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The Centre de Recherche sur les Méningites et les Schistosomes (CERMES) is a research institute depending on the Organisation de Coordination et de Coopération pour la lutte contre les Grandes Endémies - a West African Organization for Public Health - devoted to the studies on schistosomiasis and meningitis. The staff includes 32 persons with 11 scientists and one financial officer. The activities of the CERMES involving schistosomiasis concern three research units: (a) ecology of human and animal schistosomiasis transmission; the CERMES defined the different patterns of schistosomiasis transmission in Niger (involving African dry savana); in this field, we have shown, (i) the existence of important variability in conditions of transmission of S. haematobium and, (ii) natural hybridization between parasitic species of the ruminants (S. bovis and S. curassoni) and genetic interaction between human and animal parasites; (b) definition of morbidity indicators usable for rapid assessment methods, for appraisal of the severity of the disease and for the evaluation of the efficiency of control methods; we have established the correlation between ultrasonographic data and some cheap and simple field indicators; (c) immune response and protective immunity induced by recombinant glutathion S-transferase (Sm28, Sb28 and Sh28) in homologous and heterologous animal models including goats, sheep and non human primates (Erythrocebus patas). In Niger, we participate in all control programs against schistosomiasis to define control strategies, to supervise operations and to participate in their evaluation with external experts. International collaborations constitute a frame including four laboratories in Africa and six laboratories in developed countries (Europe and USA)

The construction of large dams has been shown to increase the prevalence and intensity of human schistosomiasis. However, until now no study had been carried out to assess the impact of such a project in Cote d'Ivoire. For Kossou and Taabo, two large dams which became operational in the 1970s, baseline data are available on schistosomiasis prevalence in the surrounding area before dam construction, so that the changes in schistosomiasis levels can be assessed. We re-evaluated the prevalence of Schistosoma haematobium and S. mansoni in November 1992, by analysing 548 urine and 255 stool samples, respectively, from schoolchildren from five villages around each lake. A marked increase in the overall prevalence of S. haematobium was observed, from 14% to 53% around Lake Kossou and from 0 to 73% around Lake Taabo. Baseline data for S. mansoni are only available for Lake Taabo, where a prevalence of 3% was found in 1979 and where the prevalence in 1992 was still low at 2%. The construction of these two large dams therefore led to little change in S. mansoni prevalence but to a significant increase in that of S. haematobium., Introduction It has been emphasized that the construction of large dams may result in adverse health effects, of which one of the most frequently observed is a significant increase in [...]

The populations of the potential intermediate hosts of Schistosoma mansoni and S. haematobium were studied for a year at transmission sites near three villages in the lower delta of the Senegal River. Biomphalaria pfeifferi, found to be widely distributed and increasingly abundant, appears to be well adapted to the new areas of irrigation (created by the dams at Diama and Manantali) thanks to its ability to withstand changes in temperature and to aestivate. This species is responsible for intense transmission of S. mansoni during the rainy season. In contrast, Bulinus globosus, the species responsible for the transmission of S. haematobium (which occurs during the dry season), had a more limited distribution. The changing distributions of these two snail species appear to be linked to changes in local ecology, themselves the result of the recent programme of water-development in the delta. [ABSTRACT FROM AUTHOR]

Objective To evaluate the impact on schistosomiasis of biennial treatment with praziquantel (PZQ) among school-age children in Burkina Faso, the first country that achieved full national coverage with treatment of more than 90% of the school-age population. Methods A cohort of 1727 schoolchildren (6DS14 years old) was monitored at yearly intervals through a longitudinal survey. Additional groups of schoolchildren were monitored in cross-sectional surveys. Parasitological examinations for Schistosoma haematobium and Schistosoma mansoni were performed, and prevalence and intensity of infection before and after treatment were analysed. Findings Data from the longitudinal cohort show that a single round of PZQ treatment significantly reduced prevalence of S. haematobium infection by 87% (from 59.6% to 7.7%) and intensity of infection by 92.8% (from 94.2 to 6.8 eggs/10 ml of urine) 2 years posttreatment. The impact on infection was also confirmed by a cross-sectional survey 2 years post-treatment. Importantly, the proportion of school-age children with heavy S. haematobium infection decreased from around 25% before treatment to around 2DS3% 2 years post-treatment. Cross-sectional comparison of S. haematobium infection in 7-year-old children in their first year at school, who received treatment through community-based drug delivery, also showed significant reduction in both prevalence (65.9%) and intensity of S. haematobium infection (78.4%) 2 years after single treatment. A significant reduction in S. mansoni infection was also achieved. Conclusion Significant and sustained reduction in S. haematobium infection was achieved by biennial treatment in school-age children in Burkina Faso. This may provide a cost-effective treatment strategy for similar national schistosomiasis control programmes in sub-Saharan Africa. Copyright © 2008 World Health Organization [ABSTRACT FROM AUTHOR]

