 250 individuals were analyzed. RESULTS: Sixteen percent and 47.2% of samples were positive in parasitological tests and serological tests, respectively. Parasitological methods showed that 32 (80%) individuals tested positive on the first slide, 6 (15%) on the second slide, and 2 (5%) on the third. The performance of the ELISA test in the diagnosis, using the KK method as diagnostic reference, showed a negative predictive value of 100%, with specificity and positive predictive values of 62.8% and 33.9%, respectively. CONCLUSIONS: In this study, the increase from one to three slides analyzed per sample using the KK technique was shown to be a useful procedure for increasing the diagnostic sensitivity of this technique

Natural products as new antimitotic compounds for anticancer drug development

Cell cycle control genes are frequently mutated in cancer cells, which usually display higher rates of proliferation than normal cells. Dysregulated mitosis leads to genomic instability, which contributes to tumor progression and aggressiveness. Many drugs that disrupt mitosis have been studied because they induce cell cycle arrest and tumor cell death. These antitumor compounds are referred to as antimitotics. Vinca alkaloids and taxanes are natural products that target microtubules and inhibit mitosis, and their derivatives are among the most commonly used drugs in cancer therapy worldwide. However, severe adverse effects such as neuropathies are frequently observed during treatment with microtubule-targeting agents. Many efforts have been directed at developing improved antimitotics with increased specificity and decreased likelihood of inducing side effects. These new drugs generally target specific components of mitotic regulation that are mainly or exclusively expressed during cell division, such as kinases, motor proteins and multiprotein complexes. Such small molecules are now in preclinical studies and clinical trials, and many are products or derivatives from natural sources. In this review, we focused on the most promising targets for the development of antimitotics and discussed the advantages and disadvantages of these targets. We also highlighted the novel natural antimitotic agents under investigation by our research group, including combretastatins, withanolides and pterocarpans, which show the potential to circumvent the main issues in antimitotic therapy