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.

Low use of artemisinin-based combination therapy for febrile children under five and barriers to correct fever management in Benin: a decade after WHO recommendation.

BACKGROUND: Artemisinin-based combination therapy (ACT), used to treat uncomplicated malaria cases, is one of the main strategies of malaria control and elimination. One of the main objectives of the Benin National Malaria Control Program's (NMCP) strategic plan is to ensure that at least 80% of uncomplicated malaria is treated with ACT within 24 h. Therefore, it was of great interest to measure whether the country case management of fever amongst children under five, adhered to the NMCP's strategic plan and look into the barriers to the use of ACT. METHODS: A cross-sectional survey based on a cluster and multi-stage sampling was conducted in two rural health districts in Benin. We recruited 768 and 594 children under five years were included in the northern and in the southern respectively. Data was collected on the general use of ACT and on the correct use of ACT that adheres to the NMCP's strategy, as well as the barriers that prevent the proper management of fever amongst children. To assess the certain predictors of ACT usage, logistic regression was used, while taking into account the cluster random effect. RESULTS: Among febrile children aged 6 to 59 months, 20.7% in the south and 33.9% in north received ACT. The correct use of ACT, was very low, 5.8% and in southern and 8.6% northern areas. Caregivers who received information on ACT were 3.13 time more likely in the south and 2.98 time more likely in the north to give ACT to their feverish child, PPR = 3.13[1.72-4.15] and PPR = 2.98 [2.72-3.11] respectively. Chloroquine and quinine, other malaria treatments not recommended by NMCP, were still being used in both areas: 12.3 and 3.3% in the south and 11.4 and 3.0% in the north. CONCLUSION: In Benin, the use and the correct use of ACT for febrile children remains low. The study also showed that having received information about the use of ACT is positively associated with the use of ACT. This point highlights the fact that efforts may not have been sufficiently integrated with social communication, which should be based on the behavioural determinants of populations.

First screening of Aedes albopictus immunogenic salivary proteins.

Study of the human antibody (Ab) response to Aedes salivary proteins can provide new biomarkers to evaluate human exposure to vector bites. The identification of genus- and/or species-specific proteins is necessary to improve the accuracy of biomarkers. We analysed Aedes albopictus immunogenic salivary proteins by 2D immunoproteomic technology and compared the profiles according to human individual exposure to Ae. albopictus or Ae. aegypti bites. Strong antigenicity to Ae. albopictus salivary proteins was detected in all individuals whatever the nature of Aedes exposure. Amongst these antigenic proteins, 68% are involved in blood feeding, including D7 protein family, adenosine deaminase, serpin and apyrase. This study provides an insight into the repertoire of Ae. albopictus immunogenic salivary proteins for the first time.

Criteres echographiques predictifs d'hypertension portale due a Schistosoma mansoni dans une zone d'endemie recente

Les premiers cas de bilharziose a Schistosoma mansoni ont ete depistes dans la vallee du fleuve Senegal il y a dix ans. Aujourd'hui; le niveau d'endemie est tel que certains villages presentent des prevalences superieures a 90 p. 100. Le diagnostic de schistosomose n'est parfois porte qu'au stade d'hypertension portale (rupture de varices oesophagiennes). L'endoscopie est l'examen de reference pour detecter la presence de varices oesophagiennes; mais son application sur le terrain est delicate. C'est pourquoi leur recherche par echographie; acte non invasif; est d'un grand interet. Cette etude a recherche chez 101 sujets de la region de Richard-Toll l'existence de signes d'hypertension portale; simultanement par fibroscopie digestive et par echographie. Elle a montre que moins de 10 ans apres la description du premier cas de bilharziose; il existait deja des formes compliquees d'hypertension portale dans la region. Cette etude a egalement cherche a etablir un score echographique permettant de predire l'existence d'une hypertension portale. Les items retenus ont ete l'epaississement de la paroi des vaisseaux portes; le diametre de la veine porte et de la veine splenique et l'aspect collabe ou non de la veine splenique pendant l'inspiration. Au cours de l'etude; l'echelle de score ainsi etablie a semble etre un bon temoin predictif du developpement de varices oesophagiennes. L'echographie represente un examen utile pour le depistage des formes compliquees de schistosomoses susceptibles de representer un moyen simple de surveillance des populations residant en zone d'endemie recente et intense de schistosomose

Schistosomiasis co-infection in humans influences inflammatory markers in uncomplicated Plasmodium falciparum malaria.

