Analysis of antibody responses to selected Plasmodium falciparum merozoite surface antigens in mild and cerebral malaria and associations with clinical outcomes.

Merozoite surface proteins (MSPs) are critical for parasite invasion; they represent attractive targets for antibody-based protection against clinical malaria. To identify protection-associated target MSPs, the present study analysed antibody responses to whole merozoite extract (ME) and to defined MSP recombinant antigens in hospitalized patients from a low endemic urban area as a function of disease severity (mild versus cerebral malaria). Sera from 110 patients with confirmed severe cerebral malaria (CM) and 91 patients with mild malaria (MM) were analysed (mean age = 29 years) for total and subclass immunoglobulin (Ig)G to ME and total IgG to MSP1p19, MSP2, MSP3, MSP4 and MSP5 by enzyme-linked immunosorbent assay (ELISA). Functional antibody responses were evaluated using the antibody-dependent respiratory burst (ADRB) assay in a subset of sera. There was a trend towards higher IgG1 and IgG4 levels to ME in CM compared to MM; only ME IgM responses differed significantly between fatal and surviving CM patients. Increased prevalence of IgG to individual MSPs was found in the CM compared to the MM group, including significantly higher levels of IgG to MSP4 and MSP5 in the former. Sera from fatal (24·5%) versus surviving cases showed significantly lower IgG to MSP1p19 and MSP3 (P < 0·05). ADRB assay readouts correlated with high levels of anti-MSP IgG, and trended higher in sera from patients with surviving compared to fatal CM outcome (P = 0·07). These results document strong differential antibody responses to MSP antigens as targets of protective immunity against CM and in particular MSP1p19 and MSP3 as prognostic indicators.

[Report of the 4th International Conference on Envenomations by Snakebites and Scorpion Stings in Africa, Dakar, April 25-29, 2011]. / 4(e) Conférence internationale sur les envenimations par morsures de serpent et piqûres de scorpion en Afrique : Dakar, 25-29 avril 2011.

The authors present a summary of the proceedings and the recommendations of the Fourth International Conference on Envenomations by Snakebites and Scorpion Stings in Africa, held from 25 to 29 April 2011 in Dakar. After a two-day workshop for Senegalese health personnel on the most relevant aspects of the management of envenomations, about 270 participants met to share their experiences in the field. Nearly a hundred oral and poster presentations were made on the epidemiology of snakebites and scorpion stings in Africa, the composition and action of venoms and the manufacture and use of antivenoms. The last day was devoted to an institutional debate involving experts, representatives of national health authorities and concerned professionals (physicians, pharmacists, nurses and traditional healers) as well as members of the pharmaceutical industry to discuss and elaborate a set of recommendations. It was agreed that it is necessary to improve knowledge of the epidemiological situation by case reporting. Quality control of antivenoms and procedures for their registration at the level of national health authorities should aim at improving the distribution of safe and effective antivenoms in peripheral health centers for the better assessment of victims. It was also recommended that adequate training should be provided for health personnel in all aspects of medical management of envenomations. Equitable distribution of funding and the establishment of a network of African experts were also discussed in the conference.

[Contribution of the Xpert MTB / Rif test in the diagnosis of tuberculosis of any form in Saint-Louis]. / Apport du test Xpert MTB/Rif dans le diagnostic de la tuberculose toute forme a Saint-Louis.

INTRODUCTION: The Xpert MTB / RIF assay has a dual advantage on the one hand, the rapid diagnosis of even difficult cases by the standard technique of direct microscopic examination and on the other hand by the detection of resistance to rifampicin. Our objective was to determine the contribution of the Xpert test in the diagnosis of tuberculosis of all forms. MATERIALS AND METHOD: retrospective, descriptive and analytical study carried out in the Pneumophtisiology department of the CHRU of Saint-Louis. All suspected tuberculosis cases who had received an Xpert test from 2018 to 2020 were included. The parameters studied were socio-demographic, clinical and biological data. RESULTS: 524 patient records included in the study with a sex ratio of 1.3. The mean age of the patients was 37 +/-15 years. There were 285 positive GeneXpert samples, of which 224 were of pulmonary origin and 61 of extra-pulmonary origin. The number of rifampicin resistant samples was five, all of respiratory origin. CONCLUSION: the Xpert test is a new molecular technique recommended by the WHO in the diagnosis of pulmonary tuberculosis.