In many developing countries and especially those in the Indian Ocean, the prevalences of hypertension and obesity have increased markedly over the past decade. In a community-based study set in Antananarivo, the capital of Madagascar, multi-level modelling has now been used to look for associations between blood pressure or body mass index (BMI) and levels of occupation, education and income, among 773 adults. Many (23%) of the subjects had elevated blood pressure (i.e. over 140/90 mmHg). The prevalence of such elevated blood pressure increased with age — with an odds ratio (OR) of 2.16 and a corresponding 95% confidence interval (CI) of 1.81-2.58 for each 10-year increase — but decreased with educational level (high school: OR=0.74; CI=0.41-1.31) and income (fourth quartile: OR=0.66; CI=0.35-1.27). The BMI data indicated that 18.4% of the subjects were underweight, 6.0% were overweight but not obese and 2.4% were obese. Being overweight was directly associated with level of occupation (management level: OR=3.49; CI=1.18-10.29) and income (fourth quartile: OR=3.55; CI=1.48-8.50). Despite the trends, underweight and overweight individuals and cases of elevated blood pressure were found to co-exist in all socio-economic classes. [ABSTRACT FROM AUTHOR]

Discusses the spread of biomphalaria pfeifferi in the Niger River valley, Niger. Implications for the understanding of the transmission of the parasites that cause schistosomiasis in humans; Increase in the number dispersal of the snail in the region; Appearance of biomphalaria in irrigation schemes.

Background: In sub-Saharan Africa, 112 million people are infected with Schistosoma haematobium, with the most intense infections in children 5-15 years old., Methods: We describe a longitudinal epidemiological study that evaluates the relationship between S. haematobium infection and associated morbidity in children before and after the large-scale administration of praziquantel for schistosomiasis and albendazole for soil-transmitted helminths., Results: At baseline, higher intensities of S. haematobium infection were observed in children with anemia and/or severe microhematuria, but there was no apparent association between the risk of undernutrition and intensity of S. haematobium infection. Significant reductions in the prevalence and intensity of S. haematobium infection 1 year after treatment were, however, observed. Children who benefited the most from anthelmintic treatment in terms of increased hemoglobin concentrations were those who had anemia at baseline and those with highly positive microhematuria scores at baseline., Conclusions: This study suggests that even a single round of mass chemotherapy can have a substantial impact on S. haematobium infection and its associated morbidity in children.

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.

