The usefulness of indirect diagnostic tests for Schistosoma haematobium infection after repeated rounds of mass treatment with praziquantel in Mpwapwa and Chakechake districts in Tanzania

Urogenital schistosomiasis among adult male population in an endemic area of southern Tanzania: a descriptive cross-sectional study

BACKGROUND

Urogenital schistosomiasis (UGS) caused by Schistosoma haematobium is endemic in Southern Tanzania. The disease has significant implications for both socioeconomic and public health. Because infections with S. haematobium usually peak in childhood, the majority of studies have concentrated on school-aged children leaving other groups such as males which might be continuous reservoir of infection transmission. However, despite its chronic consequences in the male population, the disease has received insufficient attention, especially in sub-Saharan Africa. This study was conducted to describe the previous and current schistosomiasis status among adult males living in high-endemic areas of southern Tanzania DESIGN, SETTING AND PARTICIPANTS: A descriptive cross-sectional study was employed to gather data on the prevalence of UGS among adult men residing at schistosomiasis endemic in the Mtama District Council. Quantitative methods of data collection which included questionnaire and laboratory procedures were used.

RESULTS

Out of 245 participants, macrohaematuria and microhaematuria were found in 12 (4.9%, 95% CI 2.4% to 7.8%) and 66 (26.9%, 95% CI 21.6% to 32.7%) participants, respectively. S. haematobium ova were recovered from the urine samples of 54 (22.0%, 95% CI 16.7% to 27.3%) participants. The median intensity of infection was 20 eggs per 10 mL of urine ranging from 1 to 201 eggs per 10 mL of urine (IQR) 60.5). Out of 245 participants 33 (13.5% 95% CI 9.0% to 17.6%) had light intensity of infection and 21 (38.9%, 95% CI; 25.0% to 52.5%) had heavy intensity of infection. Overall, the prevalence of heavy intensity of infection was 8.6% (95% CI 4.9% to 12.6%). The prevalence and intensity of UGS varied significantly by age, marital status and village of residence.

CONCLUSION

This study sheds light on the prevalence of UGS among adult males in endemic areas of southern Tanzania. The results highlight the urgent need for comprehensive intervention strategies to address the burden of the disease.

Diagnostic tests for human Schistosoma mansoni and Schistosoma haematobium infection: a systematic review and meta-analysis

BACKGROUND

Accurate diagnosis is pivotal for implementing strategies for surveillance, control, and elimination of schistosomiasis. Despite their low sensitivity in low-endemicity areas, microscopy-based urine filtration and the Kato-Katz technique are considered as reference diagnostic tests for Schistosoma haematobium and Schistosoma mansoni infections, respectively. We aimed to collate all available evidence on the accuracy of other proposed diagnostic techniques.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Embase, the Cochrane Library, and LILACS for studies published from database inception to Dec 31, 2022, investigating the sensitivity and specificity of diagnostic tests for S haematobium and S mansoni infections against Kato-Katz thick smears or urine microscopy (reference tests) involving adults (aged ≥18 years), school-aged children (aged 7 to 18 years), or preschool-aged children (aged 1 month to 7 years). We extracted raw data on true positives, true negatives, false positives, and false negatives for the diagnostic tests and data on the number of participants, study authors, publication year, journal, study design, participants' age and sex, prevalence of Schistosoma infection, and treatment status. To account for imperfect reference tests, we used a hierarchical Bayesian latent class meta-analysis to model test accuracy.

FINDINGS

Overall, we included 121 studies, assessing 28 different diagnostic techniques. Most studies (103 [85%] of 121) were done in Africa, 14 (12%) in South America, one (1%) in Asia, and one (1%) in an unknown country. Compared with the reference test, Kato-Katz thick smears, circulating cathodic antigen urine cassette assay version 1 (CCA1, 36 test comparisons) had excellent sensitivity (95% [95% credible interval 88-99]) and reasonable specificity (74% [63-83]) for S mansoni. ELISA-based tests had a performance comparable to circulating cathodic antigen, but there were few available test comparisons. For S haematobium, proteinuria (42 test comparisons, sensitivity 73% [62-82]; specificity 94% [89-98]) and haematuria (75 test comparisons, sensitivity 85% [80-90]; specificity 96% [92-99]) reagent strips showed high specificity, with haematuria reagent strips having better sensitivity. Despite limited data, nucleic acid amplification tests (NAATs; eg, PCR or loop-mediated isothermal amplification [LAMP]) showed promising results with sensitivity estimates above 90%. We found an unclear risk of bias of about 70% in the use of the reference or index tests and of 50% in patient selection. All analyses showed substantial heterogeneity (I2>80%).

