THE EFFECT OF HOOKWORM INFECTION AND URINARY SCHISTOSOMIASIS ON BLOOD HEMOGLOBIN CONCENTRATION OF SCHOOLCHILDREN LIVING IN NORTHERN MOZAMBIQUE

This study aims to assess the association between schistosomiasis and hookworm infection with hemoglobin levels of schoolchildren in northern Mozambique. Through a cross-sectional survey, 1,015 children from five to 12 years old in the provinces of Nampula, Cabo Delgado and Niassa were studied. Hookworm infection and urinary schistosomiasis were diagnosed, through Ritchie and filtration methods, with a prevalence of 31.3% and 59.1%, respectively. Hemoglobin levels were obtained with a portable photometer (Hemocue^®). The average hemoglobin concentration was 10.8 ± 1.42 g/dL, and 62.1% of the children presented levels below 11.5 g/dL, of which 11.8% of the total number of children had hemoglobin levels below 9 g/dL. A multiple linear regression analysis demonstrated negative interactions between hemoglobin levels and ancylostomiasis, this being restricted to the province of Cabo Delgado (β = -0.55; p < 0.001) where an independent interaction between hemoglobin levels and urinary schistosomiasis was also observed (β = -0.35; p = 0.016). The logistical regression model indicated that hookworm infection represents a predictor of mild (OR = 1.87; 95% CI = 1.17-3.00) and moderate/severe anemia (OR = 2.71; 95% CI = 1.50 - 4.89). We concluded that, in the province of Cabo Delgado, hookworm and Schistosoma haematobium infections negatively influence hemoglobin levels in schoolchildren. Periodical deworming should be considered in the region. Health education and improvements in sanitary infrastructure could achieve long-term and sustainable reductions in soil-transmitted helminthiases and schistosomiasis prevalence rates.     

Perceived illness drives participation in mass deworming campaigns in Laos

Multiple helminth infections are very common in communities of southern Laos. Preventive chemotherapy in combination with health education is the mainstay of control. We assessed the knowledge, perceptions and practices of rural communities related to endemic helminthiasis and their control during a mass drug administration (MDA) campaign. Short interviews with household heads (n = 192), direct observations and discussions with attendees of MDAs, and in-depth interviews with local opinion leaders (n = 21) were carried out. Quantitative and qualitative data analysis was performed. Results showed that opinion leaders and villagers were well aware of the importance of attending MDA. Leaders perceived the effectiveness of MDA against severe schistosomiasis and appreciated that it was provided for free and in their village. They encouraged villagers to attend it. Anticipated adverse events of praziquantel was a barrier for participation. A majority of leaders purchased deworming tablet (mebendazole, albendazole) in a local pharmacy for deworming when MDA is absent in their villages (19/21). Most leaders (20/21) had a good knowledge on severe schistosomiasis though only a few of them (5/21) described its cause correctly. They knew little about the disease consequences of liver fluke (3/21) and soil-transmitted helminth (4/21) infections but more about their causes. A high risk for worm infection was observed: consumption of raw or insufficiently cooked fish (100%), frequent physical contacts with Mekong River water (76.0%) and low number of latrines (14.5%). In conclusion, MDA is widely accepted in affected communities. Avoiding severe schistosomiasis was the main motivation to comply. Participation rates increased significantly with drugs provided free of charge in the villages. Better knowledge on the consequences of worm infections and on its modes of transmission will foster the distribution and acceptance of appropriate preventive treatment and other measures in helminth-endemic communities. Where multiple infections require several drugs for MDA, preceding health education and information about MDA and its benefits are a prior condition.     

Emergence of infections with Schistosoma mansoni in the Dhofar Governorate, Oman

Infections with Schistosoma mansoni were identified in an area of Dhofar (Oman), where this parasite had been virtually absent during recent years and was reported only very sporadically before 1992. In the present survey, performed late in 2001, between 1 and 13% of children (n=519) were found to excrete eggs (one Kato-Katz-smear) in four schools, from four different villages, but no infections were detected in additional five schools (n=281). Infections were light (<72 eggs/g of faeces) in 19 of the 36 children found infected. Serologic examination of sera (n=511) was done by ELISA (based on soluble worm antigen) and immunofluorescence tests (IFT, based on cryostat sections of adult S. mansoni). The prevalence according to serological tests was between 3 and 43% in the four schools with infected children. Positive test results were taken to reflect active infections, since false positive reactions could largely be excluded. According to ultrasound (US) examinations performed on 96 individuals (children and adults) from the four villages, livers were normal in all except three cases of mild pathology, which could be assigned to schistosomiasis mansoni (pattern C, ages 32-40 years). All data suggest that transmission of S. mansoni has been re-introduced only recently in Dhofar and that this emergence of schistosomiasis is limited to at most a few foci.     

