Risk factors of exposure to Aedes albopictus bites in mainland France using an immunological biomarker.

In recent decades, the invasive Aedes albopictus vector has spread across Europe and is responsible for numerous outbreaks of autochthonous arboviral disease. The aim of this study was to identify epidemiological and sociological risk factors related to individual levels of exposure to Aedes albopictus bites. A multidisciplinary survey was conducted with volunteer blood donors living in areas either colonised or not by Aedes albopictus in mainland France. Individual levels of exposure were evaluated by measuring the IgG level specific to Aedes albopictus saliva. The most striking risk factors concerned the localisation and characteristics of the dwelling. Individuals living in areas colonised prior to 2009 or recently colonised (between 2010 and 2012) had higher anti-salivary gland extract IgG levels compared with those who were living in areas not yet colonised by Ae. albopictus. The type of dwelling did not seem to impact the level of exposure to Aedes bites. People living in apartments had a higher anti-salivary gland extract IgG level than those living in individual houses but the difference was not statistically significant. Interestingly, the presence of air conditioning or window nets was associated with a noticeable reduction in bite intensity.

Controle de qualite lors de l'evaluation echographique de la morbidite due a Schistosoma haematobium au Niger

Lors d'un programme de lutte contre la bilharziose urinaire au Niger; il a ete procede a un controle de qualite au cours d'enquetes d'eva l u ation ech ographique de la morbidite due a Schistosoma haematobium. L'objectif etait d'evaluer la vari abilite et la r ro d u c t ibilite des donnees epidemiologiques fournies par deux observat e u rs independants specialement fo rmes. Trois types d'enquetes ont ete menes : etude de la variabilite inter- observateur sur donnees appariees; etude de la vari abilite inter- observateur au niveau communautaire sur les memes sujets ou des sujets differents; y compris apres traitement parpra z i q u a n t e l ; etude de la va ri ab ilite intra- observateur. Au total; 1416 habitants de 10 vill ages hyperendemiques; dont 70 p. 100 d'enfants scolarises; ont subi 1750 examens ech ographiques selon le protocole OMS du Caire legerement modifie. La vari abilite inter- o b s e rvateur au niveau individuel etait elevee pour certaines anomalies vesicales elementaires. Elle etait d'environ 20 p. 100 pour les deux indicat e u rs synthetiques que sont la presence d'au moins une anomalie urinaire et la dilat ation du tractus uri n a i re superi e u r. Au niveau communautaire; la vari abilite inter- observateur etait moderee et les deux observat e u rs donnaient globalement le meme diagnostic sur le niveau de morbidite lie a S chistosoma haemat o b i u m. Les vari ations de morbidite liees au niveau d'endemicite etait percues para llelement. Les memes observations au niveau individuel ou communautaire ont ete faites quant a la variabilite intra - o b s e rvateur. Au cours d'un programme de controle; les ultrasons sont senses fournir des indicateurs epidemiologiques de morbidite afin d'orienter les activites de lutte (selection des communautes a risque; periodicite des traitements). Dans cette optique; les variations d'eva l u ation de la morbidite liees a l'ech ograp h i s t e observees au Niger sont accep t ables au niveau communautaire

[Experimental infection of goats with Schistosoma bovis and S. curassoni: comparative pathogenic effects]. / Infestation expérimentale de caprins par Schistosoma bovis et S. curassoni: effets pathogènes comparés.

Specific mortality and morbidity have been quantified in goats experimentally infected with Schistosoma bovis or S. curassoni strains from Niger. The study involved nine animals followed during 380 days after infection with, respectively, 1,800 or 2,400 cercariae. S. bovis was significatively more pathogenic than S. curossoni in terms of mortality, weight loss and packed cell volume decrease. In addition, the intensity of clinical symptoms was significatively and positively correlated to the levels of fecal egg excretion. Compared to non-infected controls, a growth differential of, respectively, 1,600 and 880 grams per month should incite to consider S. bovis and S. curassoni as parasites of serious economical impact in sahelian countries.

Helenalin reduces Staphylococcus aureus infection in vitro and in vivo.

