[Spatiotemporal distribution of tuberculosis cases in the city of Saint-Louis Senegal from 2008-2011]. / Répartition spatio-temporelle des cas de tuberculose dans la ville de Saint-Louis du Sénégal entre 2008-2011.

BACKGROUND: We studied the incidence of tuberculosis in the health district of Saint-Louis, Senegal over a period of 4years (2008-2011). One thousand three hundred and eighty-six cases were identified, producing an annual standardized incidence ratio of 129 cases per 100,000 inhabitants. RESULTS: Men in the 15-24-year old age group were more likely to be affected, and diagnosis was more common in the second half of the year. Treatment compliance was excellent (96%), and the cure rate of patients with a TB-positive microscopic examination was 95%. The overall treatment failure rate was 1% and the 6-month morality was 2%. Seropositivity, measured in volunteer patients (48%) was 3%. CONCLUSION: A spatial and temporal map of tuberculosis in the city of Saint-Louis, Senegal has been established. A cluster appears to be very likely in Guet Ndar, a particularly dense population zone in a fishing area. There is also a possible secondary cluster at Pikine.

Central pyrogenic activity of muramyl dipeptide.

Fever can be elicited in the rabbit by the intravenous administration of relatively large doses of a synthetic immunoadjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine, or muramyl dipeptide (MDP). This response could be mediated by endogenous pyrogen because MDP has been shown to induce their production both in vivo and in vitro. The results reported here show that intracisternal injection of minute amounts of MDP could elevate fever without activating the release of endogenous pyrogen in the plasma or in the cerebrospinal fluid. Moreover, indomethacin inhibited hyperthermia produced by intracerebroventricular administration of MDP. Therefore, our findings argue in favor of a direct effect of the glycopeptide on the thermoregulatory centers besides its indirect effect through the production of leukocytic pyrogen. This molecule apparently represents the minimal requirement for the pyrogenicity of bacterial peptidoglycan because administration, even by the intracerebral route, of a mixture of muramic acid and of its dipeptide moiety did not elicit fever.

Influence of physicochemical parameters on the spatial distribution of snail species that are intermediate hosts of human schistosomes in the Senegal River Delta.

The objective of this work was to identify possible correlations between physicochemical parameters (water temperature, water flow velocity, electrical conductivity, dissolved oxygen, salinity, pH, nitrates, and phosphates) and the spatial distribution in the Senegal River delta of snail species that are intermediate hosts of human schistosomes. Eight water points (ME1 to ME4, NE1 and NE2, TA1 and TA2) were selected in the villages of Menguègne Boye, Ndellé Boye, and Thilla for biweekly monitoring of these snails and the physicochemical parameters of the water. The results show that the spatial distribution of the snail populations is related to pH, dissolved oxygen (mg/l), conductivity, temperature (̊C), and water flow velocity (m/s).

Role of environmental parameters on the density of intermediate host snails of human schistosoma during the year in the commune of Richard-Toll, Senegal.

The implementation and expansion of development projects (dams and irrigation schemes) in the Senegal River valley have led to a significant proliferation of snails. We conducted a one-year (2014) study project, monitoring their density in the commune of Richard Toll, to assess the role of environmental parameters on mollusc population dynamics. Four species involved in the transmission of human schistosomiasis were found: Bulinus globosus, B. truncatus, B. senegalensis, and Biomphalaria pfeifferi. Among the intermediate hosts, B. truncatus is the most abundant species, followed by B. globosus. Snail density depends on the nature of the water point but also on environmental parameters such as vegetation. This study showed that vegetation, water level (flood), and flow velocity influence the dynamics of the snail populations that are intermediate hosts of human schistosomes.

Homologous and heterologous protection after single intranasal administration of live attenuated recombinant Bordetella pertussis.

While single-dose mucosal immunization is best achieved by the use of attenuated live microorganisms, attenuation generally results in decreased immunogenicity. We attenuated Bordetella pertussis by the deletion of the pertussis toxin gene. A single intranasal administration of this strain protected against subsequent challenge as well as did the parent strain and better than immunization with commercial vaccine. Unexpectedly, this attenuation resulted in increased immunogenicity against the protective antigen filamentous hemagglutinin (FHA). In addition, immunogenicity was also enhanced against the Schistosoma mansoni Sm28GST genetically fused to FHA, resulting in protection against the parasite, as characterized by a reduction in worm burden and egg charge, after a single intranasal administration. Thus, attenuated recombinant B. pertussis strains are promising vectors for the simultaneous protection against pertussis and heterologous diseases by a single intranasal administration.