INTERPRETATION

Although NAATs and immunological diagnostics show promise, the limited information available precludes drawing definitive conclusions. Additional research on diagnostic accuracy and cost-effectiveness is needed before the replacement of conventional tests can be considered.

FUNDING

WHO and Luxembourg Institute of Health.

Review of Recent Prevalence of Urogenital Schistosomiasis in Sub-Saharan Africa and Diagnostic Challenges in the Field Setting

Human schistosomiasis is one of neglected tropical diseases that remain highly prevalent in sub-Saharan Africa (SSA). Human schistosomiasis is mainly caused by two species, Schistosoma haematobium and S. mansoni, leading to urogenital and intestinal schistosomiasis, respectively. The World Health Organization (WHO) recommends mass drug administration (MDA) with praziquantel as the primary method of global intervention. Currently, MDA with praziquantel covers over half of the target population in endemic SSA countries. However, an accurate diagnosis is crucial for monitoring and evaluating the effectiveness of MDA. The standard diagnosis of both urogenital and intestinal schistosomiasis relies on the microscopic identification of eggs. However, the diagnostic sensitivity of this approach is low, especially for light or ultra-light infections. This is because Schistosoma eggs are laid inside of the venous plexus of the urinary bladder or mesenteric vein, where the adult flukes live. Approximately half of the eggs circulate in the blood vessels or are packed in neighboring tissues, while the remaining half are expelled into the lumen of the urinary bladder or intestine intermittently when the blood vessels are ruptured. In the field setting, the accuracy of any diagnostic method is critical for proper management of the intervention. The present article reviews the recent prevalence of urogenital schistosomiasis in SSA and highlights the practical limitations of diagnostic methods such as urine microscopy, urine reagent strips, molecular diagnosis, and ultrasound scanning in the field setting. Despite continuous global efforts to eliminate schistosomiasis over the past 20 years, many areas still remain endemic in SSA. No single diagnostic approach achieves acceptable sensitivity and specificity in the field setting. Therefore, any field survey should employ a combination of these methods based on the purpose of the study to accurately monitor and evaluate urogenital schistosomiasis. Based on diagnostic values and a cost-benefit analysis, a urine reagent strip test can replace urine microscopy in the field setting. The WHO criteria by ultrasound diagnosis should be updated including the echogenic snow sign and contour distortion.

The trend of schistosomiasis related bladder cancer in the lake zone, Tanzania: a retrospective review over 10 years period

INTRODUCTION

Bladder cancer is a possible outcome of chronic urinary schistosomiasis in many endemic countries. In Tanzania, the Lake Victoria area is one of the areas with the highest prevalence of urinary schistosomiasis and higher incidences of squamous cell carcinoma (SCC) of the urinary bladder. A previous study in the area over one decade (2001-2010) showed SCC to be common in patients aged below 50 years. With various prevention and intervention programs there are likely to be notable changes in schistosomiasis-related urinary bladder cancer, which is currently unknown. Updated information on the status of SCC in this area will be useful for giving an insights into efficacy of control interventions implemented and help guide the initiation of new ones. Therefore, this study was done to determine the current trend of schistosomiasis-related bladder cancer in lake zone, Tanzania.

METHODS

This was a descriptive retrospective study of histologically confirmed urinary bladder cancer cases diagnosed at the Pathology Department of Bugando Medical Centre over 10 years period. The patient files and histopathology reports were retrieved and information was extracted. Data were analyzed using Chi-square and student t-test.

RESULTS

A total of 481 patients were diagnosed with urinary bladder cancer during the study period whereby, 52.6% were males and 47.4% were females. The mean age regardless of histological type of cancer was 55 ± 14.2 years. The SCC was the commonest histological type accounting for 57.0%, followed by transitional cell carcinoma 37.6%, and 5.4% were adenocarcinomas. The Schistosoma haematobium eggs were observed in 25.2% and were commonly associated with SCC (p = 0.001). Poorly differentiated cancers were observed mostly in females (58.6%) compared to males (41.4%) (p = 0.003). Muscular invasion of the urinary bladder by cancer was observed in 11.4% of the patients, and this was significantly higher in non-squamous than in squamous cancers (p = 0.034).

