[Parasitic risks (bilharziosis and intestinal parasitosis) to Mboune's valley revitalisation (Senegal)]

In order to assess the parasitic risks related to M'Boune's valley water launching, a study has been carried out from September 16 to November 24, 1998 in 12 villages: four villages surrounding the Guiers lake, four villages surrounding Ferlo already water launched 10 years ago, and four villages within M'Boune not water launched. The prevalence rate of urinary bilharziosis is 0.002% in the frist area, 1.3% in the second one and 13.7% in the third area. In these areas, intestinal parasitosis are prevaling respectively at rates of 38.2%, 36.4% and 21.3%. Although, there is no reason to fear immediately a worsening of the epidemiological situation due to M'Boune's valley revitalisation project, nevertheless, appropriate steps should be taken right now aiming at tackling the extension of conditions related to hydric medium.

[Role of Anopheles melas Theobald (1903) on malaria transmission in a mangrove swamp in Saloum (Senegal)]

From June 1995 to January 1998, entomological studies carried out in five villages located in the Delta's Saloum have allowed to better understand the contribution of An. melas Theobald (1903) to malaria transmission in mangrove swamp. Among the five villages studied, three of them (Simal, Djilor and Marlothie) located along the Saloum river, are colonised by An. arabiensis; the two others (Djifere and Diakhanor) located between the sea and the river, are colonised by An. melas. During the rainy season and at the beginning of the dry season, An. melas and An. arabiensis are sympatric. The ratio of An. melas/An. arabiensis increases when we go closer the coast where An. melas becomes quite exclusive. When An. melas is predominant, endophagy, endophily and anthropophily are very marked. The parturity rates are lower in An. melas than in An. arabiensis. In the predominance area of each species, transmission is on the same level. During the period of sympatry, An. arabiensis is responsible for the transmission and when it is absent, An. melas carries on. Transmission occurs from July to March with a maximum at the beginning of the dry season. In the villages of the mangrove swamp, its prolongation until the middle of the dry season is due to An. melas.

[Prevalence of intestinal parasitis at the King Baudouin health center of Guediawaye (Senegal)]

A prospective study carrying on 302 samples of stools of aged children of 0 to 15 years has been achieved between January 02 and April 11 2001 in the center of health Roi Baudouin of Guediawaye (SENEGAL) to appreciate the prevalence of intestinal parasitis. For every child, we made a scotch test, a macroscopic exam of stools and a microscopic exam to the direct analysis and after concentration by the method of RITCHIE simplified. The global prevalence is 56,62%. Ascaris lumbricoides arrived in head with 34,17%, follow-up of Giardia lamblia (22,50%), Trichirus trichiura (22,08%) and Amoeba (14,58%). The prevalence varied with age and the children who are 11 to 15 years have the indication of infestation the most elevated (75,86%): The difference of prevalence to the sex and according to the presence or no current water is not meaningful. On the other hand topics to weak standard of living have an indication elevated parasitis with 66,05%. So measures of efficient struggle must be undertaken to combat these intestinal parasitis.

[Antifungal drug susceptibility of Candida causing oropharyngeal candidiasis in HIV infected patients]

Candidiasis are very usual infections of HIV infected patients. By medicine pressure, susceptibility to antifungal drugs decrease in some Candida strains. This study carded out in 1997 at hospital, aimed to identify the yeast species isolated from HIV infected patients with oropharyngeal candidiasis, test their susceptibility to antifungal drugs and a previous antifungal treatment impact. Thus, 60 patients yielded to questionnary were recruited. Isolated yeast colonies from buccal tract after culture on Sabouraud medium with chloramphenicol were identified with the API 20 C AUX (BioMérieux) system by assimilation of different sugars. Susceptibility was evaluated by ATB FUNGUS (BioMérieux) system. 55 from the 60 isolated yeasts were identified and among them C. albicans and C. tropicalis were the main species with 75% and 11,7% respectively rates. In HIV1 infected patients, all specieswere isolated and C. albicans predominated (80,4%) on the other hand, C. albicans and C. tropicalis were the only isolated yeasts from the HIV2 infected patients with 83,3% and 16,6% respectively rates. Susceptibility of C. albicans was 72,2% to nystatine, 58,3% to amphotericin B, 83,3% to flucytosin, 12,8% to miconazole, 8,5% to econazole and 10,6% to ketoconazole. Susceptibility of C. albicans to polyenes was modified by a previous antifungal treatment. This study indicated emergence of saprophytic yeasts of the buccal mucosa and seemed to be more fostered by HIV1 serotype than HIV2. So, C. albicans's susceptibility to polyenes decreased by untimely use of antifungal drugs and by controlling it one could improve the clinic conditions of HIV infected patients.