Although it is established that the treatment by praziquantel reduces the urinary lesions due to Schistosoma haematobium, the frequency of mass treatment necessary to maintain a low morbidity level remains poorly known. The objective of this work was to study the impact over three years of a single praziquantel mass treatment on schistosomiasis morbidity in two different systems of disease transmission in Niger. The study was performed in 2 villages hyperendemic for schistosomiasis in the South-West of Niger presenting respectively 2 different systems of schistosomiasis transmission: Koutoukalé-Zéno (K Zéno), located close to an irrigated area of the Niger River Valley where the transmission is permanent, and Téguey located along a temporary pond where the transmission is seasonal. After the initial evaluation (1994), we carried out a survey 3 years later (1997) except in K. Zéno where an intermediate evaluation was performed 10 months after the initial survey (1995). Approximately 300 randomised people have been examined as follows: macroscopic examination of urine and reagent sticks for macro- and micro-haematuria, filtration and microscopic examination of urine for Schistosoma eggs, and ultrasound scan of the urinary tract for morbidity. The therapeutic coverage has reached 69.9% in K. Zéno and 78.2% in Téguey. The prevalence of infestation decreased from 74.1% to 56.4 % in K. Zéno (p < 0.001) and from 65.3% to 30.4% in Téguey (p < 0.001) at the end of the 3 years. The prevalence of heavy infestation (eggs > or = 50) went in the same time from 9.9% to 12.8% (p = 0.3) in K. Zéno and from 9.1% to 3.3% in Téguey (p = 0.01). Using ultrasound scan, the prevalence of the bladder lesions reached its previous level in both villages. However the prevalence of hydronephrosis decreased from 21.1% to 3.9% in K. éno (p < 0.001) and from 12.6% to 4.2% in Téguey (p < 0.001). Three years after the single mass treatment, the morbidity did not reach the initial level. The effectiveness of the treatment is better in the pond system where the transmission is seasonal. The lesions of the upper tract decreased more slowly than the bladder lesions, but a long time after the treatment. The re-infestation induced the re-appearance of the bladder lesions sooner than the lesions of the upper tract. The periodicity of the treatment should be variable according to the transmission system. It should occur every 2 years in irrigated areas and could be delayed (3 years) in temporary ponds. The control was beneficial in the pond system and induced a significant reduction of the severe lesions.

The objective of this study was to assess the effect of health education in the control of bilharziasis, as a part of an investigation on anti-urinary bilharziasis campaign in Niger. We carried out a survey in two groups of endemic villages on the Niger, one group of villages where there are health education campaigns (target villages) and a control village (no education campaign). Five hundred and seventy-seven people were interviewed in the area. The bilharziasis project has been the main source of information on bilharziasis of people in the project zone. The awareness of measures to fight against bilharziasis has been moderate. Indeed, 46.6% of people interrogated in the project area couldn't cite any means for containing bilharziasis. In the area of intervention, 41.5% of people interrogated were unaware of the intervention of an intermediate host in the transmission of the urinary bilharziasis. The notion of reinfestation remains little known. Behaviours that favour the illness were ignored by 1/3 of people interrogated in the project area. However, there was an increase in knowledge about the illness in the program zone in comparison with the control area. Despite the increase in knowledge level, changes in behaviour in relation to the illness remained low. Risky behaviour continued in about 2/3 of people interrogated. Only 33% of persons of the project area declared having adopted at least a single good behaviour. Changes of behaviour are slow to take place. Activities of health education must be sustained throughout a long period of time for sustainable profits of control actions to occur.

Of the four species of Bulinus found on Madagascar, three species: B. obtusispira, B. liratus and B. bavayi are endemic while the fourth, B. forskalii, is probably a recent introduction from the African mainland. The evolutionary relationships of these species with Bulinus species from Africa were studied by phylogenetic analysis of DNA sequence variation at two mitochondrial loci: cytochrome oxidase subunit I (COI) and large ribosomal subunit (LSU) or 16S. The observed levels of nucleotide divergence within Bulinus were substantial but may underestimate the true levels as there was evidence of 'saturation' of transitional substitutions at both loci. A putative secondary structure model for the sequenced segment of the 16S was developed. Subsequent phylogenetic analysis using transversional changes only for both loci, showed that there were contrasting levels of divergence within the four species groups. B. obtusispira was consistently placed within the B. africanus group, appearing ancestral to this group and was closest to the basal node within Bulinus. Together with B. bavayi, the two species appear to have been isolated on Madagascar for a long time, contrasting with both B. liratus and B. forskalii that appear more recent colonisers; however, estimate of exact times of divergence is problematic. A PCR-RFLP assay was developed to enable identification and discrimination of B. obtusispira and B. liratus using discriminatory variation within the COI. To enable population genetic analysis within B. obtusispira, microsatellite markers were developed using an enrichment method and 8 primer pairs are reported. Laboratory infection experiments using Madasgacan S. haematobium from the Mahabo area showed that certain populations of B. obtusispira, B. liratus and B. bavayi were compatible.

