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An epidemiological study of human T-lymphotropic virus type 1 (HTLV-1) and syphilis has been carried out in a multiethnic community of seven neighbouring 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 haemaglutination assay. The prevalence rate of anti-HTLV-1 was 8.5% and increased from 3.7% in the 5-14 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 behavioural factors in HTLV-1 transmission. [ABSTRACT FROM AUTHOR]

Less than a year after the introduction of amodiaquine (AQ)/sulfadoxine-pyrimethamine (SP) as the first-line antimalarial treatment in Senegal, our study aimed to assess patients' drug intake and check its correspondence with nurses' prescription-adherence, the national guidelines regimen and theoretical dosage. The study was conducted at five health centers. Children aged 2-10 years who were prescribed AQ/SP by the nurse were recruited. At day 3, caregivers were questioned about treatment adherence. We collected information about nurses' prescriptions and conducted in-depth interviews on prescription patterns. Among the 289 children who were recruited, 35.3% took less than 80% of the prescribed doses. Nevertheless, 47.7% and 83.7% respectively for AQ and SP received a dosage higher than the theoretical dosage. Age-weight discrepancy leads to overprescribing drugs: nurses acknowledged using the child's age more often than weight to determine the dosage if the child has a low weight. Under and overdosing are not only due to patient practices but causes related to national guidelines and health staff practices. For successful implementation and utilization of antimalarial combinations in Africa, countries should really focus on nurses' training. National guidelines should also be based on national average weight instead of international tables., (Copyright 2009 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.)

The emergence of increasing plasmodium falciparum resistance to chloroquine in Africa has prompted national malaria programmes to develop new policies regarding appropriate and essential treatment, moving from the use of chloroquine to a new set of bi-therapy methods. In Senegal, the malaria treatment policy has shifted from chloroquine to amodiaquine/sulfadoxine-pyrimethamine. The authors studied the availability of these new drugs and their use by the care providers in 10 rural health district dispensaries. Patient records were examined and nurses were interviewed on their knowledge about and implementation of the new policy. It was noted that the nurses have not yet mastered the proper use of these new medications, and the prescriptions given were not always in line with regulations and practice corresponding to the required or necessary doses. The families which were interviewed stated that they were not aware of the changes in treatment which had been recommended. The conclusion of this study was that it brought to the forefront the need to put specific emphasis on population information and awareness campaigns as well as that of ensuring that caregivers receive thorough training to secure the successful and sustainable implementation and maintenance of the new policy.

Background: In areas of seasonal malaria transmission in Senegal, two previous studies have found that maternal direct obstetrics deaths and preeclampsia were more frequent during the rainy/malaria season. These observations suggest a possible link between malaria and maternal or fetal morbidity and mortality. In this study, we explore this link in a peri urban maternity in Senegal., Methods: We carried out an exhaustive survey at "Maternité Roi-Baudouin" in Guédiawaye, which is the main maternity of the suburb of Dakar, Senegal. From August 1998 to December 1999, we included all women attending the maternity for delivery. Placental malaria was diagnosed by the presence of parasites or malarial pigment in placental apposition. Delivery diagnosis was assessed by obstetricians or midwives. Sociodemographic data and information about chloroquine intake were recorded. Multivariate analysis was performed to compare prevalence of placental malaria between normal and poor deliveries outcomes., Results: Eight thousand two hundred and seventy three women were included. There were 5597 (67.7%) normal deliveries, 1214 (14.6%) low birth weight babies (<2500 g) and 1462 (17.7%) deliveries with a maternal or fetal poor outcome. Placental malaria prevalence was 9.5% (785/8273). Placental malaria was associated with low birth weight (adjusted OR=2.06 (1.72-2.57)), preterm birth (adjusted OR=3.51 (1.84-6.68)) and perinatal mortality (adjusted OR=2.56 (1.65-3.97)). We did not find an association between placental malaria and occurrence of a maternal pathology (dystocia, preeclampsia, eclampsia, retroplacental haematoma)., Conclusion: Although malaria at delivery is not associated with occurrence of a maternal obstetric pathology, it has detrimental effects for the fetus and newborns. Effective antimalarial strategies during the antenatal period are urgently needed.