INTRODUCTION: le test Xpert MTB/RIF présente un double avantage d'une part le diagnostic rapide des cas mêmes difficiles par la technique standard de l'examen direct à la microscopie et d'autre part par la détection de la résistance à la rifampicine. Notre objectif était de déterminer l'apport du test Xpert dans le diagnostic de la tuberculose toutes formes confondues. MATÉRIELS ET MÉTHODE: étude transversale, descriptive à collecte rétrospective menée dans le service de Pneumophtisiologie de CHRU de Saint-Louis. Tous les cas suspects de tuberculose qui avaient bénéficié d'un test Xpert de 2018 à 2020avec un dossier médical accessible et exploitable ont été inclus. Les paramètres étudiés étaient les données sociodémographiques, cliniques et biologiques. RÉSULTATS: Nous avions colligés 524dossiers de malades avec un sex-ratio de 1,3. L'âge moyen des patients était de 37 ans+/-15 ans. Il y'avait 285 prélèvements positifs au GeneXpert dont 224 d'origine pulmonaire et 61d'origine extra pulmonaire. Le nombre d'échantillons résistants à la rifampicine était de cinq, tous d'origine respiratoire. CONCLUSION: le test Xpert est une nouvelle technique moléculaire recommandée par l'OMS dans le diagnostic de la tuberculose pulmonaire. Toutefois il doit être évaluer dans le diagnostic de la tuberculose extra pulmonaire.

Antidiabetic properties of aqueous barks extract of Parinari excelsa in alloxan-induced diabetic rats.

The aqueous extract of the Parinari excelsa barks at doses of 100 and 300 mg/kg/day for 7 days has a significant antihyperglycemic effect on alloxan-induced diabetic rats. At the same dose the acute oral administration of aqueous extract of the P. excelsa barks (100 and 300 mg/kg) induced a significant decrease of blood glucose on glucose-loaded normoglycaemic rats. Our results seem to confirm the rational bases for its use in traditional medicine.

[Decentralization of the immunological monitoring of people living with HIV/AIDS in a limiting setting with a low HIV seroprevalence: the experience of Senegal]. / Décentralisation du suivi immunologique des personnes vivant avec le VIH dans un pays à ressources limitées et à prévalence faible: expérience du Sénégal.

Our work aimed to propose a manual method of counting CD4 T lymphocytes which is an alternative magnetic immunoseparation followed by a reading with a fluorescence microscope as an alternative to the automated flow cytometry. This alternative technique is easier for use, less expensive and could answer the difficulties encountered for the monitoring CD4 T cells count in developing countries. The specific objectives were: 1) to train the technicians of the peripheral sites in order to make the numeration of the CD4 T lymphocytes more accessible at the peripheral level; 2) to equip the sites with necessary facilities for the T lymphocytes CD4 count; 3) to put in place a system of quality control permitting the reliability of the results. A hundred and fifty patients have been enrolled in three care services for people living with HIV/AIDS in Dakar. This population was constituted of 119 seropositive and 31 seronegative patients acting as control group to have some patients with high rates of T lymphocytes CD4. For the follow-up at peripheral level, the patients were constituted of the active line of the patients living with HIV/AIDS supported in the targeted sites. The measurements allowed studying concordances for different rates of lymphocytes: 0 to 199, 200 to 499 and over 500 cells by mm3. The results showed also a very good correlation (r = 0.97 or r = 0.98 according to the operator) between the two methods for CD4 rates inferior to 500 cells by mm3 among both the negative group and the HIV positive patients. We also discussed the profit of decentralization for the program and the patient, as well as the setting up of an external quality control to validate the alternative technique. According to the results, the Dynabeads is well correlated with the Facscount. It is a technique that can be used as an alternative in the zones with limited resources, low prevalence and for a small number of samples.