The infectivity of Schistosoma bovis cercariae administered orally was evaluated in Sahelian goats. Compared to the percutaneous route, a single massive oral dose resulted in a worm burden and in fecal egg excretion reduced by one-half. Surprisingly, tissue egg counts were increased by more than 4-fold. Fecundity of individual female schistosomes was, therefore, markedly increased. When infective doses were administered weekly for 20 wk, both worm and egg burdens were doubled without modification of the individual worm pair fecundity. Repeated oral infections seem to have induced an acquired tolerance toward parasite antigens. These results confirm the epidemiologic relevance of the oral route in a host species inclined to become infected through drinking water rather than percutaneous exposures.

The economic importance of the trematode Schistosoma bovis in African livestock has justified the development of a specific vaccine. Administered preventively to sheep, rSb28GST--the only molecule cloned from S. bovis which has demonstrated vaccine potentialities in goats and cattle--reduced the mean worm burden in vaccinated animals and improved their health status compared with that of non-vaccinated controls. As in goats, but not in bovines, the fecundity of the settled worm pairs was not modified. Therefore, rSb28GST can be proposed as a universal tool for the prevention of clinical disorders engendered by the main schistosome species affecting domestic ruminants in the African continent.

Patas monkeys were twice immunized with a Schistosoma haematobium-derived recombinant glutathione S-transferase (Sh28GST) then challenged with an homologous calibrated challenge. BCG and Freund's Complete Adjuvant (FCA) were used as adjuvants in two distinct protocols. Specific IgG and IgA antibody responses were intense and homogeneous in the animals receiving Sh28GST in the presence of FCA, whereas BCG could only induce moderate and heterogeneous antibody titres. No significant effect on worm burdens was evidenced 36 weeks post-infection in either group of Sh28GST-immunized animals compared to their matched controls receiving an irrelevant protein. Although not significant, 50% reductions in the numbers of eggs located in all tissues (FCA group) and in the urogenital system (BCG group) were noted. Moreover, the total number of excreted eggs was dramatically diminished by 60% and 77% in the BCG and FCA groups, respectively. These reductions reached 75% and 80% in the urines of vaccinated monkeys. Bladder pathology was also reduced in the animals displaying the lowest urinary egg excretions. There was no clear positive or negative correlate between antibody responses and individual levels of protection. Taken as a whole, our results show that Sh28GST was capable of significantly reducing S. haematobium worm fecundity in experimentally infected primates. Although FCA induced higher levels of protection, the efficacy of BCG as an adjuvant appeared sufficient to justify consideration of the future application of this new formulation as a vaccine against human urogenital schistosomosis.

The performance of several indirect screening tests was evaluated during the start-up phase of a urinary schistosomiasis control program in Niger. Urine tests were carried out on a total of 354 children attending 3 primary schools on five consecutive days. Tests included filtration of 10 ml of urine, search for microscopic hematuria using reagent strips, and gross examination of urine. In addition a questionnaire was administered on the first day to identify signs of dysuria and hematuria. Repeat testing had a strong effect on the epidemiological profile of urinary schistosomiasis in the 3 schools. Although day-to-day counts varied greatly, egg excretion could be considered as high in all infected subjects. The screening sensitivity of urine filtration was low when the level of endemicity was moderate (up to 55 p. 100). Microscopic hematuria was common. However the sensitivity of this method was overestimated in comparison with urine filtration alone and use of reagent strips can be inconvenient. Using carefully defined diagnostic criteria, gross examination of urine was as effective as urine filtration and easier to perform. The value of the questionnaire for evaluation of morbidity was low despite relatively good performance of the diagnostic techniques. The children's responses concerning hematuria were not objective and questions concerning dysuria were poorly understood and time-consuming. In the next phase of study, these findings will be validated by ultrasound imaging.