[Pneumocystosis in HIV infected patients presenting with acid-fast bacilli negative pneumopathy at the Central University Hospital at Dakar]

Pneumocystosis is an opportunist parasitic disease which occurs currently at Europe and United States in HIV infected patients. In Africa, the disease is not current. Pneumocystosis has been detected in the Fann medical universitary center at Dakar from HIV infected patients with acido alcoholo resistant bacilli negative pneumopathy. Analysis of broncho alveolar liquid(BAL) of 29 patients after Giemsa and Blue of Toluidin O staining allowed isolating of two cases of pneumocystosis. A man and a woman were the patients. They were HIV1 positive with at X ray bilateral interstitial syndrome. The CD4 lymphocytes count of the one was lower than 200/mm3 and for the other it was higher than 200/mm3.

[Malaria in the central health district of Dakar (Senegal). Entomological, parasitological and clinical data]

We previously investigated malaria in the southern health district of the city of Dakar, which includes the oldest neighborhoods. In this study, we investigated malaria in the central health district, corresponding to the central area of the conurbation. The study was carried out at 12 sites, from March 1996 to February 1997. The sites were selected such that the entire district was covered and included 2 sites in the shanty town and three in an old village that has been absorbed into the city. We carried out prospective monthly entomological analyses with a view to identifying the vectors and the mode of transmission of malaria. We also carried out clinical and parasitological follow up to determine the incidence of parasitemia and of bouts of malaria. Insects were collected overnight from humans and the insects remaining the next morning in 10 bedrooms in the health district were collected. For clinical and parasitological follow up, families were visited at home once per week and their clinical state was assessed. Blood smears were taken to facilitate the detection of bouts of malaria. Body temperature was measured and we checked for the presence of organisms in the blood systematically during the last weekly visit of each month. For a total of 308 collections at night from human volunteers and 1,395 bedroom collections of residual fauna, we obtained 12,879 Culicidae females, 199 (1.5%) of which were anopheles mosquitoes, with Culex quinquefasciatus accounting for 98% of the remaining mosquitoes. As in the southern district, A. arabiensis was the only species of the A. gambiae complex collected. Anopheles mosquitoes accounted for only 0.3 bites per man per night and 0.07 females per room. They were therefore poorly represented in this district and were not detected at all at five sites. They were found in large numbers only during the rainy season, especially in September, when they accounted for 2.25 bites per man per night and 0.3 females per room at 3 sites in an undeveloped zone in which 81.4% of all the anopheles mosquitoes were collected. The parturition frequency of the biting females was 32.6% and that of the females collected in houses was 50.0%. None of the A. arabiensis females dissected (98.5% of those collected) carried Plasmodium sporozoites. The clinical and parasitological follow up concerned 2,583 individuals, aged from 1 month to 80 years, from 285 families resident in Dakar who volunteered for the study; 41.9% of these individuals were less than 15 years old and 92.2% had been living in Dakar for more than 2 years. Thick and thin blood smears taken monthly showed the frequency of the parasite to be 1.0% and that of gametocytes to be 0.1%. P. falciparum was the only parasite detected in the subjects. Plasmodium infections were observed in all age groups, with a frequency of 0.4% (adults over the age of 20 years) to 1.6% (children under two years of age). Parasitized subjects were detected in every month of the study, with a frequency of 0.4% (in January) to 1.9% (in December). The largest number of cases detected in a three-month period (38.8% of all cases) was that for October to December, the three-month period immediately after the rainy season (July to September). Parasite frequency, which was no higher than 1. 2% at 10 sites, was clearly higher at two sites in the shanty town (3.8 and 6.8%), mostly inhabited by immigrants from rural areas. At the end of the study year, satisfactory weekly follow up was considered to have been achieved for 1,067 of the participants. The annual incidence of parasitemia in this cohort was 5.1% and that of malaria was 2.4%. Incidence did not vary significantly with age and was between 1.8% and 7.6% for parasitemia and between 0.8% and 3.5% for malaria. However, significant differences in incidence were observed between areas. Incidence was higher at the two sites in the shanty town, with rates of 12.1% and 36.5% for parasitemia and 6.1% and 15.9% for malaria. (ABSTRACT TR