[Tuberculosis Abscess of the Chest Wall on an Immunocompetent Patient in the Teaching Hospital of Dakar (Senegal)]. / Abcès tuberculeux de la paroi thoracique chez une patiente immunocompétente au centre hospitalier universitaire de Dakar (Sénégal).

Tuberculosis remains a problem of public health, in spite of the numerous significant advances noted in the diagnosis in recent years. The involvement of the thoracic wall is a rare extra lung shape. Its clinical presentation is not specific and a collected thoracic tumefaction is the main clinical demonstration. The diagnosis is improved by the use of non-invasive tools such as the Xpert MTB/Rif® test with a good sensibility on the pus. Medical care is based on medical treatment and sometimes associated with surgical treatment.

La tuberculose demeure un problème de santé publique, malgré les nombreuses avancées significatives notées dans le diagnostic ces dernières années. L'atteinte de la paroi thoracique est une forme extrapulmonaire rare. Sa présentation clinique est non spécifique, et une tuméfaction thoracique collectée en est la principale manifestation clinique. Le diagnostic est amélioré par l'utilisation d'outils non invasifs tels que le test Xpert MTB/Rif® avec une bonne sensibilité sur le pus. La prise en charge repose sur le traitement médical quelquefois associé à un traitement chirurgical.

[Experimental evidence of against cough activity of total alkaloids from Guiera senegalensis Lam. in guinea pig;]. / Mise en evidence de l'activité antitussive des alcaloïdes totaux de Guiera senegalensis Lam. chez le cobaye.

INTRODUCTION: Against cough activity from Guiera senegalensis' leaves has been previously scientifically studied. However, to the best of our knowledge, active principles responsible of this activity were not yet identified. Thus, we undertook this work with the aim to evaluate the effect of total alkaloids from plant's leaves in cough induced in guinea pig by ammoniac inhalation. MATERIAL AND METHODS: Guinea pigs were divided up in 5 groups of 10 and were crammed with distilled water (control), total alkaloids with 10, 25 and 30 mg/kg and codeine with 50 mg/kg. They were then exposed to ammoniac inhalations and the number of coughs was counted every hour, after cramming, during 5 min. RESULTS: Our results show, after 5 hours, with the doses of 15, 25 and 30 mg/kg per os, that total alkaloids induce against cough activity, 2 hours after cramming (p < 0.01) and the difference was still significant 3, 4 and 5 hours after (p < 0.001). These alkaloids effects were comparable with codeine activity which was used as reference product. CONCLUSION: Total alkaloids of Guiera senegalensis present an against cough activity and would be responsible of against cough activity of the plant.

[Culture and characterization of porcine coronary endothelial cells]. / Culture et caractérisation des cellules endothéliales d'artère coronaire de porc.

INTRODUCTION: Vascular endothelium possesses biological properties that are involved in important physiological functions such vascular permeability, vascular tone regulation and angiogenesis. The difficulty of culture and long-term maintenance of sufficient amount of normal endothelial cells has proven to be the limitation for the understanding of the biological function of the endothelium. Therefore, the aim of this study was to culture and characterize the porcine coronary endothelial cells. MATERIAL AND METHODS: The endothelial cells were isolated by collagenase treatment and cultured in culture dishes coated with collagen, prepared from rat tail, containing medium RPMI1640/M199 and 15% fetal calf serum supplemented with antibiotics and fungizon. The cells were maintained to grown at 37 degrees C. The medium was changed one day after and then every two day. The cells were incubated with Dil-labeled-acetylated-LDL for determination of acetylated-LDL uptake. Confluence cultures of cells were examined by phase-contrast and confocal microscopy. RESULTS: After a day of culture, the endothelial cells adhere to the collagen and began to grow. While multiplying themselves, they colonize little by little the body of the surface of culture to form to confluence a monolayer of flat cells relatively homogenous. To confluence, the proliferation of the endothelial cells is inhibited by the contact and the cells present a polygonal aspect. Our results show that all the cultivated cells were strongly positive for acetylated-LDL markers. The endothelial cells, cultivated until the second passage corresponding to the second culture of the primary cultures, continued to present a good fluorescence. CONCLUSION: Porcine coronary endothelial cells represent a useful in vitro model to study biological and physiopathological properties of vascular endothelium.

