Schistosoma haematobium infection and morbidity risk factors for pre-school age children in western Angola: A knowledge, attitudes and practices survey

Schistosomiasis; Medical risk factors; MorbidityEsquistosomiasi; Factors de risc mèdic; MorbilitatEsquistosomiasis; Factores de riesgo médico; MorbilidadBackground Urogenital schistosomiasis is one of the most prevalent parasitic diseases in sub-Saharan Africa. It is a poverty-related disease conditioned by behavioural practices. Methods Our objective is to evaluate the awareness, mindset and habits about urogenital schistosomiasis in the community of Cubal (Angola), as well as its association with infection and urinary tract morbidity in pre-school age children. A cross-sectional study of knowledge, attitudes and practices at home was conducted between February and May 2022 with 250 participants. Results Overall, 93.6% of those surveyed had some prior knowledge about schistosomiasis and, among all the symptoms associated with this disease, blood in the urine was the best known (54.4%). Nevertheless, 57.6% obtained a medium knowledge score. Regarding attitude, the majority of respondents had a high attitude score (79.2%) with 96.0% willing to participate in mass drug administration campaigns. Laundry in the river was the most common risk practice (61.2%) and 55.2% out of the total were classified with a low practice score. Conclusion Low knowledge about symptoms and transmission by caregivers was the outstanding risk factor for infection in pre-school age children (OR = 16.93, 95%CI: 3.93–72.82), and lack of knowledge that avoiding entering the river prevents schistosomiasis was the main risk factor for morbidity in PSAC (OR = 8.14, 95%CI: 1.14–58.25).This research was supported by the Red de Investigación de Centros de Enfermedades Tropicales – RICET of the PN de I+D+I, ISCIII-Subdirección General de Redes y Centros de Investigación Cooperativa RETICS), Ministry of Health and Consumption, Madrid; by CIBER de Enfermedades Infecciosas (Projects CB21/13/00056 and CB21/13/00029), ISCIII, Ministry of Science and Education, Madrid; by Project No. 2021/004 of the PROMETEO Program, Programa de Ayudas para Grupos de Investigación de Excelencia, Generalitat Valenciana, Valencia, Spain. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Prevalence and morbidity of urogenital schistosomiasis among pre-school age children in Cubal, Angola

Morbidity; Urine; SchistosomiasisMorbilidad; Orina; EsquistosomiasisMorbilitat; Orina; EsquistosomiasiBackground: Schistosomiasis is one of the most important neglected tropical diseases, with a great impact on public health and more than 200,000 deaths annually. Schistosoma haematobium causes urinary tract (UT) morbidity. Since schistosomiasis morbidity control programs focus on children older than 5 years, pre-school age children (PSAC) morbidity is not well known. Methods: We conducted a cross-sectional study in Cubal (Angola) among 245 PSAC with the objective of evaluating the prevalence of S. haematobium infection, the intensity of infection, and associated morbidity. For this purpose, urine filtration test followed by microscopic visualization and ultrasound examinations were performed. Results: The estimated overall prevalence of urogenital schistosomiasis was 30.2% (CI 95%; 24.5-35.9), with 20.3% (CI 95%; 15.3-25.3) of the samples analysed showing a high intensity of infection. A total of 54.5% (CI 95%; 47.6-61.8) of infected children presented UT lesions, showing a significant association between schistosomiasis infection and UT morbidity (p-value < 0.001). Bladder wall thickening was the most common lesion, being present in 100% of abnormal ultrasounds. We found that anaemia and severe malnutrition were not significantly associated with the development of UT lesions. Conclusions: S. haematobium infection in PSAC causes great UT detectable morbidities. Therefore, there is an evident need of including them in mass drug administration (MDA) campaigns and consequently the development of an adapted praziquantel treatment dosage for children under 2 years of age.This research was supported by the Red de Investigación de Centros de Enfermedades Tropicales–RICET (Grant No. RD16/0027/0023 and RD16/0027/0003) of the PN de I+D+I, ISCIII-Subdirección General de Redes y Centros de Investigación Cooperativa RETICS), Spanish Ministry of Health and Consumption; by CIBER de Enfermedades Infecciosas (Grant No. CB21/13/00056 and CB21/13/00029), ISCIII, Spanish Ministry of Science and Education; and by the PROMETEO Program, Programa of Ayudas para Grupos de Investigación de Excelencia, Generalitat Valenciana (Grant No. 2021/004)