[Management of severe malaria in children in developing countries. A protocol for economic evaluation]

This prospective one-year study was conducted as a preliminary phase to setting up a protocol for economic appraisal of management of severe malaria at Albert Royer Children's Hospital in Dakar, Senegal. Data was routinely collected using a standardized checklist. The four key indicators chosen for this study were nurse workload, adequacy of care (number of patients receiving adequate care), direct cost, and mortality rate. The mean daily care workload was estimated to be 27.2 minutes. This indicator assesses the relationship between supply and demand. Based on 5 criteria, care was considered as adequate in 54.5 p. 100 of patients. This indicator is helpful in judging the effectiveness of the therapeutic modalities used. The direct cost of treating severe malaria was estimated to be 45963 CFA francs. This indicator will be useful in establishing controls to reduce costs. The mortality rate was 12.2 p. 100. Comparison of this rate with previous years suggests little improvement in the outcome of malaria management at the institution. This indicator must be taken into account in the ongoing quality control program. Overall these findings should enable institutional decision-making to improve management of severe malaria based on objective measurable data.

[Assessment of the level of urinary iodine deficiency in children of Senegalese central regions]

Iodine deficiency disorders (IDD) are a major public health problem in Senegal, where strategies of salt iodization were adopted in the southern and eastern regions. The aim of this study led in four districts (Koungheul, Bambey, Mekhe and Kebemer), was to estimate by a questionnaire, the women knowleges, attitudes and practices (KAP) concerning IDD, and to measure children urinary iodine excretion by the Sandell-Kolthoff method to assess a potential deficiency. Six hundred ninety eight households were selected covering 1336 women (age 15 to 49 years) and 400 children (age 6 to 12 years). Sixty three per cent of the women knew the goiter, 89% of them considered that it was a disease and only 0.6% knew the role of iodized salt in the treatment. On the other hand, 20% of the children presented a normal range of urinary iodine excretion superior to 100 microg/l, the deficiency was light (50 to 100 microg/l) in 38% of the children, moderate (25 to 50 microg/l) in 27% and severe (< 25 microg/l) in 15% of them. These results show that other Senegalese regions are concerned by iodine deficiency disorders and need information, education and iodine supplementation programmes, notably for children and young women.

[Intestinal parasitosis in the inhabitants of a suburban zone in which the groundwater is polluted by nitrates of fecal origin (Yeumbeul, Senegal)]

This study was carried out in 1997 to 1998, to determine the prevalence of intestinal parasite infestations due to groundwater pollution at Yeumbeul, Senegal, and to follow the progression of parasite infestations following anti-parasite treatment. The study included 705 people living in a suburban zone in which the water table was polluted with nitrates of fecal origin. These individuals consumed either well water or water from springs. The overall prevalence of parasite infestation was 42.26%, but varied significantly with age (p < 0.001). Individuals who consumed well water were more frequently infested than those who consumed spring water, but the difference was not significant (p > 0.3). Giardia and Entamoeba coli were the most frequently isolated parasites, with Giardia predominating in the 0 to 9 year age-group. There was no significant correlation between the prevalence of the various parasites and indicators of water pollution (R2 = 0.0566 for nitrates and 0.1086 for fecal coliform bacteria). Similarly, no correlation was found with water pollution factors such as the depth of the water table (R2 = 0.027) and the distance between the wells and the latrines (R2 = 0.00007). Following specific treatment, the prevalence of parasite infestation fell to 30.81%. This indicates the limitations of drug treatment, which is always used alone to combat intestinal parasites, in the face of possible reinfestation.