An epidemiological study of human intestinal helminthiasis was conducted during July and August 1995, in the middle west of Madagascar, with 4571 adults and children ranging from six months to 90 years, in 61 communities between Betafo and Miandrivazo. Faecal examination utilising the MIF concentration method revealed that ascariasis was the dominant nematodosis in the middle west with high prevalences in the high-altitude communities. Ascaris lumbricoides prevalences increase among children and women. Interesting more than 50% of the pattern, ascariasis is a public health problem and its association with infant malnutrition is statistically significant. Hookworm infection prevalence is higher in low-altitude communities, it increases among adults. The Trichuris trichiura prevalences were lower than the prevalences of ascariasis and hookworm infection in all of the communities. Important variations of the prevalences of intestinal helminthiasis are observed essentially in relation with climatic conditions.

Cercarial emergence patterns were used to analyse the intraspecific variability within and between nine populations of Schistosoma haematobium collected along a transect line from the north to the South of the Ivory Coast (Africa) and using Bulinus truncatus or Bulinus globosus as intermediate snail hosts. Statistical comparison demonstrated the existence of a chronobiological polymorphism and the existence of three homogeneous groups of S. haematobium isolates with mean shedding times of the cercariae decreasing from the North to the South. The chronobiological variability observed was not correlated with the species of Bulinus (B. truncatus vs. B. globosus) implicated in the parasite transmission but with the climatic and vegetal features of the transmission area. S. haematobium from shaded sites of the forest zone (South) showed cercarial emergence patterns significantly earliest than that of S. haematobium from open sites of the savanna zone (North). Differences in sensitivity to light intensity could characterize the existence of eco-geographical races of S. haematobium one of the forest, the other from the savanna.

Studies on human and murine isolates of Schistosoma mansoni, from Richard-Toll, Senegal, were carried out by isoelectric focusing in polyacrylamide gels. Seven enzyme systems; lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PD), acid phosphatase (AcP), hexokinase (HK), glucose phosphate isomerase (GPI), and phosphoglucomutase (PGM), were used to compare the two isolates. All systems tested, apart from LDH, were found to be polymorphic for both isolates. Interestingly, one phenotype is more frequent than the remainder. The results show that there is no significant genetic variation between the S. mansoni isolates from man and the rodents, Arvicanthis niloticus and Mastomys huberti.

Characterization of schistosome populations from human in eastern Niger, through intra-uterine egg morphology of female parasites and phenotopic analyses of worms observed for acid phosphatase using electrophoretic separation, renders results that suggest an intogression of S. haematobium from man by genes of S. bovis, a parasite of domestic livestock. The origin of this introgression, that could implicate S. curassoni as well, another livestock parasite that hybridize with S. bovis, is discussed.

The relationship between iron status and degree of infection by Schistosoma haematobium was studied in 174 schoolchildren from Niger in an area endemic for urinary schistosomiasis. Iron deficiency was defined by a combination of three reliable indicators: a low serum ferritin level combined with a low transferrin saturation, a high erythrocyte protoporphyrin level, or both. Hematuria and proteinuria were found in 76.4% and 79.9% of the children, respectively, while 95.4% excreted eggs (geometric mean egg count of 31.5 eggs per 10 ml of urine). Anemia was observed in 59.7% of the subjects. The prevalence of iron deficiency was 47.1%. Anemia was associated with iron deficiency in 57.7% of the cases. The hemoglobin level and transferrin saturation decreased significantly when the degree of hematuria increased, while prevalence of anemia and prevalence of iron deficiency increased significantly. The hemoglobin level and the hematocrit were negatively correlated with egg count, while prevalence of anemia increased with increasing egg count. This inverse relationship between degree of infection by S. haematobium and iron status shows a deleterious consequence of urinary schistosomiasis on nutrition and hematopoietic status, which should be considered in the design of nutrition intervention programs.

The 28-kDa glutathione S-transferase from Schistosoma mansoni (Sm28GST) is a candidate vaccine antigen. To evaluate the antigenic and phylogenetic variations between the 28-kDa GSTs from 4 species of schistosome, we have cloned and sequenced the 28-kDa GSTs from Schistosoma haematobium (Sh28GST) and Schistosoma bovis (Sb28GST). Sb28GST and Sh28GST are more similar to each other (97%) than to Sm28GST (90%) and particularly to the 28-kDa GST from Schistosoma japonicum (Sj28GST, 77%). Antisera directed against the major Sm28GST epitopes revealed differences in the recognition of the 28-kDa GSTs from the other schistosome species suggesting that these regions have been subjected to evolutionary pressure. The consequences of such species-specific epitopes on the development of a multi-species anti-schistosome vaccine are discussed.