First field and laboratory evaluation of LAMP assay for malaria diagnosis in Cubal, Angola

Angola; MalariaAngola; MalariaAngola; MalàriaBackground Malaria is a globally distributed infectious disease. According to the World Health Organization, Angola is one of the six countries that account for over half the global malaria burden in terms of both malaria cases and deaths. Diagnosis of malaria still depends on microscopic examination of thin and thick blood smears and rapid diagnostic tests (RDTs), which often lack analytical and clinical sensitivity. Molecular methods could overcome these disadvantages. The aim of this study was to evaluate, for the first time to our knowledge, the performance of a loop-mediated isothermal amplification (LAMP) for the diagnosis of malaria in an endemic area in Cubal, Angola, and to assess the reproducibility at a reference laboratory. Methods A total of 200 blood samples from patients attended at Hospital Nossa Senhora da Paz, Cubal, Angola, were analysed for Plasmodium spp. detection by microscopy, RDTs, and LAMP. LAMP assay was easily performed in a portable heating block, and the results were visualized by a simple colour change. Subsequently, the samples were sent to a reference laboratory in Spain to be reanalysed by the same colorimetric LAMP assay and also in real-time LAMP format. Results In field tests, a total of 67/200 (33.5%) blood samples were microscopy-positive for Plasmodium spp., 98/200 RDT positive, and 112/200 (56%) LAMP positive. Using microscopy as reference standard, field LAMP detected more microscopy-positive samples than RDTs (66/67; 98% vs. 62/67; 92.5%). When samples were reanalysed at a reference laboratory in Spain using both colorimetric and real-time assays, the overall reproducibility achieved 84.5%. Conclusions This is the first study to our knowledge in which LAMP has been clinically evaluated on blood samples in a resource-poor malaria-endemic area. The colorimetric LAMP proved to be more sensitive than microscopy and RDTs for malaria diagnosis in field conditions. Furthermore, LAMP showed an acceptable level of reproducibility in a reference laboratory. The possibility to use LAMP in a real-time format in a portable device reinforces the reliability of the assay for molecular diagnosis of malaria in resource-poor laboratories in endemic areas.The work was supported by the Institute of Health Carlos III, ISCIII, Spain (www.isciii.es) grant number PI22/01721 (PFS), European Union cofinancing by FEDER (Fondo Europeo de Desarrollo Regional) ‘Una manera de hacer Europa’. We also acknowledge support by the Predoctoral Fellowship Program of Junta de Castilla y León cofounded by Fondo Social Europeo: (BDNS Identif.: 422058, BFS) and (BDNS Identif: 487971, BCV)

First field study using Strong-LAMP for diagnosis of strongyloidiasis in Cubal, Angola

