Socioeconomic determinants of Schistosoma mansoni infection using multiple correspondence analysis among rural western Kenyan communities: Evidence from a household-based study.

BACKGROUND: Socioeconomic inequality including wealth distribution is a barrier to implementation of health policies. Wealth distribution can be measured effectively using household data on durable assets. Compared to other methods of analysing Socio-economic Status (SES) using durable assets, Multiple Correspondence Analysis (MCA) can create more reliable wealth quintiles. We therefore evaluated socioeconomic determinants of Schistosoma mansoni using MCA on household data among adult population in western Kenya. The hypothesis of this study was that MCA would be a useful predictor of S. mansoni prevalence and/or intensity. METHODOLOGY: Twelve villages, 6 villages that had showed the greatest decrease in S. mansoni prevalence (Responder villages) and 6 villages that showed relatively lower decrease (Hotspot villages) between the year 2011 and 2015 were randomly selected for this study. This was according to a previous Schistosomiasis Consortium for Operational Research and Elimination (SCORE) report from western Kenya. From each village, convenience sampling was used to identify 50 adults from 50 households for inclusion in this study. An interview with a questionnaire based upon MCA indicators was conducted. One stool sample from each of the 600 adults was examined based on four slides for S. mansoni eggs using Kato Katz technique. Mean Eggs per gram(EPG) was calculated by taking the average of the readings from the four slides. A log binomial regression model was used to identify the influence of the various age-groups(<30 years, 30-60 years and >60 years), household size, wealth class, occupation, education status, main water supply, sex and sub-county of residence on S. mansoni infection. EPG was then compared across variables that were significant based on multivariate log binomial model analysis using a mixed model. PRINCIPAL FINDINGS: Overall prevalence of S. mansoni was 41.3%. Significantly higher prevalence of S. mansoni were associated with males, those aged below 30 years, those who use unsafe water sources (unprotected wells, lakes and rivers), residents of Rachuonyo North, Hotspot villages and those earning livelihood from fishing. Only sex and household size were significant predictors in the multivariate model. Males were associated with significantly higher prevalence compared to the females (aPR = 1.37; 95% CI = 1.14-1.66). In addition, households with at least four persons had higher prevalence compared to those with less than four (aPR = 1.29; 95% CI = 1.03-1.61). However, there was no difference in prevalence between the wealth classes(broadly divided into poor and less poor categories). Intensity of infection (Mean EPG)was also significantly higher among males, younger age group, Rachuonyo North residents and Hotspot Villages. CONCLUSION: Socioeconomic status based on an MCA model was not a contributing factor to S. mansoni prevalence and/or intensity possibly because the study populations were not sufficiently dissimilar. The use of convenience sampling to identify participants could also have contributed to the lack of significant findings.

The cost of a disease targeted for elimination in Brazil: the case of schistosomiasis mansoni.

BACKGROUND: Schistosomiasis mansoni is a poverty-related parasitic infection that has a variety of clinical manifestations. We consider the disability and deaths caused by schistosomiasis unacceptable for a tool-ready disease. Its condition in Brazil warrants an analysis that will enable better understanding of the local health losses and contribute to the complex decision-making process. OBJECTIVE: This study estimates the cost of schistosomiasis in Brazil in 2015. METHODS: We conducted a cost of illness study of schistosomiasis mansoni in Brazil in 2015 based on a prevalence approach and from a societal perspective. The study included 26,499 schistosomiasis carriers, 397 hepatosplenic cases, 48 cases with the neurological form, 284 hospitalisations, and 11,368.26 years of life lost (YLL) of which 5,187 years are attributable to economically active age groups. RESULTS: The total cost of schistosomiasis mansoni in Brazil was estimated to be US$ 41,7million in 2015 with 94.61% of this being indirect costs. CONCLUSIONS: The economic burden of schistosomiasis mansoni in Brazil is high and results in the loss of productivity. Its persistence in Brazil is a challenge to public health and requires inter-sectorial interventions in areas such as indoor water supply, basic sanitation, and education.

Quality of life and quality-adjusted life years of chronic schistosomiasis mansoni patients in Brazil in 2015.