Staphylococcus (S.) aureus is a major udder pathogen causing bovine mastitis. Some pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), enhance extracellular and intracellular growth of S. aureus, indicating that the inflammatory process favors S. aureus infection. Helenalin is a sesquiterpene lactone with potent anti-inflammatory properties. This study was designed to evaluate the effects of helenalin on S. aureus infection. First, in vitro experiments were conducted. These studies revealed that proliferation of S. aureus in bovine mammary epithelial MAC-T cells treated in the presence or absence of TNF-alpha was markedly reduced in the presence of helenalin. Secondly, in vivo effects of helenalin were investigated. Lactating mice treated in the presence or absence of helenalin were challenged by the intramammary route with S. aureus and the bacteria in the mammary glands were counted 12 h after infection. Significantly less numbers of bacteria were recovered from the infected glands of helenalin-treated mice compared with untreated mice. Moreover, histological examination of mammary tissue from helenalin-treated mice that were challenged with S. aureus indicated that helenalin is able to significantly reduce leukocyte infiltration in the mammary gland following S. aureus inoculation. Our results show that helenalin reduces S. aureus intracellular growth and experimental S. aureus infection. We conclude that helenalin may be of potential interest in the treatment of S. aureus-induced mastitis in the bovine species.

Delayed neutrophil apoptosis in bovine subclinical mastitis.

Bovine subclinical mastitis can be defined as a moderated inflammatory disease characterized by a persistent accumulation of neutrophils in milk. As GMCSF-mediated delay of neutrophil apoptosis contributes to the accumulation of inflammatory cells at the site of inflammation in many human diseases, we sought to determine whether subclinical mastitis in cows is also associated with a GMCSF-dependent increase in milk-neutrophil survival. We first addressed the hypothesis that GMCSF delays bovine neutrophil apoptosis by activation of the signal transducer and activator of transcription (STAT) family members STAT3 and STAT5, which are critical regulators of the expression of various Bcl-2 family proteins. Granulocyte-macrophage colony-stimulating factor significantly delayed apoptosis of blood neutrophils obtained from healthy cows. In these cells, GMCSF activated STAT5, but not STAT3, and induced an increase in the mRNA of the antiapoptotic Bcl-2 member, Bcl-xL. Granulocyte-macrophage colony-stimulating factor-dependent STAT5 activation and up-regulation of Bcl-xL mRNA were blocked by the Jak inhibitor, AG-490. This inhibition was associated with abrogation of the prosurvival effect of GMCSF, demonstrating a key role for STAT5 in delayed neutrophil apoptosis. We further found that GMCSF expression was increased in milk cells from cows affected with subclinical mastitis. Neutrophils from these cows demonstrated a significant delay of apoptosis as compared with neutrophils obtained from healthy cows and were unresponsive to GMCSF. Active STAT5 complexes were detected in these neutrophils. Finally, in the presence of AG-490, apoptosis was induced and a time-dependent down-regulation of Bcl-xL mRNA was observed in milk neutrophils from mastitis-affected cows. These results indicate that neutrophil survival is enhanced in milk of subclinical mastitis-affected cows and suggest a role for a GMCSF-activated STAT5 signaling pathway in this phenomenon. This pathway could thus represent a target for the control of persistent accumulation of neutrophils in the bovine mammary gland.

Increased nuclear factor kappaB activity in milk cells of mastitis-affected cows.

Bacterial mastitis is accompanied by a drastic increase in milk somatic cell count (SCC), with neutrophils being the predominant cell type found in the infected quarters. Accumulation and activation of neutrophils at the site of infection require local expression of many inflammatory genes encoding adhesion molecules, chemokines and cytokines. Most of the inflammatory genes contain binding sites for the nuclear factor kappaB (NF-kappaB) within their promoter and therefore partly depend on NF-kappaB for their expression. We thus hypothesized that an increase in NF-kappaB activity in the mammary gland could contribute to development of the neutrophilic inflammation that characterizes mastitis. In an attempt to verify this hypothesis, we first assessed milk cells from healthy and acute and chronic mastitis-affected cows for NF-kappaB activity using electrophoretic mobility shift assays. We next studied the relationships between the intensity of NF-kappaB activity in these cells and the degree of udder inflammation. Active NF-kappaB complexes were undetectable in milk cells from healthy cows, whereas high levels of NF-kappaB activity were always found in cells from cows with acute mastitis. In milk cells obtained from chronic mastitis-affected cows, NF-kappaB activity varied from low to high. Finally, the level of NF-kappaB activity measured in milk cells from chronic mastitis-affected cows was not correlated to SCC or to the proportion of neutrophils present in milk samples, but was highly correlated with the expression level of interleukin-8 and granulocyte/macrophage colony-stimulating factor, two NF-kappaB-dependent cytokines crucially involved in initiation and perpetuation of neutrophilic inflammation. These results suggest that NF-kappaB might play a role in mastitis pathogenesis.

