Human schistosomiasis

Human schistosomiasis-or bilharzia-is a parasitic disease caused by trematode fl ukes of the genus Schistosoma. By conservative estimates, at least 230 million people worldwide are infected with Schistosoma spp. Adult schistosome worms colonise human blood vessels for years, successfully evading the immune system while excreting hundreds to thousands of eggs daily, which must either leave the body in excreta or become trapped in nearby tissues. Trapped eggs induce a distinct immune-mediated granulomatous response that causes local and systemic pathological eff ects ranging from anaemia, growth stunting, impaired cognition, and decreased physical fi tness, to organ-specifi c eff ects such as severe hepatosplenism, periportal fi brosis with portal hypertension, and urogenital infl ammation and scarring. At present, preventive public health measures in endemic regions consist of treatment once every 1 or 2 years with the isoquinolinone drug, praziquantel, to suppress morbidity. In some locations, elimination of transmission is now the goal; however, more sensitive diagnostics are needed in both the fi eld and clinics, and integrated environmental and health-care management will be needed to ensure elimination. © Chataway et al. Open Access article distributed under the terms of CC BY

Schistosomiasis-associated pulmonary arterial hypertension: a systematic review.

Schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) is a life-threatening complication of chronic hepatosplenic schistosomiasis. It is suggested to be the leading cause of pulmonary arterial hypertension (PAH) worldwide. However, pathophysiological data on Sch-PAH are scarce. We examined the hypothesis that there are pronounced similarities in pathophysiology, haemodynamics, and survival of Sch-PAH and idiopathic PAH (iPAH).This systematic review and meta-analysis was registered in the PROSPERO database (identifier CRD42018104066). A systematic search and review of the literature was performed according to PRISMA guidelines for studies published between 01 January 1990 and 29 June 2018.For Sch-PAH, 18 studies evaluating pathophysiological mechanisms, eight studies on haemodynamics (n=277), and three studies on survival (n=191) were identified. 16 clinical registries reporting data on haemodynamics and survival including a total of 5792 patients with iPAH were included for comparison. Proinflammatory molecular pathways are involved in both Sch-PAH and iPAH. The transforming growth factor (TGF)-β signalling pathway is upregulated in Sch-PAH and iPAH. While there was no difference in mean pulmonary artery pressure (54±17 mmHg versus 55±15 mmHg, p=0.29), cardiac output (4.4±1.3 L·min-1 versus 4.1±1.4 L·min-1, p=0.046), and cardiac index (2.6±0.7 L·min-1·m-2 versus 2.3±0.8 L·min-1·m-2, p<0.001) were significantly higher in Sch-PAH compared to iPAH, resulting in a lower pulmonary vascular resistance in Sch-PAH (10±6 Woods units versus 13±7 Woods units, p<0.001). 1- and 3-year survival were significantly better in the Sch-PAH group (p<0.001).Sch-PAH and iPAH share common pathophysiological mechanisms related to inflammation and the TGF-β signalling pathway. Patients with Sch-PAH show a significantly better haemodynamic profile and survival than patients with iPAH

Paediatric and maternal schistosomiasis: shifting the paradigms.

Background: In endemic areas, schistosomiasis causes both overt and subclinical disease in young children and their mothers, as well as in returned travellers. Sources of data: Key recently published literature. Areas of agreement: An action plan for paediatric schistosomiasis and female genital schistosomiasis (FGS) is needed with expanded access to praziquantel (PZQ) treatment required. Areas of controversy: Schistosomiasis-related morbidity is underappreciated. Present and future demand for PZQ treatment is bottlenecked, imbalanced and inequitable. Current dosing, treatment algorithms and access plans are suboptimal with treatment stalled during pregnancy. Growing points: Raised dosing of PZQ (>40 mg/kg) is being explored in young children. Surveillance of female genital schistosomiasis FGS is increasing. Use of PZQ in pregnancy is safe and preventive chemotherapy guidelines are being revised in morbidity- and transmission-control settings. Areas timely for developing research: Shifting focus of population-level control to individual-case management. Detection and prevention of FGS within general health services and integration of PZQ treatment for women and children in antenatal clinics. Feasibility studies assessing alternative and expanded access to PZQ treatment to at-risk children and mothers and pregnant women