Background: Measures of health-related quality of life (HRQoL) have been used to express the impact of neglected diseases and to generate indicators for health economic assessments. Schistosomiasis mansoni is a neglected disease with various clinical manifestations, including severe repercussions, caused by parasitic worms. Here we describe the quality of life of chronic schistosomiasis mansoni patients and estimate the quality-adjusted life years (QALYs) associated with chronic schistosomiasis mansoni in Brazil in 2015. Methods: A HRQoL study was carried out using the three-level European Quality of Life 5-Dimensions (EQ-5D-3L) questionnaire in 147 chronic schistosomiasis mansoni patients at an outpatient monitoring facility of an endemic state for schistosomiasis. Results: Losses in HRQoL were observed in all five dimensions of the EQ-5D-3L. Patients >60 y and 40-49 y of age reported the highest frequencies of problems. The average utility index was 0.71, and the median index was significantly lower among female patients and patients with comorbidities (0.68; p<0.05) compared with the entire sample. Approximately 26.7 QALYs were estimated for the study population and 31.2 QALYs for the chronic schistosomiasis mansoni patients in Brazil. Conclusions: The advanced forms of schistosomiasis mansoni, even during treatment, contribute to important health losses in the population dealing with the disease.

Cost analysis of tests for the detection of Schistosoma mansoni infection in children in western Kenya.

Financial resources tend to be limited in schistosomiasis endemic areas, forcing program managers to balance financial and scientific considerations when selecting detection assays. Therefore, we compared the costs of using single stool Kato-Katz, triplicate stool Kato-Katz, and point-of-contact circulating cathodic antigen (POC-CCA) assays for the detection of Schistosoma mansoni infection. Economic and financial costs were estimated from the viewpoint of a schistosomiasis control program using the ingredients approach. Costs related to specimen collection, sample processing and analysis, and treatment delivery were considered. Analysis inputs and assumptions were tested using one-way and two-way sensitivity analysis. The total per-person cost of performing the single Kato-Katz, triplicate Kato-Katz, and POC-CCA was US$6.89, US$17.54, and US$7.26, respectively. Major cost drivers included labor, transportation, and supplies. In addition, we provide a costing tool to guide program managers in evaluating detection costs in specific settings, as costs may vary temporally and spatially.

Severe forms of schistosomiasis mansoni: epidemiologic and economic impact in Brazil, 2010.

BACKGROUND: Schistosoma mansoni infection is generally asymptomatic at the initial stage. However, patients left untreated can develop severe, potentially fatal clinical disease. In Brazil, S. mansoni transmission occurs in 19 states and, despite the contribution of infection to the cycle of poverty and disease, the economic impact of severe cases is unclear. Our objectives were to estimate the epidemiological burden and the costs of severe stages of S. mansoni in Brazil in 2010. METHODS: We conducted an epidemiologic descriptive study and a partial economic evaluation of cost-of-illness. The study population was identified from records of notifications, hospitalizations and deaths related to S. mansoni in the respective information systems. RESULTS: The mortality rate for S. mansoni was 0.3 deaths per 100 000 population, which represented 1.1% of the deaths in Brazil from infectious diseases listed in Chapter I of the International Statistical Classification of Disease and Related Health Problems, 10(th) revision (ICD 10), and almost 9.0% of deaths from infection diseases in the state of Pernambuco. We calculated 6419 potential years of life lost (PYLL) to S. mansoni. The costs estimated within the public health sector totaled R$889 049.58 (US$495 016.47) and the costs of productivity losses reached R$ 35 725 332.72 (US$ 19 891 590.86) in terms of salaries lost as a result of premature death or absence from work. The cost-of-illness related to S. mansoni in Brazil was R$ 36 614 382.30 (US$ 20 386 627.12). CONCLUSION: The severe cases of S. mansoni disease still occurring in Brazil have an important epidemiologic and economic impact, representing a significant loss for society. The development of severe cases of a neglected parasitic disease that is preventable and responsive to primary healthcare intervention should be considered an expression of inequity. Our findings provide important evidence to support the strengthening of public health measures and investment to reduce poverty-related diseases in Brazil today.

