Prevalence of schistosomiasis and soil-transmitted helminth infections among schoolchildren in Burkina Faso.

To determine the current status of schistosomiasis and soil-transmitted helminth (STH) infections among schoolchildren after 10 years of mass treatment with praziquantel. Parasitological surveys were conducted in 2013 in 22 primary schools located in 11 regions of Burkina Faso. Urine filtration methods and Kato-Katz techniques for stool were used to detect the eggs of Schistosoma hæmatobium, Schistosoma mansoni, and STH. 3514 schoolchildren aged from 7 to 11 (1.415 ± 9) years participated in the study. The prevalence of S. hæmatobium was 8.1% and of S. mansoni, 1.2%. The prevalence of intestinal schistosomiasis ranged from 0.6% to 26.2% and that of urinary schistosomiasis from 0.6% to 56.2%. The prevalence of hookworms was 1.1%, Ascaris lumbricoides 0.1%, and Trichuris trichiura 0.06%. The arithmetic mean of S. hæmatobium and S. mansoni were respectively 6 eggs/10 mL and 1.07 epg (eggs per gram). The arithmetic means of eggs were 0.07 epg, 0.03 epg, and 1.89 epg respectively for A. lumbricoides, T. trichiura, and Ankylostoma spp. This study shows the current situation for schistosomiasis and STH infections in different regions of Burkina Faso. Elimination of this parasitic disease requires the inclusion of other control methods, in addition to mass treatment.

[Comparative study of schistosomiasis transmission (urinary and intestinal forms) at 10 sites in Burkina Faso (in sub-Saharan Africa)]. / Étude comparative de la transmission de la schistosomiase (formes urinaire et intestinale) dans dix sites du Burkina Faso.

Despite great progress in schistosomiasis control over the past decade in Burkina Faso, this disease remains a public health problem. This study analyzes parasitologic data from investigations of Schistosoma haematobium, S. mansoni, and mollusks. The prevalence rate of S. haematobium varies from 3.3% to 50.4%; that for S. mansoni (tested only in the western part of the country) from 3.3% to 39.1%. Prevalence rates are higher in school-aged boys than girls, but the reverse is true among adults. Studies of mussels showed the presence of Biomphalaria pfeifferi, Bulinus truncatus, Bulinus senegalensis and Bulinus globosus in these areas. Our results indicate that behavioral factors as well as the dynamics and the distribution of the intermediate mollusks play a major role in the persistence of the disease.

Enzyme-linked immunosorbent assay with worm vomit and cercarial secretions of Schistosoma mansoni to detect infections in an endemic focus of Burkina Faso.

Cercariae and adult Schistosoma mansoni were used to prepare, respectively, cercarial secretions (CS) and worm vomit (WoV). These were used as antigens in an enzyme-linked immunosorbent assay (ELISA) to test the IgG-reactivity of sera obtained in an S. mansoni-endemic area of Burkina Faso. Among the egg-excreting individuals (n = 240), 94.6% reacted positively with WoV, but only 62.9% with CS, thus suggesting a high diagnostic sensitivity of WoV, but not of CS. Among those individuals without detectable eggs in two Kato-Katz thick smears from different stool specimens (n = 215), the respective percentages of positive IgG reactivity were 78.1% and 63.3%. These positive reactions in the absence of detectable eggs are interpreted in terms of limited sensitivity of parasitological stool examinations. Optical density values in ELISA with CS, but not with WoV, correlated negatively with age, which may reflect decreasing exposure to cercariae in older individuals.

[Recent evolution of schistosomiasis in the water project of Sourou in Burkina Faso]. / Evolution récente des schistosomoses dans le complexe hydroagricole du Sourou au Burkina Faso.