Angola; Molecular screening; StrongyloidiasisAngola; Cribado molecular; EstrongiloidiasisAngola; Cribratge molecular; EstrogiloidiasiStrongyloides stercoralis infection is a common neglected tropical disease distributed worldwide, mainly in tropical and subtropical climates. The impact of S. stercoralis infections on human health ranges from mild asymptomatic infections to chronic strongyloidiasis unnoticeable until the host is immunosuppressed. In severe strongyloidiasis, a syndrome of hyperinfection and larval dissemination to various organs can occur with high mortality rates. The diagnosis of strongyloidiasis is challenging because of the absence of a single standard reference test with high sensitivity and specificity, which also makes it difficult to estimate the accuracy of other diagnostic tests. This study aimed to evaluate, for the first time, the use of an easy-to-perform loop-mediated isothermal amplification (LAMP) colorimetric assay (named Strong-LAMP) for the molecular screening of strongyloidiasis in stool samples from patients in a low-resource endemic area in Cubal, Angola. To compare different LAMP application scenarios, the performance of the Strong-LAMP under field conditions in Angola was reassessed in a well-equipped reference laboratory in Spain and compared with a quantitative polymerase chain reaction (qPCR) method.This work was supported by the Institute of Health Carlos III, ISCIII, Spain (www.isciii.es) grant number PI22/01721 (P.F.-S.), European Union cofinancing by FEDER (Fondo Europeo de Desarrollo Regional) ‘Una manera de hacer Europa’. We also acknowledge support by the Predoctoral Fellowship Program of Junta de Castilla y León cofunded by Fondo Social Europeo (BDNS (Identif.): 422058, B.F.-S. and BDNS (Identif.): 487971, B.C.-V.)

Epidemiology of Schistosomiasis and Usefulness of Indirect Diagnostic Tests in School-Age Children in Cubal, Central Angola

<div><p>Introduction</p><p>Schistosomiasis remains a public health major problem and little is known in many areas, mainly in Sub-Saharan Africa</p><p>Objectives</p><p>To assess the burden and risk factors of schistosomiasis and intestinal parasitic helminthes in the children of Cubal, Angola, and to compare different diagnostic approaches for urinary schistosomiasis under field conditions.</p><p>Methods</p><p>A cross-sectional study was conducted. Urine and faeces samples of school children were microscopically studied. A random sample of children was obtained from an alphabetically arranged list of children, taking one of two children. Urine dipstick, colorimetric test and macrohaematuria were considered as indirect diagnostic methods and compared to direct urine examination. Possible risk factors for the infection were sex, age, distance to the river and previous treatment with praziquantel; the assessment was performed using Chi-square test.</p><p>Results</p><p>A total of 785 (61.18%) children showed <i>S</i>. <i>haematobium</i> eggs in urine; children living within 500 meters from the river had a higher odds for infection: Odds ratio 1.97 (1.45–2.7 CI 95%); urine dipstick showed sensitivity of 96% and specificity of 61.3%, with a positive predictive value; colorimetric test showed sensitivity of 52.5%, specificity of 74.6% and a positive predictive value of 77%. Proteinuria was present in 653 (51.1%) children, being more frequent in children with <i>S</i>. <i>haematobium</i> in urine (75.2%); 32 of 191 stool samples (16%) showed the presence of other intestinal parasites and 8 (4%) for <i>S</i>. <i>haematobium</i>.</p><p>Conclusions</p><p>Prevalence of urinary schistosomiasis in our study area is much higher than the national average, considering it as a high-risk community. Proximity to a source of water was a risk factor for the infection. Indirect tests, as urine dipstick and colorimetric test, were useful tools for diagnosis, due to ease of use and low cost. Proteinuria was a common finding, probably showing an early structural damage due to schistosomiasis in this group of children.</p></div

Prevalence of urinary schistosomiasis considering 13 distinct neighborhoods and their relationship to the sources of water.

<p>Prevalence of urinary schistosomiasis considering 13 distinct neighborhoods and their relationship to the sources of water.</p

Risk factors for schistosomiasis infection.

<p>OR: odds ratio. CI: confidence interval.</p><p>Risk factors for schistosomiasis infection.</p

Relationship of proteinuria with other parameters.

<p>Relationship of proteinuria with other parameters.</p

Indirect tests utility compared to gold standard (urine parasitological examination).

<p>Indirect tests utility compared to gold standard (urine parasitological examination).</p

Prevalence of intestinal parasites.

<p>CI = Confidence Interval</p><p>Prevalence of intestinal parasites.</p