[Schistosomiasis caused by Schistosoma mansoni in the Kou valley: Characterization of the transmission system and socioeconomic impact]. / Endémie bilharzienne à Schistosoma mansoni à la vallée du Kou : caractérisation du système de transmission et impact socioéconomique.

Schistosomiasis is one of the waterborne diseases which benefit from environmental and behavioral changes induced by the mobilization of surface water resources in Sahelian countries, such as Burkina Faso. Studies have established the existence of human schistosomiasis in the Kou valley, one of the oldest hydro-agricultural zones in the country. However, the role of population behavior in the transmission pattern of this disease and its socioeconomic impact in this valley are poorly understood. It is in response to these questions that this study was undertaken. The objectives of this study were to identify activities that exposed most of the Valley's population to infection by schistosomiasis, and to contribute knowledge on the consequences of this disease. The study was conducted in the cold dry season at the Kou Valley, located in the South Sudanese area of Burkina Faso. It has adopted the strategy of direct observation to examine host-parasites interactions. The study of the socioeconomic consequences of the infection has been first to identify subjects that actually carry the parasite by screening the population by the Kato-Katz method. These were then subjected to a questionnaire. Data were analyzed using Epi Info 6.4. This work has revealed six activities at risk of infection for the residents of the Valley with an increased risk of factor for rice farming, household activities and swimming. In view of these activities, women and young people seem to be most vulnerable to infection. This disease causes significant economic losses as a function of socio-professional categories of infected persons.

Rates and intensity of re-infection with human helminths after treatment and the influence of individual, household, and environmental factors in a Brazilian community.

This study quantifies the rate and intensity of re-infection with human hookworm and Schistosoma mansoni infection 12 months following successful treatment, and investigates the influence of socio-economic, geographical and environmental factors. A longitudinal study of 642 individuals aged over 5 years was conducted in Minas Gerais State, Brazil from June 2004 to March 2006. Risk factors were assessed using interval censored regression for the rate and negative binomial regression for intensity. The crude rate and intensity of hookworm re-infection was 0·21 per year (95% confidence interval (CI) 0·15-0·29) and 70·9 epg (95% CI 47·2-106·6). For S. mansoni the rate was 0·06 per year (95% CI 0·03-0·10) and intensity 6·51 epg (95% CI 3·82-11·11). Rate and intensity of re-infection with hookworm were highest among males and positively associated with previous infection status, absence of a toilet and house structure. Rate and intensity of S. mansoni re-infection were associated with previous infection status as well as geographical, environmental and socio-economic factors. The implications of findings for the design of anti-helminth vaccine trials are discussed.

The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination.

The neglected tropical diseases (NTDs) represent some of the most common infections of the poorest people living in the Latin American and Caribbean region (LAC). Because they primarily afflict the disenfranchised poor as well as selected indigenous populations and people of African descent, the NTDs in LAC are largely forgotten diseases even though their collective disease burden may exceed better known conditions such as of HIV/AIDS, tuberculosis, or malaria. Based on their prevalence and healthy life years lost from disability, hookworm infection, other soil-transmitted helminth infections, and Chagas disease are the most important NTDs in LAC, followed by dengue, schistosomiasis, leishmaniasis, trachoma, leprosy, and lymphatic filariasis. On the other hand, for some important NTDs, such as leptospirosis and cysticercosis, complete disease burden estimates are not available. The NTDs in LAC geographically concentrate in 11 different sub-regions, each with a distinctive human and environmental ecology. In the coming years, schistosomiasis could be eliminated in the Caribbean and transmission of lymphatic filariasis and onchocerciasis could be eliminated in Latin America. However, the highest disease burden NTDs, such as Chagas disease, soil-transmitted helminth infections, and hookworm and schistosomiasis co-infections, may first require scale-up of existing resources or the development of new control tools in order to achieve control or elimination. Ultimately, the roadmap for the control and elimination of the more widespread NTDs will require an inter-sectoral approach that bridges public health, social services, and environmental interventions.

A combined school- and community-based campaign targeting all school-age children of Burkina Faso against schistosomiasis and soil-transmitted helminthiasis: performance, financial costs and implications for sustainability.