The schistosome glutathione S-transferase P28GST, a unique helminth protein, prevents intestinal inflammation in experimental colitis through a Th2-type response with mucosal eosinophils.

Intestinal helminth parasites are potent inducers of T helper type 2 (Th2) response and have a regulatory role, notably on intestinal inflammation. As infection with schistosomes is unlikely to provide a reliable treatment of inflammatory bowel diseases, we have investigated the beneficial effect of a schistosome enzymatic protein, the 28-kDa glutathione S-transferase (P28GST), on the modulation of disease activity and immune responses in experimental colitis. Our results showed that immunization with recombinant P28GST is at least as efficient as established schistosome infection to reduce colitis lesions and expression of pro-inflammatory cytokines. Considering underlying mechanisms, the decrease of inflammatory parameters was associated with the polarization of the immune system toward a Th2 profile, with local and systemic increases of interleukin (IL)-13 and IL-5. Dense eosinophil infiltration was observed in the colons of P28GST-immunized rats and mice. Depletion of eosinophils by treatment with an anti-Siglec-F monoclonal antibody and use of IL-5-deficient mice led to the loss of therapeutic effect, suggesting the crucial role for eosinophils in colitis prevention by P28GST. These findings reveal that immunization with P28GST, a unique recombinant schistosome enzyme, ameliorates intestinal inflammation through eosinophil-dependent modulation of harmful type 1 responses, representing a new immuno-regulatory strategy against inflammatory bowel diseases.

Synthetic peptide vaccines against pathogens and biological mediators.

Recent advances in immunology and biotechnology have opened the way for new approaches to vaccine design. Gilles Riveau and Françoise Audibert discuss progress in the design of synthetic peptide antigens for vaccines against pathogens, and discuss the possibility that such vaccines could also be used to control the activity of endogenous mediators.

Changes in rabbit febrile responses to muramyl dipeptide (MDP) after coupling to a synthetic carrier.

Muramyl dipeptide (MDP) is a small molecular weight synthetic glycopeptide (less than 500), which has been shown to be an immunoadjuvant, and to induce a biphasic febrile response in the rabbit--probably via the release of endogenous pyrogen--accompanied by a marked leukopenia. Macromolecularization by coupling to a synthetic carrier (MW approximately or equal to 60,000) potentiates the immunostimulant properties of MDP but also its pyrogenicity. The present study demonstrates that such a conjugate induced the release of endogenous pyrogen in vivo and in vitro at lower dosage levels than free MDP. Further experiments showed that there existed several differences between free and conjugated MDP. Thus, after intravenous administration of the conjugate, the fever pattern was monophasic with a prompt defervescence and not accompanied by leukopenia at dosage levels inducing similar increase in body temperature. In addition, when fever was recorded after intracerebroventricular administration, the increase in sensitivity was much greater in the case of free MDP than of MDP-A--L.

Decrease in pyrogenicity of muramyl dipeptide after coupling with luteinizing hormone-releasing hormone.

Muramyl dipeptide (MDP) and its adjuvant active derivative lysine-MDP (Lys-MDP) have been demonstrated to be pyrogenic and to induce endogenous pyrogen (EP) production in vivo and in vitro. It has recently been shown that immunologic castration can be achieved in mice by immunization with luteinizing hormone-releasing hormone (LHRH) directly conjugated by carbodiimide to Lys-MDP, termed LHRH-Lys-MDP (cdi), or with a linear monomeric MDP-linked molecule obtained by total synthesis, termed LHRH-Lys-MDP (s). These preparations were tested in the rabbit for their capacity to induce fever and were found to be devoid of pyrogenicity at dosage levels of Lys-MDP that induced fever. This decrease of pyrogenicity of Lys-MDP after coupling to LHRH seems to be related to the structure of the conjugate because the derivative LHRH-LysNH2-MDP exhibited the same pyrogenic activity as the free glycopeptide. Surprisingly, nonpyrogenic LHRH-Lys-MDP induced production of EP and interleukin-1 (IL-1) in vitro and increased in vivo modifications of metal levels attributed to the action of IL-1. Moreover, LHRH-Lys-MDP reduced the pyrogenic effect of an exogenous dose of EP.