Impact of Drought on the Spatial Pattern of Transmission of Sehistosoma haematobium in Coastal Kenya

We analyzed temporal changes in spatial patterns of active Schistosoma haematobium infection in different age groups and associated them with ponds infested with Bulinus snails. A major drought between 2001 and 2009 resulted in drying of ponds that were known sources of infection, and we detected very few or no snails in ponds that were infested in the past. The household-level spatial pattern of infection for children of various age groups in 2009 was contrasted with historical data from 2000. The significant local clustering of high- and low-infection levels among school-aged children that occurred in 2000 was absent in 2009. We attribute the disappearance of significant clustering around historical transmission hot spots to a decade-long drought in our study area. The implications of extreme weather and climate conditions on risk and transmission of S. haematobium and their relevance to control strategies are discussed. Copyright © 2011 by The American Society of Tropical Medicine and Hygiene

Praziquantel for the treatment of schistosomiasis during human pregnancy.

In 2014, an estimated 40 million women of reproductive age were infected with Schistosoma haematobium, S. japonicum and/or S. mansoni. In both 2003 and 2006, the World Health Organization (WHO) recommended that all schistosome-infected pregnant and breastfeeding women be offered treatment, with praziquantel, either individually or during treatment campaigns. In 2006, WHO also stated the need for randomized controlled trials to assess the safety and efficacy of such treatment. Some countries have yet to follow the recommendation on treatment and many programme managers and pregnant women in other countries remain reluctant to follow the recommended approach. Since 2006, two randomized controlled trials on the use of praziquantel during pregnancy have been conducted: one against S. mansoni in Uganda and the other against S. japonicum in the Philippines. In these trials, praziquantel treatment of pregnant women had no significant effect on birth weight, appeared safe and caused minimal side-effects that were similar to those seen in treated non-pregnant subjects. Having summarized the encouraging data, on efficacy, pharmacokinetics and safety, from these two trials and reviewed the safety data from non-interventional human studies, we recommend that all countries include pregnant women in praziquantel treatment campaigns. We identify the barriers to the treatment of pregnant women, in countries that already include such women in individual treatments and mass drug administration campaigns, and discuss ways to address these barriers

A health decision analytical model to evaluate the cost-effectiveness of female genital schistosomiasis screening strategies: The female genital schistosomiasis SCREEN framework.

Female genital schistosomiasis is a chronic gynaecological disease caused by the waterborne parasite Schistosoma (S.) haematobium. It affects an estimated 30-56 million girls and women globally, mostly in sub-Saharan Africa where it is endemic, and negatively impacts their sexual and reproductive life. Recent studies found evidence of an association between female genital schistosomiasis and increased prevalence of HIV and cervical precancer lesions. Despite the large population at risk, the burden and impact of female genital schistosomiasis are scarcely documented, resulting in neglect and insufficient resource allocation. There is currently no standardised method for individual or population-based female genital schistosomiasis screening and diagnosis which hinders accurate assessment of disease burden in endemic countries. To optimise financial allocations for female genital schistosomiasis screening, it is necessary to explore the cost-effectiveness of different strategies by combining cost and impact estimates. Yet, no economic evaluation has explored the value for money of alternative screening methods. This paper describes a novel application of health decision analytical modelling to evaluate the cost-effectiveness of different female genital schistosomiasis screening strategies across endemic settings. The model combines a decision tree for female genital schistosomiasis screening strategies, and a Markov model for the natural history of cervical cancer to estimate the cost per disability-adjusted life-years averted for different screening strategies, stratified by HIV status. It is a starting point for discussion and for supporting priority setting in a data-sparse environment