A combined school- and community-based campaign targeting the entire school-age population of Burkina Faso with drugs against schistosomiasis (praziquantel) and soil-transmitted helminthiasis (albendazole) was implemented in 2004-2005. In total, 3,322,564 children from 5 to 15 years of age were treated, equivalent to a 90.8% coverage of the total school-age population of the country. The total costs of the campaign were estimated to be US 1,067,284 dollars, of which 69.4% was spent on the drugs. Delivery costs per child treated were US 0.098 dollar, in the same range as school-based only interventions implemented in other countries; total costs per child treated (including drugs) were US 0.32 dollar. We conclude that a combined school- and community-based strategy is effective in attaining a high coverage among school-age children in countries where school enrolment is low and where primary schools cannot serve as the exclusive drug distribution points. The challenge for Burkina Faso will now be to ensure the sustainability of these disease control activities.

Rapid assessment of Schistosoma mansoni: the validity, applicability and cost-effectiveness of the Lot Quality Assurance Sampling method in Uganda.

Rapid and accurate identification of communities at highest risk of morbidity from schistosomiasis is key for sustainable control. Although school questionnaires can effectively and inexpensively identify communities with a high prevalence of Schistosoma haematobium, parasitological screening remains the preferred option for S. mansoni. To help reduce screening costs, we investigated the validity of Lot Quality Assurance Sampling (LQAS) in classifying schools according to categories of S. mansoni prevalence in Uganda, and explored its applicability and cost-effectiveness. First, we evaluated several sampling plans using computer simulation and then field tested one sampling plan in 34 schools in Uganda. Finally, cost-effectiveness of different screening and control strategies (including mass treatment without prior screening) was determined, and sensitivity analysis undertaken to assess the effect of infection levels and treatment costs. In identifying schools with prevalences > or =50%, computer simulations showed that LQAS had high levels of sensitivity and specificity (>90%) at sample sizes <20. The method also provides an ability to classify communities into three prevalence categories. Field testing showed that LQAS where 15 children were sampled had excellent diagnostic performance (sensitivity: 100%, specificity: 96.4%, positive predictive value: 85.7% and negative predictive value: 92.3%). Screening using LQAS was more cost-effective than mass treating all schools (US$218 vs. US$482/high prevalence school treated). Threshold analysis indicated that parasitological screening and mass treatment would become equivalent for settings where prevalence > or =50% in 75% of schools and for treatment costs of US$0.19 per schoolchild. We conclude that, in Uganda, LQAS provides a rapid, valid and cost-effective method for guiding decision makers in allocating finite resources for the control of schistosomiasis.

Evaluation of staff performance and material resources for integrated schistosomiasis control in northern Senegal.

BACKGROUND: A project to improve integrated control of schistosomiasis in the primary health care system of northern Senegal was implemented from February 1995 until September 1999, shortly after a Schistosoma mansoni outbreak. The activities included additional training of doctors and nurses in symptom-based treatment and making praziquantel (PZQ) available for an affordable price. OBJECTIVE: To investigate staff performance and the availability and costs of diagnostic materials and PZQ at the end of this intervention project. METHODS: We performed structured interviews with staff from 55 health care facilities in five districts. RESULTS: Respondents from 23 health care facilities reported both S. haematobium and S. mansoni in the coverage area, 32 reported only S. haematobium and three only S. mansoni. The average cost to patients for consultation, diagnosis, treatment and transportation to a referral health care facility was approximately 1.60 Euro. Fifty-seven per cent of the health care facilities with reported S. haematobium in the coverage area treated patients presenting with haematuria on symptoms; 56% of the health care facilities with reported S. mansoni in the coverage area treated patients presenting with blood in stool on symptoms. Thirteen per cent performed a diagnostic test for patients presenting with haematuria and 12% for patients presenting with blood in stool. The remainder, approximately one-third of the health care facilities, referred their patients to another facility for a diagnostic test. Implementation of symptom-based treatment in all health care facilities will reduce the total costs by 0.43 Euro (29%) for patients infected with S. haematobium and 0.78 Euro (46%) for patients infected with S. mansoni. Of the 53 health care facilities with schistosomiasis in their area, 37 had PZQ in stock of which 33 (88%) sold PZQ for the recommended retail price of 0.15 Euro per tablet (or 0.60 Euro per course of four tablets) or lower. CONCLUSION: Four years after the start of the intervention project, patients presenting with schistosomiasis related symptoms can generally expect proper diagnosis and treatment at all levels of the health care system in Northern Senegal, either at the initial visited health care facility or after referral. However, a further reduction of the total costs of treatment is still possible by a better implementation of symptom-based treatment and further reduction of the costs of PZQ.