Sequential analysis of helminth egg output in human stool samples following albendazole and praziquantel administration

Large-scale administration of anthelminthic drugs currently is the most widely used intervention for controlling morbidity due to schistosomiasis and soil-transmitted helminthiasis. An important issue is drug efficacy monitoring. However, the optimal time points post-treatment for assessing the efficacy of praziquantel against Schistosoma mansoni and albendazole against hookworm infections are not known. Forty-nine schoolchildren infected with S. mansoni and 52 infected with hookworm were treated with a single oral dose of praziquantel (40 mg/kg) and albendazole (400 mg), respectively. Stool samples were collected on 19 occasions over a 44-day post-treatment follow-up period, and two Kato-Katz thick smears per sample were examined at each time point. Both the mean egg counts and observed cure rates varied depending on the time point post-treatment. The highest reduction in the geometric mean egg counts (>97%) and the highest observed cure rate (>97%) of S. mansoni infections were found 15-20 days after praziquantel administration. Among the hookworm-infected children, egg counts decreased rapidly within the first week after albendazole administration (>95%), whereas infection rates showed high and heterogeneous (45.0-71.2%) levels at later time points. Both praziquantel and albendazole were highly efficacious in reducing the overall egg burden of S. mansoni and hookworm, respectively. We suggest that 15-20 days post-treatment is the most appropriate time point for efficacy evaluation of praziquantel against S. mansoni. Although no clear conclusion can be drawn for the optimal timing of efficacy evaluation of albendazole against hookworm, a 2-3-week time frame seems a reasonable compromise. This is justified on logistical grounds (i.e. collection of stool samples only once) and growing emphasis on integrating the control of schistosomiasis and soil-transmitted helminthiasis, including drug efficacy monitoring.     

Micro-epidemiology of urinary schistosomiasis in Zanzibar: Local risk factors associated with distribution of infections among schoolchildren and relevance for control

Although it is well recognised that both behavioural and environmental factors play a role in determining small-scale heterogeneities in schistosomiasis transmission, empirical evidence of their relative importance is often limited. A study was conducted around Chaani, a village in northern Unguja (Zanzibar) where urinary schistosomiasis is endemic, in order to shed light upon the micro-epidemiology of Schistosoma haematobium and patterns of infection within schoolchildren and the intermediate host snail Bulinus globosus, that may help in adjusting recently implemented control programmes. Malacological surveys were conducted to identify transmission foci and questionnaires were devised to assess recalled water-contact patterns of 150 schoolchildren who had been screened for S. haematobium infection, finding an overall prevalence of 50.6%. Boys were more frequently and more heavily infected than girls and, accordingly, mean exposure scores were significantly higher for boys than girls. Univariate statistics revealed significant associations between infection and specific water-contact activities, including washing/bathing (odds ratio [OR]=3.01, 95% confidence interval [CI]=1.36-6.67) and playing (OR=4.03, 95% CI=1.51-10.70) in streams/ponds. In multivariate analysis, however, the strongest predictor of infection was proximity of the child's home to a site harbouring S. haematobium-infected B. globosus (P<0.001), suggesting that geography may be a better proxy for exposure than self-reported water contact. Surveillance programmes may therefore wish to prioritise evaluation of environmental risk to pinpoint transmission at the micro-geographical level, although water-contact questionnaires are also recommended as a complementary tool to rapidly identify the behaviour patterns of children at most risk of infection in the rural communities of Zanzibar. Such knowledge is a prerequisite for focusing and improving schistosomiasis control at the local level.     