Production of differentiation-stimulating factor for murine leukemic myeloblast line by monocytic cells stimulated by a nonpyrogenic muramyl dipeptide derivative.

Muramyl dipeptide (MDP) and adjuvant-active derivatives were confirmed as unable directly to induce differentiation of mouse myeloid leukemia M1 cells. They were, however, found effective in stimulating either rabbit macrophages or human blood monocytes to produce differentiation-stimulating activity (D factor). The various conditioned media (CM) thus obtained were able to induce differentiation of the myeloblastic M1 cell line as indicated by the appearance of Fc receptors and inhibition of cell proliferation. Among the synthetic glycopeptides inducing the production of D factor, murabutide (MDP[Gln]-OnBu) was as effective as MDP, although it did not stimulate monocytes to simultaneously release endogenous pyrogen. The absence of pyrogenicity in murabutide CM was attested by IV or intracerebroventricular administration to rabbits. However, in the same CM, LAF(IL1) activity estimated by potentiation of the in vitro proliferative response to phytohemagglutinin of mouse thymocytes was usually higher than that induced by MDP.

Malaria co-infection in children influences antibody response to schistosome antigens and inflammatory markers associated with morbidity.

The epidemiological coexistence of schistosomiasis and malaria is frequently observed in developing countries. Co-infection with malaria in children could influence the development of acquired immunity associated with the resistance or the pathology of schistosomiasis. In the present study, performed during May to June 1996 in Senegal, the humoral immune response to Schistosoma haematobium 28 kDa glutathione S-transferase (Sh28GST) vaccinal antigen and to soluble egg antigens (SEA) has been evaluated in individuals infected by S. haematobium. Specific immunoglobulin G3 (IgG3) and IgE responses were significantly higher in co-infected children with Plasmodium falciparum compared with children infected with S. haematobium only. In addition, circulating levels of interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and soluble tumor necrosis factor receptor II (sTNF-RII), 3 parameters associated with schistosomiasis morbidity, were significantly increased in co-infected children. Taken together, this study indicated that malaria co-infection can both influence the acquired specific immune response to schistosome antigens and unbalance the regulation of inflammatory factors closely involved in schistosomiasis pathology.

Failure of a recombinant Schistosoma bovis-derived glutathione S-transferase to protect cattle against experimental Fasciola hepatica infection.

The potential of a recombinant Schistosoma bovis 28-kDa glutathione S-transferase (rSb28GST) to protect cattle against Fasciola hepatica was tested in a vaccination trial. Thirty two calves were randomly divided into four groups of eight animals. Calves of the three vaccine groups received two intramuscular injections at 3 weeks interval, of 0.250mg rSb28GST in either aluminium hydroxide (Al(OH)(3)), Quil A, or PBS emulsified in an equal volume of Freund's complete adjuvant (FCA).Animals of the control group received injections of Al(OH)(3)/PBS only. All animals were challenged orally with a total of 360 metacercariae of F. hepatica, spread over 6 weeks. All groups of vaccinated animals produced measurable IgG antibody titers to rSb28GST after vaccination. Animals immunised with FCA adjuvanted vaccine had the highest and more durable antibody titers and only sera from this group recognised an approximately 24kDa protein band from F. hepatica, that is thought to be a F. hepatica GST. Despite a good antibody response differences in cumulative faecal egg output between the groups were not statistically significant. In addition, no significant difference was found between groups in terms of total worm numbers or percentage of immature flukes recovered at necropsy. In conclusion, the recombinant S. bovis 28kDa GST was not found to adequately protect cattle against experimental F. hepatica challenge, using either aluminium hydroxide, Quil A or FCA as adjuvant.

[Predictive ultrasonographic criteria for portal hypertension due to Schistosoma mansoni in a recently established endemiz zone]. / Critères echographiques prédictifs d'hypertension portale due à Schistosoma mansoni dans une zone d'endémie récente.

