Accuracy of the urine point-of-care circulating cathodic antigen assay for diagnosing Schistosomiasis mansoni infection in Brazil: A multicenter study

ABSTRACT Background: The World Health Organization recommends a market-ready, urine-based point-of-care diagnostic test for circulating cathodic antigens (CCA) to determine the prevalence of S. mansoni. This study evaluated the performance of the URINE CCA (SCHISTO) ECO TESTE® (POC-ECO), which is currently available in Brazil. Methods: Residents from eight sites with different prevalence estimates provided one urine sample for POC-ECO and one stool sample for Kato-Katz (KK) and Helmintex® (HTX) testing as an egg-detecting reference for infection status. Results: None of the study sites had significantly higher POC-ECO accuracy than KK. Conclusions: POC-ECO is not currently recommended in Brazilian schistosomiasis elimination programs.

Reliability of point-of-care circulating cathodic antigen assay for diagnosing schistosomiasis mansoni in urine samples from an endemic area of Brazil after one year of storage at -20 degrees Celsius

ABSTRACT Background The World Health Organization recommends reliable point-of-care (POC) diagnostic testing to eliminate schistosomiasis. Lateral flow immunoassay that detects schistosome circulating cathodic antigen (CCA) in urine to establish prevalence thresholds for intervention in endemic areas is recommended. Stored urine may be useful if surveying at-risk populations is delayed or interrupted by unforeseen circumstances, such as the current COVID-19 pandemic. This study evaluated the manufacturer's claim that Schistosoma mansoni infection can be reliably diagnosed in urine samples stored at -20°C for one year. Methods Two-hundred-forty-two subjects from an endemic site in Brazil provided one urine sample each for testing with URINE CCA (SCHISTO) ECO TESTE® (POC-ECO) and one stool sample each for testing with Kato-Katz (KK) and Helmintex® (HTX) as a robust reference standard for infection status. At least 2 ml of urine from each participant was stored at -20°C; after one year, 76 samples were randomly selected for POC-ECO retesting. Results: The POC-ECO agreement between freshly collected and stored urine was inadequate considering trace results as positive (Cohen's kappa coefficient κ = 0.08) and negative (κ = 0.36). POC-ECO accuracy was not significantly greater than that of routine KK (54%; 95% confidence interval: 42.1%-65.5%). Conclusions The precision and accuracy of POC-ECO have to be optimized in both freshly collected and stored urine before it can be recommended for use in control programs in Brazil.

Spatial distribution of Schistosoma mansoni infection before and after chemotherapy with two praziquantel doses in a community of Pernambuco, Brazil

Praziquantel chemotherapy has been the focus of the Schistosomiasis Control Program in Brazil for the past two decades. Nevertheless, information on the impact of selective chemotherapy against Schistosoma mansoni infection under the conditions confronted by the health teams in endemic municipalities remains scarce. This paper compares the spatial pattern of infection before and after treatment with either a 40 mg/kg or 60 mg/kg dose of praziquantel by determining the intensity of spatial cluster among patients at 180 and 360 days after treatment. The spatial-temporal distribution of egg-positive patients was analysed in a Geographic Information System using the kernel smoothing technique. While all patients became egg-negative after 21 days, 17.9 percent and 30.9 percent reverted to an egg-positive condition after 180 and 360 days, respectively. Both the prevalence and intensity of infection after treatment were significantly lower in the 60 mg/kg than in the 40 mg/kg treatment group. The higher intensity of the kernel in the 40 mg/kg group compared to the 60 mg/kg group, at both 180 and 360 days, reflects the higher number of reverted cases in the lower dose group. Auxiliary, preventive measures to control transmission should be integrated with chemotherapy to achieve a more enduring impact.

The prevalence of schistosomiasis in school-aged children as an appropriate indicator of its prevalence in the community

School-aged children (6-15 years) from the endemic area of Pernambuco were evaluated both as a target group for and an indicator of schistosomiasis control in the community. Parasitological data were drawn from baseline stool surveys of whole populations that were obtained to diagnose Schistosoma mansoni infection. Nineteen representative localities were selected for assessing the prevalence of schistosomiasis among individuals in the following age groups: 0-5, 6-15, 16-25, 26-40 and 41-80 years. For each locality, the prevalence in each age group was compared to that of the overall population using contingency table analysis. To select a reference group, the operational difficulties of conducting residential surveys were considered. School-aged children may be considered to be the group of choice as the reference group for the overall population for the following reasons: (i) the prevalence of schistosomiasis in this age group had the highest correlation with the prevalence in the overall population (r = 0.967), (ii) this age group is particularly vulnerable to infection and plays an important role in parasite transmission and (iii) school-aged children are the main target of the World Health Organization in terms of helminth control. The Schistosomiasis Control Program should consider school-aged children both as a reference group for assessing the need for intervention at the community level and as a target group for integrated health care actions of the Unified Health System that are focused on high-risk groups.