From morbidity control to transmission control: time to change tactics against helminths on Unguja Island,Zanzibar

In Zanzibar, the prevalence and intensity of helminth infections have markedly declined over the past 25 years, which is generally attributed to morbidity control programmes emphasising ‘preventive chemotherapy’. Here we provide an update of the current situation of soil-transmitted helminthiasis and urinary schistosomiasis on Unguja Island, and highlight socioeconomic development, improvement in sanitation and health education as additional drivers against helminthiases. Our data were obtained from cross-sectional surveys carried out between 2006 and 2009 with stool and urine samples from 2858 and 879 individuals, respectively, examined for helminth eggs and larvae. Additionally, several hundred people were interviewed on sanitation and hygienic behaviour. Data on Unguja's economic growth and improvements in access to clean water and household latrines in the recent past were derived from the extant literature. Pooled prevalences of Trichuris trichiura, Schistosoma haematobium, Ascaris lumbricoides, hookworm and Strongyloides stercoralis were 35%, 29%, 12%, 10% and 6%, respectively. However, there were considerable differences in prevalences between different age-groups and at village and district level. Moreover, some hotspots for A. lumbricoides, T. trichiura and S. haematobium were identified with prevalences above 60% among school-aged children. Availability of a latrine and washing hands before eating did not significantly lower the risk of helminth infections in our study population. Nevertheless, a considerable increase in access to household latrines (from 49% to 72%) and piped water (from 45% to 71%) between 1991 and 2005 is likely to have contributed to reducing the force of transmission of helminthiases in Zanzibar. The next logical step in Unguja is to change the tactics from morbidity control to interruption of helminth transmission and ultimately local elimination. Hence, ‘preventive chemotherapy’ needs to be further consolidated, placing particular emphasis on health education and improved access to clean water and sanitation.     

Helminth infections and risk factor analysis among residents in Eryuan county, Yunnan province, China

Whilst infections with soil-transmitted helminths are common across China, the public-health significance of Schistosoma japonicum and food-borne helminths is more focalized. Only few studies have investigated the local epidemiology of helminth infections in rural China, including risk factor analysis. We collected stool and blood samples from 3220 individuals, aged 5-88 years, from 35 randomly selected villages in Eryuan county, Yunnan province, China. Stool samples were subjected to the Kato-Katz technique and examined for helminth eggs. Blood samples were tested for Trichinella spp., S. japonicum and cysticerci-specific antibodies. Data on individual and family-level risk factors were collected using questionnaires. The prevalence of Ascaris lumbricoides, Taenia spp., Trichuris trichiura and hookworms was 15.4%, 3.5%, 1.7% and 0.3%, respectively. The seroprevalence of Trichinella spp. was 58.8% and that of cysticercosis 18.5%. The egg positivity rate of S. japonicum in the 13 known endemic villages was 2.7%, and the corresponding seroprevalence was 49.5%. We observed a strong spatial heterogeneity in the families' economic status. S. japonicum infections were more prevalent among the Han than Bai nationality (odds ratio (OR)=3.77, 95% confidence interval (CI)=1.97-7.23) and tobacco growers (OR=3.66, 95% CI=1.77-7.60) and was only found at elevations below 2150 m above sea level. A. lumbricoides and Taenia spp. infections were more prevalent at altitudes above 2150 m when compared to lower settings (OR=1.51, 95% CI=1.24-1.84 and OR=5.32, 95% CI=3.42-8.28, respectively). The opposite was found for T. trichiura (OR=0.31, 95% CI=0.14-0.70). Our findings can guide the design and spatial targeting of control interventions against helminth infections in Eryuan county.     

Use of circulating cathodic antigen (CCA) dipsticks for detection of intestinal and urinary schistosomiasis

An evaluation of a commercially available antigen capture dipstick that detects schistosome circulating cathodic antigen (CCA) in urine was conducted in representative endemic areas for intestinal and urinary schistosomiasis in Uganda and Zanzibar, respectively. Under field-based conditions, the sensitivity (SS) and specificity (SP) of the dipstick was 83 and 81% for detection of Schistosoma mansoni infections while positive predictive (PPV) and negative predictive values (NPV) were 84%. Light egg-positive infections were sometimes CCA-negative while CCA-positives included egg-negative children. A positive association between faecal egg output and intensity of CCA test band was observed. Estimating prevalence of intestinal schistosomiasis by school with dipsticks was highly correlated (r=0.95) with Kato-Katz stool examinations, typically within +/-8.5%. In Zanzibar, however, dipsticks totally failed to detect S. haematobium despite examining children with egg-patent schistosomiasis. This was also later corroborated by further surveys in Niger and Burkina Faso. Laboratory testing of dipsticks with aqueous adult worm lysates from several reference species showed correct functioning, however, dipsticks failed to detect CCA in urine from S. haematobium-infected hamsters. While CCA dipsticks are a good alternative, or complement, to stool microscopy for field diagnosis of intestinal schistosomiasis, they have no proven value for field diagnosis of urinary schistosomiasis. At approximately 2.6 US dollars per dipstick, they are presently too expensive to be cost-effective for wide scale use in disease mapping surveys unless Lot Quality Assurance Sampling (LQAS) strategies are developed.     

