[Obstacles to laboratory diagnosis of malaria in Mali--perspectives]. / Problématique du diagnostic biologique du paludisme au Mali--perspectives.

Rapid accurate laboratory diagnosis is necessary for effective malaria management. In Mali, meeting this prerequisite is impeded by underuse of laboratory diagnosis by clinicians, absence of qualified laboratory facilities in some locations, and poor continuous professional education of laboratory technicians. The twofold aim of this investigation was to perform quality control of thick smear readings made by laboratory technicians in 1998 and 1999 and to study the feasibility and diagnostic value of two rapid diagnostic tests (RDT), i.e., ParaSight and OptiMAL, in comparison with the thick smear technique in the period from 1998 to 2003. Quality control of thick smear readings indicated a 56% false positive rate with 49.3% concordance between laboratory technician readings and the reference centre. Trials using RDT showed that the OptiMAL test was more efficient with 97.2% sensibility, 95.4% specificity and 93% concordance in comparison with thick smear. A program of training, refresher courses, and regular didactic supervision (quality control) for laboratory technicians has been set up in Mali under the sponsorship of the "Fondation Mérieux" (ACTION BIOMALI) and the President's Malaria Initiative (PMI). These institutions provide funding for training as well as equipment and consumables in all public medical laboratories in Mali. The thick smear method is still being used as the reference technique, but use of RDT is to be implemented at all levels of the health care pyramid.

[Epidemiology of malaria in a village of Sudanese savannah in Mali (Bancoumana). Anti-TRAP and anti-CS humoral immunity response]. / Epidémiologie du paludisme dans un village de savane soudanienne du Mali (Bancoumana). 1. Réponse immunitaire humorale anti-TRAP et anti-CS.

Vaccine development research is an important component of malaria control strategies. Thrombospondin related anonymous protein (TRAP) and the circumsporozoite (CS) protein are two antigens of sporozoite surface. Immune response to these two antigens may contribute to the development of anti-sporozoite vaccine. Recent studies suggest that antibodies anti-TRAP may partially block sporozoites penetration in hepatocyte, and thereby reducing malaria morbidity. We carried out a study to assess the seroprevalence of anti-TRAP and anti-CS antibodies and to identify a possible role of these antibodies on malaria morbidity in children 1-9 years old living in a rural hyperendemic village. We performed 5 cross sectional surveys and a longitudinal follow up in 1993 and 1994. During each cross sectional study, children were examined for fever and splenomegaly; all febrile children received thick film examination, and serologic analysis was performed in one third of these, randomly selected. The results show that the seroprevalence of anti-TRAP and anti-CS varied with age and season (p < 0.05). Association between the prevalence of anti-TRAP and splenomegaly was observed during two cross sectional surveys (June and October 1993). The presence of anti-TRAP antibody was associated with Plasmodium falciparum infection at the beginning of the transmission season (June 1993 and July 1994). A negative association between the level of anti-TRAP title and parasitemia was observed (March and October 1994). These findings suggest no clear evidence of the protective role of anti-TRAP antibodies in uncomplicated malaria, possibly due to the limited persistence of these antibodies under natural situations.

[Epidemiology of malaria in a village of Sudanese savannah area in Mali (Bancoumana). 2. Entomo-parasitological and clinical study ]. / Epidémiologie du paludisme dans un village de savane soudanienne du Mali (Bancoumana). 2. Etude entomo-parasitologique et clinique.

We carried out five cross sectional surveys between 1993 and 1994 to assess the epidemiology of malaria in the village of Bancoumana, located in the Sudanese savannah areas of Mali. Each survey included a collection of entomological, clinical, parasitological and immunological data. The study population involved 1600 children from six months to 9 years of age. The main vector was Anopheles gambiae s.l., man bite rate and entomological inoculation rate were maximum respectively in August (peak of the transmission season) and October (end of transmission season). Plasmodium. falciparum was the main parasite species observed. Spleen enlargement rate, parasite rate, gametocyte rate and parasite density varied significantly with age and season. The parasite rate, gametocyte rate and parasite density were significantly low in October 1994 compared with October 1993 while the entomologic parameter did not show any variation over the two years. This reduction of parasitologic index between 1993 and 1994 may be related to an increase of anti-malarial drug use in the population. Our results show that malaria is hyperendemic in the village of Bancoumana.

Erythrocyte CR1 expression level does not correlate with a HindIII restriction fragment length polymorphism in Africans; implications for studies on malaria susceptibility.

Complement receptor 1 (CR1) expression level on erythrocytes is genetically determined, and in Caucasian populations is linked to high (H) and low (L) expression alleles identified by a HindIII restriction fragment length polymorphism (RFLP). Erythrocyte CR1 may be an important factor in determining malaria susceptibility, as low expression of CR1 reduces the rosetting of uninfected erythrocytes with Plasmodium falciparum-infected cells, a process that contributes to malaria pathogenesis. Prior to studying CR1 expression and malaria susceptibility, we have investigated whether the quantity of erythrocyte CR1 correlates with the H and L alleles in an African population. Mean erythrocyte CR1 in 149 Malian adults was 415 molecules per cell, which is comparable to Caucasian populations; however, there was no relationship between erythrocyte CR1 level and genotype for the HindIII RFLP (mean CR1 per erythrocyte HH = 414, HL = 419 and LL = 403, P > 0.1, Student's t-test). The conclusions of a previous study of erythrocyte CR1 expression level and malaria susceptibility in West Africa that was based on HindIII RFLP genotyping may therefore need to be re-evaluated.