[Quality control during ultrasonographic evaluation of morbidity due to Schistosoma haematobium in Niger]. / Contrôle de qualité lors de l'évaluation échographique de la morbidité due à Schistosoma haematobium au Niger.

Within the framework of a campaign to control urinary schistosomiasis in Niger, a quality control audit was performed on ultrasonographic assessment of morbidity due to Schistosoma haematobium. The purpose of this audit was to determine variance and reproductibility of epidemiological data provided by two trained independent observers. Three parameters were studied, i.e.,: interobserver variability on matched data, interobserver variance at the community level on the same or different subjects, including some after treatment with praziquantel, and intra-observer variance. A total of 1750 ultrasound examinations were carried out on 1416 inhabitants from 10 hyperendemic villages (70 p. 100 schoolchildren) according to a slightly modified version of the WHO Cairo protocol. Inter-observer variance at the individual level was high for some elementary abnormalities of the bladder. Variance was around 20 p. 100 for the 2 main indicators, i.e. presence of at least one bladder lesion and dilatation of the upper urinary tract. At the community level, inter-observer variance was moderate and the two observers' global assessment of morbidity due to Schistosoma haematobium was the same. Variations of morbidity related to level of endemicity were given perceived in parallel. Similar findings were noted for the intra-observer variability at the individual or community level. Ultrasound examination is supposed to furnish reliable morbidity data for selecting communities at risk and scheduling treatments during schistosomiasis control programs. The results of this study show that the level of inter- and intra-observer variance in ultrasonographic assessment in Niger is compatible with this critical role.

Use of gel electrophoresis for the study of enzymatic activities of cold-adapted bacteria.

Glutamate dehydrogenase (GDH) and lactate dehydrogenase (LDH) activity of 13 cold-adapted strains, isolated from cold soils and showing GDH and/or LDH activity in spectrophotometric assays, were revealed by the use of electrophoresis on a nondenaturing acrylamide gel (zymogram). Psychrophilic strains were grown at 4 degrees C and 10 degrees C and the psychrotolerant strains at 4 degrees, 20 degrees and 28 degrees C. Incubation with the specific substrate and staining were done at 4, 28 or 37 degrees C. In the most cold-adapted strains, LDH and GDH production was high at 4 degrees C. In psychrotrophic strains, enzyme production and activity were greater at 20 or 28 degrees C than at lower temperatures. LDH remained active up to 37 degrees C while GDH activity was more thermolabile. GDH activity was NAD-dependent in some psychrophilic strains. In other strains, it was dependent on NAD(P) only or on both NAD and NAD(P). Two bands were seen for GDH or LDH activity in some strains. This method, which does not require a dialysis step, can be used to study the influence of temperature on enzyme production and activity, and the co-factor dependence. It detects phenotypic differences between isozymes, providing data for systematics.

Morphogenesis and release of fowlpox virus.

Release of fowlpox virus (FWPV) as extracellular enveloped virus (EEV) appears to proceed both by the budding of intracellular mature virus (IMV) through the plasma membrane and by the fusion of intracellular enveloped virus (IEV) with the plasma membrane. Based on the frequency of budding events compared to wrapping events observed by electron microscopy, FWPV FP9 strain seems to exit chick embryo fibroblast cells predominantly by budding. In contrast to vaccinia virus (VV), the production of FWPV extracellular virus particles is not affected by N(1)-isonicotinoyl-N(2)-3-methyl-4-chlorobenzoylhydrazine (IMCBH). Comparison of the sequence of the VV F13L gene product with its FWPV orthologue showed a mutation, in the fowlpox protein, at the residue involved in IMCBH resistance in a mutant VV. Glucosamine, monensin or brefeldin A did not have any specific effect on FWPV extracellular virus production. Cytochalasin D, which inhibits the formation of actin filaments, reduces the production of extracellular virus particles by inhibiting the release of cell-associated enveloped virus (CEV) particles from the plasma membrane. Involvement of actin filaments in this mechanism is further supported by the co-localization of actin with viral particles close to the plasma membrane in the absence of cytochalasin D. Actin is also co-localized with virus factories.

Safety and immunogenicity of three doses of a Neisseria meningitidis A + C diphtheria conjugate vaccine in infants from Niger.