A comparison of thick smears, QBC malaria, PCR and PATH falciparum malaria test trip in Plasmodium falciparum diagnosis

Blood samples from 182 patients presenting at the out-patient clinic in Richard-Toll. Senegal were analysed by Thick smear microscopy, the QBC, PCR and the new dipstick PATH Malaria assay which detects the histidine rich protein II antigen of Plasmodium falciparum. Thick smear microscopy was used as the reference method. Sensitivity, specificity, predictive positive and negative values were 100%, 83.6%, 93.4% and 100% QBC respectively; 100%, 72.7%, 89.4% and 100% for PCR; 96%, 92.7%, 96.8% and 91% for the PATH assay. PATH assay failed to detect one positive sample with Plasmodium malariae. Assays were also compared with regard to the expense of equipment and reagents and speed and ease of use. The rapid PATH assay can be performed with minimal training and may be specially useful in areas where P. falciparum is the predominant malaria species, in epidemic malaria regions, and where skilled microscopy is not readily available.

[Zoophagia and alternative host selection of the marlaia vectors in Senegal]

Blood-engorged females of An. gambiae s.l., An. funestus, An. pharoensis and An. rufipes caught resting indoors were tested (precipitin or enzyme-linked immunosorbent assay) to determine the source of bloodmeal. The species of the An. gambiae complex fed mainly on human hosts in all prospected areas, except in those of the mid Senegal river valley where an important zoophily was observed within and near the irrigation zone. Among 4,597 blood-engorged females of An. gambiae s.l., 29% fed on cattle with 7.5% of mixed boodmeals, mainly human-bovine or human-equine. The presence of cattle, culicid population densities and individual mosquito safety devices were the most determinant factors of animal deviation. Blood of most domestic animals was found in the stomach of collected females, but according to areas, bovines and equines were the main hosts for zoophilic females of An. gambiae s.l. Females of An. funestus collected in the middle-west were more anthropophilic than those collected in south-eastern areas. An. pharoensis was most prevalent in the Senegal river delta where it was found to be very anthropophilic. An. rufipes was strongly endophilic but exclusively zoophilic in all prospected areas.

[Impact of the use of permethrin pre-impregnated mosquito nets on malaria transmission in a hyperendemic village of Senegal]

The efficacy of permethrin-treated bednets was evaluated in Wassadou, a hyperendemic village located in the Sudanese grasslands of southeast Senegal. Pretreatment data were collected between 1992 and 1993. Bednets were distributed to the whole population in June 1995 and impact of their use on vector populations and malaria transmission was evaluated until November 1995. This period corresponds to the rainy season during which malaria transmission is highest. Data were compared with a control village in which bednets were not distributed. Findings showed that use of bednets led to a sharp decrease in the density of the vector population and malaria transmission. The number of bites by Anopheles gambiae s.1. decreased 69%. The density of blood-laden and pregnant females inside dwellings decreased 91% and 96% respectively. The sporozoite index of females captured on the skin decreased 76% and the daily rate of entomological inoculation decreased 88%. This impact was not great enough to eliminate the risk of infection. Prolonged study over a period of 4 to 5 years is needed to evaluate the impact of long-term use of insecticide-treated bednets on vector population and malaria transmission.

[Malaria lethality in Dakar pediatric environment: study of risk factors]

To determine risk factors for fatal malaria in Senegalese children, a 3-year case-control study was carried out between October 1992 and November 1995 at the Albert Royer Hospital in Dakar. The case group included 52 children who died from documented malaria in the hospital. The matched control group consisted of children who responded favorably to hospital treatment. Exposure to risk was measured with regard to age, nutritional status, educational level of parents, self-medication prior to hospitalization, socioeconomic level, degree of fever, and blood parasite levels. Cases and controls were compared using statistical tests for matched groups. Age lower than 5 years, poor educational level of parents, delay of treatment more than 24 hours, nutritional status, and blood parasite levels greater than 5% were associated with a significantly higher risk of fatal outcome. Conversely, low socio-economic level, recent self-medication, and fever over 41 degrees C were not associated with higher fatality. These findings emphasize the need for more information campaigns to encourage people to seek institutionalized care when fever appears. Our results also suggest that prophylactic treatment may be advisable in children under 5 years of age and in some high risk groups.

[Heterogeneity of chloroquine resistant malaria in Senegal]

In order to evaluate the in vivo efficacy of chloroquine in the treatment of P. falciparum malaria, studies have been carried out in Richard-Toll, Fatick and Tambacounda, 3 areas where dynamics of transmission, population movements, as well as prophylactic and curative practises are different. Failure rates in treatment were 13% in site 1 (Richard-Toll) where medical pressure and population movements are high. In sites 2 and 3 (Fatick and Tambacounda), the failure rate was 3%. Even if medical pressure is lower in the latter site (Tambacounda), the higher transmission could be a factor in the spreading of resistance. A surveillance system and better use of chloroquine must be undertaken.