Anemia among Children Exposed to Polyparasitism in Coastal Kenya

Anemia represents a substantial problem for children living in areas with limited resources and significant parasite burden. We performed a cross-sectional study of 254 Kenyan preschool-and early school-age children in a setting endemic for multiple chronic parasitic infections to explore mechanisms of their anemia. Complete venous blood cell counts revealed a high prevalence of local childhood anemia (79%). Evaluating the potential links between low hemoglobin and socioeconomic factors, nutritional status, hemoglobinopathy, and/or parasite infection, we identified age < 9 years (odds ratio [OR]: 12.0, 95% confidence interval [CI]: 4.4, 33) and the presence of asymptomatic malaria infection (OR: 6.8, 95% CI: 2.1, 22) as the strongest independent correlates of having anemia. A total of 130/155 (84%) of anemic children with iron studies had evidence of iron-deficiency anemia (IDA), 16% had non-IDA; 50/52 of additionally tested anemic children met soluble transferrin-receptor (sTfR) criteria for combined anemia of inflammation (AI) with IDA. Children in the youngest age group had the greatest odds of iron deficiency (OR: 10.0, 95% CI: 3.9, 26). Although older children aged 9-11 years had less anemia, they had more detectable malaria, Schistosoma infection, hookworm, and proportionately more non-IDA. Anemia in this setting appears multifactorial such that chronic inflammation and iron deficiency need to be addressed together as part of integrated management of childhood anemia

Expanding Praziquantel (PZQ) Access beyond Mass Drug Administration Programs: Paving a Way Forward for a Pediatric PZQ Formulation for Schistosomiasis.

Treating preschool age children (PSAC) with schistosomiasis remains a challenge. Without a pediatric praziquantel (PZQ) formulation, the inclusion of this age group in control programs is limited, and general access to treatment in routine care settings is severely bottlenecked. There are, however, current platforms that target PSAC in primary health care such as the integrated management of childhood illnesses (IMCI), which could integrate PZQ in their portfolio and deliver a pediatric PZQ formulation when available. In addition, other age groups such as school-aged children (SAC) could also benefit from the IMCI’s successful strategy and be treated in health centers using a similar approach. This Viewpoint article reports a summary of a symposium held at the American Society of Tropical Medicine and Hygiene national meeting in 2014 that brought together six experts in different areas in the field of pediatric schistosomiasis to form a working group that could provide recommendations for the inclusion of PSAC in the IMCI and other existing preschool outreach programs. This was to develop and adapt methodologies to fill existing gaps left by current mass drug administration (MDA) programs and synergize efforts for schistosomiasis control more broadly. Foremost, this includes a better definition of subclinical disease in young children to integrate into ICMI guidelines and further demonstration of the benefit of expanded access of treatment to children of all ages by encouraging universal access

Use of face masks and other personal preventive measures by Hajj pilgrims and their impact on health problems during the Hajj.

BACKGROUND: The Hajj is one of the world's largest pilgrimage and gathers millions of Muslims from different nationalities every year. Communicable diseases have been reported frequently, during and following the Hajj, and these have been linked to individual behavioural measures. This study aimed to measure the effect of personal preventive measures, such as face mask use, hand hygiene and others, adopted by pilgrims in reducing the acquisition of infectious diseases. METHODS: We conducted a cross-sectional study at the Hajj terminal in King Abdulaziz International Airport in Jeddah, Saudi Arabia. Pilgrims were approached in the airport lounges after the 2017 Hajj season and prior to the departure of their flights from Jeddah to their home countries. An electronic data collection tool ('Open Data Kit') was used to gather survey data in regards to health problems and preventive measures during the Hajj. RESULTS: A total of 2973 Hajj pilgrims were surveyed. In all, 38.7% reported symptoms of upper respiratory tract infections (URTIs) and 5.4% reported symptoms of travel diarrhoea. Compliance with face mask use was 50.2%. Changing a face mask every 4 h was found to be significantly associated with lower prevalence of URTIs [adjusted odds ratio 0.56 (95% confidence interval 0.34-0.92), P = 0.02]. There was no statistical difference between overall face mask use and URTI acquisition. The main sources of food, eating raw vegetables/food, frequency of hand washing or use of hand sanitizers were not found to be significantly associated with reported travellers' diarrhoea. Unlicensed barbers were used by 12% of pilgrims and 9.2% of pilgrims reported using blades that were reused by other pilgrims. CONCLUSION: Preventive measures are the most effective way to prevent infections. Pilgrims can benefit from face masks by changing them frequently. There is still limited information on the effect of the use of face mask in decreasing the risk of URTI in mass gatherings