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

This work had the objective of assessing the present epidemiological situation regarding schistosomiasis through performing Kato-Katz coproscopic tests on representative samples of schoolchildren from each of the 43 municipality of endemic area of the state of Pernambuco, Brazil. The methodology is recommended by the World Health Organization to conduct sampled surveys among children at elementary school levels, ideal target group for baseline surveys: (i) schools are accessible; (ii) the greatest prevalence of schistosomiasis is found within this group; (iii) the data gathered from this age group can be used for intervention within the community as a whole. The following infection indicators were utilized: positivity (percentage of individuals examined with eggs of Schistosoma mansoni in the feces) and severity (geometric mean number of eggs per gram of feces, epg). These indicators allowed the area in general and the municipalities in particular to be categorized into prevalence and severity classes for S. mansoni. The prevalence classes were: low (<10 percent), medium (> 10 and < 50 percent), and high (> 50 percent); the severity classes were: low (1-99 epg), moderate (100-399 epg), and severe (> 400 epg). For the geohelminthic diseases, the following indicators were used: positivity for each geohelminth (percentage of individuals examined with eggs of geohelminths), and cumulative positivity (percentage of individuals examined with eggs of at least one geohelminth). The municipalities were categorized by means of their cumulative positivity into the following geohelminth prevalence classes (WHO 2002): low (< 50 percent), medium (> 50 and < 70 percent), and high (> 70 percent). The study covered 271 schools in 179 different localities, thus giving a total of 11,234 examinations performed. The overall positivity for S. mansoni was 14.4 percent and the egg count for this parasite in the feces gave a geometric mean of 67.9 epg which suggests...

Reliability of current estimates of schistosomiasis prevalence in the Rainforest Zone of the state of Pernambuco, Northeastern Brazil

The Program for Schistosomiasis Control within the Unified Health System (PCE-SUS) was implemented by 1999 in the Rainforest Zone or "Zona da Mata" of Pernambuco (ZMP) aiming to carry out biennial stool surveys of whole populations through municipal health organs followed by treatment of the positives through the local units of the Family Health Program (PSF). Yearly reports from the Health Department of Pernambuco State (SES/PE) from 2002 to 2004 on the PCE-SUS surveys were assessed to evaluate whether the current estimates of prevalence in the municipalities of the ZMP are based on reliable samples so as to allow considerations on the real situation of schistosomiasis in that area. The surveys carried out in that period did not follow the major principles underlying sampling design, thus posing problems in both precision and validity of the estimates. Only 12 out of 43 municipalities had minimally reliable estimates: five with moderate prevalence (10-50 percent) and seven with low prevalence (< 10 percent). Surveys with appropriate sampling procedures aimed either at representative target groups (school-aged children) or communities are recommended for the ZMP and other endemic areas not only to provide reliable information on the current situation of schistosomiasis but also to plan adequate control strategies.

Attaining the minimum target of resolution WHA 54.19 for schistosomiasis control in the Rainforest Zone of the state of Pernambuco, Northeastern Brazil

Resolution 19 of the 54th World Health Assembly (WHA-54.19) urged member nations to promote preventive measures, ensure treatment and mobilize resources for control of schistosomiasis and soil-transmitted helminthiases (STH). The minimum target is to attend 75 percent of all school-age children at risk by year 2010. The Brazilian Ministry of Health (MoH) recommends biennial surveys of whole communities and treatment of the positives through the Schistosomiasis Control Program within the Unified Health System (PCE-SUS). However, by 2004 the PCE-SUS had covered only 8.4 percent of the 1.2 million residents in the Rainforest Zone of Pernambuco (ZMP). Six of the 43 municipalities still remained unattended. Only three of the municipalities already surveyed reached coverage of 25 percent or more. At least 154 thousand children in the 7-14 years old range have to be examined (and treated if positive) within the next five years to attend the minimum target of the WHA 54.19 for the ZMP. To make this target feasible, it is suggested that from 2006 to 2010 the PCE-SUS actions should be complemented with school-based diagnosis and treatment, involving health and educational organs as well as community associations to include both children in schools and non-enrolled school-age children.