Malaria and schistosomiasis are the two major parasite diseases present in developing countries. The epidemiological co-infection with schistosomiasis could influence the development of the physiological reaction associated with Plasmodium falciparum infection in human. Most studies have demonstrated the association of circulating levels of interferon-gamma (IFN-gamma), tumour necrosis factor-a (TNF-alpha), interleukin-10 (IL-10), transforming growth factor (TGF-beta) and soluble Tumour Necrosis Factor Receptors (sTNF-RI and sTNF-RII) with the morbidity of malaria. In the present study, we showed that Schistosoma haematobium co-infection influences, in an age-dependent manner, the unbalance between pro- and anti-inflammatory circulating cytokines that play a key role during malaria infection. Indeed, children co-infected by S. haematobium have higher levels of IFN-gamma and sTNF-RII than children infected only by P. falciparum. In contrast, co-infected adults presented a significant increase of IFN-gamma, IL-10, TGF-beta, sTNF-RI and sTNF-RII rates and IL-10/TNF-alpha ratio. Taken together, this study indicates that schistosomiasis co-infection can unbalance the regulation of inflammatory factors in uncomplicated P. falciparum malaria. The possible consequences of the schistosomiasis co-infection for age-dependent malaria morbidity are discussed.

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.

Gender-dependent specific immune response during chronic human Schistosomiasis haematobia.

The cellular and humoral acquired immune responses to Schistosoma haematobium 28 kD gluthathione S-Transferase (Sh28GST) antigen were evaluated in a Senegalese population chronically infected with S. haematobium parasite. We show a gender-dependent immune response in adult individuals presenting similar intensities of infection. Indeed, the specific IgA response and production of TGF-beta and IL-10 were found significantly higher in females compared to males. In addition, we showed that this profile was combined with a weak production of Th1-related cytokines (TNFalpha and IFNgamma) and was associated with an absence of proliferation to the antigen. A significantly higher Nuclear Matrix Protein 41/7 secretion, an apoptosis marker, was specifically observed in mononuclear blood cell cultures of females suggesting that a specific cell death process was engaged in a gender-dependent manner. This specific profile could be associated with the so-called T helper type-3 (Th3) immune response specifically promoting the production of IgA and would be developed upon the down-regulation of the specific Type-1 response by a probable cell death mechanism. This gender-dependent immune regulation, which may be under the influence of nonimmunological factors like sexual hormones, may be related to the chronicity of the infection.

[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.

Sex-dependent neutralizing humoral response to Schistosoma mansoni 28GST antigen in infected human populations.

The reduction of Schistosoma fecundity observed after experimental vaccination with the Schistosoma mansoni 28-kDa glutathione S-transferase (Sm28GST) antigen has been related to the inhibition of glutathione S-transferase (GST) enzymatic activity by specific antibody. The humoral immune response to the protective antigen Sm28GST and to the epitopes involved in the enzymatic site (amino acid ¿aa sequences 10-43 and 190-211) was evaluated in infected individuals before chemotherapy treatment. The capacity of the serum samples to inhibit GST enzymatic activity was assessed. Specific IgG3 response was predominant in the male population with a low intensity of infection and was associated with maximal GST inhibition. In contrast, the neutralizing activity of serum samples from women with a low intensity of infection was correlated with high specific IgA response specifically directed toward the 190-211 epitope. These results strongly support the hypothesis that GST-neutralizing IgG3 and IgA isotypes are sex dependent. The relationship of this specific acquired immune response with the level of intensity of infection is discussed.

Cellular immune responses of a Senegalese community recently exposed to Schistosoma mansoni: correlations of infection level with age and inflammatory cytokine production by soluble egg antigen-specific cells.

A recently reported epidemic of Schistosoma mansoni infection in Senegal provided an opportunity to study the dynamics of the development of immunity to human schistosomiasis. We report here on the cell-mediated immune response in a population of 99 females and 95 males, with particular emphasis on the relationship between intensity of infection and age. We found that the intensity of infection correlated negatively with age in females but not in males. In men and women, both Th1- and Th2-type cytokines were detected upon in vitro stimulation of PBMCs with soluble egg antigen (SEA) or soluble adult worm antigens (SWAP). In the female group, SEA-induced PBMC proliferation was associated with the production of IFN-gamma, IL-2 and IL-5, all of which correlated negatively with intensity of infection. Most cytokine production correlated positively with age. Spontaneous production of TNF-alpha, IL-6 and IL-10 was higher in the infected population than in an uninfected control group. Our results suggest that immunity to infection could be more pronounced in the female population and associated with a Th0/1 + 2 pattern of cytokine secretion mediated by soluble egg antigen (SEA).