Soil-transmitted helminth egg contamination from soil of indigenous communities in selected barangays in Tigaon,Camarines Sur,Philippines

Objective: To provide baseline data on the prevalence and intensity of soil-transmitted helminthiasis egg contamination in the soil among indigenous communities.Methods: A total of 317 soil samples from three barangays of indigenous communities communities in Tigaon, Camarines Sur, Philippines were examined for soil-transmitted helminthiasis egg contamination using optimized sugar flotation method.Results: Of the soil samples examined, 141(44.48%) were contaminated by Ascaris spp., Toxocara spp., and Trichuris spp. with cumulative prevalence varying across the study sites(P0.01). Ascaris spp. was predominant in all study sites, followed by Toxocara spp. and Trichuris spp. with a prevalence of 41.96%, 7.57%, and 5.36%, respectively. Interestingly, Toxocara pp. has the highest intensity of contamination, followed by Ascaris spp. and Trichuris spp. in term of geometric mean soil-transmitted helminthiasis eggs recovered per one gram soil sample(34.25, 21.45, and 11.85 respectively). Each study site harbors significant amount of soiltransmitted helminthiasis eggs and zoonotic Toxocara eggs, which present high risk of soil-transmitted helminthiasis infection, particularly among children observed to play and cohabitate with animals known to be hosts of these parasites. Conclusions: The alarming rate of soil-transmitted helminthiasis and Toxocara egg contamination reported in this study suggests that additional measures should be undertaken to control soil-transmitted helminthiasis and zoonotic intestinal infections in the country.     

Changing patterns of forest malaria among the mobile adult male population in Chumkiri District, Cambodia

Forest malaria remains a major problem in many parts of Southeast Asia and South America. In Cambodia, where a significant reduction of malaria morbidity and mortality has been observed in the last 20 years, the forest malaria situation was studied in Chumkiri District by analysing the available passive case detection data and conducting malariometric (n=1018) and questionnaire surveys (n=374) in four forest-fringe villages. There has been a decreasing trend of malaria incidence from 2001. Plasmodium falciparum was highly predominant and P. vivax was rare. The nearby-forest villages showed significantly higher parasite rates than the far-from-forest villages (9.0% vs. 1.2%, p<0.01). Malaria was highly restricted to the male adults but was nearly non-existent in other accompanying family members, including small children and females. Low income and working in forests were strongly associated with the malaria risk. Our results suggest that transmission has greatly reduced in forest-fringe villages, but remains active in forests, which is primarily maintained between the forest vector Anopheles dirus and ethnic minority inhabitants. Specific interventions directed to these previously neglected in-forest inhabitants to protect themselves and male adult villagers during their forest activities are necessary to achieve an ultimate goal of malaria elimination from Cambodia.     

Integrated control programmes for schistosomiasis and other helminth infections in P.R. China

The prevalence of human schistosomiasis and soil-transmitted helminthiasis (STH) has decreased significantly in the People's Republic of China (P.R. China), particularly after 2005 when the national control programmes were reinforced by forming of integrated control strategies. Furthermore, social-economic development also contributed to the decrease of schistosome and soil-transmitted helminth infections. The prevalence of the zoonotic helminthiasis, including clonorchiasis and echinococcosis, on the other hand, is either underestimated or has in fact increased due to changes in social and environmental factors. In comparison with the control strategies in force and their effects on those four kinds of helminthiasis, the challenges and control priorities for the potential transfer from control to elimination of each disease is reviewed, to provide evidence for policy-makers to act upon.     