The host-parasite relationships of a Schistosoma haematobium isolate, originating from Niger, and the white mouse are described. Swiss OF1 albino mice were exposed individually to 200 cercariae and worms were recovered 9, 12, 16 and 20 weeks post infection. The mean worm returns ranged between 10.54 and 13.05% and did not alter significantly between 9 and 20 weeks post infection. The sex ratio of worms was always in favour of males; from 7.09:1 at 9 weeks after infection it decreased regularly to 3.28:1 at 20 weeks. Male worms reached a mean length of 8.72 mm at 20 weeks. From the 12th week post infection, a high number of eggs was found in the liver and gut. At 20 weeks, eggs were also found in the bladder. Viable eggs and infective miracidia were obtained. The infection of Bulinus truncatus from Niger succeeded with a mean rate of 61% after the first passage through mice. The isolate of S. haematobium was maintained in the laboratory during 3 successive passages through mice. These entirely new results are very probably linked to genetic characteristics peculiar to the S. haematobium populations from Niger.

A comparative study on the extent of urinary tract abnormalities detected by ultrasound was conducted in two villages in an irrigated area of Niger where the pretreatment prevalences were 64.3% and 58.8% respectively. Fewer bladder lesions (20% of abnormalities) and fewer renal lesions (6% of abnormalities) were observed after four consecutive years of follow-up and treatment with praziquantel in the study village as compared to the control village where 54% bladder abnormalities and 36% renal abnormalities were observed. This study suggests that morbidity due to Schistosoma haematobium infection can be reduced by annual treatment over several years in a highly endemic area without other associated interventions.

A populational study of the compatibility between Schistosoma haematobium and its potential vectors has been carried out in the Niger, confronting samples of S. haematobium populations from three epidemiologic foci with Bulinus populations originating from the same focus (sympatric infection) and with Bulinus populations from other foci (allopatric infections). The three transmission foci selected were irrigation canals in ricefields along the Niger river where one finds: Bulinus truncatus rohlfsi, Bulinus globosus, Bulinus forskalii and Bulinus senegalensis; temporary pools in the Sahel area where one finds B. truncatus and B. senegalensis; permanent pools of the "guelta" type in Sahara area where only B. truncatus occurs. As a compatibility test, the snail infection test was selected, with particular emphasis on optimising its reliability. Snail-infection experiments showed that B. truncatus and B. senegalensis are very good potential vectors, with infection rates ranging between 71.5 and 85.9%. B. globosus and B. forskalii, on the other hand, are totally incompatible. The mean infection percentages in the sympatric and allopatric combinations carried out with the S. haematobium-B. truncatus couple were very similar. This character strongly suggests a lack of isolation in schistosome populations and a circulation of the parasite genome through the mobility of infected human populations (Peuls and Touaregs) in Sahel zone. This study, in relation with snail surveys carried out in parallel, shows that the main types of aquatic environments on the Niger act as high risk areas for schistosome transmission.

In two villages of the Aïr (Republic of Niger) the authors have found a Schistosoma haematobium overall prevalence of 24.1% at Timia and 43.5% at El Meki. At El Meki, the distribution of prevalences by age group accords to that which is usually found. The maximum is found in the 5-14 years age group and highest in men than in women. At Timia, the prevalence among young pupils is low, this seems to be due to the application of sanitary education measures. At El Meki, Bulinus truncatus rohlfsi, present in a permanent pool ("guelta") is the intermediate host of schistosomes. The role of this snail in the transmission of urinary schistosomiasis at Timia has not been demonstrated. The role of Bulinus senegalensis, found in both villages has yet to be proved.