Dermal endothelial cells and keratinocytes produce IL-7 in vivo after human Schistosoma mansoni percutaneous infection.

The parasite Schistosoma mansoni infects its definitive mammalian host through an obligatory cutaneous penetration. In this work, we studied early immune response following migration of larvae through human skin, the first immunocompetent organ encountered by the parasite. For this purpose we used an experimental model of severe combined immunodeficient mice engrafted with human skin and injected with autologous PBL. Six days after percutaneous infection, we observed an infiltration of lymphocytes within the human skin, predominantly composed of CD4+ T cells. Moreover, among the cytokines potentially present in the infected skin, immunohistochemistry analysis revealed an in vivo expression of IL-7 in the epidermal layers and strikingly at the level of vascular endothelium. Using an in vitro coculture system, we showed that the S. mansoni larvae directly trigger IL-7 production by human dermal microvascular endothelial cells but not by keratinocytes. Finally, measurements of IL-7 concentrations in plasma of 187 S. mansoni-infected individuals showed that the youngest, which are also the most infected, displayed the highest IL-7 levels. Together, these findings describe dermal endothelial cells as a novel source of IL-7, a cytokine particularly important in schistosomiasis.

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.

Bordetella pertussis filamentous hemagglutinin enhances the immunogenicity of liposome-delivered antigen administered intranasally.

In an attempt to increase the immunogenicity of mucosally delivered antigens, we incorporated the Bordetella pertussis filamentous hemagglutinin (FHA) adhesin into liposomes containing the glutathione S-transferase of Schistosoma mansoni (Sm28GST) as a model antigen. Outbred mice immunized twice intranasally with liposomes containing a constant suboptimal dose of Sm28GST and increasing doses of FHA produced anti-Sm28GST antibodies in a FHA dose-dependent manner. The addition of 3 microg of FHA to the liposomes induced more than 10-fold-higher anti-Sm28GST antibody titers, compared to those induced by liposomes without FHA. The presence of FHA did not alter the nature of the humoral immune response, and the sera contained anti-Sm28GST immunoglobulin G1 (IgG1), IgG2a, and IgG2b. However, anti-Sm28GST IgA was only detected when at least 3 microg of FHA was added to the preparation. These results show a promising potential for FHA to enhance the immunogenicity of mucosally administered antigens incorporated into liposomes.

Glutathione S-transferases of 28kDa as major vaccine candidates against schistosomiasis.

For the development of vaccine strategies to generate efficient protection against chronic infections such as parasitic diseases, and more precisely schistosomiasis, controlling pathology could be more relevant than controlling the infection itself. Such strategies, motivated by the need for a cost-effective complement to existing control measures, should focus on parasite molecules involved in fecundity, because in metazoan parasite infections pathology is usually linked to the output of viable eggs. In numerous animal models, vaccination with glutathione S-transferases of 28kDa has been shown to generate an immune response strongly limiting the worm fecundity, in addition to the reduction of the parasite burden. Recent data on acquired immunity directed to 28GST in infected human populations, and new development to draw adapted vaccine formulations, are presented.

Local transient induction of inflammatory cytokines after intranasal administration of recombinant Bordetella pertussis.

Inflammatory cytokines have been described to play a critical role in the orientation and amplification of the IgA immune response. In this study, we show that the intranasal administration of a Bordetella pertussis strain expressing the protective antigen glutathione-S-transferase of Schistosoma mansoni (Sm28GST) induced an inflammatory response in the lungs of mice, characterized by the production of inflammatory cytokines, such as Tumor Necrosis Factor alpha, Interleukin-6 and Transforming-Growth Factor beta. The production and the secretion of these cytokines in lung tissues were early and transient. Their presence was observed only during the first week after administration despite the persistence of the bacteria for 1 month. Two weeks after inoculation, Interleukin-10 secretion was detected in the lungs, which could explain the decrease in the production of inflammatory cytokines. These inflammation-regulating cytokines, induced in the lungs by the presence of the bacterial vector, could be part of the process generating the local immune response, in particular the anti-Sm28GST IgA response.

[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.