Efficacy of artesunate and praziquantel in Schistosoma haematobium infected schoolchildren

Praziquantel is the current mainstay for morbidity control of schistosomiasis. Artemisinin and its derivatives, widely used for the treatment of malaria, also display antischistosomal properties. The present study is an effort to assess the therapeutic efficacy of artesunate, an artemisinin derivative, in Schistosoma haematobium infections in a human population. The efficacy of artesunate and praziquantel were comparatively studied in primary schoolchildren from two villages, Lampsar (n=180) and Makhana (n=108), located along the Lampsar river in the delta of the Senegal River Basin in Northern Senegal (West Africa). In each village, half of the infected children were treated with a single oral dose of 40 mg/kg praziquantel and half with artesunate following the recommended malaria monotherapy regimen. For both drugs, cure and egg count reduction rates were, without apparent explanation, higher in Makhana than in Lampsar. In both villages, high and nearly comparable egg count reduction rates were obtained with both drugs at each follow-up after treatment (5, 12 and 24 weeks) in the heavy infected group of children (>50 eggs/10 ml of urine). No major adverse effects were observed. The results demonstrate that artesunate is effective against S. haematobium, but the results obtained with praziquantel were consistently better.     

An evaluation of urine-CCA strip test and fingerprick blood SEA-ELISA for detection of urinary schistosomiasis in schoolchildren in Zanzibar

To develop better monitoring protocols for detection of urinary schistosomiasis during ongoing control interventions, two commercially available diagnostic tests - the urine-circulating cathodic antigen (CCA) strip and the soluble egg antigen enzyme-linked immunosorbent assay (SEA-ELISA) - were evaluated for detection of Schistosoma haematobium infections in 150 schoolchildren from Zanzibar. The children originated from five primary schools representative of different levels of disease endemicity across the island; using standard urine filtration assessment with microscopy, mean prevalence of S. haematobium was 30.7% (95% confidence interval (CI) = 23.4-38.7%) and a total of 35.3% (95% CI = 27.7-43.5%) and 8.0% (95% CI = 4.2-13.6%) children presented with micro- and macro-haematuria, respectively. Diagnostic scores of the urine-CCA strip were not satisfactory, a very poor sensitivity of 9% (95% CI = 2-21%) was observed, precluding any further consideration. By contrast, the performance of the SEA-ELISA using sera from fingerprick blood was good; a sensitivity of 89% (95% CI = 76-96%), a specificity of 70% (95% CI = 60-79%), a positive predictive value of 57% (95% CI = 45-69%) and a negative predictive value of 90% (95% CI = 86-98%) were found. At the unit of the school, a positive linear association between prevalence inferred from parasitological examination and SEA-ELISA methods was found. The SEA-ELISA holds promise as a complementary field-based method for monitoring infection dynamics in schoolchildren over and above standard parasitological methods.     

Control of soil-transmitted helminthiasis in Yunnan province,People's Republic of China: Experiences and lessons from a 5-year multi-intervention trial

The current global strategy for the control of soil-transmitted helminthiasis emphasises periodic administration of anthelminthic drugs to at-risk populations. However, this approach fails to address the root social and ecological causes of soil-transmitted helminthiasis. For sustainable control, it has been suggested that improvements in water, sanitation and hygiene behaviour are required. We designed a 5-year multi-intervention trial in Menghai county, Yunnan province, People's Republic of China. Three different interventions were implemented, each covering a village inhabited by 200–350 people. The interventions consisted of (i) initial health education at study inception and systematic treatment of all individuals aged ≥2 years once every year with a single dose of albendazole; (ii) initial health education and bi-annual albendazole administration; and (iii) bi-annual treatment coupled with latrine construction at family level and regular health education. Interventions were rigorously implemented for 3 years, whilst the follow-up, which included annual albendazole distribution, lasted for 2 more years. Before the third round of treatment, the prevalence of Ascaris lumbricoides was reduced by only 2.8% in the annual treatment arm, whilst bi-annual deworming combined with latrine construction and health education resulted in a prevalence reduction of 53.3% (p < 0.001). All three control approaches significantly reduced the prevalence of Trichuris trichiura and hookworm, with the highest reductions achieved when chemotherapy was combined with sanitation and health education. The prevalence of T. trichiura remained at 30% and above regardless of the intervention. Only bi-annual treatment combined with latrine construction and health education significantly impacted on the prevalence of Taenia spp., but none of the interventions significantly reduced the prevalence of Strongyloides stercoralis. Our findings support the notion that in high-endemicity areas, sustainable control of soil-transmitted helminth infections necessitates measures to reduce faecal environmental contamination to complement mass drug administration. However, elimination of soil-transmitted helminthiasis will not be achieved in the short run even with a package of interventions, and probably requires improvements in living conditions, changes in hygiene behaviour and more efficacious anthelminthic drugs and treatment regimens.     