BACKGROUND: High rates of endemic disease and recurrent epidemics of serogroup A and C meningococcal meningitis continue to occur in sub-Saharan Africa. A meningococcal A + C polysaccharide diphtheria-toxoid-conjugated vaccine may address this issue. METHODS: In Niger three doses of a bivalent meningococcal A + C diphtheria-toxoid-conjugated vaccine (MenD), containing 1, 4 or 16 microg of each polysaccharide per dose, administered at 6, 10 and 14 weeks of age, were compared with Haemophilus influenzae type b-tetanus toxoid-conjugated (PRP-T) vaccine given with the same schedule or with a meningococcal A + C polysaccharide vaccine (MenPS) given at 10 and 14 weeks of age. One blood sample was taken at the time of enrollment (6 weeks of age) and another was taken 4 weeks after the primary series. RESULTS: All doses of MenD were well-tolerated. After the primary series a higher proportion of infants had detectable serum bactericidal activity against serogroup A for each dose of MenD (from 94% to 100%) than for MenPS (31%) or H. influenzae type b-tetanus toxoid-conjugated vaccine (18.9%); P < or = 0.05. Significant differences were also observed for serogroup C MenD 4 microg or MenD 16 microg (100%) vs. MenPS (69.7%) or Haemophilus influenzae type b-tetanus toxoid-conjugated vaccine (24.3%); P < or = 0.05. When MenPS vaccine was given to 11-month-old children, the immune response measured by both enzyme-linked immunosorbent assay and serum bactericidal assay was greater in those previously immunized with MenD than in those immunized with MenPS vaccine. CONCLUSION: MenD was safe among infants in Niger, and immunization led to significantly greater functional antibody activity than with MenPS. The 4-microg dose of MenD for both the A and C serogroups has been selected for further studies.

[Reduced morbidity of schistosomiasis: report from an expert workshop on the control of schistosomiasis held at CERMES (15-18 February 2000, Niamey, Niger)]. / Réduire la morbidité des schistosomoses: compte-rendu d'un atelier d'experts sur le contrôle des schistosomoses réunis au CERMES (15-18 février 2000, Niamey, Niger).

Schistosomiasis remains a problem for public health in sub-Saharan Africa. Despite past efforts, cases have not decreased significantly. Schistosoma haematobium and S. mansoni are endemic in all the West African countries. The distribution of both parasites is focal. During a workshop held at CERMES in Niamey, in February 2000, a group of experts recommended that schistosomiasis control be considered as a public health priority in all the endemic West African countries, and National Control Programmes rapidly implemented. The objective of these control programmes would be to reduce schistosomiasis-related morbidity. Case detection should be based on clinical symptoms such as haematuria or bloody diarrhoea, and be carried out at two levels: health care centres and schools, in order to reach patients and school-age children. Health workers should be trained in case detection and community based control of schistosomiasis. The assembled experts advocated the use of praziquantel dosed at 40 mg.kg-1, which therefore must be made available and accessible in outlying areas. Associated measures consist of sanitation, water supply and health education, especially aimed at improving patients' treatment-seeking behaviour. A West African network for schistosomiasis control was created during the workshop. It runs on the Web site of CERMES as network co-ordinator. (http://www.mpl.ird.fr/cermes/).

The oral route as a potential way of transmission of Schistosoma bovis in goats.

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.

Schistosoma bovis: vaccine effects of a recombinant homologous glutathione S-transferase in sheep.

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.

Vaccine potential of a recombinant glutathione S-transferase cloned from Schistosoma haematobium in primates experimentally infected with an homologous challenge.

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.

Response to conjugate Haemophilus influenzae B vaccine among infants in Niamey, Niger.

Despite near elimination of Haemophilus influenzae b (Hib) meningitis from several industrialized countries following introduction of conjugate Hib vaccines into infant immunization schedules, Hib remains a major cause of meningitis and pneumonia in resource-poor countries. In Niger, Hib causes nearly 200 cases of meningitis per 100,000 children < one year of age, and > 40% of cases are fatal. We evaluated the immunogenicity of Hib polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) administered in the same syringe as diphtheria-tetanus-pertussis (DTP) vaccine among infants in Niger. Infants were randomized into group 1 (PRP-T at six, 10, and 14 weeks), group 2 (PRP-T at 10 and 14 weeks), or a control group (meningococcal A/C polysaccharide vaccine). By 14 weeks of age, all subjects in groups land 2 had > or = 0.15 microg/ml of anti-PRP antibody, and 82% versus 76% had > or = 1.0 microg/ml of antibody (P=not significant). By nine months of age the proportion of infants with > or = 0.15 and > or = 1.0 microg/ml was group I=97% and 76%; group 2=93% and 67%; controls=10% and 2.6%. Four weeks after the first, second, and third doses of PRP-T, infants in group 1 showed geometric mean titers (GMTs) of 0.19, 3.97, and 6.09 microg/ml while infants in group 2 had GMTs of 2.40 and 4.41 microg/ml four weeks after the delayed first and second doses. Both PRP-T groups had significantly higher GMTs at 18 weeks and nine months of age than infants in the control group. The Hib PRP-T vaccine was immunogenic in infants in Niger. The strong response after PRP-T was initiated one month after the first DTP vaccination may reflect carrier priming. Two dose schedules of PRP-T should be given serious consideration, particularly if their reduced cost permits vaccine introduction that would be otherwise unaffordable.