A comparative analysis of the cost-effectiveness of treatment based on parasitological and symptomatic screening for Schistosoma mansoni in Burundi.

OBJECTIVES: To assess the cost-effectiveness of three alternative screening strategies in delivering treatment to patients presenting with symptoms suggestive of S. mansoni, using data collected from 17 PHCCs in the Rusizi Plain, Burundi. The three strategies were: (1) screening all symptomatic patients using a Kato-Katz smear and treating only the ones found positive; (2) treating all symptomatic patients or (3) treating only those presenting with symptoms of severe diarrhoea (blood in stool). METHODS: The database consisted of 41 051 visits of symptomatic patients to the 17 PHCCs during 1990. Effectiveness was measured as the number of infected patients treated (gold standard: 25-mg Kato-Katz smear). Cost-effectiveness ratios (CERs) (cost in US$ per infected patient treated) were used to compare the control strategies. Sensitivity analysis was performed to assess the effect of drug price and prevalence of infection on the CERs. RESULTS: The overall prevalence of S. mansoni infection was 9.5% (95% CI = 9.1%, 9.9%). Treating only those with severe symptoms of infection would have left 92% of infected patients untreated. Performing a Kato-Katz smear to confirm the diagnosis was more cost-effective than treating all symptomatic patients on a presumptive basis, with CERs of 4.2 US$ and 12.43 US$ per infected person treated, respectively. Sensitivity analysis showed that, for a cost of 0.99 US$ per dose of praziquantel, the Kato-Katz option remained the most cost-effective approach for prevalences under 76%. For a drug price of 0.21 US$ per dose, both strategies would have become equivalent. The latter value varied extensively per PHCC (range 0.17 US$ to 0.51 US$), due to the different prevalences of infection (range 0.5% to 34.3%). CONCLUSION: We found that using severe diarrhoea as an indicator for infection was not appropriate, and that screening symptomatic patients with the Kato-Katz method remained the most cost-effective approach in the given setting. The CER of treating all symptomatic patients on a presumptive basis depended very much on the drug price and the endemic level.

An investigation into the interaction between drug efficacy and drug price of praziquantel in determining the cost-effectiveness of school-targeted treatment for Schistosoma mansoni using a population dynamic model.

A population dynamic model of schistosome transmission was used to investigate the interaction between drug efficacy and drug price of different brands of praziquantel in determining the cost-effectiveness of school-targeted treatment for Schistosoma mansoni. In this analysis, costs were affected by coverage, drug price and distance travelled, and effectiveness by coverage and drug efficacy. Four effectiveness measures were assessed: the number of infection case-years prevented, heavy infection case-years prevented, hepatomegaly case-years prevented and fibrosis case-years prevented. The interactions between drug efficacy and drug price were complex. In particular, there was a highly nonlinear relationship between drug efficacy and cost-effectiveness, with drugs of low efficacy producing high and variable cost-effectiveness ratios, particularly when other programme costs related to distance travelled were high. The results suggest that given the current price range of praziquantel, a drug with less than a 50% chance of killing the worms is not to be recommended. This has important practical implications for the widespread use of praziquantel, since most international agencies procure praziquantel purely on the basis of price. There is clearly a need for studies which evaluate the efficacy of new brands of praziquantel, and more credence should be given to the use of high efficacy brands, not only in terms of maximizing the cost-effectiveness of the intervention programme, but also in delaying the onset of drug resistance.

Geographical and socioeconomic factors relating to the distribution of Schistosoma mansoni infection in an urban area of north-east Brazil.