The authors present the results of a survey with ultrasonography conducted to evaluate the prevalence of hepatic fibrosis as a complication of infection by Schistosoma mansoni. Because of the specific images it yields, ultrasonography appears to be highly valuable for the diagnosis of Symmer's fibrosis. It allows the assessment of morbidity from Schistosoma mansoni, which has previously only been performed indirectly by physical examination.

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.

In this study, dip-stick examination for the detection of hematuria and proteinuria, and macroscopic examination of the urine as diagnostic methods for mass screening for urinary schistosomiasis, were compared with the technique of urinary filtration for Schistosoma haematobium eggs. Dip-sticks and macroscopic examination were proved to be simple and rapid. Before treatment, the revealing of hematuria by dip-stick was shown to be a sensitive method by comparison with filtration, but it is not specific. The tests for proteinuria, and macroscopic examination are more specific, but less sensitive. Nevertheless, all these methods give similar prevalences as distributed by age groups. Dip-sticks and macroscopic exams could therefore be duly considered for the detection of new high endemic regions. After treatment, these methods result in less valid prevalences than those obtained by filtration, but their specificity increases; they become good indicators of clinical improvement.

Among the chemicals which might be used against the larvas of Schistosoma, some surface active substances show some high activity at very low concentrations (0,1-5 ppm) against the miracidiums and the cercariae. The laurylamidopropylbetain has shown out of a group of products which were tested, a very high activity by lowering considerably the infection by the larvas of the hosts, like molluscs and mice, which were in contact with them. After a serie of tests made in Nigeria, these products showed a satisfactory remanence in tropical waters, in spite of the biodegradation and the adsorption on the suspended particles. It was faced to put that betain into soaps at a concentration of 5% which will permit to renew constantly the active product and which will reduce heavily any infection.

In a dry savanna village in Upper-Volta, after mass treatment with metrifonate (four doses of 7,5 mg/kg at three weeks intervals) checking of the population was carried out for the three following years. In children and adolescents, results show a progressive decline in the cure rate (69.0% one year after treatment, 38.1% three years after treatment) and in egg-output reduction (69.9% one year after treatment, 75.4% three years after treatment). In adults, these two parameters still remain high three years after treatment (90.0% for cure rate and 87.3% for egg-output reduction). The authors point out that in a dry savanna village with a sedentary population and a transmission limited to a small collection of water, chemotherapy even employed alone is an appreciable control method to relieve populations.

The metrifonate standard cure consisted of three doses of 7.5 to 10 mg/kg at a fortnight interval. These repeated doses increase the total cost of the treatment and the number of incomplete cures. We wanted to verify whether a reduced cure gets still a good efficacy. 286 people from three villages situated near Niamey (Niger) where treated at random with either 1, 2 or 3 doses of 10 mg/kg metrifonate. Before treatment the mean egg-output was 40 eggs/10 ml; 4 months later the cure rate was different only between the 1 dose trial and the 3 doses one. Moreover, this rate is low (35.3%) and the mean egg-output is also low (40.3%) for one dose. These results are more significant according to the first mean egg-output level. Below 5 eggs/10 ml, the cure rate is good with 2 or 3 doses (62% and 70%, 4 months later treatment), between 6 and 50 eggs/10 ml the results are still acceptable (55 and 53%). On the other hand, above 50 eggs these results are insufficient even with 3 doses. The single dose does not give sufficient result even in low egg-output.

Twenty-seven patients with proved urinary schistosomiasis and echographic bladder lesions were selected for cystoscopic examination and biopsy. All patients had specific lesions at cystoscopic investigation. Histologic examination confirmed diagnosis 26/27 cases. Ultrasonography appears as a very efficient method for detection of schistosomiasis bladder pseudo-tumors.

A simple method, using urine collectors, was devised to obtain sufficient and reliable samples of urine from infants (0-4 years old) for the quantitative diagnosis of urinary schistosomiasis. The use of urine collectors is readily accepted by rural populations and it avoids possible interchange between young children. Urine collection and examination from as many as 100 infants can be undertaken daily by a small, well-trained survey team. Our present observations on S. haematobium among infants in Niger show surprisingly high (14.06 per cent) prevalence rates and suggest that this age group may play a considerable role in the transmission of the infection in some endemic foci.