[Popular nosology of infantile diseases in West Côte-d'Ivoire and consequences for malaria care management]. / Nosologie populaire des maladies infantiles dans l'Ouest de la Côte-d'Ivoire. Implications pour le paludisme.

In a rural area of intense and permanent malaria transmission in Southwest Côte-d'lvoire, traditional midwifes of the Yacouba ethnic group, with also an important function for the children health and care, were interviewed in 2002 about their knowledge of the infantile pathologies. Their nosology is greatly based on symptoms and etiologic explanations of the disorder of secretions. The accumulation of a viscous liquid in different parts of the body, especially in the chest, the throat or the head, explains numerous febrile or afebrile diseases, including malnutrition. Some pathologies, particularly convulsions, are described by analogy with animals behaviour Relations between these entities and the biomedical ones are difficult to establish. The traditional care and treatments result from these concepts. A vomiting child or a child suffering from diarrhoea is subject to devices to evacuate his excess of liquid. Yellow brews are used against jaundice. Furthermore, an important mistrust remains towards medical treatments particularly for all parenteral therapies. Health facilities are only used as a the last resort. Their bad reputation is confirmed by the high rate of mortality of patients coming often too late. To improve malaria care management, health-care workers have to take into consideration these concepts and also prove their abilities to ensure good medical practices.

[Influence of social perceptions and practices on the use of bednets in the malaria control programme in Ivory Coast (West Africa)]. / Representations sociales et pratiques liées à l'utilisation des moustiquaires dans la lutte contre le paludisme en Côte d'Ivoire (Afrique de l'Ouest).

The National Malaria Programme in Ivory Coast has encountered difficulty in winning public acceptance of insecticide-treated bednets. We speculate that resistance to the use of bednets could be rooted in social perceptions, beliefs and practices in the communities. The purpose of this study was to identify sociocultural and environmental factors that could be used to support promotion strategies and acceptance of impregnated bednets in Ivory Coast. Survey findings confirmed that bednets were not in widespread use among the population (25%). The most widely used methods were burning mosquito coils (50%) and indoor spraying (31%). Use of impregnated bednets was low (6%). Most survey respondents (73%) indicated initial appreciation for the effectiveness of bednets in protecting against mosquitoes as a nuisance. However only 9% of respondents thought that impregnated bednets provided protection against malaria although they did not necessarily use them. Design was a determinant factor for the use, and even acceptance, of bednets. The population want rectangular, permanently impregnated bednets large enough to accommodate at least 2 persons. Cost was a major obstacle to wider use by the population. According to our data the best price for the population would be between 2000 and 2500 FCFA as compared to the current price of 3500 FCFA in Ivory Coast.

Antigenic components of partially purified antigens of Leishmania donovani infantum recognized by sera from dogs with asymptomatic or active visceral leishmaniasis.

The antigenic components of a semipurified fraction of Leishmania donovani infantum were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis using 14 serum samples from dogs with symptomatic visceral leishmaniasis and 11 serum samples from apparently healthy dogs collected in an area endemic for canine visceral leishmaniasis (CVL). It was found that these antigens were composed of many polypeptides, among which seven components recognized by symptomatic CVL sera, had molecular weights of approximately 18, 28, 30, 33, 63, 70, and 72 kilodaltons (kD); two components of 63 and 70 kD were recognized by three of 11 healthly dog sera. These findings suggest that specific antigens induce humoral immune response in dogs with asymptomatic or active visceral leishmaniasis. Infected dogs are not readily identifiable by their symptoms. The potential interest of the immunoblot test for CVL diagnostic purposes is discussed.

Enzyme immunoassays for detection of malarial antigens in human plasmas by Plasmodium falciparum monoclonal antibodies.

The screening of blood donors for the detection of dangerous disease carriers is a mandatory requirement for blood transfusion centers. Enzyme immunoassay (EIA) is a suitable method for the examination of large populations. We describe a sandwich EIA allowing the detection of soluble malarial antigens in plasma using 11 mouse monoclonal antibodies. Among the 121 combinations tested, 2 were selected for their sensitivity and specificity. Both were applied to plasmas of (a) acute patients, (b) people living in malarious areas, (c) blood donors at risk (travelers), and (d) sedentary blood donors without risk. With 1 of the 2 combinations, the percentage of positive answers was 68.4% (n = 38) for a, 62.6% (n = 206) for b, 4.5% (n = 398) for c, and 0.8% (n = 485) for d; with the other combination, the percentage of positive answers was 68.4% for a, 46.1% for b, 1.5% for c, and 0% for d. Using 2 combinations simultaneously, the positive results were 94.7% for a, 70.4% for b, 5% for c, and 0.8% for d. The 2 assays are complementary and the pair can be used for maximum Plasmodium falciparum antigen recognition in prospective donors.