CONCLUSION

Schistosomiasis-related cancers of the urinary bladder in the Lake zone of Tanzania is still a problem. Schistosoma haematobium eggs were associated with SCC type indicating the persistence of infection in the area. This calls for more efforts on preventive and intervention programs to reduce the burden of urinary bladder cancer in the lake zone.

Prevalence and Associated Risk Factors of Urinary Schistosomiasis among Primary School Pupils in the Jidawa and Zobiya Communities of Jigawa State, Nigeria

Background

Urogenital schistosomiasis (UgS) is a parasitic disease caused by Schistosoma haematobium and can lead to chronic ill-health. Nigeria is endemic for schistosomiasis, but epidemiology of UgS has not been studied in most states. This study was conceived with the aim to contribute towards an accurate national picture of UgS in Nigeria. The prevalence of UgS and the associated risk factors were for the first time investigated among primary school pupils in Jidawa and Zobiya communities of the Dutse Local Government Area (LGAs) of Jigawa State, Nigeria.

Method

Focus group discussions with teachers and parents were conducted. After obtaining written consent from parents, questionnaires were administered to pupils to obtain socio-demographic data and information on water contact activities. Urine samples (279) were collected and processed by the urine filtration technique to evaluate haematuria and the presence of S. haematobium eggs.

Results

Prevalences of 65.7% (90/137) and 69.0% (98/142) were recorded in the Jidawa and Zobiya communities, respectively. In both communities, there was a significant association between gender and UgS: 63.3% of the infected pupils were males as compared to 36.7% females (χ2 = 5.42, p = 0.020). Grade 5 students had a significantly higher prevalence (χ2 = 17.919, p = 0.001) (80.0%) compared to those in grades 2, 3, 4, and 6 (63.8%, 66.7%, 61.5%, and 64.6%, respectively). Water contact activities showed that pupils involved in fishing, irrigation, and swimming were at greater risk of becoming infected in Jidawa and Zobiya, with odds ratios (risk factors) of 5.4 (0.994-28.862) and 4.1 (1.709-9.862), respectively (p = 0.05).

Conclusion

Both the Jidawa and Zobiya communities of the Dutse LGAs of Jigawa State are hyperendemic for UgS. In collaboration with the State Ministry of Health, mass administration of praziquantel was carried out in the Jidawa and Zobiya communities after this study.

Urogenital schistosomiasis prevalence, knowledge, practices and compliance to MDA among school-age children in an endemic district, southern East Tanzania

Background

Tanzania has a high prevalence of urogenital schistosomiasis. Praziquantel is administered to school-age children on an annual basis as part of efforts to reduce transmission and morbidity associated with heavy infections. We investigated the prevalence, knowledge, and practices of urogenital schistosomiasis transmission, as well as compliance with mass drug administration (MDA) among schoolchildren in Masasi District.

Materials and methods

A cross-sectional survey was conducted in five primary schools. A pre-tested questionnaire was used to assess knowledge and practice related to the transmission of urogenital schistosomiasis, as well as compliance with MDA. Collected urine samples were examined macroscopically for macrohematuria. They were then tested for microhematuria and Schistosoma haematobium (S. haematobium) eggs with urine dipsticks and filtration technique, respectively.

Findings

The study included 389 primary school children in total. Overall, 27 (6.9%) of children had S. haematobium infection, and 37 (9.5%) had microhematuria. The mean (SD) intensity was 123.4 (247.4) eggs per 10 ml of urine. A total of 10 (2.6%) had heavy intensity of infection. The majority (94.9%) reported having complied to the previous round of MDA six months prior to this study, and 308 (79.2%) were aware that water contact is associated with an increased risk of urogenital schistosomiasis infection. Nevertheless, 182 (46.8%) of the participants engaged in swimming activities, with 92 (50.9%) of the participants being female. The prevalence of urogenital schistosomiasis was higher (10.9%) among children who participated in swimming activities versus those who did not (3.4%) (P = 0.003).

Conclusion

Despite high MDA compliance, urogenital schistosomiasis is still prevalent among primary school children in Masasi District. Children who swim in freshwater bodies such as rivers and ponds are more likely to contract urogenital schistosomiasis.