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BACKGROUND During healthy pregnancy, T helper (Th) 1-type and inflammatory-type responses are down-regulated, and Th2-type and proinflammatory-type responses predominate. In Plasmodium falciparum-infected females, these responses induce enhanced production of tumor necrosis factor- alpha and interferon- gamma. METHODS To assess the respective implication of monocytes and T cells in this placental immunomodulation, we cocultured cells from delivering females living in an area where malaria is endemic. Monocytes and T cells from both peripheral and intervillous blood were crossed in in vitro cultures, to compare the proliferative response to several antigens. Moreover, monocyte cell-surface molecules were quantified by flow cytometry. RESULTS Coculture results confirmed placental immunomodulation and suggested that the most affected cells are not the intervillous monocytes, which are as able to present the antigen as the peripheral monocytes, but the intervillous T cells. Monocyte staining showed significant increases in human leukocyte antigen D-related, CD54, CD80, and CD86 surface markers in intervillous blood, compared with peripheral blood, which suggests a relative activation of monocytes in the placenta. CONCLUSION A state of T cell deactivation and monocyte activation is present at delivery. The T cell deactivation in reaction to purified protein derivative could be explained by the presence of local T cell immunoregulatory factors.

Auteur(s) : Jean-Yves Le Hesran* jean-yves.lehesran@ird.fr * Medecin epidemiologiste, IRD, UMR 216, Laboratoire de Parasitologie, Faculte de Pharmacie, Universite Paris V, Paris, France Voir version PDF.

Summary. Multistate Markov models are frequently used to characterize disease processes, but their estimation from longitudinal data is often hampered by complex patterns of incompleteness. Two algorithms for estimating Markov chain models in the case of intermittent missing data in longitudinal studies, a stochastic EM algorithm and the Gibbs sampler, are described. The first can be viewed as a random perturbation of the EM algorithm and is appropriate when the M step is straightforward but the E step is computationally burdensome. It leads to a good approximation of the maximum likelihood estimates. The Gibbs sampler is used for a full Bayesian inference. The performances of the two algorithms are illustrated on two simulated data sets. A motivating example concerned with the modelling of the evolution of parasitemia by Plasmodium falciparum (malaria) in a cohort of 105 young children in Cameroon is described and briefly analyzed.

Some of the remarks made by M. Nacher about potential biases that may have occurred in our field study are interesting but I do not think that they call into question our results in such a radical way. In particular the arguments concerning the definition of severe malaria do not appear to be compatible with a negative association between severity of malaria and Ascaris infection as he suggests in his letter. Firstly repeated vomiting is indeed a recognized clinical criterion of severity of malaria according to the WHO definition. Secondly a significant proportion of these children presented not only with repeated vomiting but also with other unquestionable criteria of severity such as alterations in consciousness coma or convulsions which would bring our figures far beyond the 60% figure of ‘really severe malaria’ quoted by M. Nacher. Lastly an ideal situation would be to have a complete clinical parasitological and biological definition of the cases. This is very seldom possible particularly in a rural area of Senegal where the latest biological techniques are not available. We were therefore obliged to define severity on a clinical basis with the utmost rigour in the assessment of diagnostic criteria. Cases were identified by skilled nurses or physicians and systematically checked by parasitologists from the IRD (Institut de recherche pour le developpement) team who have had a long experience of malaria surveys in such rural settings. (excerpt)

An epidemiological study of human T-lymphotropic virus type 1 (HTLV-1) and syphilis has been carried out in a multiethnic community of seven neighboring villages located in eastern Gabon on 1240 subjects over 5 years old (82.7% of the population in this age range). Antibodies to HTLV-1 (anti-HTLV-1) were detected by ELISA with confirmation by Western Blot and antibodies to syphilis by Venereal Diseases Research Laboratory assay with confirmation by the Treponema pallidum hemaglutination assay. The prevalence rate of anti-HTLV-1 was 8.5% and increased from 3.7% in the 5 to 14 years age group to 23.8% in the over 60 years age group. Logistic regression showed that the positivity for anti-HTLV-1 was associated with age ethnic group and sex (higher prevalence in females). The seroprevalence rate of syphilis was 8.2%. Seropositivity for syphilis and HTLV-1 were related but age was a confounding variable in this relationship. This study showing a highly heterogeneous distribution of HTLV-1 in a geographically limited area suggests the role of environmental and behavioral factors in HTLV-1 transmission. (authors)

Helminthic infections concomitant with malaria are common in inter-tropical areas. A recent study showed that mice co-infected with Schistosoma mansoni and Plasmodium chabaudi develop higher P. chabaudi parasitaemia and had a higher mortality rate. This important observation deserved to be further investigated among human populations. Malaria attacks were recorded in 512 children aged 6–15 years living in Richard Toll (Northern Senegal) among whom 336 were infected by S. mansoni, and 175 were not. The incidence rate of malaria attacks was significantly higher among S. mansoni-infected individuals, particularly those carrying the highest worm loads, as compared to uninfected subjects (26.6% versus 16,4 %). In contrast, the rate of malaria attacks was lower, without reaching significance, in medium grade S. mansoni infections. Thus, infection by S. mansoni affects susceptibility to malaria, but this can vary according to the intensity of parasite load. The immunological mechanisms underlying this dual effect need to be further explored.