[Comparison of the transmission of malaria in 2 epidemiological patterns in Senegal: the Sahel border and the Sudan-type savanna]

From September 1992 to October 1993 a longitudinal entomological study was carried out in two villages located in different ecological conditions of Senegal, a sahelian area and a sudan-type savanna. Mosquitoes were sampled by night-bites catches and by daytime pyrethrum spray collections. In both villages Anopheles gambiae s.l. is the main vector with An. gambiae in the savanna area of Wassadou and An. arabiensis in the sahelian area of Thiaye. Malaria transmission is mainly seasonal with a man biting rate (ma) and an entomological inoculation rate (h) higher in Wassadou than in Thiaye. In this last one (sahelian area), a high variation of An. gambiae s.l. density was observed, females disappear in the dry season. In the rainy season the main biting rate increases but no infected bite was recorded. In Wassadou (sudan-type savanna), a great difference in An. gambiae s.l. specific composition was observed with An. gambiae predominant in the rainy season and An. arabiensis generally more abundant in the dry season. The biting and inoculation rates were minimum during the dry season (ma = 4 bites/man/night; h = 0.07 infected bites/man/night-, they increase during the rainy season (ma: 52 bites/man/night; h = 1.6 infected bites/man/night). An inhabitant of this village gets annually some 63, bites and 220 infected bites of An. gambiae s.l., mainly during the six months of the rainy season and the early dry season.

[Scanning electron microscope sudy of the morphology of fungi isolated from patients at the Aristide La Dantec Hospital in Dakar, Senegal]

In order to improve the identification of fungi usually isolated among some patients at Dantec Hospital, a study by scanning electron microscopy has been carried out. It deals with four species of yeasts (Candida albicans, Candida parapsilosis, Rhodotorula rubra Sacharomyces cerevisiae) six species of dermatophytes (Trichophyton rubrum, Trichophyton soudanense, Trichophyton interdigitale, Microsporum canis, Trichophyton violaceum, Microsporum audouinii); two species of mildew, (Aspergullus flavus, Aspergillus niger) and one species of dimorphic fungi (Histoplasma duboisii). The yeasts get a smooth surface with, often, a mark of but on it. Microsporum canis presents some echinulate macroconidia. Trichophyton violaceum is characterized by the appearance of echinulate chlamydoconidium with a twofold bulge and Microsporum audouinii by a echinulate chlamydoconidium with a bulge only. Trichophyton rubrum presents macroconidia with smooth surface and in "sausage" form, as for Trichophyton soudanense it presents some arthroconidia that are cells which get more or less rectangular form and with smooth surface. Aspergillus flavus is characterized by the presence of a conidiophore with a verrucosis surface and an aspergillary head of about 36 microns having some spores with almost smooth inner surface. On the other hand, Aspergillus niger gets a conidiophore with smooth surface. As for Histoplasma duboisii, the surface of the chlamydoconidium presents some verrucosis that are real conidia in formation. The scanning electron microscopy enables use to discover the existence of characters that are likely to be used for the identification of fungi.

[Prevalence of malaria in Dakar, Senegal. Comparative study of the plasmodial indices in pregnant and non-pregnant women]

The comparison of the prevalence of malaria in pregnant and non pregnant women living in Dakar has interested 1819 women among whom 950 pregnant and 869 non pregnant. For all the examined women, the global plasmoidic index was 2.6% and the gametocytic index 0.1%. Plasmodium falciparum was the only observed species. According to the obtained results, pregnant women, with a plasmoidic index of 4.5% are more often parasited than the non pregnant women, only affected in a proportion of 0.5% Whatever the age, the number of previous pregnancy, the place of residence, the duration of the stay in Dakar may be, the pregnant women are always more often parasited than the non pregnant women and the registered differences are statistically significant. That situation could come from a greater receptivity of the pregnant women what is admitted by some authors. But a more important proportion of natives from rural area was observed among the pregnant women, from where a difference in the exposure to the risk of impaludation between the two groups that could explain the registered results. The global plasmoidic index of 2.6% obtained in the examined women, reflects well the present situation of the malaria endemy in Dakar, a weak hypo-endemic area.