We report the impact of the free access to health facilities on malaria morbidity in children from two to 15 years old, during a malaria transmission season in Niakhar, Senegal. Between July and December 2002, 227 malaria attacks occured in 566 children. Only one case of severe malaria was observed and no death has been reported. Our results demonstrate furthermore that easier access to health facilities and to early treatment is playing a key role in malaria control.

During pregnancy, maternal immune tolerance of the fetal semi-allogeneic graft is partly the consequence of extravillous trophoblast HLA-G expression and its interaction with natural killer (NK) cells. Plasmodium falciparum malaria is frequently associated with maternal and fetal complications. Local HLA-G expression and the number of NK cells were evaluated immunohistochemically in P. falciparum-infected and uninfected placentas (15 each) collected in a seasonal malaria-hypoendemic area. In control placentas, HLA-G was almost always expressed in extravillous trophoblast whereas, in infected placentas, it was significantly more weakly expressed in extravillous trophoblast but was also detected in intervillous space macrophages. NK cells were evaluated in intervillous and intravillous spaces and in basal plate. NK cells were always more abundant in basal plate than in intervillous and intravillous spaces in infected or control placentas. For each area, more NK cells were seen in infected than control placentas. These data suggest that HLA-G down-regulation and more NK cells in placentas may be among the mechanisms involved in poor birth outcome associated with P. falciparum infection.

Background: This study aimed at analyzing the short-term effects of an improvement in care offer on dispensary activity in a rural area of Senegal., Methods: The Niakhar health center, situated 150 km east of Dakar, underwent significant changes during the years 1998 and 1999: a hospital unit was built, the maternity ward was extended and the patient reception facilities were refurbished and reorganized. We examined dispensary registers before (1997) and after (2000) this period of time. We focused on data reporting activity and utilization of the health center. We also studied the users'perception of these improvements. Interviews were conducted with 39 families to measure the consequences of this change on their attitudes towards treatment., Results: The number of consultants increased by 49.8% from 1997 to 2000. Activity peaked during the rainy season, during which consultations were twice as numerous in 2000 as in 1997. However a similar increase was noticed in another health center close to Niakhar and could be attributed to the high precipitation rate observed in this area in the year 2000. For children, there was no difference in center utilization between the two study years as each child went to the dispensary 1.18 and 1.21 times a year in 1997 and 2000 respectively. The maternity activity exhibited a 68% increase in deliveries. Families interviewed said the dispensary was significantly improved, but they were not able to change their practice, due to lack of financial resources and poor drug supply., Conclusion: The changes in care offer did not seem to have yielded the expected effect on care activity. The appointment of a midwife as well as improvements in both technical facilities and awareness contributed to the increase in maternity use.