The first cases of Schistosoma mansoni infection were reported in the Senegal River Basin ten years ago. Today endemicity is so high that prevalence rates exceed 90 p. 100 in some areas. Schistosomiasis sometimes goes undiagnosed until the occurrence of portal hypertension with rupture of esophageal varices. Endoscopy is the gold standard for detection of esophageal varices but it is impractical in remote areas. Ultrasonography has been proposed as a non-invasive alternative. The purpose of this study is to describe the results of simultaneous endoscopic and ultrasonographic assessment in 101 subjects from the Richard-Toll area of the Senegal River Basin. Findings showed that severe forms of schistosomiasis complicated by portal hypertension were already present in the region less 10 years after description of the first case. This study also proposes a diagnostic score for portal hypertension based on ultrasonographic findings. The features included in this score are thickening of portal vessel walls, portal vessel diameter, and collapsed appearance of the splenic vein during inspiration. In our hands this score allowed reliable prediction of the development of esophageal varices. Ultrasonography is a good tool for identifying severe forms of schistosomiasis. It should be useful for routine screening in recently established endemic zones.

[Infectious etiology of diarrheal morbidity in a Senegalese region of high exposure to Schistosoma mansoni]. / Etiologie infectieuse de la morbidité diarrheique dans un foyer sénégalais fortement exposé à Schistosoma mansoni.

Endemic schistosomiasis due to Schistosoma mansoni has been observed in Richard-Toll (The Senegal River basin) in Senegal since 1990. Because of its high prevalence, schistosomiasis is assumed to be the cause of most cases of diarrhea observed in the region. The purpose of the present study carried out within the framework of the ESPOIR program for control of bilharziasis in the Senegal River region was to confirm the exact etiology of diarrhea in the region. A total of 109 subjects presenting diarrhea including 57 children under the age of 5 years were included in the study. In all cases, stool examination using appropriate techniques was performed to detect bacterial, viral, and parasitic agents. Schistosoma mansoni was identified in 47 cases (43.1%). Stool cultures were positive in 28 cases (25.6%) for Escherichia coli (n = 9), Shigella spp. (n = 18), and Salmonella spp. (n = 1). With regard to Shigella, a predominance of the Shigella dysenteriae type I stereotype (10/18) and a high incidence of co-infection involving Shigella spp. and Schistosoma was noted. Rotavirus infection was observed in 6 cases involving subjects under the age of 5 years. The relative incidence of the different infectious agents varied widely in function of age. This study in an endemic area of bilharziasis in Senegal demonstrates that Schistosoma mansoni should not be assumed to account for all cases of diarrhea occurring in the area.

Differential effect of MDP treatment on magnesium in rat tissues.

Magnesium determinations were performed by atomic absorption spectrophotometry on several tissues of MDP-treated and control rats. Sixteen hours after a single administration of 1 mg of MDP, Mg concentrations were increased in both the liver and the adrenals. After three daily injections of the same MDP doses, statistically significant increases of Mg concentration were observed in the liver, the brain and the adrenals. For the latter, however, the results were significant only when Mg concentrations were referred to the weight of tissue water but not when they were referred to the dry weight. Blood, thymus, spleen, kidneys, cardiac and skeletal muscle Mg determinations were also performed; no significant effect of MDP has been observed under our experimental conditions. The present results show that MDP modifies the distribution of Mg in various compartments of the body and suggest the possible role of Mg in some biological actions of MDP.

Influence of indomethacin on various immunopharmacological effects of muramyl dipeptide (MDP).

Muramyl dipeptide (MDP) is a low molecular (less than 500 daltons) synthetic analogue of a streptococcal peptidoglycan subunit. It was demonstrated to be the minimal structure essential for eliciting the adjuvant effect ascribed to Freund's complete adjuvant (FCA). MDP was likewise shown to represent the minimal requirement for peptidoglycan-induced changes in temperature and it was at first concluded that there was an almost perfect correlation between pyrogenicity and adjuvant activity. However, other experiments showed that certain MDP derivatives were as adjuvant active without eliciting a febrile response in the rabbit. Moreover an anti-inflammatory substance such as indomethacin completely inhibits the pyrogenic effect of MDP but does not affect or even enhance various of its immunostimulant properties. Inhibition of MDP-induced fever is not associated with modification of leucopenia or production of circulating endogenous pyrogens observed after MDP injection. Indomethacin incubated with peritoneal macrophage cultures at a dose which blocks prostaglandin synthesis, does not decrease the production by MDP of endogenous pyrogens.