Antigenic components of excretory-secretory products of adult Fasciola hepatica recognized in human infections.

The antigenic components of excretory-secretory products (ESP) of adult worms of Fasciola hepatica were revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis using sera from 20 patients infected with F. hepatica. Sera from 184 other parasitic infections and 20 healthy volunteers were also analyzed. It was found that the ESP were composed of more than 11 polypeptides; five components detected in fascioliasis sera had molecular weights of 12.4, 16.4, 19.4, 25, and 27 kilodaltons (kD). Only the 25- and 27-kD components were recognized by all 20 fascioliasis sera. Using the ESP as antigen, it was possible to perform an enzyme-linked immunosorbent assay with a sensitivity of 95% and a specificity of 97%. Sera from other parasitic infections had antibodies to antigenic components with apparent molecular weights of 37, 38.4, 52, 63, 73, 87, 109, and 116 kD that were also found in sera from fascioliasis patients. These findings suggested that the 25- and 27-kD antigenic components may be sensitive and specific for the diagnosis of human fascioliasis.

Serodiagnosis and screening of canine visceral leishmaniasis in an endemic area of Corsica: applicability of a direct agglutination test and immunoblot analysis.

For effective control of visceral leishmaniasis caused by Leishmania infantum in the Mediterranean area, the detection of infected dogs is of utmost importance. To assess the suitability of a direct agglutination test (DAT) and immunoblot analysis in serodiagnosis and screening of infected dogs under field conditions, a study was performed on 113 dogs in an endemic area of Corsica. Twenty one of 22 parasitologically confirmed cases were correctly diagnosed by both tests, and 100% specificity was found when 11 dogs with other diseases were examined. Interestingly, eight of 80 apparently healthy dogs from the same area were found to be parasite-positive by the DAT test as well as by the immunoblot. Although both tests were equally sensitive and specific, based on both the feasibility of its application in field conditions and ease of performance, we consider the DAT to be more suitable for serodiagnosis and large-scale screening of infected dogs.

Inhibition in vivo of both infective Leishmania major and L. mexicana amazonensis mediated by a single monoclonal antibody.

Monoclonal antibodies raised against a strain of Leishmania infantum isolated in Greece were produced and tested for their protective effect in an in vivo system (in BALB/C mice). A single monoclonal antibody, IgG2b isotype, can prevent the development of two Leishmania strains in vivo: one of L. major and one of L. mexicana amazonensis. This antibody-mediated protection may be dependent on complement.

Specificity of auto-antibodies in malaria and the role of polyclonal activation.

Sera of 173 individuals living in a malaria endemic region in Upper Volta (Donsé village) were screened for the presence of 14 auto-antibodies by the indirect immunofluorescent and/or passive haemagglutination techniques. At least one auto-antibody (AAb) was detected in sera of 72% (124 out of 173) subjects. No differences in the AAb frequency was observed in the sex or age groups. Conversely, a significant relationship between a high frequency of auto-antibodies, high malaria antibody titres and high IgM levels was observed. Antinuclear antibodies (ANA) (87% of total AAb) and particularly those of speckled pattern of fluorescence were by far the most frequently observed. Smooth muscle antibodies (SMA), heart and gastric parietal cell antibodies and thyroglobulin antibodies were found at a normal frequency. This selective increase in the frequency of one AAb (and not of others) cannot, in our opinion, result from a non-specific polyclonal activation. An alternative hypothesis involving both a specific antigenic and a non-specific mitogenic signal is proposed.

Vaccination and treatment trials against murine leishmaniasis with semi-purified Leishmania antigens.

Antigens with molecular weight ranges of 94-67 kDa (LiF2), 30-20 kDa (LiF5), or below 20 kDa (LiF6), isolated from lysates of Leishmania infantum promastigotes by electroelution from polyacrylamide gels were injected into mice which were genetically either partially resistant (C57BL/6) or susceptible (BALB/c) to Leishmania infection. One month after the completion of the intravenous (C57BL/6) or subcutaneous (BALB/c) schedules, the mice were challenged with 1 x 10(3) L. major promastigotes. All mice immunized with LiF2, LiF5 and LiF6 were completely resistant. Furthermore, the C57BL/6 mice immunized with LiF2 resisted a second challenge with 1 x 10(4) L. major amastigotes. 5 months later, LiF2 antigen was used for immunotherapy of L. major leishmaniasis; parasites disappeared from the treated skin lesions, although ensuing systemic infection could not be averted.

Abnormal anti-single stranded (ss) DNA activity in sera from Plasmodium falciparum infected individuals.