Evaluation of tests based on the antibody response to keyhole limpet haemocyanin and soluble egg antigen to differentiate acute and chronic human schistosomiasis mansoni

Specific IgG and IgM responses to soluble egg antigen (SEA) and keyhole limpet haemocyanin (KLH) were measured by ELISA in patients with acute and chronic schistosomiasis. The tests based upon IgM and IgG antibodies responses to KLH presented the best diagnostic discrimination, and can be used in conjunction with clinical and epidemiological data to the differential diagnosis of acute schistosomiasis.

Impact of antihelminthic treatment on infection by Ascaris lumbricoides, Trichuris trichiura and hookworms in Covas, a rural community of Pernambuco, Brazil

Este trabalho avalia o impacto do tratamento antihelmíntico sobre a infecção por A. lumbricoides (Al), T. trichiura (Tt) e ancilostomídeos (Anc) na população de Covas, Pernambuco. Durante março/2001 e março/2002, quatro inquéritos parasitológicos foram realizados. Em cada um foram coletados dois exames de fezes por morador. O diagnóstico foi feito pelos métodos de Kato-Katz e Hoffmann. Em abril/01, os indivíduos positivos foram separados em dois grupos para tratamento com albendazol (n = 62) ou mebendazol (n = 57). As proporções de indivíduos positivos reduziram-se significativamente um mês pós-tratamento: Al (de 47,7 por cento para 6,6 por cento), Tt (de 45,7 por cento para 31,8 por cento) e Anc (de 47,7 por cento para 24,5 por cento); permanecendo abaixo do nível inicial um ano pós-tratamento. Os casos de monoinfecção, exceto os por Tt, e infecções múltiplas reduziram-se após o tratamento. A negativação foi significativa para Al (94,0 por cento), Anc (68,3 por cento), mas não para Tt (45,5 por cento) e foi maior para Al. A negativação não diferiu significativamente entre os tratados com mebendazol ou albendazol. A intensidade da infecção reduziu-se significativamente nos indivíduos que permaneceram positivos para Tt. Recomenda-se que o tratamento seja seletivo, administrado anualmente, de preferência com albendazole, devido ao seu custo-benefício.

Longitudinal Study on the Natural Infection of Biomphalaria straminea and B. glabrata by Schistosoma mansoni in an Endemic Area of Schistosomiasis in Pernambuco, Brazil

The abundance of snail hosts and the rates of infection with Schistosoma mansoni were monitored monthly for four years in two representative localities subjected to repeated chemotherapy of infected persons. Snail abundance varied from 1.0 to 4.4 collected per person/minute/station for Biomphalaria straminea and from 0.1 to 7.0 for B. glabrata. Infection rates of snails in nature varied from 0 percent to 15 percent for the former and from 0 percent to 70 percent for the latter species. Human infection increased from 35.5 percent to 61.9 percent in the locality occupied by B. straminea, and decreased from 40.3 percent to 20.8 percent in that occupied by B. glabrata. No relationship could be detected between human infection and the snail variables. Despite seasonal variations, natural infection persisted throughout the monitoring period in both snail species. It reached remarkably high levels in B. straminea when compared to those obtained by other authors probably because of differences in methodology. It is recommended that longitudinal studies should be carried out focally and periodically to avoid underestimating the prevalence of schistosome infection in snails

Replacing oxamniquine by praziquantel against Schistosoma mansoni infection in a rural community from the sugar-cane zone of Northeast Brazil: an epidemiological follow-up

A group of 52 villagers was followed-up for three years regarding Schistosoma mansoni infection. All villagers were periodically surveyed by the Kato-Katz method. In March 1997 and March 1998 the positives were treated with oxamniquine (15-20 mg/kg), and in March 1999, with praziquantel (60 mg/kg). All infection indices decreased substantially between March 1999 and March 2000: prevalence of infection (from 32.7 percent to 21.2 percent), prevalence of moderate/heavy infection (from 7.7 percent to 1.9 percent), intensity of infection (from 23.1 epg to 7.4 epg) and reinfection (from 35.7 percent to 14.3 percent). Negativation increased from 53.8 to 82.4. An optimistic prognostic is assumed in the short term for the introduction of praziquantel in the study area