Strengthening human genetics research in Africa: report of the 9th meeting of the African Society of Human Genetics in Dakar in May 2016.

The 9th meeting of the African Society of Human Genetics, in partnership with the Senegalese Cancer Research and Study Group and the Human Heredity and Health in Africa (H3Africa) Consortium, was held in Dakar, Senegal. The theme was Strengthening Human Genetics Research in Africa. The 210 delegates came from 21 African countries and from France, Switzerland, UK, UAE, Canada and the USA. The goal was to highlight genetic and genomic science across the African continent with the ultimate goal of improving the health of Africans and those across the globe, and to promote the careers of young African scientists in the field. A session on the sustainability of genomic research in Africa brought to light innovative and practical approaches to supporting research in resource-limited settings and the importance of promoting genetics in academic, research funding, governmental and private sectors. This meeting led to the formation of the Senegalese Society for Human Genetics.

Le 9ème congrès de la Société Africaine de Génétique Humaine, en partenariat avec le Groupe d'Etude et de Recherche sur le Cancer (GERC) et le Consortium H3Africa, s'est tenu à Dakar, au Sénégal. Le thème était «Renforcer la recherche en Génétique Humaine en Afrique¼. Les 210 participants sont venus de 21 pays africains et de six non africains. L'objectif était de valoriser la génétique et la génomique à travers l'Afrique avec comme but ultime d'améliorer la santé des populations, et de promouvoir les carrières des jeunes chercheurs Africains. Une session sur la pérennité de la recherche génomique a révélé des approches innovantes et pratiques supportant la recherche dans des contextes de ressources limitées et l'importance de promouvoir la formation universitaire en génétique, le financement de la recherche par les gouvernements et le privé. Ce congrès conduisit à la création de la Société Sénégalaise de Génétique Humaine.

[Mechanisms of action of acetonic and hexanic extracts of leaves of Vernonia colorata (Willd.) Drake (Composeae) on blod glucose regulation]. / Mecanismes d'action des extraits acetonique et hexanique de feuilles de Vernonia colorata dans la regulation de la glycemie.

INTRODUCTION: This study aimed to investigate the mechanism of action of acetonic and hexanic extracts of the leaves of Vernonia colorata on blood glucose regulation. MATERIALS AND METHODS: Experiments were performed in normoglycaemic, type 1 and 2 diabetic rats. The effects of acetonic and hexanic extracts on blood glucose were evaluated. The antagonism effect of hexanic extract on the decrease of blood glucose induced with glibenclamide and metformin was also tested. RESULTS: The hexanic extract of the leaves of V. colorata (HELVC) dose dependently increased the blood glucose in normoglycaemic rats. At the dose of 30 and 100 mg/kg, the glycaemia varied from 0.84 +/- 0.02 to 1.11 +/- 0.10 g/l and 0.68 +/- 0.02 to 1.31 +/- 0.30 g/l (p<0.05, n = 5). Such glibenclamide, the acetonic extract of the leaves of V. colorata (AELVC) induced hypoglycaemia in normoglycaemic rats. The HELVC prevents significantly the AELVC and glibenclamide induced hypoglycaemia. The chronic administration of the AELVC and HELVC as well as glibenclamide in type 1 diabetic rats did not change significantly the level of blood glucose. In type 2 diabetic rats, the single dose administration of metformin (300 mg/kg, per os) decreased the glycaemia which is completely prevented by a HELVC pretreatment. CONCLUSION: These results suggest that: i) The respective hypo- and hyperglycaemic effects of AELVC and HELVC require the presence of the pancreatic beta cells. ii) The AELVC would act by a sulfonylurea-like mechanism as glibenclamide to induce an hypoglycaemic effect.