[Evaluation of malaria chemoprevention among 359 pregnant women attending a health center in Dakar]

The authors carried out an epidemiological survey from october 12 to december 4, 1995, at Medina's mother and Child care centre (MCC) in Dakar in order to assess chemoprophylaxis among pregnant women in Dakar. The midwife/pregnant women ratio is 0.08 The mentioned diagnosis criteria were relevant regards to the references established for most of the answers because since the latter base malaria diagnosis on the following signs: fever, chills, headaches and vomiting. 64.6% of them assume compliance to antimalarial chemoporphylaxis. Education level seems to be the main determining factor in this trend. Although chloroquine is the most widely used drug, nevertheless 11.9% of pregnant women assuming compliance use it at inappropriate posology. Besides, pyrimethamine is used by 12.3% of them. 34% of pregnant women do show chloroquine in urine. The plasmodial index is 1.4%. Only 8.1% of these women are supplied by health centres where shortages are noted.

[Evaluation of parasitic risks for the population bordering on the Mbeubeuss public waste disposal, Dakar]

The authors carried out a parasitologic survey on 367 inhabitants of Malika, a village located in the immediate surroundings of M'Beubeuss disposal, as well as on 433 other residents of Keur Massar, a location 2 km farther, in order to assess parasitic hazards encountered by people neighbouring this disposal. As far as intestinal parasitosis are concerned, the prevalence rate was significantly higher in Malika (61.3%) than in Keur Massar (48.5%) The sex, social and economic status, level of education as well as the time of dwelling in the neighbouring area were identified as the risk factors of intestinal parasitism. Only the last one can be considered as significantly and independently related to a risk of intestinal parasitism. As for malaria, the plasmodial index in Malika was 6% versus 7.6% in Keur Massar (no significant difference). Thus, if it does exist for neighbouring people, an infestation risk by intestinal parasites related to exposure duration, contrarily, it does not exist for malaria. Appropriate steps should be taken to prevent the hazards encountered by inhabitants of surrounding villages.

[Prevalence of malaria in Dakar, Senegal. Results of serological survey of pregnant and non-pregnant women]

The study of malarial seroprevalence in Dakar has interested 598 women among whom 377 pregnant and 221 non pregnant, between 15 to 45 years old and happens during the dry season, period of which malaria transmission is practically stopped in the locality. Among the tested serums by indirect immunofluorescence with Plasmodium falciparum asexual blood forms as antigen, 24.4% contained antimalarial antibodies. The serological index does'nt vary significantly according to the months during the dry season, the women age and their previous pregnancy number. On the contrary, the women who live in Dakar since less than 2 years, have e higher seropositivity rate of 33.7% than those who are there since more than 2 years, 20.0%. It is likewise for the women practicing chemoprophylaxy with chloroquine of whom 16.5% have antibodies against 26.0% among those who don't practice it. The seropositivity rate doesn't vary significantly according as the women are pregnant (24.7% of positive) or not pregnant (24.0% of positive). The weakness of the serological rate in the examined women, can be explained by the situation of Dakar in a weak malarial hypoendemic area. II shows that the major examined subjects have lost or have never had contact with Plasmodium what predispose them to make severe and complicated malarial attacks.

[Strongyloidiasis: current incidence in the Dakar pediatric environment]

The authors have conducted from November 20th 1992 to May 26th 1993 a study about the incidence of Strongyloidiasis in two pediatric units in Dakar. Direct examination followed by Lee and Baerman's concentration technic both applied to 610 stool specimen, have shown that 26.6% of children were carrying parasites. 9 cases of strongyloidiasis have been shown the incidence was 1.4%. These cases represent 5.5% and ranks at fifth position among intestinal parasitic diseases. They all come from suburbs of Dakar. Malignant forms could be easily detected among children suffering a secondary immune deficiency due to malnutrition, or corticotherapy.

[Endemic parasitoses in the villages surrounding the Saloum fossil valley, Senegal]

In order to determine the prevalence rates of malaria, urinary schistosomiasis and intestinal parasitosis in Saloum's valley, the authors carried out a study which took place from november 16 to november 24, 1996. For malaria, the global parasites index was 22% (146/662). Malaria prevails at a hypoendemic level in N'Diobène and N'Guent-paté villages and at a medium-endemic level in Ribo-Escale and N'Dodj. The infestation index for urinary schistosomiasis was 8.9% (137/154) About intestinal parasite, among 868 persons screened, 124 showed one or several parasites, that is an infestation index of 14.3%. Appropriate steps should be taken to prevent an extension of these conditions along the fossil Saloum's valley.