In order to help the hydro-agricultural projects in the management of water resources together with a schistosomiasis control programme, it is important to evaluate the extent of the problem. This is the reason why parasitological and clinical surveys were conducted in schools associated with malacological surveys in transmission sites of several water projects including the one from Sourou. The data-collecting for the research on molluscs was carried out in surface water and as for parasitologic investigations on school-aged children, urine filtration and Kato-Katz were used to evaluate the parasitic load. The levels of prevalence were respectively in Guiédougou, Niassan, Di and Toma-île, in 2000, 60.5%, 40%, 48.8% and 51.9% for the urinary schistosomiasis, 5.3%, 0%, 6.9% and 50.6% for the intestinal schistosomiasis and in 2002, 56%, 51.9%, 51.6% and 43.4% for the urinary schistosomiasis, 10.1%, 8.2%, 22.7% and 90.8% for the intestinal schistosomiasis. The molluscs species collected and identified were: Biomphalaria pfeifferi for the intestinal schistosomiasis and Bulinus truncatus rohlfsi and B. senegalensis for the urinary schistosomiasis. B. senegalensis and B. truncatus were found naturally infested by S. haematobium. Water projects constitute amplifying factors of the proliferation of the species and parasitic exchange. All the actors (developers, populations, scientists) are questioning the means at their disposal to reduce the development of schistosomiasis which decrease the expected benefit of hydro-agricultural installations.

[Schistosomiasis endemic in Burkina Faso]. / L'endémie bilharzienne au Burkina Faso.

Burkina Faso, through the works of many teams of the OCCGE based in Bobo-Dioulasso, has signi-ficant data on several tropical endemics of which schistosomiasis. With the complementary works, it appears to be possible to establish a distribution of the schistosomiasis which reveals its importance. It will be the first stage of the planned national control program. The parasitologic data-gathering which covers the period of 1951 to 2000, used all the standard techniques. It is about Kato-Kartz and MIF for the intestinal schistosomiasis, centrifugation, filtration, serology reagent strips, macroscopy of urines and echography of the urinary system for the urinary schistosomiasis. All the eleven medical areas of the country have many sites submitted to parasitologic investigation. As regard the distribution of the two parasites involved with man (Schistosoma haematobium and S. mansoni), the data of prevalence (1% to 100%) and their distribution confirm their endemicity and the focal transmission. S. mansoni is located in eight medical areas particularly in the South and the West. S. haematobium is present in all the eleven medical areas of the country. In hydraulic planning as Sourou where the prevalences went from 23% to 70% for S. haematobium and from 0% to 69% for S. mansoni between 1987 and 1998. The situation requires a continuous monitoring. The spatial distribution of the six species of intermediate hosts shows that Bulinus truncatus and B. senegalensis Soudano-Sahelian species are present in all the ecological zones. B. globosus and Biomphalaria pfeifferi meet preferentially in the southern half of the country which reinforces the observation according to which the 14th northern parallel is often considered as the limit of septentrional extension of these two species. The other species Bulinus forskalii and B umbilicatus could have preference areas. All the species show a certain affinity with a type of biotope. The rarity and temporary aquatic systems lead to a concentration of the domestic and especially entertaining children activities around these biotopes very often contaminated. The phenomenon is amplified by the increase of contacts man-water, whose frequency and intensity are themselves dependent on activities related to hydro-agricultural planning. The analysis of the data shows, that in terms of colonization of the biotopes by molluscs and the relations between parasites and intermediate and final hosts, hydraulic planning turns out to be an amplifying factor of the species proliferation and parasitic flux host-parasite.

[Epidemiology and management of snake envenomations in the Dano health district, Ioba province (Burkina Faso) from 1981 to 2000]. / Epidémiologie et prise en charge des envenimations ophidiennes dans le district sanitaire de Dano, province du Ioba (Burkina Faso) de 1981 à 2000.

A series of investigations concerning snakebites and management of envenomations was carried out from 1981 to 2000 in the medical District of Dano, Province of loba in Burkina Faso. Viper bites were more frequent than Elapid ones. The seasonal distribution of the envenomations reflected the cycle of field work and other specific activities. Care seeking within the Traditional System of Health Care (STSS) was more frequent than within the Conventional System of Health Care (SCSS). Lethality was higher at STSS level in cases of viper bites and, conversely, higher in SCSS in the cases of Elapid envenomations. This highlighted the interest in medicinal plants for treating snakebites particularly in case of neurotoxic envenomation. We classified several dozens medicinal plants within an inventory. Some of them have been studied and deemed worthy of interest. Others are used for the treatment of other types of poisoning (pesticides, plants toxic) and/or used in traditional rites. We hope to follow the Côte d'Ivoire experience such that African snake venom, neutralised by modern antivenom, might also be neutralised by the African natural resources.