Sera from 32 subjects with Plasmodium falciparum parasitaemia were screened for the presence of antibodies to native-double stranded (ds) DNA and to heat-denaturated-single stranded (ss) DNA by a Farr DNA binding radioimmunoassay. In addition anti-dsDNA antibodies were also studied by indirect immunofluorescence using Crithidia luciliae and rat liver sections as substrates. Immunoglobulin (G, A, M) levels and plasmodial antibodies titres (PA) were concomitantly evaluated. The anti-ssDNA activity was higher in malarious individuals with high IgM levels than in normal or malarious individuals with normal IgM levels. This activity was higher during the acute stage of infection than after recovery. A positive and significant relationship was found between the anti-ssDNA activity and the IgM levels but not with IgG, IgA or PA titres. Speckled antinuclear antibodies (ANA) were also observed in sera from 43.8% of the individuals and the mean ssDNA activity was higher in these ANA positive patients. Conversely anti-dsDNA antibodies could not be detected by any of the tests performed. This preferential production of anti-ssDNA Ab and not anti-dsDNA Ab is additional evidence that the autoantibodies observed in malaria infection are not a consequence of a generalized and non-specific polyclonal activation.

Application of an in vivo culture system for rapid demonstration of anti-Leishmania activity of monoclonal antibodies.

In mice, infection with Leishmania by the subcutaneous route becomes evident after about 2 months. This delay impedes the selection of monoclonal antibodies able to interfere with the infectiousness of the parasite. Using an in vivo culture system--intraperitoneal injection of TG 180 sarcoma cells along with promastigotes or amastigotes--it was possible to define within 15 to 20 days a monoclonal antibody preventing the development of Leishmania. Pretreatment of promastigotes and amastigotes of several Leishmania species with a monoclonal antibody raised against Leishmania infantum prevented infection equally in either system. These cross-reactions may be of importance in designing new approaches of immunotherapy.

Relevance of autoantigens to autoimmunity in African trypanosomiasis: study of DNA and thyroglobulin antibodies.

In order to investigate whether the autoantibody production in the course of African trypanosomiasis is the result of a generalized polyclonal activation or if it is a specific (antigen-dependent) phenomenon we looked for the presence of autoantibodies directed against autoantigens likely to be released (DNA) or unlikely to be released (thyroglobulin) into the circulation during human T. gambiense infection. Sera from 21 patients with African trypanosomiasis were screened for anti-native DNA or anti-denatured DNA antibodies by a Farr DNA binding radioimmunoassay. In addition, antibodies to native DNA were also assessed by indirect immunofluorescent assays using Crithidia luciliae or rat liver sections as substrates. Anti-thyroglobulin antibodies were studied by the passive hemagglutination technique. IgM levels and fluorescent anti-trypanosomal antibodies (FATA) were concomitantly evaluated. The denaturated DNA binding capacity was significantly higher in the sera from trypanosomiasis patients than in sera from healthy blood donors. These capacities were greater in patients with high IgM levels and high FATA titres. Anti-native DNA or anti-thyroglobulin antibodies were not detected. This preferential formation of anti-denatured DNA antibodies suggests a specific antigen-dependent) activation of autoreactive cells rather than a generalized polyclonal activation.

Interactions between the human monocytic leukaemia THP-1 cell line and Old and New World species of Leishmania.

The human promyelocytic THP-1 cell line has been found to support the growth of Leishmania parasites. THP-1 cells, differentiated with retinoic acid, cease replication while remaining in suspension. 72 +/- 8% of THP-1 cells became infected after inoculation with promastigotes of several Old and New World Leishmania species. The resulting amastigotes (19 +/- 5 per infected cell) were easy to harvest, capable of reinfecting cultures of normal human cells and, in the case of L. major and L. infantum, caused specific lesions in BALB/c mice. This culture system should facilitate biochemical and immunological studies on amastigotes and be of use in screening anti-parasite drugs.

[Rubella epidemiology in rural Upper Volta]. / Contribution à l'étude de l'épidémiologie de la rubéole en milieu rural voltaïque.

A survey aiming at evaluating the proportion of the female population aged 0-29 years, with a positive anti-rubella antibody titer, was carried out in two Upper-Volta villages, representative of the Sahel (Oursi) and the Savannah (Donsé) biotopes. A technique of inhibition of haemagglutination was used and 40 or more was considered as a positive titer. Seventy per cent of 230 serums were positive, all ages confounded. The proportion positive was 96% in the age group 12-18 years and 76% in the age group 19-29 years. Extrapolating these findings to the Upper-volta rural population we estimated the risk of congenital infection to justify the decision against or in favour of a vaccination campaign. On the basis of our results, it is suggested that rubella has low priority in public health planning in rural Upper-Volta and that mass vaccination is at present not justified.

General considerations on endemic treponematosis in the rural Sahel region of Upper Volta.