Inhibition of endogenous pyrogen-induced fever by a muramyl dipeptide derivative.

N-acetylmuramyl-L-alanyl-D-isoglutamine, or muramyl dipeptide (MDP), is a synthetic immunoadjuvant analogue of a bacterial peptidoglycan subunit that has a definite pyrogenic effect in the rabbit. Some adjuvant-active derivatives such as murabutide [MDP(Gln)-OnBu] or murametide [MDP(Gln)-OMe] are not pyrogenic. Murabutide did not stimulate human or rabbit cells to release endogenous pyrogen (EP), but murametide induced EP production at the same dosage levels as MDP. Moreover, plasma from rabbits treated with murametide transferred into untreated recipients elicited a febrile response typical of EP fever and comparable with that induced by plasma from MDP-treated animals. Murametide not only inhibited the central effect of EP that is generated but also the effect of an extra dose of EP administered later by the intravenous route. Moreover, pretreatment of rabbits with murametide decreased fever responses induced by certain high-molecular-weight exogenous pyrogens as mediated through the production of EP.

Control of schistosomiasis pathology by combination of Sm28GST DNA immunization and praziquantel treatment.

Today the control of schistosomiasis infection relies only on the use of praziquantel (PZQ) chemotherapy. However, PZQ treatment cannot prevent reinfection and progressive development of the pathology. We assessed in a mouse model the efficiency of a combined therapy, based on the combination of PZQ chemotherapy with Schistosoma mansoni 28-kDa glutathion S-transferase (Sm28GST) DNA vaccination, designed to limit the pathology. Following this combined therapy, the long-term survival of the mice was significantly enhanced in comparison with the survival of mice either vaccinated only or treated with PZQ only. In addition, the development of the pathology observed in the control groups was almost completely prevented in the vaccinated-PZQ-treated mice and was associated with a dramatic reduction of egg deposition in the tissues. We showed that PZQ treatment induced the unmasking of the native GST enzyme at the surface of the worms, thus permitting its neutralization by the antibodies raised by DNA immunization. This study provides insights into the synergistic mechanisms involved in an immunointervention strategy associated with chemotherapy for the control of a chronic infection and its associated pathology.

Influence of phospholipid composition on antibody responses to liposome encapsulated protein and peptide antigens.

The effect of phospholipid composition on mouse IgG antibody responses to liposomal bovine serum albumin (BSA), murine monoclonal antibody GK1.5 (anti-CD4) or a 21 amino acid peptide from the second conserved domain of HIV gp120 after s.c. administration, and on the IgA, IgE, and IgG antibody response to liposomal Shistosoma mansoni glutathione-S-transferase (Sm28GST) after oral administration, was determined. Antibody responses were compared with alum-adsorbed and N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP)-antigen mixtures. For the s.c. route, dipalmitoylphosphatidylcholine (DPPC)/dimyristoylphosphatidylglycerol (DMPG) liposomes induced 54-60% IgG1 and 35-44% IgG(2a+2b). DPPC/dipalmitoylphosphatidylethanolamine (DPPE) liposomes induced 73-78% IgG1 and 15-25% IgG(2a+2b). DPPC/ phosphatidylserine (PS) liposomes induced 86-89% IgG1 and 8-12% IgG(2a+2b). Alum and MDP induced 79-91% IgG1 and 4-17% IgG(2a+2b). The rank order of adjuvanticity for induction of IgG antibody was DPPC/DMPGDPPC/PE > > alum > > MDPDPPC/PS for all three antigens. DPPC/DMPG liposomes were the only effective adjuvant for the induction of secretory IgA and circulatory IgE and IgG antibodies against Sm28GST after oral administration. The failure of liposome-antigen mixtures to elicit an antibody response showed that liposomal incorporation of the antigens was obligatory for adjuvant activity. These results demonstrate that the correlation between phospholipid composition and adjuvanticity is independent of liposome charge, antigen, or route of administration.