[Prevalence of malaria in the Senegal river basin in 1991]

In order to determine the prevalence of malaria and its epidemiological characteristics, a survey was carried out in 11 villages situated in all the Basin of River Senegal (B.R.S.). 3306 (0-14 years) children are examined. The results show that malaria is hypo-endemic in the B.R.S. with a plasmodic index of 8.6% and a splenic index of 9.9%. But these malariametric indexes change according to the areas visited. Thus, malaria prevails at a hypo-endemic level in Dagana and Podor districts while at a medium if not hyperendemic level in Matam and Bakel districts. The plasmodial index also change according to age reaching a maximum within children from 10 to 14 years. As for the spleen index, it is low among children from 10-14 years. As for the spleen index, it is low among children from 0 to 4 years old, then increases among those aging from 5 to 9 years, before decreasing within children ranging from 10 to 14 years. P.falciparum is the most prevalent species, representing 96% of the cases; it is followed by P.malarioe (3%) and P.ovale (1%). If our results are compared with those obtained before by other authors, we can conclude that the recent hydro-agricultural plannings carried out in the area, have not yet provoked an increase of the cases of malaria. But, in order to avoid this risk, it is necessary to take from now some preventive measures.

[Malaria in an urban environment: the case of the city of Rufisque in Senegal]

From April to November 1994, we carried out a study in Rufisque, an urban area located in Dakar Region. During dry season, 5.32% of febrile outpatients were infected with Plasmodium falciparum with a mean parasitic density evaluated at 12,471 p/microliter. One case of cerebral malaria was noted. During raining season, malaria represented 58.75% of the fevers. Ten presented neurological signs; the mean parasitic density was high, 131,140 p/microliter. Two children died. Good efficiency of quinine was noted but chloroquine treatment failures was present: 50%. Generally malaria is less prevalent in urban areas. But in Rufisque ecological conditions are main factors which permit spreading of the disease. Prior measures of control such correct treatment of cases and good management of environment must be done.

[Malaria in the southern sanitary district of Dakar (Senegal). 1. Parasitemia and malarial attacks]

A survey of endemic malaria in Dakar was carried out in the southern sanitary district covering the city centre and neighbouring areas. The survey was scheduled from June 1994 to May 1995 in 12 sites distant from each other by 1000 to 1500 meters. Clinical and parasitological data were collected during weekly medical follow-ups at the patients' home with the systematic research of Plasmodium once a month. The study included 2,337 persons aged between 1 month and 88 years and belonging to 284 volunteer resident families. Through monthly parasitological examinations, a parasite rate (P.R.) of 0.3% and a gametocyte rate (G.R.) of 0.005% were recorded. Only Plasmodium falciparum was observed. The P.R. varied according to age: from 0.1% in the children under 2 years to 0.7% in the young adults (15-20 years) who appeared significantly more affected than the other age groups, including that of children from 2 to 9 years, of whom only 0.3% were infected by the parasite. The P.R. varied also according to the site surveyed: from 0% in the city centre to 1.3% at the periphery of the sanitary district and according to the time of year, reaching its height of 0.8%, between October and December, that is just after the rainy season. At the end of the year of survey, 929 among those surveyed were considered to have been satisfactorily followed. Their annual incidence rate was 2.4% for the parasitemia and of 1.5% for the malaria attacks. None of the participants aged under 2 years had the parasite. Among the others, the annual incidence rate varied according to the age--although not significantly--passing from 1.1% to 5.3% for parasitemia and from 0.4% to 3.0% for malaria attacks. Theses rates did not differ significantly according to site; the cases registered varied between 1% and 8% for parasitemia and 1% and 5.8% for malaria attacks. Only 10.6% of febrile subjects suffered from malaria attacks, but this rate seemed to go up between October to December, rising to 26.6% which corresponds to 1 case of malaria attacks for 4 cases of hyperthermia in that period. Weak density of Anopheline population and satisfactory medical surveillance explain the recorded results.