The prevalence of serum hepatitis B virus (HBV) deoxyribonucleic acid (DNA) was measured in a Gabonese community at high risk for HBV infection. Among 698 subjects 5 to 24 years old, the prevalence of HBsAg was 11.1% vs. 57.9% for anti-HBs and 7.2% for anti-HBc alone. The prevalence of HBeAg among HBsAg-positive subjects was 26.5% vs. 59.5% for anti-HBe. The prevalence of HBV DNA tested by a hybridization spot test was 2.1% in the overall population and 18.7% among HBsAg-positive subjects. HBV DNA was found in 15 of 21 HBeAg-positive subjects but in none of the subjects positive for anti-HBe or negative for both HBeAg and anti-HBe. HBV DNA was not detected in any HBsAg negative subjects. The prevalence of HBV DNA decreased with age. This low prevalence of HBV DNA contrasts with the high level of endemicity in the study population.

The authors report the results of 4 sample surveys carried out in Equatorial Guinea and Cameroon in the Bonny's Bay area, to evaluate the main malarial indexes. In rural and semi-rural areas one notice a high rate of fever attacks and splenomegaly. Parasitaemia is more important in rural areas than in urban areas and is decreasing where the therapeutic pressure is strong and long-lasting. Immunological indexes are high everywhere.

One hundred dental surgeons practising in western France were immunized against hepatitis B virus, using the same batch of HEVAC B vaccine from the Pasteur Institute. The vaccine was very well tolerated. Seroconversion at 10 m IU/ml was 94% after 3 injections and 98% after the booster dose. From a kinetic study of anti-HBs antibodies we were able to determine different levels of post-immunization serological response and to classify responders as very good, good and fairly good. The effectiveness of the booster dose was manifest after 10 days. In view of the efficacy and safety of this vaccine, confirmed by other studies in sanitary personnel, we do not hesitate to recommend it to dental surgeons exposed to the disease.

Additional file 1. Questionnaire WP3: Access to medicines in general population GLOBALMED project.

WHO proposal of a new strategy for the control of malaria, intermittent treatment using sulfadoxine-pyrimethamine, encounters various conceptual and logistic problems. First, the treatment is dedicated only to a very small part of the population which is not representative of the population at risk. Secondly, it largely underestimates the risks of this type of drugs. At last, the difficulties of its management should lead to hamper this strategy. It would be preferable to study the real causes of the current strategy failure and to take it into account for a new strategy.

Additional file 2: Table S3. Details regarding SNP and amino acid changes of the seven main G6PD variants along with sequences of the PCR primers, allele-specific primers and locus-speficic probes used to test samples collected from Cambodian males, Cambodia, National Malaria Survey 2013.

Additional file 1. Sensitivity analysis based on chi-square test to highlight a possible memory bias related to time.

Additional file 1. Questionnaire WP3: Access to medicines in general population GLOBALMED project.

Additional file 2. Trade names of pharmaceutical drugs used by caregivers to treat children under twelve in Cotonou, Benin, May 2016.

International audience

Additional file 2. Trade names of pharmaceutical drugs used by caregivers to treat children under twelve in Cotonou, Benin, May 2016.

Additional file 2: Table S3. Details regarding SNP and amino acid changes of the seven main G6PD variants along with sequences of the PCR primers, allele-specific primers and locus-speficic probes used to test samples collected from Cambodian males, Cambodia, National Malaria Survey 2013.

HTLV-1 infection is endemic in Japan, black Africa, the Caribbean and several regions of South America. In these foci, the infections is very heterogeneously distributed (variations from village to village, intrafamilial clustering). The virus is transmitted from mother to child, and breast feedings seems to play a major role. Sexual transmission is usually from man to woman. The frequency of transmission by blood transfusion must not be underestimated. It justifies the systematic detection of HTLV-1 infection in areas where it is economically feasible.

The micro-wave oven permits a rapid drying of thick blood smears classically used for parasitological malaria diagnosis. In order to evaluate this type of drying on the microscopic reading, a study was carried out in an hyperendemic area of malaria with 382 asymptomatic volunteers of all ages. Two thick smears were made for each volunteer, one immediately dried with a micro-wave oven for one minute, the second dried in the open air without any intervention. A single microscopist examined all the thick smears. The observation of Plasmodium falciparum trophozoites differed significantly between the two methods, the prevalence was 50% by normal drying versus 41% by the micro-wave oven. The geometric mean of the trophozoite number for positive thick smears was significantly lower with the micro-wave oven. When the parasitological density with normal drying was lower than 200 trophozoites/microliter of blood, 54% of results were wrongly negative with the micro-wave oven. On the other hand, the observation of P. falciparum gametocytes was significantly facilitated after drying with the micro-wave oven; the prevalence was 8% with normal drying versus 12% by micro-wave oven. In conclusion, the use of the micro-wave oven for the drying of thick smears is not recommended for malaria diagnosis although it improves the observation and counting of P. falciparum gametocytes.

Additional file 1. Sensitivity analysis based on chi-square test to highlight a possible memory bias related to time.

Additional file 3. PCR-based ligase detection reaction-fluorescent microsphere assay (PCR-LDR-FMA) protocol.

Additional file 3. PCR-based ligase detection reaction-fluorescent microsphere assay (PCR-LDR-FMA) protocol.

An agro-industrial program involving sugar cane farming was established in Mbandjock (Cameroon) in the 1960's. We studied the impact of this development project on the health of the population by determining the prevalence and distributions of the major parasitic diseases according to district, ethnic origin, age and sex. Three main conclusions can be drawn. First, in the study area, economic development was not associated with deteriorating health conditions. Indeed, the incidence of parasitic disease was lower in Mbandjock than in surrounding areas. Second, imported diseases (loaiasis and schistosomiasis for example) did not develop locally despite the large population concentrations created by the implantation of the agro-industrial complex. Third, endemic parasitic diseases (malaria, onchocerciasis and intestinal infection by helminths or protozoan) were found only in a few districts. Thus, integrated control measures should be taken in these areas as a priority.