A study was carried out in Santo Antonio de Jesus, a town in Bahia State, north-east Brazil, to determine the relationship between various biological, socioeconomic, behavioural, and geographical factors and the prevalence and intensity of Schistosoma mansoni infection. The town's population was around 45,000 and the study was targeted at all children born in 1970-71 who were living in the town at the time of the survey (August-November 1984). An extensive questionnaire was used to collect information on each child and on family and household conditions; samples of stools were also taken for examination (Kato-Katz method). A survey of water snails was also carried out and information on the distribution of their breeding sites was plotted on a map of the area. The overall prevalence of S. mansoni infection was 31.0%. Several variables that reflected different aspects of the population's way of life were strongly associated with the prevalence and the intensity of infection. Some of the findings are valuable for understanding the mechanisms involved in the occurrence of schistosomiasis and its distribution in urban locations as well as for defining high-risk groups, all of which are important for planning control strategies.

Field study of different oxamniquine dose for Schistosoma mansoni in Gezira, Sudan.

Two hundred and ninety-six individuals of whom 126 were children and 170 adults with positive stool for Schistosoma mansoni were randomly given oxamniquine treatment in a dose of either 20, 40 or 60 mg/kg body wt. They were followed in the field for ova excretion at 1, 3 and 6 months for adults and at 1, 3, 6 and 8 months for children. The cure rates in adults at 6 months are 93%, 87% and 73% for the 60, 40, 20 mg/kg-1 treatments in order. For children the cure rates at 6 months are 36%, 58% and 63% and at 8 months are 16%, 21% and 26% for corresponding doses. There is no difference in egg reduction for those not cured between the three treatments at 6 months. It is concluded that oxamniquine need not be given in the previously recommended 60 mg/kg body wt. A choice between 40 and 20 mg/kg body wt is suggested with the 40 mg/kg body wt to be reserved for individuals leaving the endemic area, and the 20 mg/kg body wt for those continuing to stay there with substantial exposure for reinfection. The overall proper cure rates for children with a possible advantage of the low treatment in the long term for this age group is noted.

The costs of schistosomiasis control in a Sahelian country.

The cost of schistosomiasis control in Mali was calculated on the assumption that the programme is fully nationalized and organized using the experience gained during the past seven years. In order to expand the model and to extrapolate from actual cost that arose, activities have been standardized into preparatory, baseline and follow-up sample surveys for monitoring purposes and into blanket and case mass chemotherapy for interventions. Health education is contained in them as a component, sanitation is seen as a standard item linked at a fixed cost to the duration of the intervention phase. These activities were divided into months of action and their unit cost was calculated on the basis of requirements of field allowances, transport, drugs, expendable materials, and equipment. Fixed operational costs were calculated on a yearly basis for salaries, data processing and administrative overheads. Using these unit costs, and on the basis of present knowledge of the prevalence, epidemiology and efficiency of control, the need and quantity of activities and the probable duration of a programme to achieve the goals set in the national health plan were estimated. If a population of 180,000 persons in about 300 villages is to be included in a programme that has as target to diminish the prevalence of both, Schistosoma haematobium and S. mansoni to less than 20% and that plans to diminish the prevalence of intensive infections of both parasites to less than 5%, a total amount of DM 6.9 to 7.5 million over a period of seven to nine years are required.(ABSTRACT TRUNCATED AT 250 WORDS)

[Schistosomiasis mansoni: dynamics of transmission]. / Esquistossomose mansónica: dinámica da transmissão.

The following remarks were addressed at the round table that discussed the alternative approaches to schistosomiasis control. The address begins with a short analysis of the progressive spread of the area of distribution of the disease, and of the difficulties faced by those in charge of control programs, conventional or otherwise. A model was sketched, taking into consideration the distinct classes of factors involved in the dynamics of transmission: biological, immunological, ecological, socio-cultural, and economical. The true significance and pertinence of such a model was analysed, and the relevant questions that must be answered before a true representative model can be constructed, were listed.

Schistosomiasis in a mining area: intersectoral implications.

The high prevalence (greater than 90%) and intensity of infection (50% of those infected excreted greater than 600 eggs per gram of faeces) of schistosomiasis in a tin mining area in eastern Zaire is related to extensive man-made ecological changes and intensive man/water contact. Construction of latrines, water supply and availability of diagnosis and treatment through occupational health services have been used in control efforts. The integration of environmental measures is limited by their high costs. The control of schistosomiasis in this area of intense transmission would require repetitive chemotherapy and other measures which are beyond available resources.