[Parasitological profile of urinary schistosomiasis of the Sourou hydroagricultural complex of Burkina Faso]. / Profil parasitologique de la schistosomose urinaire du complexe hydroagricole du Sourou au Burkina Faso.

In the Sourou area of Burkina Faso, parasitological and malacological surveys of urinary schistosomiasis have been carried out in the constructed sites of Guédougou, Niasan and Débé dating respectively from 1967, 1986 and 1996. The investigations covered also the traditional villages of Lanfiera, Di, Poro, Tiao and Mara situated in the middle of the hydroagricultural planning for the first, very close to the lake for the second and about twenty kilometres distant for the three last. These towns represent the main sites in the Sourou area. The results of the parasitological surveys showed that urinary schistosomiasis was present in all sites. The levels of prevalence varied considerably: 70.3% in Guiédougou, 40.8% in Niassan, 8.5% in Débè in the irrigated zone, 55.6% in Lanfiéra, 56.8% in Di, 13.2% in Poro, 83.3% in Tiao and 64.7% in Mara. Concerning the malacological investigation, two species (Bulinus senegalensis and B. truncatus) were shown to be intermediate hosts of Schistosoma haematobium. The first was endemic to the area while the second was compatible with S. haematobium from the Sourou and other zones. Compared to the results of earlier investigations, the endemic had worsened with differences according to sites. This disparity of prevalence levels which has already been observed in other hydroagricultural area results from many factors, among which the impact of irrigation activities, the aquatic biotope system (irrigation canals, natural lake, pools and temporary rivers) and the type of contact of human communities with water rank high. Schistosomiasis expansion is amplified by the intermediate host dynamics and the introduction of new schistosomes carried by the new workers arriving from all over the country. In these conditions, in order to reduce rapidly prevalence levels, preventive measures should be centred on chemotherapy for the population. The treatment should be administered during a period of weak intermediate host density and be directed towards in-coming workers. Such an approach should be able to check the spread of schistosomiasis naturally occurring with the irrigation of new sites.

[Comparative study of 3 Schistosoma haematobium foci in Burkina Faso]. / Etude comparative de trois foyers bilharziens à Schistosoma haematobium au Burkina Faso.

The comparative study of the three most common schistosomiasis foci in Burkinabé villages shows a great disparity both in parasitological and malacological results. Parasitological investigations by reagent strips and urine filtration conducted on school children indicated respective prevalence rates of 85% at Thion, 37.5% at Donsin and 10.5% at Djerma. Malacological prospections found two species (Bulinus senegalensis and Bulinus truncatus) of intermediate hosts of schistosomiasis in the water biotopes in Thion and Donsin, and only one species (B globosus) at Djerma. We speculate that this situation could be related to initial levels of endemicity, to the distance between living quarters and sites of transmission, to sociological practices as well as to the mollusc vector species. Given the large distribution of these foci throughout the country, the Burkinabé medical authorities should recognise their importance with regard to the disease on a public health level and support the current orientation of the national schistosomiasis control programme which is coordinated around district health services.

[Schistosomiasis in the region of Ziga (Burkina Faso) before the construction of a dam]. / Les schistosomoses dans la région de Ziga (Burkina Faso) avant la construction du barrage.

The authors report the results of a survey on schistosomiasis in the zone of Ziga (Burkina Faso) where a dam is going to be built. They examined 438 children aged from 7 to 15 years in 5 villages. The appraisal of macroscopic or microscopic hematuria, urine filtration, stool analysis and ultrasonographic examination made possible the assessment of the prevalence and severity of both schistosomiasis. The area was hyperendemic for urinary schistosomiasis. The general prevalence of S. haematobium was higher than 46% and 55% of the children presented at least one lesion of the bladder and 2% of hydronephrosis at ultrasonography. Intestinal schistosomiasis was not observed although few cases have been described in the regional hospital and intermediate host snails have been collected in the area. A surveillance of schistosomiasis, based on school surveys, was strongly recommended in the dam area.