Recent urban growth and urinary schistosomiasis in Niamey, Niger

A cluster sample survey was conducted in 1998 in 30 schools to assess the effect of the growth of Niamey during the last decade on a urinary schistosomiasis urban focus described in 1989. Two thousand and forty-two children (11.0 + 0.1 years old) had a urine filtration test and answered a behavioural questionnaire. Snail populations of the sites used by schoolchildren were followed up in 1999. The global prevalence was 15.7% in 1998, as opposed to 23.7% in 1989. The prevalence was very low in schools far from the river and higher in those along the Niger banks, particularly in villages on the periphery of the urban area. Geographical factors were more important than socio-economic ones in explaining the distribution of the disease. Only 46% of the children in Niamey reported water contact; mainly in the river, rarely in pools and the canal. The infection risk was low in pools (RR = 1.6), high in the river (RR = 3.5) and very high in the canal (RR = 12.5). Malacological studies confirmed the location of transmission sites obtained through parasitological studies and the questionnaire. Sixty-one per cent of the children travelled outside Niamey to the hyperendemic surrounding areas. However, these movements did not increase their infection level. The results are discussed in relation to water contact behaviour and Schistosoma haematobium transmission features.     

Praziquantel treatment of school children from single and mixed infection foci of intestinal and urogenital schistosomiasis along the Senegal River Basin: monitoring treatment success and re-infection patterns

Following major water development schemes in the 1980s, schistosomiasis has become a serious parasitic disease of children living in the Senegal River Basin. Both urogenital (Schistosoma haematobium) and intestinal (Schistosoma mansoni) schistosomiasis can be highly prevalent in school-aged children, with many individuals infected with both parasites. In order to investigate the transmission and re-infection dynamics of both parasite species, single and mixed infection foci at three villages (Nder and Temeye; S. mansoni and S. haematobium foci and Guia; S. haematobium focus) were studied. In each focus infected children were identified and selected for a 12-month study involving two treatments with praziquantel (40 mg/kg) three weeks apart at the beginning of the study and again 6 months into the study. Urine and stool samples were examined for schistosome eggs before and at 6 weeks and 6 months after chemotherapy. Prevalence and intensity of infection were recorded for each child at each time point. Before treatment, in all three villages, the prevalence and intensity of infection was extremely high for both S. mansoni (79–100%) and S. haematobium (81–97%). With the first round of chemotherapy sufficient cure rates (CRs) of both species were achieved in all villages (38–96%) with high egg reduction rates (ERRs) (97–99%). The data show that high and rapid re-infection rates occur, especially for S. mansoni, within a six-month period following treatment. Re-infection must be highly linked to ecological and seasonal factors. The persistence of S. mansoni in Nder could raise concern as levels of infection intensity remain high (geometric mean intensity at baseline 653 epg changed to 705 epg at 12 months) after four rounds of chemotherapy. This phenomenon could be explained by extremely rapid re-infection dynamics or a sub-optimal efficacy of praziquantel against S. mansoni in this village. High intensities in mixed infections may influence disease epidemiology and control warranting further studies. The disease situation in the SRB must be monitored closely and new treatment regimes should be designed and implemented to control schistosomiasis in the school-age population.     