Murine immune responses to Schistosoma haematobium and the vaccine candidate rSh28GST.

Longitudinal studies of Schistosoma haematobium infection in CBA mice revealed a progressive down-regulation of cellular immune responses, as measured by mitogenic and antigenic stimulation of in vitro lymphocyte cultures. Antigen-stimulated production of the Th1 cytokine IFN-gamma by splenocytes increased progressively up to 14 weeks post infection, (four weeks after the onset of parasite egg production), before declining swiftly. Levels of the Th2 cytokine IL-4 in the same cultures remained low until 14 weeks, after which they rose rapidly as IFN-gamma declined. High levels of IL-10 coincided with the peak in IFN-gamma production, suggesting a non Th2-restricted role for this cytokine. Both total and antigen-specific immunoglobulin production confirmed parasite egg deposition as being a major stimulus for host humoral responses. The S. haematobium infection failed to elicit detectable T cell responses to the antifecundity vaccine candidate rSh28GST. However, low levels of antibody were detectable in infected mouse serum and strong IgG and IgA production was induced by vaccination with rSh28GST plus adjuvant.

The 131-amino-acid repeat region of the essential 39-kilodalton core protein of fowlpox virus FP9, equivalent to vaccinia virus A4L protein, is nonessential and highly immunogenic.

The immunodominant, 39,000-molecular weight core protein (39K protein) of fowlpox virus (FP9 strain), equivalent to the vaccinia virus A4L gene product, contains highly charged domains at each end of the protein and multiple copies of a 12-amino-acid serine-rich repeat sequence in the middle of the protein. Similar repeats were also detected in other fowlpox virus strains, suggesting that they might confer a selective advantage to the virus. The molloscum contagiosum virus homolog (MC107L) also contains repeats, unlike the vaccinia virus protein. The number of repeats in the fowlpox virus protein does not seem to be crucial, since some strains have a different number of repeats, as shown by the difference in the size of the protein in these strains. The repeat region could be deleted, indicating that it is not essential for replication in vitro. It was not possible to delete the entire 39K protein, indicating that it was essential (transcriptional control signals for the flanking genes were left intact). The repeat region is partly responsible for the immunodominance of the protein, but the C-terminal part of the protein also contains highly antigenic linear epitopes. A role for the 39K protein in immune system modulation is discussed.

The WHO collaborating centre for research and control of schistosomiasis at Niamey, Niger

The Centre de Recherche sur les Meningites et les Schistosomes (CERMES) is a research institute depending on the Organisation de Coordination et de Cooperation pour la lutte contre les Grandes Endemies - a West African Organisation 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 parasite 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 sample field indicators; (c) immune response and protective immunity by recombinant glutathion S-transferase (Sm28, Sb28 and Sh28) in homologous and heterologous animal including goats, sheep and non human primates (Erythocebus 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 labotatories in developed countries (Europe and USA).

The WHO Collaborating Centre for Research and Control of Schistosomiasis at Niamey, Niger.

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).

PIP: The Centre de Recherche sur les Meningites et les Schistosomoses (CERMES), a research center in Niamey, Niger, affiliated with a West African public health organization, conducts studies in the areas of parasitology, epidemiology, and immunology. Significant variability in factors related to transmission of Schistosoma haematobium have been noted. Experimental research on the Schistosoma-bulinid compatibility and field surveys of the geographic distribution and role of snails in transmission have been essential to the design of parasite control interventions in West Africa. A CERMES-sponsored project, supported by the European Community, is examining urinary schistosomiasis control in the Niger river valley and the impact of treatment on ultrasonically visualized urologic lesions. The Experimental Vaccine Unit seeks to improve the route of administration and choice of adjuvant and to propose a vaccine protocol for field testing. Recombinant proteins have been found to alter the development of the parasite either by inducing a reduction in the parasite burden or an inhibition of the fecundity of the parasite.