Objectives: This study aimed at describing the burden of malaria at delivery in a urban maternity in Senegal. We measured the prevalence of placental malaria infection. We described the association between placental malaria and low birth weight and the impact of chemoprophylaxis., Study Area: Guediawaye is the most important suburb of the city of Dakar, Senegal, surrounded by a permanent marsh (niayes). Malaria in this area is hypo endemic transmission: 1 infective bite/person/year. An. arabiensis is the principal vector and P. falciparum (98%) the most frequent species. The Maternité Roi Baudoin in Guediawaye is the gynecologic and obstetrical reference centre of this area with more than 6000 deliveries/year., Methods: We carried out an exhaustive survey from August 98 to December 99 at the maternité Roi Baudoin in Guediawaye. The socio-demographic data, the clinical data and information about prophylaxy were collected by questionnary. For each woman at delivery, one placental apposition was carried out. Presence of trophozoïtes or schizontes indicated malaria placental infection., Results: 8310 women were included in the study. They were from 13 to 49 years old with an average age of 26.1; 28% were primigravidae. The prevalence of placental malaria infection was 8.1% (674/8310) [Ic95: 7.4-8.8%]. Schizontes were present in 80.5% of infected placenta. The prevalence was 8.8% within primigravidae group and 7.4% in the other parity groups, p = 0.28 (NS). Placental infection was present all the year long. However, there were important seasonal variations. The risk of placental infection increased during seasonal transmission (> 10%) compared to the period of low transmission (3%). The prevalence of placental malaria was lower in the group of women who declares regular chloroquine intake compared with those who declared taking no prophylaxy or irregular prophylaxy (RR = 0.78 [0.62-0.98]). The risk of low birth weight was of 1.9 [1.6-2.1] when the placenta was infected compared with non infected placenta., Conclusion: This study indicates that placental malaria infection is frequent in this low transmission area where more than 70% of women declared taking regular chloroquine. This observation could be explained by a resistance of P. falciparum to chloroquine or a poor observance of chemoprophylaxis.

Malaria is generally recognized as the main cause of infant mortality and/or morbidity in tropical regions of Africa. However the exact impact of the disease is still difficult to evaluate due to the lack of adequate facilities for data collection and screening. Another major unsolved problem involves diagnosis of malaria attacks in infants. Due to repeated exposure to the parasite and progressive development of immunity to malaria, a child's susceptibility changes with age. In addition the clinical, parasitological and immunological form of the disease varies from one child to another depending on his or her risk and protection factors as well as genetic, physiological and environmental factors. Because of these special features, diagnosis of malaria is complicated not only in the neonatal period but also throughout infancy. A better understanding of these features, which determine the expression of the disease in infants, will be required to optimize management of malarial attacks and improve preventive measures implemented in Africa to lower malaria-related morbidity and mortality.

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.

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.

Using stringent Western blot (WB) criteria, human T cell lymphotropic virus (HTLV) type I seroprevalence among 3783 persons from representative rural populations of Cameroon averaged 1.1% and was higher in females (1.5%) and in Pygmies (2.0%), increasing with age. Furthermore, an HTLV-I Gag-indeterminate WB profile (HGIP), exhibiting strong reactivities to p19, p26, p28, p32, p36, and pr 53 but lacking both p24 and env reactivity, was observed in 1.6% of the same populations. The prevalence of the HGIP was similar between males and females, did not increase with age, and appeared to cluster in tropical forests of southern Cameroon, especially among Pygmies (reaching 4%). These contrasting epidemiologic features, together with the lack of detection by polymerase chain reaction of HTLV-I sequences in the peripheral blood mononuclear cells of the persons with HGIP, strongly suggest that such a WB profile does not appear to reflect an HTLV-I-related viral infection but possibly an environmental (viral or parasitic) factor endemic in tropical rain forest areas.

T cell responses to leucoagglutinin, PPD, and seven Plasmodium falciparum blood stages antigens were investigated in 164 cord blood samples from Cameroonian neonates. In vitro T cell responses were measured by lymphocyte proliferation, and IL-2, IFN-gamma, and IL-4 release in the presence of crude schizont extract, purified Pf155/RESA protein, and synthetic peptides from Pf155/ RESA. Following culture in presence of leucoagglutinin or PPD, proliferation and cytokine production were very low, as compared to adults from the same area. Interestingly, following stimulation of cord blood lymphocytes by malaria antigens, the percentage of responders and the mean level of positive responses were of the same order than those observed in adults for IL-2 production, while proliferative and IL-4 responses were only marginally decreased. Conversely, IFN-gamma production was highly reduced, as compared to adults. Our results demonstrate that prenatal immune priming to malarial antigens is common in this area and that the fetal immune system is able to respond to antigenic stimuli, as cells proliferate and generate cytokines. As cord blood lymphocytes may be induced to differentiate into effector cells producing predominantly Th1 or Th2 cytokines, malaria during pregnancy might direct the functional capacity of fetal T cells to respond to further infection.