[Large dams, health and nutrition in Africa: beyond the controversy]. / Grands barrages, santé et nutrition en Afrique: au-delà de la polémique.

The population in sub-Saharan Africa is growing faster than increases in food production, resulting in a net decrease in food production per capita. The Food and Agriculture Organization has stated that there is a "risk of widespread hunger" which could be prevented by "effective planning of water resources". However, the potential effects of such schemes on the human population are often inadequately assessed and the effect of large dams on human health is not clear. The potential risk to human health of water resources was emphasized a few years ago but no effective preventive programs were implemented, probably because of inadequate availability of information and lack of awareness. The effects on health of "large" water resource projects are not uniform within a population. Decision-makers have tended to focus on the positive effects, to obtain support for their plans. These include: 1) improvement in the well-being of the population (safe water more readily available, new infrastructure, better access to health care) and 2) increases in the food supply (more vegetables and fish available due to irrigation). Thus, there has been a logical expectation that more, better quality food will become available as a result of these schemes, whereas in fact, health and nutrition has often worsened, particularly in young children. Most of the diseases associated with water resource management are communicable, including diseases directly related to the presence of large quantities of water, such as: malaria, which increases in incidence immediately after the building of the dam, after which a new balance develops between the human population and the parasites, schistosomiasis, the disease which increases most in response to the building of dams, particularly in its most severe gastrointestinal form, diarrhea, as water is a major means of dissemination for many organisms, including those causing digestive tract infections and gastroenteritis (amebiasis, salmonellosis, cholera), due to poor sanitation, other parasitic infections, such as onchocerciasis and trypanosomiasis, which should be monitored as they may also threaten the population. Other communicable diseases may appear or increase in incidence with the influx of migrants to the irrigated area. Sexually-transmitted diseases and HIV infection are a particular problem. The large numbers of insects (mosquitoes, blackflies) may also have harmful effects on populations adapting to the new environment. These effects are related to each other and to the environmental changes. New types of food affect people's feeding habits and generate new sources of income. However, they may also lead to new and higher expenditure. There are also likely to be major socio-demographic changes associated with changes in reproductive behavior and women's activities. The location and nature of new homes and infrastructure (e.g. schools, health centers, roads) also contribute to the success or failure of the dam project. There are many constraints to be considered and a more comprehensive approach to the problem is required. Health and nutritional status may be used as simple indicators of the ability of the population to adapt to a new environment. This makes it possible to construct a causal model to identify the most effective and relevant areas of intervention. Health and nutrition issues are of vital importance and scientific findings should be used in decision-making processes for planning future large dam schemes.

Distribution spatiale des mollusques hotes intermediaires potentiels des schistosomes et de leurs biotopes au Burkina Faso

La repartition des hotes intermediaires des schistosomes de l'homme et du betail montre que chaque espece a sa propre niche ecologique avec quelques particularites liees a la complexite de chaque plan d'eau. Le Burkina Faso offre une large gamme de biotopes qui hebergent la plupart des hotes intermediaires presents en Afrique de l'Ouest

Hotes intermediaires et prevalence de la bilharziose au Burkina Faso

Parmi les nombreuses maladies d'origine hydrique; les bilharzioses ou schistosomiases representent actuellement la 2eme endemie mondiale derriere le paludisme avec 400 a 600 million de malades a travers le monde soit 1 homme sur 10. Au Burkina Faso; les taux de prevalence a l'echelle nationale ne sont jamais inferieures a 30 pour cent avec une decroissance progressive de l'infestation des populations du nord au sud du pays pour la bilharziose urinaire et du sud au nord pour la bilharziose intestinale. La repartition des hotes intermediaires resultant des prospections malacologiques semble correspondre aux zones ecologiques deja decrites au Burkina Faso par Guinko (1984); ainsi l'endemie bilharzienne qui en resulte se trouve en correlation avec les hotes intermediaires et le decoupage climatique du pays