[Malaria associated with bacterial infection in the department of infectious diseases at the National and University Hospital of Fann, Dakar]. / Paludisme grave et infections bacteriennes associees au service des maladies infectieuses du centre hospitalier National et Universitaire de Fann a Dakar.

OBJECTIVES: To describe severe malaria cases with bacterial infection. PATIENTS AND METHODS: We conducted a prospective, descriptive and analytical study over 8 months. RESULTS: 15 of the 86 severe malaria cases had bacterial infections: enteritis (7 cases), urinary tract infection (4 cases), meningitis (4 cases), pneumonia (cases), sepsis (1 case), and sinusitis (1 case). Convulsions, jaundice, abnormal bleeding, pulmonary edema were more frequent in patients with associated infections. The average number of leukocytes and CRP were significantly higher in patients with bacterial infection. The mean parasite density was higher in patients without bacterial infection (56,362/mm3 vs. 239,162.2 ± 3326/mm 3 ± 7175.3). Lethality was higher in patients with bacterial infection (20% versus 16.9%). CONCLUSION: Bacterial infections are common in severe malaria and may influence the prognosis.

OBJECTIFS: Décrire les cas de paludisme grave avec infection bactérienne associée. PATIENTS ET MÉTHODES: Etude prospective, descriptive et analytique sur 8 mois. RÉSULTATS: Parmi les 86 cas de paludisme grave, 15 avaient des infections bactériennes: Entérite (7 cas), Infections urinaires (4 cas), méningites (4 cas), pneumopathies (cas), septicémie (1 cas), sinusite (1 cas). Les convulsions, l'ictère, le saignement anormal, l'œdème pulmonaire étaient plus fréquents chez les patients présentant des infections associées. Le nombre de leucocytes moyen et la CRP était significativement plus élevé chez les patients avec infection bactérienne. La densité parasitaire moyenne était plus élevée chez les patients sans infection bactérienne (56362/mm3 ± 239162,2 Vs 3326/mm3 ±7175,3). La létalité était plus élevée chez les patients avec infection bactérienne (20% contre 16,9%). CONCLUSION: Les infections bactériennes ne sont pas rares au cours du paludisme grave et peuvent en influencer le pronostic.

[Profiles of IgG responses against CSP, GLURP and LSA-3NR2 in urban malaria (Dakar): relations with haemoglobin levels and parasite densities]. / Profils des réponses IgG dirigées contre CSP, GLURP et LSA-3NR2 dans le paludisme urbain à Dakar : influence sur l'hémoglobinémie et les parasitémies circulantes.

Malaria remains a major health problem in sub- Saharan African countries despite substantial decreases in morbidity and mortality due to sustained control programs. Vaccines candidates were mainly tested in rural endemic setting; however increasing proportion of the population is living in urban area. Evaluation of the qualitative or quantitative immune responses to key targets of anti-Plasmodium immunity requires further investigation in urban area. In a cohort of 144 patients with mild malaria living in Dakar, we analyzed IgG responses against target antigens of P. falciparum: CSP, LSA-3NR2 and GLURP by ELISA. A mean age of 15 yrs (4-65 yrs) was found and patients were separated in 59 adults (<15yrs) and 85 children (≤15 yrs). Parasites densities (0,01-15%) did not differ between the two age groups. In contrast, haemoglobin levels appeared lower in children (4.5-16.6 g/dl) (p<0.01). For the immune results, the most recognized antigens were GLURP and CSP compared to LSA-3NR2. Levels of IgG against these antigens were significantly different between the two age groups and they were positively correlated (rho = 0.32; p<0.001). In addition, levels of IgG anti-GLURP were associated with low parasitemia (≤1%) and absence of anemia (≥11g/dl), particularly in adults (p<0.001). In a multiple regression analysis, no significant relationship was found between parasite densities and IgG responses against all the tested antigens. Our study shows the implication of IgG anti-GLURP in humoral immune response against the parasite. The present work contributes to determine IgG levels that can be used as relevant immunologic biomarkers in urban clinical malaria.