To investigate the mechanisms underlying the increased susceptibility to malaria in pregnant women, we determined the level of malaria-specific immunity in primigravidae. Humoral and cellular in vitro responses to unpurified (a crude schizont extract and a gametocyte preparation) and purified (affinity-purified Pf155/ring-infected erythrocyte surface antigen [RESA]) Plasmodium falciparum proteins, an immunodominant 45/47-kilodalton antigen from Mycobacterium bovis, and leucoagglutinin were compared between 52 primigravidae and 52 nonpregnant women from a semirural area of Cameroon. In vitro cellular responses were investigated in terms of lymphocyte proliferation, as well as production of interleukin-2 (IL-2), interferon-gamma (IFN-gamma), and IL-4. Cells from primigravidae exhibited a reduced proliferative response to schizont and gametocyte antigens, as well as to the M. bovis antigen. Conversely, the IL-2 response to Pf155/RESA was reduced. Interleukin-4 and IFN-gamma production did not appear to be affected in primigravidae. Antibody levels were also similar between pregnant and nonpregnant women. Our results underline the importance of examining several parameters of T cell activation with different types of antigens for a correct evaluation of the ability of lymphocytes to respond to malaria.

T- and B-cell responses to the Plasmodium falciparum blood-stage antigen Pf155/RESA were investigated in 104 Cameroonian women, half of whom were pregnant. We used purified protein and six synthetic peptides representing T- and B-cell epitopes. In vitro T-cell responses were measured by proliferation and IL2, IFN-gamma, and IL4 release. B-cell responses were assessed by plasma antibodies. All peptides induced a cellular response in some individuals. A proliferative response was induced in 25% of the donors by Pf155/RESA, and in 7 to 11% by any peptide. Cytokine release occurred in 23 to 30% of the Pf155/RESA-stimulated cultures, and in 8 to 25% of the peptide-stimulated cultures. Overall, each peptide induced a cellular response (proliferation and/or cytokine release) in 44% of the donors. T-cells from 23% of the donors failed to respond to any peptide. Responding cells did not usually respond in all readouts, and proliferation and release of any of the three cytokines were not correlated. Similarly, antibody and T-cell responses were not related. Selected epitopes of Pf155/RESA, an important vaccine candidate, are well recognized in naturally exposed individuals and are able to activate T-cells to proliferate and to produce various lymphokines in numerous individuals from a malaria endemic area.

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.

The limitation of aerobic exercise capacity of athletes with the sickle cell trait (SCT), under conditions of limited oxygen availability, is still controversial. To study this, we took advantage of an unique setting, the International Mount Cameroon Ascent Race, a 34.1-km race over difficult terrain, slopes ranging from 7 to 40%, and altitudes varying from 615 to 4095 m, combined with high prevalence rates of SCT among the African runners. Of 266 Cameroonian runners, SCT was detected in 33 athletes (12.4%), a prevalence similar to that of the ethnically corrected general population. However, in runners of the Bakoueri tribe whose performance is contingent with social stature, SCT was present in only 1 of 41 runners (2.4%), as compared with 15.6% in the general population of the Bakoueri tribe (P < 0.03). In general, performance times of SCT runners were not different from non-SCT runners, except during the portion of the race at altitudes ranging from 3800 to 4095 m, where significantly longer times were clocked by SCT subjects (P < 0.02). We conclude that prolonged aerobic efforts in hypobaric hypoxic conditions may be associated with a detrimental effect on performance in SCT carriers. If this is true, it might account for the reduced prevalence of SCT among those runners representing the Bakoueri tribe, provided an objective measure of performance at altitude was employed to select these representatives.

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.

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.