Urinary tract lesions due to Schistosoma haematobium infection assessed by ultrasonography in a community based study in Niger

The comparative prevalences of urinary tract lesions in 2 villages where urinary schistosomiasis was endemic and in a control village free from infection were assessed by ultrasonography. Of the 822 residents greater than 4 years of age in the first village (Sébéri) where the prevalence of infection was 57%, 279 were examined by ultrasonography. The prevalence of bladder lesions was 71% in those 5-14 years of age, 57% among adult men, and 24% among women in this endemic village, compared to 10%, 16%, and 6%, respectively, in the control village. Renal lesions were infrequent among adults and there was no significant difference in the rates between Sébéri and the control village. Among children, moderate hydronephrosis was absent in the control village, but was observed in 19% of the boys 5-14 years of age and 2% of the girls 5-14 years of age in Sébéri. Sixty schoolchildren of the second endemic village with urinary egg counts greater than or equal to 100 eggs/10 ml of urine were examined by ultrasonography. The overall prevalence and the severity of bladder lesions in the 2 endemic villages were significantly related to the urinary egg count.     

A national survey of the prevalence of schistosomiasis and soil transmitted helminths in Malaŵi

Background  

Past estimates have put the prevalence of schistosomiasis between 40% and 50% in the Malawi population overall based on studies undertaken ten years or more ago. More recent surveys in known high risk areas find similar levels. However control measures, changing ecology and migration may have led to changes in the prevalence of schistosomiasis in different parts of Malawi. A national schistosomiasis and soil-transmitted helminth (STH) survey was undertaken to measure the distribution, prevalence and intensity of infection in November 2002.     

Schistosomiasis in infants and preschool-aged children: Infection in a single Schistosoma haematobium and a mixed S. haematobium-S. mansoni foci of Niger

The burden of schistosomiasis in infants and preschool-aged children and their mothers is poorly known. We carried out a cross-sectional epidemiological survey in two villages in Niger: Falmado is endemic for Schistosoma haematobium only, whereas a mixed S. haematobium-S. mansoni focus has been reported from Diambala. The survey examined 282 children (149 girls, 133 boys, average age: 2.6 years) and 224 mothers (average age: 30.1 years). For S. haematobium diagnosis, two urine samples obtained on consecutive days were subjected to the standard urine filtration method. Additionally, macro- and microhaematuria were determined. The diagnosis of S. mansoni was based on a single stool sample with duplicate Kato-Katz thick smears. In Diambala, a standardised, pre-tested questionnaire was administered to mothers, which recorded demographic data, treatment history with anthelminthic drugs, household sanitation and water supply, and bathing practices for their children. Prevalence of egg-patent S. haematobium infections among young children and their mothers was respectively 50.5% and 55.6%, in Falmado, and 60.5% and 72.2% in Diambala. The prevalence of S. mansoni infection in Diambala was 43.8% among children and 52.1% in mothers. Mixed egg-patent infections of S. haematobium and S. mansoni were revealed in 28.6% of the children and 37.3% of the mothers. Questionnaire data showed that 69.8% of the children were accompanied by their mothers to schistosomiasis transmission sites before they were 1 year of age, and that three-quarter of the mothers used water directly drawn from the irrigation canals to wash their children. To conclude, a substantive proportion of children below the age of 5 years had egg-patent schistosomiasis, inclusive of co-infection with S. haematobium and S. mansoni. In the context of schistosomiasis control, more attention should be paid on preschool-aged children and women of childbearing age, so that they can benefit from preventive chemotherapy, which in turn might increase effective coverage of those infected.     

Reduced serum concentrations of retinol and alpha-tocopherol and high concentrations of hydroperoxides are associated with community levels of S. mansoni infection and schistosomal periportal fibrosis in Ethiopian school children

To study the relationship between micronutrient malnutrition and schistosomiasis mansoni, a cross-sectional study was undertaken involving 421 schoolchildren (mean age 12.6 years; 333 from schistosomiasis mansoni-endemic villages (Workemado and Sille) and 88 non-endemic controls from Sheno). Prevalence of schistosomiasis mansoni infection in Workemado and Sille was comparable (90.6% versus 95%, respectively), and prevalence of PPF in Workemado was significantly higher than in Sille (7.0% versus 0.6%, P < 0.001). Compared with non-endemic controls, serum retinol concentrations were significantly lower and hydroperoxides were significantly higher in subjects from schistosomiasis mansoni-endemic areas. Furthermore, serum alpha-tocopherol concentrations in subjects from an area with high prevalence of PPF were significantly reduced while the concentrations in subjects from an area with low prevalence of PPF were comparable to the levels found in non-endemic healthy controls. In conclusion, micronutrient malnutrition and oxidative stress are associated with Schistosoma mansoni infection and levels of schistosomal PPF.