[Healing activity of methanolic extract of the barks of Spathodea campanulata Beauv (Bignoniaceae) in rat experimental burn model]. / Activite cicatrisante de l'extrait methanolique des ecorces de Spathodea campanulata Beauv (Bagnoniaceae) sur un modele de brulures experimentales chez le rat.

Spathodea campanulata Beauv. (Bignoniaceae) is widely distributed through Africa and found in particular in Cameroon and Senegal. It is used in traditional herbal medicine for the treatment of ulcers, filaria, gonorrhea, diarrhea and fever. S. campanulata was also known in Cameroon traditional medicine to have a healing activity in burn wounds. The aim of the present study was to assess the burn healing effectiveness of the methanolic extract of the barks of S. campanulata ointment (MEBSCO) in comparison to those of Centella asiatica and Peru's balm in experimental burn model in rats. Experimental burn was made in rat under chloral anaesthesia with electric iron (200 degrees C) on the right and left side of the medianus line. Topical applications of MEBSCO (2%, 10% and 49%) dose-dependently decreased the score damage of the burn site. Treatment with 10% and 49% of MEBSCO varied the score damage from 5 to 1 +/- 0.4 and 5 to 0.2 +/- 0.5 (p < 0.05, n = 5) respectively, at day 15 after experimental burn. As well as C. asiatica (1%) and Peru's balm (1%) ointments, MEBSCO (10% and 49%) induced a complete burn healing on the 19-20th post burn day. This study shows for the first time, the burn healing effectiveness of MEBSCO in experimental burn model. It also provides a rational use of the S. campanulata barks in traditional medicine to promote burn healing.

[IgG responses to candidate malaria vaccine antigens in the urban area of Dakar (Senegal): evolution according to age and parasitemia in patients with mild symptoms]. / Analyses des réponses IgG dirigées contre des antigènes candidats vaccins dans le paludisme urbain non aggravé à Dakar (Sénégal): variations suivant l'âge et les densités parasitaires.

Malaria remains a major problem in African countries despite substantial decreases in morbidity and mortality due to sustained control programs. Studies for the evaluation of qualitative or quantitative Ab responses to key targets of anti-plasmodium immunity were mostly done in rural endemic setting compared to urban area. In a cohort of 200 patients with mild malaria and living in Dakar, we analyze total and subclasses IgG responses to a panel of P. falciparum blood stage antigens: MSP1p19, MSP3, EB200, GST-5 and R23. A mean age of 15 yrs (4 to 56 yrs) and parasitemia between 0.1 to 17% were found. Levels of IgG anti-MSP3 were higher in patients with low parasitemia (≤1%) and appear negatively correlated to parasite densities (Rho =. 0.54; p= 0.021). This correlation is more significant in children (≤ 15 yrs). In addition, an increase of IgG responses against MSP1p19 is highly observed in adults having a parasitemia less than 1%. In those patients, we find that IgG1 subclasses were predominant (p <0.01). Our study shows an association between Ab responses and parasitemia. This association is dependant to IgG anti-MSP3 in children and IgG anti-MSP1p19 in adults living in urban area.

Immune responses to P. falciparum-MSP1 antigen: lack of correlation between antibody responses and the capacity of peripheral cellular immune effectors to respond to this antigen in vitro.