A sero-immunological survey conducted by indirect immunofluorescence technique has made it possible to determine accurately the prevalence and distribution of treponematoses in the Sahel rural region of Upper Volta. The number of carriers of antitreponemal antibodies varies from one place to another, but is particularly high in a nomad community, where prevalence attains 84.2%. The magnitude of endemic foci can also be expressed in terms of maximal titer and geometric mean of antibody titers. The seropositive values increase as a function of age, but sex is not a significant factor as regards prevalence, which would appear to depend essentially on the way of life, habits and promiscuity.

A screening of serological syphilis in Mauritania.

A survey aiming at assessing the frequency and the distribution of serological syphilis has been carried out on a sample of 6049 subjects aged 6-18 years in Mauritania. 33.4% of the samples had a reciprocal titer of 150 or more as determined by means of an immunofluorescence technique. However, frequencies in the different villages ranged from 7.5 to 47.6% and were strongly associated with the percentage of Black elements in the community. A significant difference was found between the age-groups 6-13 and 14-18, with a mean increase of 56%. These results suggest that an intervention program might be necessary in Mauritania.

Cytokines and T-cell response in malaria.

The intracellular protozoan Plasmodium sp induces a complex immune response which sometimes implies serious pathological effects for the host. According to in vitro studies and epidemiological surveys, several effector mechanisms are displayed against plasmodial blood stages and a large interaction between humoral and cell-mediated immunity is presumed to occur among protected individuals. The key role of T cells in the antiplasmodial immune response is now well established, but all the regulatory heterogenous mechanisms are not yet fully known. An increasing body of data shows a dual role during malaria attack for some cytokines released by monocytes and macrophages (TNF, IL-1, IL-6) or by T cells (IFN-gamma, lymphotoxin (LT), IL-4). The importance of some plasmodial proteins in the cytokine-induced pathology and the stimulation of a preferential TH1 or TH2 mediated immune response to achieve protective immunity against Plasmodium sp are discussed.

In vitro study of the anti-leishmanial activity of biodegradable nanoparticles.

Leishmania are obligate intracellular parasites, responsible for leishmaniasis. Leishmaniasis are transmitted via insect vector to vertebrate hosts including humans. The infection was reproduced in vitro with promastigotes which can infect murine resident peritoneal cells. Amphotericin B was incorporated into poly(D, L-lactide-co-glycolide) nanoparticles, biodegradable drug carriers, to allow specific targeting inside the cell. The interaction of the drug with infected cells was determined by exposing macrophage cultures to drug carriers. The toxic effects of polymeric drug carriers were defined prior to exposing cells to drug-loaded nanoparticles. For contact times up to 4h, cells tolerated polymer concentrations of 0.01%. The viability of parasites after treatment was determined. Infected macrophages were incubated at 26 degrees C (which allows the transformation of amastigote to promastigote) along with loaded and unloaded nanoparticles, as well as the free drug alone, and a count of the parasites in the medium was recorded. Anti-leishmanial activity was observed with drug-free nanoparticles. This activity may arise through the release of hydrogen peroxide following the activation of macrophages. The incorporation of amphotericin B did not enhance this effect. Interestingly, trehalose, a cryoprotector of the freeze-dried nanoparticles, altered parasite growth and activated macrophages.

Exploitation of parasite-derived antigen in therapeutic success against canine visceral leishmaniosis. Veterinary Group of Lupino.

In an attempt to obtain therapeutic success against canine visceral leishmaniosis, the potential of LiF2 antigen (Leishmania infantum-derived Fraction 2, 94-67 kDa), given alone or in combination with the chemotherapeutic agent N-methylglucamine antimonate, was compared with conventional chemotherapy with that drug. Absence of any parasite in direct microscopic examination of bone-marrow aspirates in treated dogs was considered a parasitological cure, i.e. therapeutic success. Results showed that the disappearance of clinical symptoms did not always indicate parasitological healing in dogs. The parasitological healing rates with chemotherapy and immunotherapy alone were 37.5% and 25% respectively, in contrast to the 100% cure rate observed with chemotherapy combined with immunotherapy. The development of a protective response in dogs, as measured by the in vitro leishmanicidal activity of monocyte-derived macrophages in the presence of autologous lymphocytes, was found to correlate well with the success of therapy. The overall findings of this study give an important insight into the immunotherapeutic strategy by which therapeutic success can be achieved in canine visceral leishmaniosis.

Immunization of dogs with a Leishmania infantum-derived vaccine.

A partially-purified extract of Leishmania infantum has been administered to healthy dogs. Post-immunization sera were found to neutralize the infectivity of L. infantum and to abate the development of L. major. Muramyl dipeptide and one of its derivates, murabutide, were the best adjuvants.