Protective immunity to P. falciparum blood stage infection is thought to be dependent on IgG antibodies, although the mechanisms that underlie such immunity are not clearly understood. One of the antigens thought to be involved in this protective response is MSP1. The present study has examined the levels and distribution of IgG (and IgM) antibodies to the C-terminal 19 kDa fragment of MSP1 in plasma from P. falciparum immune adult Senegalese and the capacity of the peripheral blood mononuclear cells from these patients to either proliferate or secrete IFN-gamma, IL-10 or IL-4 in vitro in response to this antigen. Specific antibodies were found in 74% of individuals' plasma; 44% of mononuclear cells proved capable of proliferating in vitro and IFN-gamma, IL-10 and IL-4 were detected in 37, 23 and 0% of culture supernatants, respectively. No significant association was found between the presence of antibodies and immune cell reactivity under the culture conditions used. This study emphasizes the complexity of the mechanisms responsible for the sustained production of potentially protective antibodies in response to proposed T-cell dependent P. falciparum blood stage antigens.

Imbalanced distribution of IgM and IgG antibodies against Plasmodium falciparum antigens and merozoite surface protein-1 (MSP1) in pregnancy.

In malaria endemic areas, pregnancy is assumed to be associated with a specific reduction in immunity to Plasmodium falciparum malaria. To understand some of the mechanisms which underlie such a poor immunity, we have attempted to examine the frequency and distribution of IgM and IgG antibodies to a crude antigenic extract of parasitized erythrocytes and to the merozoite surface protein-1 (MSP1), in a population of mothers compared to control non-pregnant women, all living in Dakar and suburbs. Specifically, this work describes: (i) the responses of mothers and control women; (ii) the balance between IgM and IgG responses; and (iii) responses to malarial antigen and to MSP1. An unexpected balance between P. falciparum-specific IgM and IgG is shown, associated with a substantial increase in anti-MSP1 IgM, and a decrease in anti-MSP1 IgG in parturients.

Serological HLA class I alleles in Senegalese blood donors detected HBs Ag positive.

We analysed the HLA class I alleles in 96 blood donors HBs Ag positive compared with 93 healthy control individuals (HBs negative). The most frequent HLA-A, -B, -C alleles found were, A23 (33.6%); A2 (25%); A30 (25%); B8 (31.5%); B7 (16.3%); B58 (11.9%); B35 (11.9%); B49 (11.9%); B53 (10.8%); Cw7 (39.1%); Cw3 (36.9%); Cw4 (36.9%). Significant differences (P<0.001) were found between the blood donors and the controls for the following HLA alleles, A1; A23; B8 and Cw3. The detection of HBe antigen was positive in 26/84 blood donors. It was observed a significant difference (P<0.01; odds ratios (OR)=6.25) between positive and negative HBe antigens blood donors for HLA-A1 allele.

Host factors affecting the delay of reappearance of Plasmodium falciparum after radical treatment among a semi-immune population exposed to intense perennial transmission.

To investigate host factors affecting the delay of reappearance of malaria parasites after radical treatment, a study was undertaken in Dielmo, Senegal, an area of intense perennial malaria transmission. A 7-day course of quinine was administered to 173 asymptomatic persons from 1 to 85 years of age and reappearance of malaria parasites in the peripheral blood was monitored weekly for 14 weeks. Additional thick blood films were made in case of fever as part of a daily clinical surveillance. The median times before reappearance of Plasmodium falciparum were 22, 39, and 53 days among persons 1-6, 7-14, and > or = 15 years of age, respectively (P < 0.0001). Multivariate analysis indicated that the daily rate of reappearance of P. falciparum was 2.2 (95% confidence interval [CI] = 1.2-4.5) times lower in sickle cell trait carriers than in AA individuals, and 1.5 (95% CI = 1.1-2.1) times lower in bed nets users than in non-users. The risk ratio for the daily risk of reappearance was significantly related to the level of parasitemia before treatment. No influence of glucose-6-phosphate dehydrogenase deficiency, HLA-B53, and DR13 were observed. Findings show that monitoring during a few weeks the reappearance of malaria parasites after treatment among a small cohort of individuals naturally exposed to malaria is relevant for investigating host resistance factors. This suggest that small, low-cost, field trials may be very informative on the potential of new malaria vaccine candidates.